Chapter 15Chapter 15

The Skeletal SystemThe Skeletal System

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FunctionsFunctions

►Act as the framework of the bodyAct as the framework of the body►Support and protect some of the Support and protect some of the

internal organsinternal organs►Contains and protects the red bone Contains and protects the red bone

marrowmarrow►Provides a storage site for excess Provides a storage site for excess

calciumcalcium

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Structures of the Skeletal Structures of the Skeletal SystemSystem

►BonesBones►CartilageCartilage►LigamentsLigaments► JointsJoints►BursaeBursae

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Bones Bones

►Related Combining FormsRelated Combining Forms oss/e, oss/ioss/e, oss/i oste/o, ost/ooste/o, ost/o

►TissuesTissues Periosteum (Periosteum (peri-peri- means surrounding) means surrounding) Compact Bone – forms outer layer of bonesCompact Bone – forms outer layer of bones Spongy Bone – found inside bones – makes Spongy Bone – found inside bones – makes

them lighter and contains red bone marrowthem lighter and contains red bone marrow Endosteum – lines the medullary cavityEndosteum – lines the medullary cavity

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Classification of BonesClassification of Bones

► LongLong Longer than they are Longer than they are

widewide The shaft is hollow The shaft is hollow

and contains yellow and contains yellow bone marrowbone marrow

Examples include the Examples include the bones of the upper bones of the upper and lower extremities and lower extremities (except for the wrists (except for the wrists and ankles)and ankles)

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Classification of BonesClassification of Bones

► ShortShort Roughly cuboidalRoughly cuboidal Comprised mostly of Comprised mostly of

spongy bone with a spongy bone with a thin covering of thin covering of compact bonecompact bone

Examples: Wrist, Examples: Wrist, ankle, kneecapankle, kneecap

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Classification of BonesClassification of Bones

►FlatFlat Made of a thin layer of spongy bone Made of a thin layer of spongy bone

sandwiched between layers of compact sandwiched between layers of compact bonebone

Spongy bone usually contains red bone Spongy bone usually contains red bone marrowmarrow

Used to protect internal organsUsed to protect internal organs Examples: skull, ribs, etcExamples: skull, ribs, etc

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Classification of BonesClassification of Bones

► IrregularIrregular Includes bones that do not fit into any of Includes bones that do not fit into any of

the previous categoriesthe previous categories Composed of spongy bone with a thin Composed of spongy bone with a thin

layer of compact bone on the outsidelayer of compact bone on the outside Red bone marrow is contained in the Red bone marrow is contained in the

spongy bonespongy bone Examples: vertebrae, facial bones, etcExamples: vertebrae, facial bones, etc

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Anatomical LandmarksAnatomical Landmarks

► DiaphysisDiaphysis Shaft of a long boneShaft of a long bone

► EpiphysisEpiphysis Wide end of a long bone Wide end of a long bone

(covered with articular (covered with articular cartilage)cartilage)

Can be identified as proximal Can be identified as proximal or distalor distal

► ForamenForamen Opening in the bone through which structures Opening in the bone through which structures

can pass (ex blood vessels, nerves, etc)can pass (ex blood vessels, nerves, etc)► ProcessProcess

Normal projection on the surface of a bone that Normal projection on the surface of a bone that serves as an attachment for tendons and serves as an attachment for tendons and ligamentsligaments

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Bone Marrow Bone Marrow

► Primary Functions Primary Functions Red bone marrow forms red and white blood Red bone marrow forms red and white blood

cells and plateletscells and platelets►Stem cellsStem cells►Makes up all the marrow in an infantMakes up all the marrow in an infant

Yellow bone marrow stores fat Yellow bone marrow stores fat ►Replaces part of the red bone marrow in Replaces part of the red bone marrow in

mature humansmature humans

► Related Combining FormRelated Combining Form myel/omyel/o (also means spinal cord)(also means spinal cord)

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CartilageCartilage

► Functions as a shock absorber and a Functions as a shock absorber and a structural element structural element

► Creates a smooth surface for motion within Creates a smooth surface for motion within the joints. the joints. Protects the ends of the bones.Protects the ends of the bones. Chondr/oChondr/o means cartilage means cartilage

► 3 types3 types HyalineHyaline ElasticElastic FibrocartilageFibrocartilage

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CartilageCartilage

►Hyaline cartilage covers the ends of bones Hyaline cartilage covers the ends of bones where they join to provide a smooth surfacewhere they join to provide a smooth surface AKA Articular cartilageAKA Articular cartilage

► Elastic Cartilage is found in the ear and in Elastic Cartilage is found in the ear and in the larynxthe larynx

► Fibrocartilage is found between the Fibrocartilage is found between the vertebrae and where ligaments and tendons vertebrae and where ligaments and tendons join to bonejoin to bone

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OssificationOssification

►Process by which cartilage in the fetus Process by which cartilage in the fetus is changed into boneis changed into bone Bone matrix is produced by osteoblasts Bone matrix is produced by osteoblasts

(-blast(-blast means embryonic cell) means embryonic cell) Process begins at the center of Process begins at the center of

ossification (center) of the boneossification (center) of the bone► long bones also have centers of ossification in long bones also have centers of ossification in

their epiphysestheir epiphyses Osteoclasts reabsorb bone matrix in the Osteoclasts reabsorb bone matrix in the

interior of the bones interior of the bones (-clast(-clast means break means break down)down)

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LigamentsLigaments

►Tough bands of fibrous connective Tough bands of fibrous connective tissue that link bones, cartilages, or tissue that link bones, cartilages, or other body structures togetherother body structures together

► In the skeletal system, ligaments hold In the skeletal system, ligaments hold bones together at joints to prevent bones together at joints to prevent dislocation or excessive movementdislocation or excessive movement Ligament/oLigament/o means ligamentmeans ligament

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JointsJoints

►AKA ArticulationsAKA Articulations►Connections between bonesConnections between bones►Some allow bones to move, some do Some allow bones to move, some do

notnot Arthr/oArthr/o andand articul/o articul/o bothboth mean jointmean joint

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Types of JointsTypes of Joints

►SutureSuture Formed when bones are very close Formed when bones are very close

togther togther ►Only separated by fibrous connective tissueOnly separated by fibrous connective tissue

ImmovableImmovable Most common in the skull where the Most common in the skull where the

cranial bones meetcranial bones meet►Formed when the fontanels present in the Formed when the fontanels present in the

infant’s skull are ossifiedinfant’s skull are ossified

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Types of JointsTypes of Joints

►SymphysisSymphysis Two bones joined together with cartilage Two bones joined together with cartilage

to function as one boneto function as one bone Only slightly movableOnly slightly movable Example: pubic symphysis, vertebrae, ribs Example: pubic symphysis, vertebrae, ribs

to sternumto sternum

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Types of JointsTypes of Joints

► SynovialSynovial Two bones held in proximity by ligamentsTwo bones held in proximity by ligaments

►Synov/o, synovi/oSynov/o, synovi/o MovableMovable Come in different typesCome in different types

►Ball and socket – wide range of movement in Ball and socket – wide range of movement in any direction (hips, shoulders)any direction (hips, shoulders)

►Hinge – movement primarily in one direction Hinge – movement primarily in one direction (elbows, knees, etc)(elbows, knees, etc)

Covered by a fibrous capsule and a synovial Covered by a fibrous capsule and a synovial membrane that secretes synovial fluidmembrane that secretes synovial fluid

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BursaeBursae

►Primary Function Primary Function Cushions areas of joints that are subject Cushions areas of joints that are subject

to friction during movement. to friction during movement. Basically a fluid-filled sac located between Basically a fluid-filled sac located between

the skin and jointthe skin and joint

►Related Combining FormRelated Combining Form burs/oburs/o

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SkeletonSkeleton

►206 Bones in the adult human body206 Bones in the adult human body►To help organize, the bones are divided To help organize, the bones are divided

into the Axial and Appendicular Skeletoninto the Axial and Appendicular Skeleton AxialAxial

►80 bones80 bones►Consists of the skull, spine, ribs and sternumConsists of the skull, spine, ribs and sternum

AppendicularAppendicular►126 bones126 bones►Consists of the bones of the upper and lower Consists of the bones of the upper and lower

extremitiesextremities

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Axial SkeletonAxial Skeleton

► SkullSkull Made up of Made up of 88 cranial bones, cranial bones, 1414 facial bones, and facial bones, and

66 auditory ossicles auditory ossicles Cranial bonesCranial bones

►Protect the brain (Protect the brain (crani/ocrani/o means skull) means skull) Frontal (forehead)Frontal (forehead) 2 Parietal (roof and sides of skull)2 Parietal (roof and sides of skull) Occipital (floor and back of the skull)Occipital (floor and back of the skull) 2 Temporal (sides and part of the base)2 Temporal (sides and part of the base) Sphenoid (part of the base of the skull, floor Sphenoid (part of the base of the skull, floor

and sides of the orbit)and sides of the orbit) Ethmoid (part of the nose, orbit and Ethmoid (part of the nose, orbit and

cranium)cranium)

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Axial SkeletonAxial Skeleton

Auditory OssiclesAuditory Ossicles►Malleus, Incus, Stapes (x2)Malleus, Incus, Stapes (x2)

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Axial SkeletonAxial Skeleton Facial BonesFacial Bones

►2 Nasal bones (bridge of nose)2 Nasal bones (bridge of nose)►2 Zygomatic bones (cheekbones)2 Zygomatic bones (cheekbones)►2 Maxillae (upper jaw)2 Maxillae (upper jaw)►2 Palatine bones (part of the hard palate and 2 Palatine bones (part of the hard palate and

floor of the nose)floor of the nose)►2 Lacrimal bones (inner corner of orbit)2 Lacrimal bones (inner corner of orbit)►2 Inferior Chonchae (interior of nose2 Inferior Chonchae (interior of nose►Vomer (nasal septum)Vomer (nasal septum)►Mandible (lower jaw – only movable bone of Mandible (lower jaw – only movable bone of

the skull)the skull) Temporomandibular joint (TMJ)Temporomandibular joint (TMJ)

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Axial SkeletonAxial Skeleton

►Thoracic Cage Thoracic Cage 25 bones25 bones Sternum Sternum

►AKA breastboneAKA breastbone►Form the center of the anterior chest wallForm the center of the anterior chest wall►3 parts3 parts

Manubrium –upper part of the sternumManubrium –upper part of the sternum Body – middle of the sternumBody – middle of the sternum Xiphoid process – cartilage, lower part of Xiphoid process – cartilage, lower part of

sternumsternum

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Axial SkeletonAxial Skeleton

RibsRibs►Protect the lungs, heart, liver, spleenProtect the lungs, heart, liver, spleen►AKA Costals (AKA Costals (cost/o cost/o means rib)means rib)►12 pairs12 pairs

First 7 pairs are called true ribs because First 7 pairs are called true ribs because they are attached anteriorly to the sternumthey are attached anteriorly to the sternum

Next 3 pairs are false ribs because they do Next 3 pairs are false ribs because they do not directly attach to the sternum, but they not directly attach to the sternum, but they do attach to the cartilage that joins to the do attach to the cartilage that joins to the sternumsternum

Last 2 pairs are called floating ribs because Last 2 pairs are called floating ribs because they are not attached anteriorlythey are not attached anteriorly

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Axial SkeletonAxial Skeleton

►Vertebral ColumnVertebral Column Supports the head and protects the spinal Supports the head and protects the spinal

cordcord►Vertebr/o, spondyl/oVertebr/o, spondyl/o mean vertebraemean vertebrae►Rachi/o, rach/i, spin/oRachi/o, rach/i, spin/o mean spinemean spine

Bodies of adjacent vertebrae are Bodies of adjacent vertebrae are separated by discs of fibrocartilage separated by discs of fibrocartilage (symphysis joints)(symphysis joints)

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Axial SkeletonAxial Skeleton 26 vertebrae26 vertebrae

►Cervical vertebraeCervical vertebrae – first 7, form the – first 7, form the neck (neck (cervic/ocervic/o means neck) means neck) C1 is known as the atlas, C2 is C1 is known as the atlas, C2 is

known as the axisknown as the axis►Thoracic vertebraeThoracic vertebrae – 12, form the – 12, form the

upper backupper back►Lumbar vertebraeLumbar vertebrae – 5, form the lower – 5, form the lower

backback►Sacrum Sacrum – triangular shaped, forms – triangular shaped, forms

the lower, lower back (5 bones fused the lower, lower back (5 bones fused in childhood)in childhood)

►Coccyx Coccyx – tailbone, end of spine (4 – tailbone, end of spine (4 small vertebrae that fuse together)small vertebrae that fuse together)

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Appendicular SkeletonAppendicular Skeleton

►Upper ExtremitiesUpper Extremities Pectoral GirdlePectoral Girdle

►Clavicle – collarbone, connects manubrium to Clavicle – collarbone, connects manubrium to scapula (scapula (clavicul/oclavicul/o)) Most frequently fractured bone in the bodyMost frequently fractured bone in the body

►Scapula – shoulder blade (Scapula – shoulder blade (scapul/oscapul/o)) Acromion – extension of the scapula that Acromion – extension of the scapula that

forms the high point of the shoulderforms the high point of the shoulder

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Appendicular SkeletonAppendicular Skeleton

ArmsArms►Humerus – upper arm (Humerus – upper arm (humer/o)humer/o)►Radius – lateral side of forearm Radius – lateral side of forearm

(smaller bone) ((smaller bone) (radi/o)radi/o)►Ulna – medial side of forearm Ulna – medial side of forearm

((uln/ouln/o))►Olecranon process – projection of Olecranon process – projection of

ulna that forms the point of the ulna that forms the point of the elbow (funny bone)elbow (funny bone)

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Appendicular SkeletonAppendicular Skeleton

Wrist and HandWrist and Hand►AKA Carpus (AKA Carpus (carp/ocarp/o means wrist) means wrist)►8 short bones known as 8 short bones known as carpalscarpals►5 5 metacarpalsmetacarpals ( (meta-meta- means next) means next)

Form the palm of the handForm the palm of the hand►28 28 phalangesphalanges ( (phalang/ophalang/o))

Singular: phalanxSingular: phalanx Fingers have 3 phalanges (distal, medial, Fingers have 3 phalanges (distal, medial,

proximal)proximal) The thumb has 2 phalanges (distal and The thumb has 2 phalanges (distal and

proximal)proximal)

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Appendicular SkeletonAppendicular Skeleton

► Pelvic GirdlePelvic Girdle Forms the pelvic cavity (Forms the pelvic cavity (pelv/i pelv/i means pelvis)means pelvis) 2 pubic bones, each with 3 parts2 pubic bones, each with 3 parts

►IliumIlium – broad, flat bone – broad, flat bone (ili/o(ili/o) ) ►IschiumIschium – lower posterior portion of the pubic – lower posterior portion of the pubic

bone (bone (ischi/oischi/o))►PubisPubis – forms the anterior portion of the pubic – forms the anterior portion of the pubic

bone (bone (pub/opub/o)) The two bones join at the The two bones join at the pubic symphysispubic symphysis and and

connect with the sacrum at the connect with the sacrum at the sacroiliacsacroiliac joint joint The lower extremity joins to the pelvic bone at The lower extremity joins to the pelvic bone at

the the acetabulumacetabulum (hip socket) (hip socket)

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Appendicular SkeletonAppendicular Skeleton

► LegsLegs Femur – thigh boneFemur – thigh bone

►Largest, strongest bone in the Largest, strongest bone in the human bodyhuman body

►Femor/oFemor/o Patella – kneecapPatella – kneecap

►Popliteal is a term used to Popliteal is a term used to describe the posterior surface describe the posterior surface of the knee (of the knee (patell/opatell/o))

Tibia – shinbone, forms the Tibia – shinbone, forms the anterior of the lower leg (anterior of the lower leg (tibi/o)tibi/o)

Fibula – smaller bone of the lower Fibula – smaller bone of the lower leg (leg (fibul/ofibul/o))

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Appendicular SkeletonAppendicular Skeleton

►Ankles and FeetAnkles and Feet AKA Tarsus (AKA Tarsus (tars/otars/o means ankle) means ankle) 5 short bones called tarsals5 short bones called tarsals

►Ex calcaneus or heel boneEx calcaneus or heel bone

5 metatarsals form the body of the foot5 metatarsals form the body of the foot Each toe is made up of 3 phalanges, Each toe is made up of 3 phalanges,

except for the big toe (hallux), which only except for the big toe (hallux), which only has 2has 2