Anatomy – Exam 1
Introduction to Anatomy ○ Objectives
Describe anatomical position. Why is it significant?
Identify the planes of reference used to locate the structure of the body
Define and be able to properly use descriptive and directional anatomical terms
○ Anatomical Position – standing erect, palms forward
○ Supine – reclining, face up
○ Prone – reclining, face down
○ Body Regions
Axial region – contains thorax and abdomen
Appendicular regions
Upper limb
Arm – shoulder to elbow
Forearm – elbow to wrist
Wrist, hand, fingers
Lower Limb
Thigh – hip to knee
Leg – knee to ankle
Ankle, foot, toes
○ Anatomical Planes
Saggital – divides into right and left halves
Midsaggital – right at midline
Coronal (frontal) – divides into anterior and posterior
Transverse (horizontal) – divides top and bottom
○ Terms of Position
Ventral (anterior) – front of body
Dorsal (posterior) – back of body
Superior (cranial) – toward the head
Inferior (caudal) – toward the feet
Midline
Medial – toward the midline
Lateral – away from the midline
Core
Internal – toward the core
External – away from the core
Surface
Superficial – toward the surface
Intermediate – between the surface
Deep – away from the surface
Attachment
Proximal – close to the point of attachment
Distal – away from the point of attachment
○ Terms of Movement
Angle
Flexion – decrease the angle between two bones
Extension – increase the angle between two
bones
Midline
Abduction – moving away from midline
Adduction – moving toward the midline
Rotation – movement around a long axis
Circumduction – circular movement where the structure forms a cone
Palms
Latin Singular vs Plural
Singular Plural Example -a
-ax
-en
-ex
-is
-is
-ix
-ma
-on
-um
-us
-us
-us
-x
-y
-yx
-ae
-aces
-ina
-ices
-es
-ides
-ices
-mata
-a
-a
-era
-i
-ora
-ges
-ies
-ices
Axilla, axillae
Thorax, thoraces
Lumen, lumina
Cortex, cortices
Diagnosis, diagnoses
Epididymis, epididymides
Appendix, appendices
Carcinoma, carcinomata
Ganglion, ganglia
Spetum, septa
Vicus, viscera
Villus, villi
Corpus, corpora
Phalanx, phalanges
Ovary, ovaries
Calyx, calices
Because radius and ulna rotate over each other
Supination – turning palms up
Pronation – turning palms down
Foot
Dorsiflexion – bring foot up
Plantar flexion – push foot down
Sole of Foot
Inversion – turn sole of foot medially
Eversion – turn sole of foot laterally
○ Select Surface Landmarks in Anatomical Position
Cephalic – head
Cervical – neck
Cheek – buccal
Mental – chin
Inguinal – groin
Olecranal – back of elbow
Popliteal – hollow behind the knee
Sural – calf of leg
Femoral - thigh
Calcaneal – heel of foot
Acromial – shoulder
Axillary – arm pit
Brachial – arm
Cubital – hollow of elbow
Antebrachial – forearm
Pollex – thumb
Coxal – hip joint
Tarsal – ankle
Hallux – great toe
Organization of the Nervous System ○ Objectives
Describe the basic anatomical organization of the nervous system
Diagram a typical neuron and list its parts. Identify distinguishing characteristics of motor and sensory neurons
Describe the gross anatomical features of the spinal cord
Describe the location, organization and structure of the spinal meninges
Diagram a cross section through the spinal cord. Be able to label all of the parts as described in class
Describe the components of a typical spinal nerve and explain the normal branching pattern
Explain the numbering of spinal nerve pairs
Give the definition of a spinal cord segment. Explain the difference between the spinal cord segment and the vertebral level
Define the term dermatome and state its clinical significance Give the anatomical basis for administering a successful lumbar puncture
○ Two ways to organize
Functional Organization
Somatic components – somatic afferents (receive sensory information) and somatic efferents (send
muscle information)
Visceral (autonomic) components – visceral afferents and efferents that innervate smooth muscle,
cardiac muscle and glands
Anatomical Organization – more common
Central Nervous System – brain and spinal cord
Peripheral Nervous System
○ Cranial Nerves – mostly directly attached to brain
12 pair; Innervate head and neck
○ Spinal Nerves – 31 pair, attached to spinal cord; innervate everything else
○ Types of Neurons
Multipolar – many processes; motor neurons
Pseudounipolar - primary sensory neurons
Peripheral process - „dendrite‟
Central process – „axon‟
○ Definitions
Nucleus – collection of neuronal cell bodies within the CNS (collected because they do the same thing)
Ganglion – collection of neuronal cell bodies outside the CNS
Tract – nerve processes (axons) bundled together in CNS
Nerve – nerve processes bundled together in in PNS
Gray matter – unmyelinated
○ Spinal Cord
Connects brain to body; responsible for spinal reflexes; continuous with brain
Afferent (sensory) – receives from body
Efferent (motor) – sends away from CNS
Size and shape
In general it tapers as it gets down to coccyx since less information is transmitted as you go down
Cervical Enlargement – between C4-T1, due to upper limb connections
Lumbar Enlargement – between L3-S3, due to lower limb connections
Conus Medullaris – tapered inferior end of spinal cord
Cauda equina - „horse tail‟ – a continuation of dorsal & ventral rootlets for spinal nerves below vL2
(where spinal cord stops)
Protection
Vertebral Column – spinal cord housed in vertebral foramen
Meninges – three connective tissue coverings that surround the brain and spinal cord
○ Dura mater – (tough mother) outermost layer, dense CT
Continues into sacrum to vS2 (it is longer than spinal cord) and is anchored to coccyx
○ Arachnoid mater – thin transparent membrane with thin weblike extensions that connect to pia
mater
Normally contacts dura mater
Ends at S2 with the dura mater
○ Pia mater – (delicate mother), very thin layer of CT which can‟t be taken off spinal cord
Follows every contour of CNS
Filum Terminale – inferior extension of the pia mater from the conus medularis
○ Attached inferiorly to inferior part of dura at vS2
○ Inferior anchor for spinal cord
Denticulate Ligaments – lateral extensions of pia mater
○ Act as lateral anchors (and connect to dura mater?)
Spaces Between Meninges
○ Epidural Space – between dura and bone
○ Subdural Space – between arachnoid and dura mater
only a potential space, nothing is there normally
○ Subarachnoid Space – between arachnoid and pia
Contains CSF
Internal Structure of Spinal Cord
Gray and white matter
Dorsal horn – contains axons involved with sensory reception
Ventral horn – contains nuclei of multipolar motor neurons
Lateral horn – contains autonomic neurons
○ only in T1-L2 & S2-S4
Spinal Nerves
Formation of Spinal Nerves
○ Dorsal Root – sensory, between dorsal horn and dorsal root ganglion
○ Dorsal Root Ganglion – where nuclei of pseudounipolar sensory neurons are housed
○ Ventral Root – contains axons of motor neurons
○ Spinal Nerve – DRG and ventral root unite and form spinal nerve
Are mixed nerves because they have afferent and efferent neurons
○ Intervertebral foramen – where spinal nerve comes out
Only visible when two vertebra are stacked on top of each other
Branches of Spinal Nerve
○ Each branch of the spinal nerve is still a mixed nerve
○ Dorsal primary ramus – innervates skin and muscles of back
○ Ventral primary ramus – innervates all other skin and muscles (trunk, limbs, etc.)
Is much bigger because it innervates more things
Number of Spinal Nerves
○ 31 pairs
○ Numbering – all spinal nerves (except the cervical ones) exit below the vertebra they are named
after (ex. T1 exits below T1)
Exception – C1 spinal nerve exits above vC1, C2 spinal nerve exits below vC1
○ C8 exits below vC7
○ Cervical – 8
○ Thoracic – 12
○ Lumbar – 5
○ Sacral – 5
○ Coccygeal – 1
Spinal cord level vs Vertebral level
○ Spinal Cord Segment – portion of spinal cord that contributed to the formation of the spinal
nerve
○ Vertebral Level – anatomical landmark that is associated with a specific vertebrae
Ex. Spinal cord ends at vertebral level L2
○ Why? At birth spinal cord and vertebral column end at same place, but vertebra grows
Dermatome – area of skin supplied by a single spinal nerve
Lumbar Puncture – done in area of cauda equina so that spinal cord is not affected
This allows for CSF to be sampled from the dural sac
Back ○ Objectives Vertebral Column
Define the normal and basic pathological spinal (postural) curvatures
Identify the features of typical vertebra
Distinguish the characteristics of vertebrae from different regions of the vertebral column
Describe the joints and ligaments of the vertebral column. Understand how these contribute to movements of the
vertebral column
Describe the craniovertebral joints (atlanto-occipital; ligaments between atlas, axis and occiput)
Understand how spinal nerves emerge from the vertebral column.
Describe the relationship between the number of spinal cord segments/spinal nerves and vertebral level
Describe how the length of the spinal cord changes during development relative to the length of the vertebral canal
Explain the blood supply of the spinal cord and vertebral column and identify the sources Muscles of the Back
Define the muscle groups associated with the back. Contrast their actions and innervation
Identify the attachments and compare the functions of the superficial (extrinsic) back muscles; trapezius, latissimus
dorsi; levator scapulae and rhomboids (these will also be considered with the upper extremity)
Identify the attachments and compare the functions of the basic attachments of intrinsic back muscles
○ Movements of the Back
Extension, flexion, lateral flexion, rotation
○ Vertebral Column
31-33 Vertebrae
7 Cervical, 12 Thoracic, 5 Lumbar, 5 Sacral (fused), 2-4 Coccygeal (fused)
Sacral Hiatus – opening in the inferior portion of the sacrum that you can feel
Closed by a membrane
Contains – filum terminale (which passes through to coccyx) and fat
Important for caudal anesthetic
Curvatures of the Vertebral Column
Types
○ Kyphosis – anteriorly concave curvature of the vertebral column
Occurs normally in thoracic and sacral regions
Abnormal exaggeration occurs in the thoracic region
○ Lordosis – anteriorly convex curvature of vertebral column
Occurs normally in cervical and lumbar regions
Abnormal exaggeration usually occurs in lumbar region
○ Scoliosis – abnormal lateral curvature of the spine
Development of Curvature
○ Primary curvature – anything that is kyphotic (thoracic, sacral)
Early in development all curvature is kyphotic
○ Secondary curvature – anything that is lordotic (cervical, lumbar)
This curvature is associated with weight bearing
First to develop is lumbar (right around birth)
Typical Vertebra
Vertebral Body –
Pedicle – attaches directly to vertebral body
Lamina – connects pedicle to spinous process
Vertebral Arch = lamina + pedicle
Vertebral foramen = lamina + pedicle + vertebral body
Spinous process
Transverse process
Superior and Inferior articular processes
Zygapophyseal joint – superior articular process + inferior articular process from above
○ One on each side of the spinous process
Superior vertebral notch + inferior vertebral notch = intervertebral foramen
○ Spinal nerve passes through intervertebral foramen (so does DRG)
Distinguishing Characteristics of Vertebrae
Cervical (8) ○ Transverse foramen – hole in transverse process where vertebral artery passes through
○ Transverse process has posterior tubercle and anterior tubercle
○ Spinous process is bifid
○ Vertebral body is more square
Thoracic (12) ○ Has facets for the ribs (flat connecting points)
Each rib has three contact points, one on the transverse process, one on the superior facet of
vertebral body, one on inferior facet of vertebral body on the vertebra above
Ribs are only in the thorax
○ Spinous process is angled inferiorly
○ Vertebral body is heart-shaped
Lumbar (5) ○ No transverse foramen or rib facets
○ Spinous process is short and sturdy
○ Vertebral body is large and kidney-shaped
Special Vertebral Bones
Both have transverse foramen just like other cervical vertebrae
Atlas (C1) – “holds world on shoulders” – the skull rests on it
○ Lacks vertebral body – has anterior and posterior arches instead
○ Superior articular facet touches skull
Axis (C2) –
○ Dens (odontoid process) – used to be the vertebral body of C1, but now it is fused to C2
Vertebral Ligaments
Anterior Longitudinal – on anterior side of vertebral body
Posterior Longitudinal – on posterior side of vertebral body, inside vertebral canal
Supraspinous ligament – on dorsal side, connects spinous processes
○ From cervical region on up this ligament is called the nucal ligament
Here it becomes triangle shaped? And fills up a greater area
Interspinous ligament – in between spinous processes (lots of CT)
Ligamentum Flavum – covers vertebral arch
○ Connects adjacent laminae
○ Flavum = yellow
Intervertebral Discs
Numbering – eg L4-5 disc is between L4 and L5
There is no disc between C1 & C2
Anulus Fibrosis – outermost part of disc
○ Contains fibrocartilage rings that are thinner posteriorly (where rupture occurs)
○ Vascularized
Nucleus Pulposus – inner part of disc
○ Contains mucoid – made of reticular & collagen fibers
Avascular
70%-90% water
Water content decreases with age and is associated with decrease in height, decrease in
compresibility and increased probability of rupture
Disc Herniation
○ Nucleus pulposus protrudes through annulus fibrosis
○ Occurs most frequently in cervical and lumbar regions
○ Most frequent site = in posterolateral direction (often to either side of the posterior longitudinal
ligament)
This will compress the spinal nerve
○ Affects lower spinal nerve root
Ex. L4-5 disc herniation affects L5 nerve root
Atlanto-Occipital Joint
Anterior Atlanto-occipital membrane - ?
Posterior Atlanto-occipital membrane – connects posterior skull to posterior portion of C1
○ Covers spinal cord
Internal Ligaments (plate 22)
○ Tectorial Membrane – continuation of posterior longitudinal ligament starting at C2
○ Cruciform ligament – where the bands cross it holds posterior of dens in place, composed of
three bands
Superior longitudinal band – connects to skull?
Transverse band – connects laterally to C1
Inferior longitudinal band – connects to vertebral body of C2
○ Alar Ligaments – laterally connect dens to skull (two of them)
○ Apical ligament of dens – connect anterior of dens to skull
○ Back Muscles
Origin – more medial, less movement
Insertion – more lateral, more movement
Overview of Musculature
Extrinsic Back Muscles (quick overview)
○ Control Upper Limb Trapezius – connects shoulder to neck Latissimus dorsi – connects lower back to side?
Rhomboid mm (major and minor) – connects shoulder blade to spine
Levator Scapulae –
○ Accessory respiratory mm
Serratus posterior inferior muscle – lower ribs to lower back
Serratus posterior superior muscle ○ Innervation
Ventral rami of spinal nerves
Accessory n (CN XI) for Trapezius
Intrinsic Back Muscles
○ True back muscles, maintain posture, move vertebral column and head
○ Superficial Layer
Looks like one bundle, but splenius cervicis is inferior
Spine to head
○ Intermediate Layer
Erector spinae mm
○ Deep Layer
Transversospinal (starts on TP ends in spine?)
○ All extend spine or head
○ All rotate to opposite side
○ All are TP to SP
○ Innervation
○ Dorsal rami of spinal nerves
Intrinsic Back Muscles
Origin Insertion Action
Superficial Layer
Splenius Capitis – more
medial than cervicis
SP (T3-C3) -superior
nuchal line -mastoid
process
-Bilateral – extends head
-Unilateral – laterally flexes and rotates head to same side
Splenius Cervicis SP (T3-6) TP (C1-3) -Bilateral – extends head
-Unilateral – laterally flexes and rotates cervical spine to same
side
Intermediate Layer - Erector spinae
Spinalis -
most medial
Capitis
Cervicis
Thoracis
SP SP Bilateral – extends spine & head
Unilateral – lateral flexion
Longissimus
Capitis TP & AP mastoid
process
rotates head to same side
Bilateral – extends spine & head
Unilateral – lateral flexion (only
acts against gravity) Cervicis TP & AP TP
Thoracis -Sacrum
-iliac crest (common tendon)
-SP and TP
-Ribs
-TP
Iliocostalis -
most lateral
Cervicis ribs TP Bilateral – extends spine Unilateral – lateral flexion Thoracis ribs ribs
Lumborum -Sacrum
-iliac crest (common tendon) -TF
-ribs
-deep TF
Deep Layer - Transversospinal
Semispinalis - highest TP SP Bilateral – extends spine & head Unilateral – lateral flexion,
rotates to opposite side
Multifidis – mostly in
lumbar
TP SP Note - origin and insertion 2-4
vertebrae apart
Rotatores TP SP Note - Origin is 1 vert below
insertion
○ Note – SP = spinous process, TP = transverse process, AP = articular process, TF =
thoracolumbar fascia
○ Note – thoracolumbar fascia is the covering of deep back muscles
Innervation
○ Dorsal Rami innervate
Intrinsic back muscles
Middle skin of back
○ Sensory Innervation
Dorsal rami – innervates middle of back
Ventral rami – innervates lateral parts of back
○ Ex. Supraclavicular nerves (from cervical plexus)
○ Ex. Lateral branches of intercostal nerves
Vasculature (Plates 171 & 172)
○ Arteries
Neck
○ Vertebral Artery – supplies vertebral column in the neck
○ Ascending cervical artery -
○ Deep cervical artery -
Posterior intercostals artery - in thorax
Lumbar arteries – in abdomen (a small branch goes into the canal)
Lateral sacral arteries – in pelvis
○ Feeder Arteries
Two Paths
○ Thoracic aorta → posterior intercostals artery → spinal branch →
radicular artery → ant and post segements to dorsal and ventral roots
segmental medullary artery → ant and post segements to dorsal and ventral roots →
spinal arteries From there both the radicular and segmental medullary arteries split into posterior and anterior segments and supplies dorsal
(including DRG) and ventral roots
The segmental medullary then goes on to supply the spinal cord (via spinal arteries), the radicular artery does not
Extra notes
○ Spinal branch – at posterior aspect of vertebral body and vertebral arch
○ Segmental medullary artery varies in level of origin and number
Average 8 anterior and 12 posterior
Great anterior segmental medullary artery – supplies 2/3rds of spinal cord
Mainly in thoracolumbar region
○ Spinal arteries – 2 posterior and 1 anterior
○ Veins (plate 173)
Drainage of spinal cord
○ anterior and posterior spinal veins (inside pia mater, right between halves of spinal cord)
→ radicular and segmental medullary veins (they look the same) → internal venous
plexus (inside vertebral canal in extradural fat) → external venous plexus (surrounds
vertebral column
Extra notes
○ Veins inside the spinal cord (and head and neck) are valveless, but radicular and medullary
veins do have valves
○ Clinical point – due to the low venous pressure (since no valves?) venous stasis can cause
dangerous change in pressure within the spinal cord
Clinical signs include gait disturbances, spastic paralysis and sensory deficits
Development of Extraembryonic Membranes and Bilaminar Embryo ○ Objectives Define and describe: hypoblast, epiblast, primitive streak, primitive node, notochordal process, prochordal plate, cloacal
plate, notochord, ectoderm, mesoderm, endoderm
Describe the formation of the bilaminar embryonic disc from the inner cell mass
Describe the formation of the extraembryonic mesoderm
Describe the formation of the primary and secondary yolk sacs
Describe the formation of the body (connecting) stalk
List three functions of the secondary yolk sac
Define and describe: lacuna, intervillous space, deciduas basalis, deciduas capsularis, deciduas parietalis, amnion, chorion
Describe the formation of the amnion and the chorion List the functions of the placenta
Describe the morphological changes that occur during the development of placental villi
Describe the components of the placental membrane or “barrier”
Describe the formation of the amniotic fluid
List several functions of the amniotic fluid
Define amniocentesis and list several indications for the procedure
Integument ○ Objectives List and describe the morphology and function of the layers in the skin
List and describe the morphology and arrangement of the layers and components in the epidermis, dermis and hypodermis
List and describe the morphological and functional changes in epidermal cells as they move from the basal lamina to be sloughed off at the surface of the stratum corneum
List and describe the morphology and function of all cells in the epidermis
Describe the morphology of the epidermis/dermal junction and its functional significance
Define and describe the cleavage linds of Langer and their clinical significance
Describe the arrangement of the blood supply to the skin and relate it to temperature regulation
List and describe the functions of the skin
Integrate the morphology of the skin to its functions
List and describe the arrangement and location of skin appendages (hair, glands, nails)
List and describe the arrangement of the parts and layers of the hair and hair follicle
Relate the layers of the epidermis to those of the hair follicle and nails
Define and describe terminal, vellus hair and lanugo hair; give their distribution over the body List the parts and describe the growth cycle of hair
Describe the process by which a hair shaft increases in length
Integrate the morphology of hair and its function
List and describe the morphology, function and secretion of the 3 types of glands (sebaceous, sudoriferous and ceruminous)
List the distribution of different types of glands across the body
List and describe the morphology and function of the parts of nails
List and describe the morphology, function and location of the sensory receptors of the skin (free epidermal nerve endings,
Merkel endings, Pacinian corpuscle, and Meissner‟s corpuscle)
○ Integument Overview
Consists of Two Components
Appendages of Skin – derived from the epidermis and associated with the skin
○ Hair, glands (sweat, sebaceous, ceruminous), nails
Skin (Integument)
○ Covers entire surface of body
○ Variable thickness across body, thicker on dorsal surface, thickest between shoulders on back
○ Continuous with mucosal linings of the body orifices
○ Mucocutaneous junction – (ie. lips) reddish due to blood in capillaries and lack of keratin in
cells
Basic Structure of Skin
Epidermis Dermis Hypodermis
Stratified squamous
keratinized epithelium
Derived from ectoderm
Avascular
Sits on basement membrane
Has 5 layers
Stratum Basale
Stratum Spinosum
Stratum Granulosum
Stratum Lucidum
Stratum Corneum
Dense irregular connective tissue
Derived from mesenchyme
Vascular – supplies nutrients to
epidermis
Has 2 Layers
Papillary Layer – superficial
layer immediately underneath
epidermis
Characterized by dermal
papillae Reticular Layer – deepest
and thickest layer, contains
skin appendages
is not part of the skin
Areolar connective tissue
(loose CT with fat in it)
Other names -
subcutaneous/superficial
fascia and panniculus
adiposus (when in
abdomen)
Dimples – where dermis is tightly attached to underlying deep fascia or bone
Functions of the Skin
Mechanical Protection – trauma, bacteria, UV
Maintenance of Body Fluids – prevents dessication (waterproof), prevents absorption
○ Excretion – sweat glands secrete water, ions, urea, ammonia (just like kidney)
Maintenance of Body Temperature – sweat cools body, blood vessels bring warm blood to
surface to radiate heat, adipose tissue insulates
Synthesis of Vitamin D ○ In Skin: Vit D precursor + UV → another precursor (cholecalciferol)
○ In Liver: cholecalciferol → 25 hydroxy cholecalciferol
○ In Kidney: 25 hydroxy cholecalciferol → vitamin D
○ Function – Vit D stimulates Ca and PO absorption in gut
Immunity – contains wandering cells of immune system
Reception of Sensory Stimuli ○ Communication – embarrassed, nervous, cyanosis, jaundice, age, nerve damage
Repair – repairs and forms scars
Morphology of Skin
Epidermis
○ Layers of Epidermis
"Ball State Girls Love Cock"
Stratum Basale (Germanitivum)
○ Deepest layer
○ Diagnostic Characteristic – single layer of cells sit upon basement membrane
○ Shape - Cuboidal to columnar
○ Mitosis occurs here (constantly resupplies epidermis with new cells)
Stratum Spinosum ○ Diagnostic Characteristic – spiny appearance, the „spines‟ are where desmosomes attach
and hold adjacent cells toether into one unified sheet
○ Several layers
○ Shape - irregularly shaped cells
○ Artifact – gaps between cells form due to shrinkage during tissue processing
Stratum Granulosum ○ Diagnostic Characteristic – contains numerous, darker staining keratohyalin granules
(which are involved in keratinization)
○ Narrow layer, 3-5 cells thick
○ Shape – flattened with nuclei disappearing (as you get more superficial)
Stratum Lucidum
○ Diagnostic Characteristic – cells and nuclei are not visible at light level
At EM level, the cells are indistinguishable from stratum corneum (thus can be
considered part of stratum corneum)
○ 2-3 cells thick
Stratum Corneum
○ Diagnostic Characteristic – no nuclei visible
○ Numerous layers of dead cells
○ Cells filled with keratin
○ Stratum disjunctivum – part of stratum corneum where superficial cells slough off
○ Types of Epidermis
Thick (Glabrous) Skin – lacks hair and sebaceous glands
○ Refers to thickness of epidermis only, not thickness of entire skin with dermis
○ Epidermis more than 1mm thick
○ Found only on palms and soles
Thin (hairy/non-glabrous) Skin – characterized by presence of hair & sebaceous glands
○ Another Diagnostic Characteristic – reduced thickness of stratum corneum, granulosum &
spinosum (basically the three outermost)
○ Stratum lucidum is absent
○ Found everywhere else
○ Epidermal Cell Types
Keratinocyte – produces keratin, main cell of epidermis
○ Derived from ectoderm
Melanocyte – pigmented cell
○ Found only in stratum basale
○ Derived from neural crest cells
Langerhans cell – mobile immune system cells scattered in stratum spinosum
○ Appearance - Stellate shape with many branches, clear cytoplasm
○ Present antigens to helper T cells
Merkel cell – cutaneous mechanoreceptors responsible for light touch
○ In stratum basale
○ Appearance – small clear cell
○ Do not contain catecholamiens (why is this important?), innervated by single axon
○ Keratinocytes in More Detail
Create the protective, waterproof barrier
Cytomorphosis – differentiation and maturation (takes 26-30 days)
○ Keratinocytes do this, they start in the stratum basale and move to stratum corneum
As keratin builds up the cells start to die, this is the degeneration phase
Keratin – fibrous proteins that make up intermediate filaments
○ Amount of keratin in the cell increases as it migrates toward surface
Keratinization in Each Layer
○ Fibronectin in basement layer regulates rate of keratinization
○ Epidermal growth factor – stimulates proliferation of keratinocytes
○ The cytology of cells in different layers reflects maturation and keratinization
○ Stratum Basale
Main function is mitosis (mitotic structures present)
Tonofilaments - Small bundles of keratin (start to appear here)
Desmosomes – attatch cells to other cells
Hemidesmosomes – attach cells to extracellular matrix
○ Stratum Spinosum
More keratin is produced to make more tonofilaments
Tonofibrils – tonofilaments eventually form these
Lamellar granules – membrane bound granules rich in glycolipids.
Appear as light and dark bands.
Extruded as cells approach top (to make waterproof barrier)
○ Stratum Granulosum
Keratohyalin granules – irregularly-shaped, dense staining inclusions in cytoplasm
Eventually extruded
Tonofilaments continue to increase in cytoplasm
Filaggrin – a protein that cross-links tonofilaments
Involucrin – attachment to cell membrane, crosslinking done by transglutaminase.
Creates water impermeable cell membrane that helps cause cell death
Lamellar Granules increase in the intercellular space
Because they are glycolipids, they form a waterproof barrier between cells
Move from synthesis phase → degenerative phase
Cell nuclei begin to disappear
○ Creating the waterproof barrier
Impermeability due to buildup of keratin in cells
Thickening of cell membrane due to involucrin
Presence of glycolipids between keratinocytes
○ Stratum Lucidum - Keratinocytes are dead, lack nuclei, lots of waterproofing
○ Stratum Corneum – the cells in this layer are called squames
There are no keratohyalin granules or lamellar granules remaining
Epidermal Proliferation Unit (EPU) - The original keratinocyte and all its progeny?
○ Original stem cell produces 10ish basal cells which migrate laterally?
As more proliferation occurs the unit of cells moves upward as a group?
○ Melanocytes in more Detail
Artifact - Actually looks clear at LM level because it doesn‟t have desmosomes and shrinks
Highly branched
Normal Skin – about 1000 melanocytes/mm
Pigmented Skin (areolae, genital, etc.) – about 2000 melanocytes/mm
Different Races – have same number of melanocytes just have different # of melanin granules
Skin Color Caused By
○ Melanin – only pigment produced by skin
○ Carotene – yellow exogenous plant pigment deposited in stratum corneum and adipose
○ Oxyhemaglobin – red protein in blood
Melanin Epidermal Unit – melanocyte and associated keratinocytes (keratinocytes that have
melanin made by that melanocyte)
○ Located in the stratum basale and spinosum
Production of Melanin
○ Tyrosinase – converts tyrosine → melanin in melanocyte vesicles
○ Premelanosomes – small vesicles containing a little bit of melanin. Arise from Golgi
○ Melanosomes – more developed with more melanin
○ Melanin Granules – mature melanosomes
Migrate out to ends of branches??
The end of the process is pinched off into the cytoplasm of the keratinocytes??
cytocrine secretion??
○ Melanosome Complex – forms after keratinocyte and melanin granules fuse with
lysosomes. These form a cap over the nucleus
Slowly degenerate
Dark skinned races: 1. Produce more melanin, 2. have longer lasting melanosome
complexes, 3. have granules in all layers
Function of Melanin
○ Protects nucleus from UV rays
○ UVA – 320 nm (short)
Causes wrinkling, sagging of skin, skin cancer
does not burn the skin (tanning salons use it)
○ UVB – 370 nm (long, this gets in farther)
Causes sunburn – induces inflammation of blood vessels in dermis
Most sunscreens only block this
Melanin Related Clinical Applications
○ Tanning – darkening of melanin with exposure to sunlight and increased tyrosinase
activity over several days of continued exposure
○ Albino – lack of tyrosinase but same number of melanocytes
○ Vitiligo – depigmentation genetic disorder in skin and hair characterized by scattered
patches of white skin and white hair
Melanocytes are destroyed
Michael Jackson
○ Freckle – patch of skin with slightly higher concentration of melanin granules
○ Nevus (mole) – benign localized overgrowth of melanocytes arising during early life
○ Malignant melanoma – very malignant
○ Diseases of the Epidermis
Psoriasis – chronic condition characterized by patches of red-brown area with whitish scales
○ Due to excessive proliferation of keratinocytes
○ Takes 1 week, instead of 4 for keratinocytes to reach top, they aren‟t mature when at top
Waterproof barrier not formed because cells not fully keratinized, lamellar granules not
secreted
○ Cause unknown
Eczema – characterized by edema, exudation, crusting & severe itching
○ Dermis also affected (edema and infiltration of immune cells)
○ Cause thought to be immunological
Phemphigus – autoimmune disease against desmosome proteins in epidermis resulting in
severe blistering and loss of fluids
○ Makes it easier for infectious agents to enter
○ Potentially fatal
Basal Cell Carcinoma – cancer of the keratinocytes in the stratum basale
○ Most common of all skin cancers, but does not readily metastasize
Squamous Cell Carcinoma –
○ Second most common skin cancer, readily metastasizes
Not a disease – DMSO – a penetrating agent used for arthritis (unofficially) that can bring
foreign substances into the body
Dermis
○ Papillary Layer – composed of modified areolar CT
Immediately below epidermis, and is the thinner of the 2 dermal layers
Epidermal-Dermal Junction – interdigitation of dermal papillae and epidermal pegs or
ridges to prevent side shearing forces from separating the two layers
○ Dermal papillae – fingerlike projections of CT of dermis into epidermis
Thin vs. Thick Skin
○ Thin Skin – dermal papillae present but are simply rounded bumps or mounds of CT
○ Thick Skin – has more pronounced ridges (makes fingerprints and improves grip)
interpapillary peg of epidermis divides primary dermal ridge into 2 secondary
ridges
the primary dermal ridges correspond to the epidermal ridges?
○ Reticular Layer – composed of dense irregular CT and is rich in collagen and elastic fibers
Bundles of collagen fibers interwoven and oriented in all directions to resist shearing
Thickest layer in dermis
Cleavage lines of Langer – predominant direction of the bundles of collagen in a region of
the body
○ Important for surgery – if parallel incision then little scar, if across then big scar
○ Stretch Marks – tear of the dermis but epidermis remains, due to skin being too tight
Gap is repaired by scar tissue
Blood Supply for Skin
○ Blood supply derived from arteries in the hypodermis (subcutaneous fascia)
○ 3 Layers
Subcutaneous Plexus – located in the hypodermis
○ The deepest layer; all the blood supply originates here
Cutaneous Plexus – located in the dermal-hypodermis junction
Subpapillary Plexus – located just below the papillary layer
○ Capillary loops run up into the dermal papillae
○ Vasculature and Temperature Regulation
A-V Shunts – control blood flow and are located between cutaneous and subpapillary plexi
○ Found in Apical Skin, not Non-Apical Skin???
Apical Skin – found in finger and toe tips, nail beds, nose and lips
Normal Temp – AV shunts partially closed to allow warm blood to flow near surface
High Temp – AV shunts completely closed and vessels dilate passively to increase skin blood
Cold Temp – AV shunts completely closed and precapillary sphincter closes to prevent blood
from going to surface
Norepinephrine – causes vasoconstriction, released by sympathetic nervous system
Acetylcholine – usually causes vasodilation
○ Clinical Applications
Decubitus Ulcers (bedsores) – compromised circulation in area of skin usually due to
compression of vessels
Contusion (bruise) – leakage of blood out of capillaries
Erythema – redness of skin due to enlarged capillaries
Capillary hemangioma (birth mark) – benign vascular tumor of dermal capillaries
Appendages of Skin
Hair
○ Hard keratinous epithelial fiber composed of keratinocytes
○ Hair Follicle – where the hair is anchored, tubular invagination of the epidermis which extends
down through the dermis to the hypodermis
Enters skin obliquely
Surroundings
○ Dermal Sheath – CT surrounding follicle
○ External Root Sheath – extension of the stratum basale and spinosum, completely
surrounds
○ Internal Rooth Sheath – derived from outside region of matrix
Goes only half way up, cells slough off before sebaceous gland
Contains soft keratin
Subdivisions
○ Hair Shaft – the actual hair above the surface
Cuticle of Hair – outer single layer of hard keratin
Cortex – inner bulk of hair, hard keratin
Medulla – center area made of soft keratin
○ Root of Hair – from center of follicle down to bulb
○ Bulb – nutrient supply to hair follicle, enlargement at deep end
Contains dermal papillae composed of CT
Zones
○ Matrix/germativum Zone – where proliferation of keratinocytes occurs, equivalent of
stratum basale in epidermis
From here keratinocytes move upward and differentiate via keratinization
○ Keratogenous Zone – where cells become fully keratinized
Hard Keratin – has more disulfide bonds than soft keratin
○ Hair Color
Melanocytes in matrix produce pigment which is transferred to the keratinocytes
Pheomelanin – yellow, develops from tryptophan
Eumelanin – brown & black, develops from tyrosine
Gray Hair – melanocytes lack tyrosinase (which is responsible for producing melanin)
White Hair – pigment lacking + air pockets that reflect light
○ Associated Structures
Errector Pili Muscles – smooth muscle which connects basement membrane of dermal
papillae to dermal sheath
Sebaceous Gland – oil gland in acute angle of hair shaft near top
○ Hair Cycle
Hair does not grow continuously, it grows in cyclic stages
All hairs are in different phases of the cycle
Anagen Phase (growth phase) – due to proliferation of matrix
○ Different length of growth phase in different areas of body
Catagen Phase (transitional phase) – growth stops, but hair remains in follicle (short time)
Telogen Phase (resting phase) – hair shaft falls out and bulb involutes
Glands
○ Sebaceous – secrete sebum, oily substance
Associated with hair follicles
Morphology – simple or branched alveolar
○ Secretory unit – single alveolus (IS THIS REDUNDANT??)
Duct – single duct opening into hair follicle
Mode – holicrine (entire cell degenerates and is secreted)
Clinical Connection – when infected by bacteria they cause acne
○ Sex hormones at puberty increase secretion
○ Sudiferous Glands – sweat glands
Eccrine Sweat Glands – secrete serous and mucus substance, most common sweat gland
○ Separate from hair follicle
○ Morphology - simple coiled tubular glands
○ Duct – open at top of friction ridges (when they are present)
○ Mode – merocrine (secreted through exocytosis)
○ Function – temp regulation, excrtetion of ions (like a kidney)
○ Types of Cells
Clear Cells – serous
Dark Cells – mucous
Myoepithelial cells – help expel secretions
○ Hyperhidrosis – excessive sweating
Apocrine Sweat Glands – secrete serous substance
○ Duct opens into hair follicle
○ Morphology - simple coiled tubular glands
○ Mode - merocrine, not apocrine
○ Don‟t function until puberty
○ Located in axilla, pubic region, etc.
○ Modified Glands Meibomian (tarsal) Glands – secrete oily substance
○ Modified sebaceous glands on inner surface of eyelids
Ceruminous Glands – secrete wax (cerumen)
○ Modified apocrine sweat glands in external auditory canal
Mammary Glands – modified apocrine glands
Nails
○ Nail Plate – main body of nail containing keratinocytes with hard keratin
Replaces stratum corneum
Lateral Nail Groove – lateral edge of nail plate
Nail Root – proximal portion where nail plate starts
○ Nail Matrix – portion near nail root where keratinocytes proliferate to form nail
Lunula – whitish crescent that is distal-most part of nail matrix
○ Nail Bed – portion of epidermis where nail plate lies
Continuous with strata basale & spinosum
○ Eponychium – flap of skin that grows over the root of the nail
○ Hyponychium – excess stratum corneum under free edge of nail
Sensory Receptors
It is difficult to match functional classification with morphological classification because they mix
Functional Classification
○ Mechanoreceptor – touch, pressure, stretch
○ Thermoreceptor ○ Nociceptor – pain, itch, etc.
Morphological Classification
Free Nerve Ending Lack Schwann cells and myelin
at terminal end
Thermoreceptors &
nociceptors
Free nerve ending
Merkel Cell Ending Between keratinocytes in
stratum basale
Light touch
mechanoreceptor
Unmyelinated nerve
terminating on Merkel cell
Meissner’s Corpuscle Located in dermal papillae of
papillary layer
Light touch
mechanoreceptor
Encapsulated
Pacinian Corpuscle Large onion-like structure in
lower dermis and hypodermis
Pressure and vibration
mechanoreceptor
Encapsulated
Ruffini Corpuscle Elongated in lower dermis and
hypodermis
Tension
mechanoreceptor
Encapsulated
Krause End Bulb Located in conjunctiva, oral
cavity, tongue
Unknown Delicate capsule (axon
branches within capsule)
Development of Trilaminal Embryo ○ Objectives
Define and describe: hypoblast, epiblast, primitive streak, primitive node, notocordal process, prochrodal plate, cloacal
plate, notocord, ectoderm, mesoderm, and endoderm.
Describe the formation of the bilaminar embryonic disk from the inner cell mass.
Describe the formation of the notocord.
Descirbe the formation of the intraembryonic mesoderm.
List the derivatives of each of the three basic germ layers.
Describe a somite and its derivatives.
Briefly describe the intraembryonic coelom and its formation.
Briefly describe the folding processes that occur in the embryo and the consequences of these processes.
Briefly describe the changes in appearance of the embryo and the fetus during development.
Folding of the Embryo, Basic Body Form, Coelom Formation ○ Objectives
Describe the results of the lateral and longitudinal folding processes that occur in the embryo
Define: coelom, mesentery, septum transversum Describe/define the adult structures derived from the primitive intraembryonic coelom
Describe/define the origin of the cells lining the intraembryonic coelom and its definitive derivatives
Describe the configuration of the intraembryonic coelom following the development of the head fold
Describe/define the pleuropericardial membranes and the pleuroperitoneal membranes
Describe the relative position of the (thoracoabdominal) diaphragm during early development
List the four major tissue sources contributing to the definitive diaphragm. Correlate each with the related area of the
definitive diaphragm
Describe the probable developmental errors that produce: congenital posterolateral diaphragmatic hernia, congenital hiatal
hernia, congenital retrosternal hernia
Integumentary System – Embryology & Wound Healing ○ Objectives
List the embryological origin of the epidermis, dermis and skin appendages
Relate the types of wound healing and burns to the morphology and function of the skin
Define and describe the periderm and vernix caseosa. Be able to describe their origin, formation and function
Describe the origin and usual destination of melanocytes. Describe what occurs if migration and proliferation fail. Be able to describe what determines skin color
Describe the process of hemangioma formation
Describe the formation of sweat glands, sebaceous glands and mammary glands. Relate the causes of polythelia and
polymastia
Describe the formation of the hair follicle and hair shaft
Describe the formation of a fingernail/toenail
○ Embryology
Just Know Chronology, not specific weeks
Epidermis and Dermis
Epidermis - derived from ectoderm
Dermis - derived from mesoderm
Development of Layers
○ 3 Weeks – single layer of ectodermal cells resting on layer of mesenchyme
○ 4-5 Weeks – surface ectoderm forms two layered structure
Periderm – superficial layer of squamous epithelium
○ Cells undergo keritinization and are sloughed off
○ Secretes amniotic fluid
Basal Germanitive Layer – layer of basal cells that make periderm
○ 11 Weeks - Intermediate Layer forms and makes up bulk of skin
○ 21 Weeks – periderm stops sloughing off and forms normal stratum corneum
This is influenced by many factors (epidermal growth factor, etc.)
Vernix caseosa (greasey layer) – forms now to cover fetus and protect it from amniotic fluid
○ Turns baby into greased pig
○ Contains sloughed periderm cells and sebum
Clinical Application – hyperkeratinization
○ Lamellar Icthyosis – scale-like appearance of skin, usually lacks hair and sweat glands
○ Harlequin Icthyosis – extreme hyperkeratinization, „alligator skin‟, deep fissures, fetus dies
Fingerprints – form at 10 weeks, completed by 17 weeks
Other Cells
○ 1st, Langerhans Cells – arise from bone marrow and enter epidermis
○ 2nd
, Neural Crest Cells – arise from neuroectoderm and enter dermis
Once in dermis → melanoblasts → once in basal layer then melanocytes
○ 3rd
, Merkel Cells – appear in stratum basale
Hair
Hair follicle is formed by both epidermis and dermis
Stages (hair germ → hair bud → hair bulb)
○ Stage 1 – hair germ forms (slight invagination of epidermis into dermis)
○ Stage 2 – elongation of the bud into hair bud
○ Stage 3 – characterized as club-shaped and is called hair bulb (looks like full follicle)
Types of Hair
○ Lanugo Hair – first hair to form
Very fine and covers entire fetus by 5 months. Falls out before birth
○ Vellus Hair – found on fetus at birth. Very downy, (65% of adult female hair)
○ Terminal Hair – coarse hair of scalp, pubic & eyebrows (95% of male body hair)
Hirsutism – excessive hairiness in women & children due to vellus hair turning into terminal hair
by increased androgen
Hypertrichosis – excessive hairiness due to excessive hair follicles or persistence of them
Glands
Apocrine and sebaceous glands form with hair follicle
Eccrine sweat glands are not associated with hair follicles
○ Epidermal bud elongates to dermis → cells form coil → central cells degenerate to form lumen
→ outer cells differentiate into secretory cells
○ All eccrine sweat glands are formed prior to birth
Nails (about 10 weeks)
Nail starts on palmar surface of digit, but migrates to dorsal surface quickly
Primary nail field forms nail bed → nail field drives wedge of cells into dermis → wedge forms
nail matrix which produces nail plate → eventually nail folds show
Periderm/epidermis covering of nail eventually degenerates by birth
Nail plate only reaches end of finger tip by 32 weeks
○ If nail plate isn‟t at end of the finger then it is an indicator of prematurity
○ Wound Healing
Epidermal Wound Healing Process
Note - Only epidermis is affected
Clot Formation – blood clot is formed by leakage of blood from capillaries in underlying dermis
○ Platelets and fibronectin in clot provide matrix for macrophages and keratinocytes
○ Platelets release a bunch of growth factors to start wound closure
Activation/Proliferation - chemotactic factors recruit neutrophils and monocytes
○ These enter via extravasation, which requires p-selectin
○ Neutrophils cause keratinocytes and fibroblasts to proliferate
○ A bunch of growth factors are released
Migration – keratinocytes migrate along bottom of wound towards its center via diapedesis
○ Migration occurs beneath or through clot
○ Requires metalloproteinases to break hemidesmosomes of basal lamina (like a basement
membrane)
○ Plasmin is also used
Maturation – keratinocytes meet in the center of the wound and stop proliferating via contact
inhibition ○ Now normal keratinization takes over to resurface the epidermis
○ Basal lamina synthesis occurs. Scab eventually sloughed off
Deep Wound Healing Process
Note - Dermis is also affected
Inflammation Phase – blood clot forms and vasodilation of capillaries (due to histamine) cause
extravasation of neutrophils and macrophages
Proliferative Phase – fibroblasts and keratinocytes proliferate due to growth factors
○ These cells begin to secrete matrix to form granulation tissue
Migratory Phase – keratinocytes and fibroblasts migrate through blood clot to form granulation
tissue
○ Blood vessels grow into granulation tissue
○ Fibroblasts at edge are transformed into myofibroblasts which produce actin and myosin in cells
to cause contraction of the wound
Maturation Phase – granulation tissue slowly turned into dense irregular CT
Note - Scars are lighter because melanocytes don‟t migrate into them
Burns
1st Degree Burns – only epidermis is affected
○ Causes redness and mild pain (like a sunburn)
2nd
Degree Burns – epidermis and upper part of dermis affected
○ Causes blisters, pain and edema (touching stove)
3rd
Degree Burns – full thickness of skin is affected
○ Causes charred skin, no pain in center of burn, just around edges where pain receptors intact
○ Systemic effects are greater threat to life than the local effects
Dehydration, bacterial infection, renal shut down (due to ↓ removal of urea), shock (blood
circulation is reduced due to loss of fluid, reduced urine production due to low blood volume)
Shoulder ○ Objectives
Define the skeletal and ligamentous elements of the shoulder girdle. What is the shoulder girdle?
Define the muscles acting on the shoulder: extrinsic, intrinsic, pectoral, serratus anterior, arm muscles
Know their origins, insertions, innervations and primary actions Identify the shoulder muscles that comprise the “rotator cuff” and discuss their function
Identify the boundaries and contents of the quadrangular and triangular spaces
○ Shoulder Movements
Scapular Movements - Very flexible, but this causes lack of stability
Abduction (protraction) and Adduction (retraction)
Elevation and depression
Upward/downward rotation – reference point is glenoid cavity (if it rotates, then it is rotation)
Glenohumeral movements – joint between arm and scapula
Flexion/extension – tends to deviate to middle with flexion (not completely perpendicular to body)
Abduction/adduction – only to 90
Medial/lateral rotation
Circumduction
○ Skeleton
Scapula (has superior, medial and lateral border, superior and inferior angle) superior angle is closer to
medial border than superior border
Acromion – highest point of scapula, comes out posteriorly
Spine of Scapula – on posterior surface, continuous with acromion
Coracoid process – comes out anteriorly
Suprascapular notch –
○ Superior transverse scapular ligament – goes across the suprascapular notch to form
supracapular foramen ○ Suprascapular artery – goes over the ligament
○ Suprascapular nerve – goes below the ligament
“Army goes over the bridge, Navy goes under the bridge”
Supraspinous and Infraspinous Fossa – cavities above and below spine of scapula
Subscapular fossa – on anterior of scapula
Greater scapular notch – things go through here (under one end of spine of scapula)
Glenoid cavity – where arm attaches
○ Supra- and infraglenoid tubercles – above and below glenoid cavity
Humerus
Head of humerus – where it contacts glenoid cavity
○ Much bigger than the glenoid cavity (gives more flexibility, but less stability)
Anatomical neck – just surrounding head of humerus
Surgical neck – many fractures occur here
Posterior View – can see greater tuberosity
Anterior View
○ Lesser tuberosity – more medial
○ Bicipital groove (interubercular sulcus) – biceps brachii goes through this
○ Greater tuberosity – more lateral
○ Deltoid tuberosity – midway down bone, in line with bicipital groove. Where deltoid attaches
○ Synovial Joint
Fibrous capsule – outermost part
Synovial membrane - contains synovial fluid which surrounds joint and bathes hyaline cartilage on
bone
Synovial Fluid – produced by synoviocytes, contains hyaluronic acid
Cushions, lubricates and nourishes via diffusion which requires movement
○ Shoulder Joint
Sternoclavicular Joint – true to name (connects sternum to clavicle)
only bony attachment of upper limb to axial skeleton
Sternoclavicular ligament (anterior and posterior) – true to name
Interclavicular ligament – true to name
Costoclavicular ligament – attaches to rib
Acromioclavicular Joint (AC Joint) – true to name
Acromioclavicular ligament - if torn → shoulder separation
Coracoclavicular ligament – attaches coracoid to the last quarter of the clavicle
Coracoacromial Arch – prevents superior displacement of humerus
○ Coracoid process
○ Coracoacromial ligament – just forms roof so humerus doesn‟t displace (connections on same
bone)
○ Acromion
Glenohumeral Joint - true to name
Shoulder dislocation – disruption of this joint
Fibrous Joint Capsule
○ Glenohumeral ligaments – strengthen anterior part of capsule
Contains thickenings called superior, middle, and inferior
○ Coracohumeral ligament – strengthens superior part of capsule
Transverse humeral ligament – strengthens superior part of capsule
○ Holds tendon of biceps in bicipital groove
Glenoid labrum – fibrocartilage ring around circumference of glenoid cavity, deepening it
Bursae – a synovial sac which facilitates movement of a structure over bone
○ Subacromial & subdeltoid bursa – looks like shoulder pads over just the shoulder
Does not communicate with glenohumeral joint cavity
○ Subtendinous bursa of subscapularis – over glenohumeral ligaments and does communicate
with glenohumeral joint cavity
○ Muscles
Extrinsic Muscles
Extrinsic Muscles
Origin Insertion Action Nerve
Axial skeleton → scapula
Pectoralis
minor
ribs (3-5) coracoid process -stabilize scapula -protraction
-pull tip of shoulder downward
medial and lateral pectoral nerve
Serratus
anterior –
curves around
ribs to inner part
of scapula
ribs (upper 8) medial border of
scapula
-holds scapula against thorax,
protraction (abduction) -rotates scapula to direct glenoid
cavity upwards
-essential for raising arm above
head
long thoracic nerve
Trapezius -ligamentum
nuchae
-SP of vertebrae
-spine and acromion
of scapula
-lateral portion of clavicle (wraps around
front)
-elevate and depress scapula
-retraction (adduction) of scapula
-rotate glenoid process of scapula↑
-accessory nerve
(motor)
-C3-4 (proprioception)
Levator
scapulae
C1-C4 -superior angle of
scapula
-medial border of
scapula
-elevate scapula
-rotate glenoid cavity↓
-If insertion point is fixed then it can laterally flex neck
dorsal scapular nerve
Rhomboid
major &
minor
SPs of thoracic
vertebra
medial border of
scapula
-retracts (adducts) scapula dorsal scapular nerve
Axial Skeleton → humerus
Pectoralis
major
-clavicular head
-sternocostal
head
lateral lip of
bicipedal groove
-adductor of arm
-medial rotation of arm
medial and lateral
pectoral nerve
Latissimus
dorsi
-T7 to sacrum -iliac crest
Intertubercular sulcus
-Adducts arm -medial rotator of arm
-extends arm
thoracodorsal nerve
Axial Skeleton → clavicle
Subclavius rib 1 clavicle -depression of clavicle -anchoring of clavicle
nerve to subclavius
Other Serratus posterior
superior
SP (C7-T3) Ribs 2-5 Expands ribs Ventral rami
Serratus posterior
inferior
SP (T11-L2) Ribs (last 4) Expands ribs Ventral rami
Note – "Lady between two Majors"
○ The latissimus dorsi has its insertion point in bicipital groove (intertubercular sulcus) which is
between two insertions of 'major' muscles on the medial and lateral edge of bicipital groove
Note - „medial‟ and „lateral‟ pectoral nerve based on origin of nerve, not what they innervate
Intrinsic Muscles
Origin – all scapula
Insertion – all humerus
Action – all act on humerus and help stabilize joint
Intrinsic Muscles
Origin Insertion Action Nerve
Rotator Cuff – group of muscles and tendons that stabilize glenohumeral joint by attaching the scapula to the humerus
Teres Minor Scapula – lateral border greater tuberosity lateral rotation Axillary
Infraspinatis Scapula – infraspinous fossa greater tuberosity lateral rotation Suprascapular
Supraspinatus –
goes through scapular notch
Scapula – supraspinous
fossa
greater tuberosity abduction (initiates) Suprascapular
Subscapularis Scapula – subscapular fossa lesser tuberosity medial rotation Subscapular
Other Intrinsic Muscles of Shoulder
Deltoid Scapula (front and back)
- lateral 1/3 of
clavicle - acromion
- spine of scapula
deltoid tuberosity -Abduction
-extends
-flexes -medial & lateral
rotation
Axillary
Teres Major Scapula – lateral border medial edge of
bicipital groove
-medial rotation
-(a little adduction)
Lower subscapular
○ Scapular Rotation with Humeral Abduction
0-30 Degrees - Abduction at glenohumeral joint only via supraspinatus
30-120 Degrees – abduction at glenohumeral joint via supraspinatus & deltoid
scapular rotation via trapezius & serratus anterior
>120 Degrees – scapular rotation only
(humerus has hit acromion and can‟t move anymore
Axilla and Brachial Plexus ○ Objectives
Axilla
Define the skeletal and muscular boundaries of the axilla
Identify the contents of the axilla. From what structure is the axillary sheath derived? What structures are included in
the axillary sheath
Brachial Plexus and Axillary Vasculature
Define the typical branching pattern of the brachial plexus. What landmarks can be used to find each level of the
plexus: roots (ventral rami) → trunks → divisions → cords → terminal nerves
○ What are the supraclavicular branches and what do they innervate? What are the infraclavicular branches and what
do they innervate?
○ What are the terminal nerves of the brachial plexus? Which groups of muscles do they innervate
Autonomics of the Upper Extremity
At which spinal levels do preganglionic sympathetic fibers destined for the upper extremity arise?
Do parasympathetic fibers innervate vasculature of the upper extremity?
Blood Supply of the Upper Extremity
Which branches of the subclavian artery supply structures of the shoulder?
Where does the subclavian artery change its name to the axillary artery?
Which branches of the axillary artery supply structures of the shoulder and upper arm?
Understand the concept of collateral circulation and its application to this region
Lymphatics of the Upper Extremity
Understand the basic lymphatic drainage of the upper extremity. How does lymph from the right upper extremity reach
the right brachiocephalic vein?
How does lymph from the left upper extremity reach the left brachiocephalic vein
○ Borders of the Axilla
Apex – rib 1, upper edge of scapula &
clavicle
Base – skin (subcutaneous tissue and deep
fascia)
Anterior Wall – pec major and minor,
subclavius muscles & clavipectoral fascia
Posterior Wall – scapula, subscapularis,
latissimus, teres major, long head of tricep
Medial Wall – ribs 1-4, intercostal and
serratus anterior muscles
Lateral Wall – humerus
○ Contents of Axilla
Axillary Artery – continuation of subclavian
Axillary Vein – thinner walled than axillary artery
Axillary lymphatics and nodes – most common site of breast metastasis. In axillary fat
Axillary Sheath – extension of prevertebral fascia
Contains – brachial plexus, axillary artery, axillary vein
Brachial Plexus – C5-T1 nerves (ventral rami)
○ Brachial Plexus
“Randy Travis Drinks Cold Beer”
Made of ventral rami of spinal nerves
Note – Posterior cord is posterior to axillary artery
Note – Radial nerve goes medial, axillary nerve goes lateral
Outline
Roots – in posterior cervical triangle, contains 5
Trunks – at/above clavicle, contains 3
Divisions – posterior to clavicle, lots of crosses
Cords – around axillary artery, back to 3
Terminal Branches – 5 named mixed nerves
Terminal Branches
Vertebral Motor Sensory
Axillary C5-6 shoulder Over deltoid
Musculocutaneous C5-7 arm flexors Anterolateral forearm
Median C5-T1 mainly forearm, but a little hand Palmar surface lateral 3.5 digits
Ulnar C8-T1 mainly hand, but a little forearm Palmar surface medial 1.5 digits
Radial C5-T1 extensors of arm and forearm (and
a few others)
Posterior forearm & dorsolateral
hand
○ Note – motor innervation for radial nerve “BEST – brachioradialis, extensors, supinator, triceps”
○ Note – musculocutaneous pierces coracobrachialis (a good place to orient yourself)
○ Note – the more caudal the spinal nerve that innervates a terminal branch the more likely it is to
innervate a distal structure When testing for damage of the brachial plexus, you can test sensory areas or muscles. When testing muscles
remember that as you move distally on the arm you test lower aspects of the brachial plexus
Other Nerves
Don‟t worry about specific spinal nerves, just know groupings
Supraclavicular Nerves Infraclavicular Nerves
1. Dorsal scapular – C5 5. Lateral pectoral – C5-7
2. Suprascapular – C5-6 6. Medial pectoral – C8-T1
3. Subclavian – C5-6 7. Medial cutaneous nerve of arm – C8-T1
4. Long Thoracic – C5-7 8. Medial cutaneous nerve of forearm – C8-T1
9. Upper subscapular – C5
10. Thoracodorsal – C6-8
11. Lower subscapular – C6
Note – medial pectoral pierces pec minor and innervates pec major
Note – medial cutaneous nerve of the arm joins the intercostalbrachial nerve (a branch of T2)
Areas of Dermatome to test specific spinal cord levels of the Brachial
Plexus
C5 – upper lateral arm
C6 – pad of thumb
C7 – pad of index finger
C8 – pad of little finger
T1 – medial elbow
○ Axillary Artery
Subclavian artery → lateral border of rib 1 → axillary artery → ends at
lower border of teres major → brachial artery
Parts of Axillary Artery
Parts Branches Structures Supplied Notes
1 - Proximal to
pec minor Superior thoracic a.
-Pectoral mm
-Thoracic wall mm -Serratus anterior m
2 - Posterior
to pec minor
Thoracoacromial a.
-Clavicular branch
-Acromial branch
-Deltoid branch -Pectoral branch
This supplies branches
"Cadavers Are Dead People"
Lateral thoracic a.
-Serratus anterior m.
-Pectoralis minor
-Mammary glands
Not always there
“L-L” Lateral goes with
Long thoracic nerve
3 - Distal to
pec minor
Subscapular a.
Subscapularis m Largest branch of axillary artery Circumflex scapular a.
- posterior scapula
- teres minor - infraspinatus
Thoracodorsal a.
- latissimus dorsi
Anterior humerial
circumflex a
-Deltoid -triceps brachii mm
Smaller
Posterior humerial
circumflex a
-Deltoid
-triceps brachii mm
Larger
Note – "Screw The Lawyer, Save A Patient"
Note – the two humerial circumflex arteries go around humerus and eventually join
○ Spaces and Intervals
Contents Boundaries
Triangular Space -Circumflex scapular a (deep to it)
-Teres major -Teres minor
-Long head of tricep
Quadrangular
Space
-Axillary nerve -Posterior circumflex
-humeral a.
(these go through)
-Teres major -Teres minor
-Long head of tricep
-Lateral head of tricep
Triangular
Interval
-Profunda brachii a. -Radial n.
(deep to it)
-Teres major -Long head of tricep
-Lateral head of tricep
○ Scapular Arterial Anastomoses
End to end joining of blood vessels which provides redundancy
Basically, two blood vessels venture down, one branches off and connects head on with the other
Suprascapular ↔ circumflex scapular artery
Posterior circumflex artery ↔ anterior circumflex artery?
Dorsal scapular artery ↔ posterior intercostals arteries
○ Venous Drainage
Superficial Veins
Both originate on the dorsum of the hand
Basilic vein – continues as axillary, becomes a deep vein (so it is both a deep and superficial vein)
○ On medial side of arm
Cephalic vein – on lateral side of arm, joins axillary after going through the clavipectoral triangle
○ Clavipectoral triangle – made by deltoid, pectoral and clavicle
Deep Vein?
Paired and on either side of accompanying arteries (vein, artery, vein)
○ Lymphatic Drainage
Are not within the axillary sheath
Lateral & Anterior & Posterior → Central → Apical → Subclavian lymph trunk → venous system
Note - apical lymph node drains all other nodes and the mammary glands
Cellular Controls in Development ○ Objectives
Briefly explain why the conceptus is not immunologically rejected by the mother during and following the process of
implantation
Define/describe homeotic genes (homeobox genes). What is their role in development? How are they regulated?
Define the term critical (sensitive) period of development. List several examples of critical periods and the results of
alterations in the regional microenvironment within the embryo/fetus during them
Describe the principle of cranio-caudal and proximo-distal growth sequences
Define induction and give two examples of induction during embryonic development
Describe the following processes that are important in development: tissue aggregation, cell death, differentiation, growth and regeneration
Define teratology
Give and example of a defect caused by each of the following classes of teratogen:
Environmental: infectious agents, radiation or chemical, hormonal
Chromosomal or genetic: autosomal abnormalities, sex chromosome abnormalities
Arm and Forearm ○ Objectives
Veins of the Upper Extremity
What are they and where are they?
Arteries of Upper Extremity
What is the course and branching pattern of the brachial artery?
Which arteries contribute to collateral (and recurrent) circulation of the elbow?
What happens to the brachial artery as it passes into the forearm?
Compartments of the Arm
Which muscles are found in the flexor (anterior) compartment?
What are their attachments and what are their primary actions?
What nerve innervates the muscles of the flexor compartment?
Which muscles are found in the extensor (posterior) compartment?
What are their attachments and what are their primary actions?
What nerve innervates the muscles of the extensor compartment?
Compartments of the Forearm
What are the boundaries and contents of the cubital fossa?
Which muscles make up the Flexor-Pronator group?
What are their attachments and what are their primary actions?
What nerves innervate these muscles?
Which muscles make up the Extensor-Supinator group?
What are their attachments and what are their primary actions?
What nerves innervate these muscles?
○ Movements of the Arm and Forearm
Glenohumeral Movements
Flexion – extension
Abduction – adduction
Medial rotation – lateral rotation
Circumduction
Elbow and Forearm
Flexion – Extension
Pronation – supination
○ Arm/Elbow
Skeleton
Foramen for nutrient artery – hole for a blood vessel into bone
Radial Groove – where radial nerve travels along the bone
Distal Humerus
○ Lateral suprachondylar ridge –
○ Radial fossa – for radial head, on anterior side
○ Coranoid fossa – for coranoid process of ulna, on anterior side
○ Capitulum – a round protrusion, on anterior side
○ Trochlea – a „valley‟ on the distal end
○ Lateral epichondyle –
○ Medial epichondyle – ulnar nerve passes behind it
○ Olecranon fossa – on posterior side, accepts olecronon of ulna
Forearm
○ Ulna – the stable bone
Olecranon process – what you feel at the elbow
Trochlear notch – on the other side of the olecranon process (huh?)
Coranoid process – outside of the other end of the notch (huh?)
Radial notch – accepts radius
Ulnar tuberosity – accepts brachialis insertion
Styloid process – on distal end of ulna
○ Interosseous membrane – connects radius and ulna and has openings at top and bottom
○ Radius – the rotator
Head of radius –
Neck of radius –
Radial tuberosity – accepts biceps tendon
Styloid process – on distal end, the ulna also has one
Elbow Joint
Fibrous Capsule – all the CT holding the joint together
○ Radial Collateral Ligament – thickening on lateral/radial side
○ Ulnar Collateral Ligament – thickening on medial/ulnar side
Anular ligament of radius – wraps around radius like a „ring‟ to hold it in place while letting it
rotate
Muscles around Humerus
Muscles around Humerus
Origin Insertion Action Nerve
Anterior (Flexor) Compartment
Biceps brachii
Long Head -
Supraglenoid tubercle
-biceps tendon to radial
tuberosity
-bicipital aponeurosis (which blends with deep fascia)
Elbow - Flexor
Elbow - Supinator
Musculocutaneous Short Head –
coracoids process
Brachialis Humerus – body Ulna – ulnar tuberosity Elbow - Flexor (Pure)
Coracobrachialis Coracoid Humerus – medial body -Arm – flexor
-Arm – adductor
Posterior (Extensor) Compartment
Triceps brachii
Long Head
infraglenoid tubercle
Lateral Head humerus – shaft
Medial Head (same as
lateral head?)
Ulna – olecronon Elbow - extensor
Radial
Aconeus Humerus – lateral
epichondyle
Ulna – proximal Elbow – extensor
Stabilizer
○ Note – humerus is mainly in anterior compartment
○ Note – Long head of biceps brachii is based on the length of the tendon
○ Note – brachialis is covered by bicep
Cross Section
○ Lateral intermuscular
septum – separates
anterior (flexor) from
posterior (extensor)
compartment
○ Brachial Fascia – a “deep
fascia” which surrounds
both compartments
maintains integrity of
the muscles; allows
them to function as one;
helps venous return
Arteries
At inferior part of teres major
the axillary artery becomes
the brachial artery
The profunda brachii artery branches off the brachial artery and then becomes the radial
collateral
The brachial artery branches just after passing under the bicipital aponeurosis into the radial
artery and the ulnar artery
Redundancy
○ The proximal end of the elbow joint is supplied by three collaterals
○ The distal end is supplied by three recurrent arteries
○ All of these connect at the elbow to form anastamoses
Veins
Paired brachial veins – deep to the bicep
Medial cubital vein – the cephalic and basilic vein merge to form this
○ A good place for drawing blood
Nerves
Musculocutaneous – is motor in the proximal portion, but sensory in the distal portion (the
forearm)
○ Penetrates the coracobrachialis
○ When in the forearm it is only sensory and is called the cutaneous portion of the
musculocutaneous nerve
Median – no major branches in arm
Ulnar – no major branches in arm, travels behind the medial epichondyle
Note – medial and ulnar travel with the brachial artery in the arm
Radial – is motor in the posterior arm compartment and sensory in lateral and posterior arm?
See cross section
○ Note – paired brachial veins, radial nerve barely sits in the radial groove, “deep artery and veins
of arm” = profunda brachii
○ Forearm
Note – basically, when a muscle passes over a joint it will play a part in moving it
Compartments
Lateral intermuscular septum – between radius and deep fascia
Interosseous membrane – between radius and ulna
Medial intermuscular septum - between ulna and deep fascia
Flexor-Pronator
Note – superficial muscles have origin on medial epichondyle or
humerus OR proximal-anterior radius/ulna
Flexor-Pronator
Origin Insertion Action Nerve
Superficial Muscles – have origin on medial epichondyl
Pronator teres
Hu
mer
us
– m
edia
l
epic
ho
nd
yle
Ulna – head
Radius - middle Pronator Flexor - elbow
Med
ian
Flexor carpi
ulnaris
2nd
metacarpal Flexor – wrist
Palmaris longus Palmar aponeurosis (deep fascia in palm)
Flexor – wrist
Flexor digitorum
superficialis –
beneath the other
superficial muscles
Radius -
body
Middle phalanges Flexor – digits (and
wrist)
Flexor carpi
ulnaris
Wrist – pisiform
bone
Flexor – wrist Ulnar
Deep Muscles – have origin on radius and ulna on anterior side
Flexor digitorum
profundus
-Ulna
(-Radius)
Distal phalanges Flexor – digits (and
wrist) Ulnar side = ulnar
Radial side = median
Flexor pollicis
longus
-Radius
(-Ulna)
Distal phalanx of
thumb
Flexor – thumb
M ed ia n
Pronator
quadratus
Ulna – distal Radius – distal Pronator
○ Note – „carpi‟ = wrist
○ Note – 'quadtratus' looks like a quadrangle
Extensor-Supinator
Extensor-Supinator
Origin Insertion Action Nerve
Superficial Muscles
Brachio-radialis suprachondylar ridge Radius – styloid process Flexor – elbow
Rad
ial
Extensor carpi
radialis longus
suprachondylar ridge II metacarpal Extensor – wrist Radial deviation (abduction) -
wrist
Extensor carpi
radialis brevis
late
ral
epic
ho
nd
yle
III metacarpal Extensor – wrist
Radial deviation (abduction) - wrist
Extensor
digitorum
Distal phalnx of fingers Extensor – fingers and wrist
Extensor carpi
ulnaris
V metacarpal Extensor – wrist
Ulnar deviation (adduction) –
wrist
Extensor digiti
minimi
V distal phalanx Extensor – pinky
Deep Muscles Supinator -Lateral epichondyle
-Ulna
Radius – proximal Supinate
Rad
ial
Extensor Indicis -Ulna -Interosseus membrane
II distal phalanx (index finger)
Extensor – index finger
Snuff Box
Abductor pollicis
longus
-Radius
-Interosseus membrane
I metacarpal Extensor – base of thumb
Rad
ial
Extensor pollicis
brevis
-Radius -Interosseus membrane
I base of proximal phalanx
Extensor – middle of thumb
Extensor pollicis
longus
Ulna I distal phalanx Extensor – end of thumb
Note – Superficial muscles have origin on lateral epichondyle OR proximal-anterior radius/ulna
Note – „pollex‟ = thumb
Note – the „brevis‟ vs. „longus‟ refers to the tendon
○ Cubital Fossa
Space at elbow that contains biceps tendon, brachial artery (and its
radial and ulnar branches), brachial vein, parts of median and radial
nerves
Boundaries
Superior – intercondylar line (imaginary)
Lateral – brachioradialis muscle
Medial – pronator teres muscle
Floor – brachialis & supinator muscles
Roof – deep fascia including bicipital aponeurosis & skin
○ Note that the median cubital vein is also here (the place for
drawing blood)
○ Arteries (skipped hand arteries)
Brachial artery branches in cubital fossa →
Radial artery – basically goes to hand
Ulnar artery – branches just past elbow into:
○ Common interosseous – can be very short; branches into:
Anterior Interosseous – supplies deep flexors of forearm
Posterior Interosseous – supplies extensors of forearm
Note – he made a big point of this
○ Nerves (skipped hand nerves)
Median
Ulnar
Radial
Deep Branch – muscular, goes through supinator (goes through posterior interosseous???)
Superficial Branch – cutaneous
Development of the Muscular System ○ Objectives
Define and describe the location of three types of muscle tissue: skeletal, cardiac and smooth
List and describe the differences between the developmental origins for the skeletal muscle of the body: trunk muscles,
pharyngeal arch muscles, ocular muscles, tongue muscles and muscles of the limbs
Define and/or describe: epaxial musculature, hypaxial musculature
Describe the process of muscle cell maturation
List the major regulatory factors that influence muscle cell maturation
List/describe the origin of cardiac and smooth muscle
○ Initial formation of the muscular system is independent from skeletal system, but later maturation is
closely tied
○ Phases of Development
Commitment to myogenic lineage
Activation of a myogenic program
Proliferation of myogenic precursors
Specification of specific myogenic cells
Fusion of mononucleated precursors to form multinucleated fibers
Organization of contractile proteins of the sarcomere
○ Formation from Mesoderm
Muscle system develops mainly from mesoderm
Exception – muscles of iris and ciliary body
Mesoderm condenses into 3 layers
Paraxial – around axis
○ Head
○ Somite
Sclerotome – cartilage, ribs and vertebrae of axial skeleton
Myotome – axial muscle tissue
Dermatome - dermis
Intermediate → kidney & gonads
Lateral
○ Somatic (dorsal layer) → CT & vascular smooth muscle
○ Splanchnic (ventral layer) → smooth muscle of GI and cardiac muscle
Somitogenesis
Somitomeres – unsegmented mesoderm that develop into somites which are segmented
○ Differentiation is helped by somitomere expression of adhesion proteins causing compaction
○ Initiated by tyrosine kinase receptors called Eph which receive Ephrin signal molecules from
surrounding tissue
○ After about 20 somitomeres form, then the 8th one begins to differentiate into a somite
This development starts rostrally and ends caudally (rostral → caudal)
The first 7 somitomeres do not develop into somites
○ These first 7 → muscles of face, jaw and throat
Axial Specification of Somites
Sclerotome somites (skeletal) that are experimentally moved to a different region will make the
structure they are programmed to make in that new region.
○ Myotome somites don‟t do this, they are more influenced by the signals in the tissue which they
migrate to
Somites are programmed where to go before being fully formed
○ Cells within a somite are only told to differentiate into a specific muscle after the somite is fully
formed
Somite Differentiation
Cells within a somite will need to differentiate into sclerotome, myotome and dermatome
The ventral region of somite wall forms the sclerotome
The dorsal wall forms the dermomyotome, this differentiates into:
○ Dermatome – forms dermis of back
○ Myotome – forms below dermatome in two stage process
1st – MyoD and Myf5 cause some cells in dermomyotome to commit to myogenic lineage
2nd
– myogenic precursors move away from dermomyotome to form their own layer
○ the myotomic cells then split into an epaxial region and a hypaxial region
Epaxial Myotome – found dorsomedially
○ Forms extensor muscles of neck & deep muscles of the back (ex. Erector spinae,
transversospinosus)
○ Innervated by dorsal ramus of spinal nerves
Hypaxial Myotome – found ventrolaterally
○ Forms muscles of lateral and ventral body wall, limbs, tongue
Flex trunk and rotate vertebral column
○ Innervated by ventral ramus of spinal nerves
○ Extends aroundish the developing embryo
Pharyngeal Myotome – from the 1st 7 somitomeres which didn‟t develop into somites
○ Forms muscles of mastication, facial expression, pharynx and larynx
Myogenesis
MyoD & Myf5 continue to influence myotome
○ Induce specification to myogenic fate (this is already accomplished)
○ Promote fusion of myogenic cells to form muscle fibers
○ Direct the organization of contractile proteins within the maturing muscle fibers
Somites in different rostro-caudal levels form appropriate muscle groups
Limb Muscles
Limb buds form from mesenchyme overlain by ectodermal tissue
Limb muscles form from the lateral portions of limb level somites, specifically the hypaxial area
○ These differentiate into myoblasts and then myotubules
Upper limb buds form around day 24 from C5-T1 somites
Lower limb buds form around day 28 from L2-S3 somites
Within a limb bud the myoblasts form two masses
○ Dorsal Limb Bud Mass – forms all limb extensor muscles (upper limb suppinators, all lower
limb abductors)
Innervated by dorsal branch of ventral rami
○ Ventral Limb Bud Mass – forms all limb flexor muscles (upper limb pronators, lower limb
adductors)
Innervated by ventral branch of ventral rami?
Limb bud masses eventually split to form specific muscles
○ Which muscle they become is not an intrinsic property of the myoblast, instead they get their
cues from the surrounding CT
○ Muscle fiber type (fast, slow, red, white) is specified by intrinsic properties of myoblasts
Craniofacial Muscles
Pharyngeal Arches – 4 archlike masses of neuroectodermal cells which help create the face,
mouth, nasal cavities, larynx and pharynx and differentiate into head and deep neck muscles
○ Form during the 4th and 5
th weeks of gestation
○ Form from unsegmented somitomeres
○ Aggregate into pre-muscle masses
○ CT elements lay down tracks so that these somitomeres can migrate to the proper place to form
the pharyngeal arches (this is a long way)
○ Innervated by cranial nerves once they make the pharyngeal arch, these nerves stay with the
myoblasts as they move to their final destination
Pharyngeal Arch Cranial Nerve Muscles
1st V Mastication
2nd
VII Facial Expression
3rd
IX Stylopharyngeus
4th
X-XI Larynx, pharynx
Muscle Cell Fusion
Myoblasts → Skeletal Muscle Fibers
○ 1. Fusion of myoblasts to form multinucleated myotubules
Two classes of progenitor cells form
○ Founder Cells – primary cells which seed a distinct muscle
○ Fusion-Competent Cells – secondary cells which aggregate around the founder cell and
fuse with them to form myotubules
Fusion requires – cell-cell recognition and attraction, adhesion, alignment, fusion
○ 2. Expression of contractile proteins and arrangement of sarcomeres
Here the fiber type is established
○ CT sheath plays a part in expression of proteins for different fiber types? (contradiction??)
Muscle Cell Regeneration
Satellite Cells – mononuclear mygenic precursors that can divide at a slow rate to sustain self
renewal and growth of muscle tissue
○ Replicate themselves due to Pax7
○ Differentiate into proper muscle cells via MyoD and Myf5
Regeneration is rare, but can happen after mechanical tearing or muscular disease
○ Smooth Muscle
Derived primarily from splanchnic mesoderm
GI – splanchnic mesoderm surrounding primordial gut
Vessels – somatic mesoderm
Iris & Ciliary Body – ectoderm
Mammary & sweat glands – myoepithelial cells derived from somatic endoderm
Note – splanchnic and somatic mesoderm from lateral plate mesoderm
○ Cardiac Muscle
Develops from splanchnic mesoderm surrounding the developing heart tube
Do not undergo fusion, instead they develop cell-to-cell connections (gap jnx, intercalcated discs)
Hand ○ Objectives
Skeleton of Hand and Wrist
What are the bones of the hand and wrist? Be able to identify them in bone specimens as well as on X-rays
What is the carpal tunnel and what are its contents? What nerve is affected in carpal tunnel syndrome?
What is the Canal of Guyon and what are its contents?
Blood Supply of the Hand
Where is the radial artery at the wrist and how does it enter the hand?
Where is the ulnar artery at the wrist and how does it enter the hand?
How do the radial and ulnar arteries contribute to the collateral circulation of the hand?
Cutaneous Innervation of the Hand
What spinal levels innervate the thumb?
What spinal levels innervate the little finger?
Which portion of the hand would you test for median nerve innervation?
Which portion of the hand would you test for ulnar nerve innervation?
Which portion of the hand would you test for radial nerve innervation?
Muscles of the Hand
What are the extrinsic muscles of the hand and what are their primary actions?
What are the intrinsic muscles of the hand and what are their primary actions?
What are the snuff box muscles and what are their primary actions?
What intrinsic hand muscles are innervated by the median, ulnar, and radial nerves?
Clinical Conditions
What nerve is damaged in “crutch palsy”?
What are the typical effects of an upper brachial plexus paralysis?
What are the typical effects ini the hand of a lower brachial plexus paralysis?
○ Skeleton
Carpal Bones – “Some lovers try positions that they cannot handle”
Start at thumb on lower level
Proximal - Scaphoid (skiff boat), Lunate, Triquetrum (3 sides), Pisiform (you can feel this?)
Distal – Trapezium, Trapezoid, Capitate (little head), Hamate (hook)
Metacarpals – I-V starting with thumb
Phalanges – Proximal, Middle and Distal (though thumb only has proximal and distal)
Note – radius is big at the wrist
Scaphoid Fracture
Scaphoid bone is the most common wrist bone to be fractured if you catch fall with hands
Blood comes into scaphoid at its distal end and so if fracture happens below that circulation may be
compromised and nonunion or avascular necrosis could develop
○ This can lead to arthritis
○ Surgery necessary to treat this
○ Movements of the Wrist and Fingers
Wrist – remember that the palm is face up in anatomical position
Extension/Flexion
Abduction (radial deviation)/Adduction (ulnar deviation)
Fingers – think of the middle finger as the midline
Abduction (away from middle finger)/Adduction (toward middle finger)
Extension/Flexion
Thumb
Extension/Flexion – tricky, „main flexion action of thumb‟
Abduction (move thumb anterior to 4 fingers)/adduction
Opposition – movement unique to thumb and pinky
○ Joints of the Fingers
Metacarpophalangeal Joint (MP Joint) – 1st knuckle
Proximal Interphalangeal Joint (PIP Joint) – 2nd
knuckle
Distal Interphalangeal Joint (DIP Joint) – Knuckle sandwich
○ Aponeurosis and Synovial Sheaths
Palmar Aponeurosis – a condensation of deep fascia which protects the palm
Comes from the tendon of palmaris longus
Common Sheath – underneath palmar aponeurosis and protects tendons, contains synovial fluid
Fibrous Digital Sheaths – on inner side of fingers, contains synovial fluid
○ Muscles
Muscles of the Hand
Origin Insertion Action Nerve
Superficial Muscles – Hypothenar Muscles
Abductor digiti
minimi
Pisiform Proximal phalanx Abductor Ulnar
(deep
branch) Flexor digiti
minimi
-Hamulus
-Flexor retinaculum
Proximal phalanx Flexor
Opponens digiti
minimi
-Hamulus
-Flexor retinaculum
5th metacarpal Oppose
Superficial Muscles – Thenar Muscles
Abductor pollicis
brevis
-Scaphoid -Trapezium
-Flexor retinaculum
Pro
xim
al
Phal
anx
Abductor Median nerve
(recurrent
branch)
Except
deep
head, it
is ulnar
Flexor pollicis
brevis
Superficial Head: flexor retinaculum
Flexor
Deep Head: capitate &
trapezium
Opponens pollicis Trapezium 1st metacarpal Oppose
Deep Muscles Dorsal
interosseous mm
(4)
Metacarpals -Proximal Phalanx
-dorsal expansion
“extensor hood”
Abducts Ulnar
(deep
branch)
Palmar interosseus
mm (3)
Metacarpals -Proximal Phalanx
-dorsal expansion “extensor hood”
Adducts
Adductor pollicis -Metacarpal III
-Capitate
Proximal phalanx of
thumb
Adducts
Lumbricals (4) Tendons of flexor digitorum profundum
Extensor hood -Flexes MP joint -Extends DIP and PIP Joints
Ulnar and
Median
Dorsal interosseous mm – “DAB” – dorsal interosseous abducts
Proximal interosseous mm – “PAD” – palmar interosseous adducts
Note – note the number of each deep muscle
Note – lumbricals on palmar side, superficial to interosseous
○ Extensor Hood
Muscles attaching to it
Lumbricals, dorsal interosseous, palmar interosseous,
abductor digiti minimi, adductor pollicis, abductor pollicis
brevis
Lots of the muscles involved in handwriting
○ Arterial Supply
Radial and Ulnar arteries anastamose on the palmar side of
the wrist and give off branches for the fingers
Both are underneath palmar aponeurosis
Superficial Palmar Arch – a little more distal than deep palmar arch
Mainly supplied by ulnar artery
Ulnar artery → Superficial palmar arch → common palmar digital arteries (single in the middle)
→ proper palmar digital arteries (two on sides)
○ "USC Poonani"
Deep Palmar Arch – proximal to superficial palmar arch
Mainly supplied by radial artery (which is on the thumb side)
Deep palmar arch → palmar metacarpal arteries → proper palmar digital arteries
○ Nerves
Superficial Branch of Radial Nerve – sensory only in
hand
Ulnar Nerve
Deep Branch of Ulnar – motor to intrinsic hand
muscles
Superficial Branch of Ulnar – sensory
Palmal Branch of Ulnar – sensory
Median Nerve
Recurrent Branch of Median – supplies thenar
muscles
○ Goes through carpal tunnel
Palmar Branch of Median – sensory
○ Goes through carpal tunnel
Digital Branch of Median – sensory
Dermatome Hotspots
C6 – palmar tip of thumb
C7 – palmar tip of index finger
C8 – palmar tip of pinky
○ Carpal Tunnel
Flexor retinaculum covers palmar area containing tendons and nerves
Connects to Scaphoid (1), Pisiform (4), Trapezium (5) and Hamate (8)
Contents
4 Tendons of flexor digitorum superficialis – superficial
4 Tendons of flexor digitorum profundus – deeper
Median Nerve – thumb side near surface (except digital branch)
Tendon of flexor pollicis longus – thumb side deeper than median
Other Tunnels not part of Carpal Tunnel
Ulnar Tunnel – contains ulnar artery and nerve, is above the flexor retinaculum
Tendon of flexor carpi radialis – inside flexor retinaculum on thumb side
○ Anatomical Snuff Box
Boundaries
Palmar – tendons of extensor pollicis
brevis and abductor pollicis longus
Dorsal – tendon of extensor pollicis
longus
Proximal – extensor retinaculum
Floor – scaphoid & trapezium
Roof – superficial fascia containing
branches of superficial branch of radial nerve
Contains the radial artery
○ Clinical Connections
Brachial Plexus Injuries
Erb-Duschenne Palsy – upper plexus injury (C5-6)
○ Caused by stretching arm or neck in funny ways
○ Nerves
Injures axillary, musculocutaneous & suprascapular nerves
Suprascapular prone to injury because it is fixed at suprascapular notch
○ Note - Supraspinatous and infraspinatous muscles are paralyzed most often
○ Symptoms
Arm lacks normal abduction and external rotation
Arm cannot be raised over head because deltoid (axillary) and supra- infraspinatous muscles
(suprascapular) are paralyzed
Elbow flexion weakened because biceps (musculocutaneous) is paralyzed
If roots damaged above their junction then additional paralysis of rhomboids (dorsal scapular)
and serratus anterior (long thoracic) producing weakness in scapular retraction and protraction
Klumpke Paralysis – lower plexus injury (C8-T1), much less common, short hand muscles
affected
○ Results in claw hand
Median Nerve Paralysis – results in atrophy of thenar muscles – Abductor pollicis brevis, Opponens
pollicis
Flexor pollicis brevis maintains some function because deep head is innervated by ulnar
Ulnar Nerve Paralysis – results in interosseous muscle atrophy
Wrist deviates to radial side since no flexor carpi ulnaris
Hyperextension of 4th and 5
th MP joints
Flexor digitorum profundus weakend – cannot flex 4th and 5
th DIP
Flexion of 2nd
and 3rd
DIP
Dupuytren’s Contracture – thickening of palmar aponeurosis
Shortening and thickening of digital bands pulls fingers into flexion (esp ring and pinky)
Colle’s Fracture – fracture of wrist resulting from falling on outstretched hand
Force transmitted through thenar eminence to lateral carpal bones and end of radius
Distal fragment displaced posteriorly („dinner fork deformity‟)
Development of the Skeletal System ○ Objectives
Understand how mesoderm and neural crest contribute to skeletal system formation
Understand the basic processes involved in development of the axial skeleton
Understand the principal molecules and genes involved in somite differentiation that relate to skeleton development
Vertebrae and Ribs ○ Describe how vertebrae and ribs are formed by endochondral ossification of sclerotome regions of somites
○ Describe the formation of intervertebral discs
○ Understand the principal molecules and genes involved in development of vertebral column
What are brevicollis, spina bifida, and scoliosis; what are some of the causes for these defects
○ Describe how ribs form from lateral processes of thoracic vertebrae
○ Describe how the sternum and clavicle are formed
What is cleidocranial dysplasia?
Understand the basic processes involved in development of the appendicular skeleton
Describe how somatic lateral plate mesoderm forms the skeleton of the appendages – the limb bones and appendicular
girdles
Describe how the appendicular skeleton is formed by endochondral ossification of cartilage models
Understand the role of the apical ectodermal ridge (AER), zone of polarizing activity (ZPA), and the molecules that establish axes of polarity in the limb
Describe how digits (fingers and toes) are formed. What is the role of cell death?
Describe limb rotation and the consequences for muscle compartments
What are Amelia, meormelia, and achondroplasia?
What are the epiphyses and diaphyses and what are their significance?
Describe how synovial joints are formed
○ Derivatives of Mesoderm
Paraxial Mesoderm – forms somites (mesoderm around a small cavity)
Gives rise to sclerotome which forms the axial skeleton
Intermediate Mesoderm – connects paraxial and lateral plate mesoderm
Lateral Plate Mesoderm – lines intraembryonic cavity, becomes parietal and visceral layers
Forms appendicular skeleton
○ Skeletal Development
Begins during week 4
Many develop from pre-existing cartilage
○ Development of Axial Skeleton
Somitic sclerotome – forms all cartilages and bones of axial skeleton
Somite Development and Axial Skeleton
Somites develop into dermomyotome (which becomes dermatome and myotome) and sclerotome
Cells migrate ventromedially (toward notochord) to make sclerotome
Sclerotome formation induced by notochord and neural tube via noggin and sonic hedgehog
Sclerotome then expresses Pax1 which initiates cartilage and bone forming gene expression
Origin of Specific Bones
Vertebrae
○ Formed by endochondral ossification
○ Develops in cranial → caudal sequence from 42-44 somite pairs
Which vertebrae a somite becomes influenced by cominations of Hox genes
4 Occipital Somites – 1 degenerates
8 Cervical Somites – the 1st cervical and remaining 3 occipital fuse to form skull base
12 Thoracic
5 Lumbar
5 Sacral – fuse to form sacrum
8-10 – coccygeal fuse to form coccyx (last 5-7 degenerate)
○ Development of Individual Vertebra
Sclerotome from each side of body converge to make each vertebrae and disc
Developing spinal nerve splits each somite and causes Cranial + Caudal parts of adjacent
somites to combine and form vertebra
Ventromedial part of each vertebra forms centrum (future vertebral body)
○ Influenced by sonic hedgehog
Dorsal part of each vertebra forms costal processes (future TP) and vertebral arch
○ Influenced by roof plate of neural tube
Why Resegment?
○ Causes myotomes to span intervertebral discs (allows muscles to move vertebra)
○ Intersegmental arteries (which were originally between sclerotomes) pass over middle of
vertebral body
○ Spinal nerves near intervertebral disks pass through intervertebral foramen
○ Development of Intervertebral Discs
Developed from lower somite (ex. C5-C6 disc is from C6 somite)
Nucleus Pulposis – derived from notochord (notochord regresses from area of vert. body)
Annulus Fibrosis – formed by condensation of other sclerotome cells
Thus, the disc has two origins, notochord and sclerotome
○ Vertebral Defects
Klippel-Feil Syndrome (Brevicollis) – congenital failure to segement cervical vert
(especially C2 & C3)
○ Causes – short neck, ↓ cervical motion, low hairline, scoliosis, hearing loss
○ Gene locus on Ch 8
Faulty Hox Gene Expression
○ Due to ↑ retinoic acid consumption or metabolic disturbances in mother
○ Results in messed up cranial-caudal gradient
Ex. If ↑ retinoic acid then type of vertebrae shift more caudally
Spina Bifida – incomplete development of vertebral arch
○ 1° Cause – failure of normal vertebral induction
○ 2° Cause – failure of neural tube to close dorsally
○ Can result in herniation of spinal cord and/or meninges
Scoliosis – defective formation of one side of vertebral column
Formation of Atlas and Axis
○ The last occipital somite and the first cervical combine to form proatlas which makes
basioccipital bone and the top of the dens
○ Remember that the atlas does not form a vertebral body (called centrum in dev), thus cells that
would normally form the centrum of C1 fuse with axis of C2 to form the dens
Ribs – form as outgrowths of thoracic vertebrae during month 2
○ Sclerotome cells migrate within somatic lateral plate mesoderm around body curvature toward
ventral surface
Sternum – forms from unification of ventral aspect of ribs 1-7 (via migrating sclerotome cells)
○ Join with two vertical cartilaginous bands
○ Costal Cartilage joins ribs to sternum
○ Then segments into elements
○ Split xiphoid process is a common malformation
Clavicle
○ Forms by intramembranous ossification (different from most others)
○ Ossification begins earlier than most bones (weeks 5-6) and is the last to complete the process
(around 21-25 years)
○ Cleidocranial Dysplasia – aplasia or hypoplasia (poorly formed) clavicles
Also affects development of head (flat nose) and teeth (too many and they don‟t fall out)
○ Note - somitic mesoderm is in somites, somatic mesoderm is in the body
○ Origin of Appendicular Skeleton
Made of appendicular girdles (shoulder and pelvic) and intrinsic limb bones
All formed by endochondral ossification except clavicle
All formed from somatic lateral plate mesoderm (including cartilage)
Note – upper limbs form before lower limbs
Overview of Limb Development Mesenchyme core develops
Ectoderm surrounds and apical ectodermal ridge is formed
Limb bud develops
Cartilage mesenchyme condenses
Cartilage models begin to form
Cartilage models completed and ossification begins
Active ossification of fetal limbs
Limb Bud
Initially consists of:
○ Mesenchyme from lateral plate mesoderm – forms skeleton, CT and some BV
○ Mesenchyme from somites – forms muscle
○ Neural crest cells – form Schwann cells and melanocytes
Apical ectodermal ridge (AER) – thickened distal border which prevents mesenchyme from
differentiating and instead causes it to proliferate rapidly (so that limb elongates)
○ Expresses SER2
○ Causes limb outgrowth and induced by factors from lateral plate mesoderm
These factors are different depending on which limb it is
○ If AER is experimentally removed then limb will stop proliferating and start differentiating
The entire limb bud is covered by ectoderm
○ Dorsal part expresses radical fringe
○ Ventral part expresses engrailed (just know that different things are expressed on either side)
The Process (mainly just understand the point)
○ Bone morphogenic factors (BMPs) in ventral ectoderm induce AER formation
○ AER restricted to distal tip of limb by radical fringe
○ Radical fringe induces SER2 expression in AER
○ Engrailed represses expression of radical fringe to maintain the polarization
○ AER then expresses FGF4 & 8 to proliferate cells
○ As limb elongates, the proximal mesenchymal cells start to differentiate as the AER gets farther
away from them
Zone of Polarizing Activity (ZPA) – cluster of cells at caudal border of limb that establish the
cranio-caudal polarization (proper location of digits etc.)
○ Produces retinoic acid which initiates expression of sonic hedgehog
Absence of SHH causes regression of AER (Why???)
○ As limb grows the ZPA moves distal to keep up with the AER
Dorsoventral Axis – regulated by BMPs in ventral ectoderm
○ BMPs cause expression of engrailed on ventral side, which represses stuff that is secreted by
dorsal side
○ LMX1 specifies cells to be dorsal
HOXd Expression Patterns in Limb
○ Pattern limb along proximodistal axis
○ Influenced by combinations of SHH and others
○ ↑ number means more distal
Development of Digits
○ Process
Apoptosis in specific parts of AER creates separate ridge for each digit
Apoptosis in interdigital spaces separates digits
○ If cell death does not occur → syndactyly (abnormal digit formation, too many or too few)
○ Apoptosis also important for separation of radius/ulna & tibia/fibia & axilla
○ Digit Specification - BMP concentration is highest between digit 4&5 and this causes digit 4 to
be digit 4. BMP concentration is lowest between 1&2 and this causes 1 to become 1
Limb Rotation
○ At first all limbs are oriented so that flexors are on one side and extensors on the other
○ Then upper limb rotates laterally and lower limb rotates medially so that the muscles are in the
right spot
Amelia – complete absence of limbs
Meromelia – partial absence of limb
○ Phocomelia – proximal structures small or absent
Epiphyseal Plates – temporary plate of cartilage between the diaphysis (middle of bone) and
epiphysis (end of bone)
○ Long bones have one at each end, small bones only have one, irregular bones have multiple
○ Achondroplasia (dwarfism) – abnormal ossification of cartilage that mainly affects long bones
Epiphyseal growth retarded and ceases early
Joint Formation
○ Cartilage present and differentiated
○ Joint “interzone” created by cells proliferating and increasing in density
○ Joint cavity formed by cell death, but surrounding cells stay to form joint capsule
Blood
○ Objectives (she emphasized these)
Identify the components of the blood and describe their functions
Identify sites of hematopoesis and describe what happens there
Explain the importance of stem cells and how they relate to hematopoiesis
Describe the functional anatomy of the bone marrow
Distinguish the developmental stages of formed elements
Describe the functions of granulocytes
○ Funciton – transport gases, buffer, transport hormones, produce & transport antibodies
○ Hematocrit – RBC % after centrifugation
Usually 45% RBCs, though in women it is lower
1% of it is WBCs and platelets, forming buffy coat
○ neutrophils > lymphocytes > monocytes > eosinophils > basophils
○ Granular leukocytes – neutrophils, eosinophils, basophils
○ Agranular leukocytes – monocytes, lymphocytes (T cells, B cells)
○ Nice picture??
The other 65% is plasma, just water, proteins and solutes
7% proteins – created in liver and confined to bloodstream
○ albumin – maintains blood osmotic pressure
○ immunoglobulins – antibodies
○ fibrinogen – for clotting
1-2% - electrolytes, nutrients, hormones, waste products, gases
○ RBCs
Important Structures
Band 3 – ion transporter & site for ankyrin to hold onto
Spectrin + Band 4.1 + actin – lets RBC be pliable
Reticulocytes – immature RBCs in circulation
Identifiable because they have a thin band of ribosomes
Anemia – deficiency in hemoglobin
Normochromic anemia
○ Hereditary spherocytosis – abnormal spectrin causes RBC shape deformity
○ Sickle Cell Disease – Valine substituted for glutamate. Can have reverisibly and non-reversibly
sickled RBCs
Hypochromic anemia – Iron deficiency of some sort (poor diet, blood loss)
Polycythemia – net increase in RBCs resulting in ↑ hematocrit and ↑ blood viscosity
Can be caused by stem cell disorder or ↑ erythropoietin
○ WBCs
Type Picture % Diameter Targets Nucleus Look
Neutrophils
60-70 10-12 -Bacterial first
defense
-phagocytes
multilobed Clear granules
you can‟t see
Eosinophils
2-4 10-12 -antiparasitic
-inhibits
histamine
-phagocytizes
antigen-antibody
complexes
Bilobed Pink granules
Basophils
<1 12-15 -Inflammatory
-Allergic
bilobed Dark blue
granules
Lymphocytes
20 7-8 T-Cells
B-Cells
Takes up
much of
the cell
Big nucleus,
very dark
because of
dense chromatin
Monocytes
3-8 14-17
biggest
-precursors to
macrophages
Kidney
shaped
-can find
nucleolus in
each lobe
-chromatin
not condensed
Megakaryocyte
Huge -doesn‟t
circulate
-makes platelets
Complex,
multilobed,
<64N
Note – neutrophils don‟t circulate, they marginate in capillaries and organs and sit there until needed
Note – eosinophil chemoattraction inhibited by steroids
Note – basophils involved with inflammatory response by release of histamine, heparin and serotonin
Serotonin and heparin are main culprits for anaphylactic shock since they help relax muscles?
Basophils also involved with allergic response via release of leukotrienes
Note – Monocytes are antigen presting cells, osteoclasts in bone, and Kupffer cells in liver (which help
recycle RBCs)
Lymphocytes
T-Lymphocytes – cell mediated immunity, many made as children and live forever
○ immune memory, 90% in blood
○ Present antigen to B-Cells
B-Lymphocytes – 4-10% in blood, mediate humoral immunity
○ Synthesize and secrete antibodies
Platelets
Hyalomere – outer visible ring containing microtubules allowing it to be contractile
Granulomere – internal structure of platelet (no nucleus)
○ Surface-opening tubule – where granules are released
○ Dense tubular system – machinery of platelets
Cytoplasm of megakaryocytes just buds off and platelets are formed
Thromboembolism – platelets blocking vessels
Coagulation disorders can be caused by Vitamin K deficiency, hemophilia
Thrombocytopenia – low # of platelets
○ Can be caused by leukemia, cancer, chemo drugs
○ Can result in petichiae (little bruises) and ecchymoses (big hemorrhages)
Types of Granules
All granulocytic leukocytes have azurophilic granules which are part of the lysosome and are clear
Neutrophils have three types of granules, but all are clear
Major Basic Protein – a specific granule found in eosinophils that helps fight against parasites
○ Bone Marrow
Clavicle is 1st place where bone marrow is formed
Cells in bone marrow ↓ with age
All cells in bone marrow are derived from one stem cell?
Megakaryocytes are always located near sinuses
Erythroblastic island – where RBCs are formed
Nurse cell – in the middle that phagocytizes old RBCs (a macrophage)
Hematopoetic cord – the cellular part
Adventitial Cells – can make fat and turn marrow into yellow marrow, this is reversible if necessary
These are the big clear cells in bone marrow
Reticular fiber used to hold everything together
Hematopoesis
Stem cells can make anything
Progenitor cells – high mitotic activity, self-renewing. Often have „forming cell‟ in the name
Precursor cells – high mitotic activity, not self-renewing. Often have „blast‟ or „myelocyte‟ in name
Mature cells - no mitotic activity, first cells to be seen in blood
Erythropoiesis
○ Cell gets smaller at each stage
○ Amount of RNA ↓ and amount of hemoglobin ↑ as process progresses
○ Proerythroblast – first cell you can visually identify
Responds to erythropoietin (only one to do so) which is released by kidney
○ Basophilic erythroblast – lots of protein (hemoglobin) and RNA synthesis
○ Polychromatophilic erythroblast – RNA becomes visible and nucleus darkens
Concentration of ribosomes and hemoglobin is equal
○ Orthochromatophilic erythroblast - Mitosis occurs up until this stage, afterwards nucleus is
extruded and mitosis stops
Nucleus is near one side
Granulopoiesis
○ Promyelocyte – gives rise to all granule cells. oval nucleus with nucleoli
○ Myelocyte stage – granules specific to each cell begin to form
○ Metamyelocyte stage – nucleus changes shape, more granules present
○ (Band Cell) – specific to neutrophils, nucleus like a horseshoe
○ Mature phenotype
Monopoiesis (difficult to find)
○ Monoblast → promonocyte → monocyte → differentiates into macrophage
○ Promonocyte has well developed golgi, RER, mitochondria, lysosomes