1 2 6.1 Functions of the Skeletal System Support Protection Attachment sites for skeletal muscles Blood cell production Mineral storage 3 6.2 Bone Structure There are four basic types of bone based on shape Long bones e.g. thigh bone Short bones e.g. wrist bone Flat bones e.g. skull Irregular bones e.g. spine bone 4 5 Structure of a Long Bone Epiphysis Articular cartilage Diaphysis Epiphyseal plate (line) Periosteum Spongy bone Compact bone Medullary cavity Endosteum 6 Spongy (cancellous) bone Interior of small bones, skull bones, and epiphyses Consists of trabeculae and spaces filled with red bone marrow Reduces bone weight without reducing strength
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12 6.1 Functions of the Skeletal System
SupportProtectionAttachment sites for skeletal musclesBlood cell productionMineral storage
3 6.2 Bone Structure
There are four basic types of bone based on shapeLong bones e.g. thigh boneShort bones e.g. wrist boneFlat bones e.g. skullIrregular bones e.g. spine bone
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Structure of a Long BoneEpiphysisArticular cartilageDiaphysisEpiphyseal plate (line)PeriosteumSpongy boneCompact boneMedullary cavityEndosteum
6Spongy (cancellous) boneInterior of small bones, skull bones, and epiphysesConsists of trabeculae and spaces filled with red bone marrowReduces bone weight without reducing strength
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7Compact boneWall of diaphysis and surface of diaphysis
Spongy (cancellous) boneLack osteonsReceive nutrients by diffusion through canaliculi
111213 6.3 Bone Formation
Ossification is the process of bone formation during the 6th or 7th week of embryonic life
Two types of bone formation1. Intramembranous ossification2. Endochondral ossification
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For both types of bone formationPrimitive connective tissue cells become osteoblastsOsteoblasts deposit bone matrix around themOnce trapped in matrix, osteoblasts become osteocytes
161. Intramembranous OssificationForms most skull bonesSteps involvedConnective tissue membranes form at sites of future intramembranous bonesSome cells become osteoblasts and deposit spongy bone within the membrane starting in the center of boneOsteoblasts from the covering membrane (periosteum) deposit a layer of compact bone over the spongy bone
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To produce the correct bone shapeUse osteoclasts to remove bone matrixUse osteoblasts to reform new bone matrix
192. Endochondral OssificationForms most bones of the bodyExample: long bones
20Steps involvedPrimary ossification center forms in center of cartilage Periosteal osteoblasts form a collar of compact bone around primary ossification centerCartilage in the primary center calcifies and chondrocytes die
21Blood vessels and nerves penetrate the center, bring osteoblasts with themOsteoblasts form spongy bone at the primary ossification centerSecondary ossification center forms in the epiphyses
Osteoblasts form spongy bone at the primary ossification centerSecondary ossification center forms in the epiphysesOsteoclasts remove the spongy bone and form the medullary cavity
22Bone continues to growAt the end of the process, the epiphyseal plate separates the epiphyses from the diaphysis
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Continued growth in diameter due to formation of compact bone beneath the periosteumContinued growth in length takes place at the epiphyseal diskCartilage grows on the epiphyseal sideCartilage is converted into bone on the diaphysis side
Osteoblasts and osteoclasts continually reshape the bone as it growsBone growth in length continues until age 25Epiphyseal plate is completely replaced by boneEpiphyseal line is all that remains
25Homeostasis of BoneBone is continually remodeled due to activity of osteoclasts and osteoblasts
Remodeling can be affected byPhysical activityDietary calcium intakeAge
26 6.4 Divisions of the Skeleton
Skeleton is divided into two divisionsAxial skeletonBones along the longitudinal axis of the body
Appendicular skeletonPectoral girdle and upper extremities
Appendicular skeletonPectoral girdle and upper extremitiesPelvic girdle and lower extremities
2728 6.5 Axial Skeleton
SkullDivided into two segmentsCranium - 8 fused bonesFacial bones - 13 fused bones
Bones joined by suturesImmovable joints
29Several bones possess paranasal sinuses
30CraniumFrontal boneAnterior part of craniumTwo frontal sinuses
Parietal bonesSides and roof of craniumsagittal suture, coronal suture
Occipital bonesPosterior portion and floor of craniumforamen magnum: a large opening through which the brain stem extendsoccipital condyles: articulates with first vertebra (atlas) Fig 6.9lambdoidal sutures: joined to the parietal bones
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CraniumTemporal bonesInferior to parietal bones on each side of the craniumSquamosal sutures (parietal), lambdoidal sutures (occipital)external auditory canal: leads inward to eardrummandibular fosssaanterior to the auditory canala depression that receives the mandibular condyletemporomandibular joint
processeszygomatic process: projects anteriorly to join with zygomatic bonemastoid process: a large, rounded projection inferior to the auditory canal. attachment site for some neck muscles
styloid process: medial to the mastoid process, spikelike
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Sphenoid bone"Keystone" of the craniumit articulates with all other cranial bones
sella turcicaa depression that contains the pituitary gland
Two sphenoidal sinuses below sella turcica
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Ethmoid boneAnterior portion of cranium, including medial surface of eye orbit and roof of nasal cavity (ethmoid sinus)perpendicular plate: form most of the nasal septum
Anterior portion of cranium, including medial surface of eye orbit and roof of nasal cavity (ethmoid sinus)perpendicular plate: form most of the nasal septumsuperior and middle nasal conchaecribriform platethe roof of the nasal cavitycrista galli (cock's comb): to which meninges are attached
41Facial BonesMaxillaeForm upper jaw, anterior portion of hard palate, part of lateral walls of nasal cavity, floors of eye orbitsEach maxilla is formed separately, but they are joined at the midline during embryonic development → (cf. cleft lip)
palatine process → hard palate
alveolar process → teeth
alveoli: the sockets containing the teethMaxillary sinus: below orbits
Palatine bonesForm posterior portion of hard palate, lateral wall of nasal cavity
4243 zygomatic (=yoke)
Zygomatic bonesCheek bonesAlso form floor and lateral wall of each eye orbittemporal process (zygomatic bone) + zygomatic process (temporal bone) = zygomatic arch
44Lacrimal bonesMedial surfaces of eye orbits
Nasal bonesForm bridge of nose
45 vomer (=plowshare, 보습)
VomerIn midline of nasal cavity
VomerIn midline of nasal cavityForms nasal septum with the ethmoid bone
46Inferior nasal conchaeAttached to lateral walls of nasal cavity
F. hyoïde < L. hyoides < Gk. ὑοειδής huoeidēs= "shaped like the letter υ" → Y,u (upsilon ← hu)
Found in anterior portion of neck, inferior to mandibleDoes not articulate with any other bonessuspended from the styloid processes by ligamentsUsed as attachment site for tongue muscles
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The infant skullNewborn skull is incompletely developedPossess fontanelsNon-ossified areas Allow for flexibility during birth and growth afterwards6 fontanels
Allow for flexibility during birth and growth afterwards6 fontanelsanterior (1), mastoid (2), posterior (1), sphenoid (2)
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Vertebral ColumnExtends from skull to pelvisFlexible and sturdy longitudinal support for trunkFormed by 24 movable vertebrae, a sacrum, and a coccyxPossess intervertebral discsShock absorbers
Possess four distinct curvaturescervical, thoracic, lumbar, pelvic
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Structure of a VertebraAll vertebrae have common featuresBodyNeural archVertebral foramen
Spinous processTransverse processSuperior and inferior articulating facets Intervertebral foramina
55Cervical vertebraeC1-C7, Support neckPossess unique transverse foramena passageway blood vessels and nerves
56Atlas: cervical vertebra 1
56Atlas: cervical vertebra 1Articulate occipital condyles of occipital boneSupports head
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Axis: cervical vertebra 2Possesses the odontoid process (dens)Serves as a pivot point for axis
59Thoracic vertebraeT1-T12spinous processes are longer and slope downwardRibs articulate on the transverse processes and bodies
60Lumbar vertebraeL1-L5Heavy, thick bodies to support greater stress and weightBlunt spinous processes - attachment of back muscles
74ScapulaLocated on each side of vertebral columnDoes not articulate with the axial skeletonHeld in place by muscles to allow free shoulder movement
Scapular spineacromion process
Scapular spineacromion processglenoid cavitycoracoid process
75HumerusArticulates with scapula at the shoulder and ulna and radius at the elbowHead fits into glenoid cavity of the scapulagreater tubercle: lateralintertubercular groovelesser tubercle: medialneck: anatomical vs. surgical (fracture)deltoid tuberositydeltoid muscle
condylestrochlea: medial → ulna
capitulum: lateral → radius
lateral, medial epicondylesfossacoronoid f.: anterior, coronoid process of ulnaolecranon f.: posterior, olecranon process of ulna
76UlnaMedial bone in forearmBone does not move with hand rotationolecranon processfits into olecranon fossa (of humerus)
trochlear notcharticulates with trochlea (of humerus)
coronoid processfits into coronoid fossa (of humerus)
head: distal, articulates with medial surface of radius
fits into coronoid fossa (of humerus)head: distal, articulates with medial surface of radiusstyloid process: ligaments of the wrist
RadiusLateral bone in the forearmBone that rotates when the hand is rotatedhead: proximal, articulates with capitulumradial tuberosity: biceps musclestyloid process: ligaments of the wrist
77CarpalsWrist bones
MetacarpalsBones of the palm of the hand
PhalangesBones of the fingers
78Pelvic GirdleConsists ofTwo coxal bonesSacrum
Forms a rigid, bony pelvis
79Coxal BonesAttachment site for the legsFormed by three fused bonesIliumiliac crestgreater sciatic notch
iliac crestgreater sciatic notchsacroiliac joint
IschiumPubis
80Coxal BonesAttachment site for the legsFormed by three fused bonesIliumiliac crestgreater sciatic notchsacroiliac joint
Ischiumischial tuberosityischial spine: determines the diameter of the pelvic opening during childbirth
Pubis
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Coxal BonesAttachment site for the legsFormed by three fused bonesIliumiliac crestgreater sciatic notchsacroiliac joint
Ischiumischial tuberosityischial spine
Pubisobturator foramensymphysis pubis
obturator foramensymphysis pubis
Three bones join at acetabulum
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The pelvic girdles of males and females have several structural differences
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Lower ExtremityFemurThigh boneLargest and strongest bone in the bodyhead ( → acetabulum)
PatellaKneecap, anterior to the knee jointIt is a sesamoid bone, which refers to a bone that is embedded in the tendon
88TibiaShinboneLager, medial bone in lower legBears body weightlateral (medial) condyle: femurtibial tuberosity: patellar ligamentmedial malleolus: medial prominence of the ankle
FibulaSlender, lateral bone in lower leglateral malleolus: lateral prominence of the ankle
Slender, lateral bone in lower leglateral malleolus: lateral prominence of the ankle
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Tarsalsankle bonestalus: the prominent tarsal bonecalcaneus: heel bone
MetatarsalsBones of the instep
PhalangesToe bones
9192 6.7 Articulations
An articulation is a joint or junction between two bonesJoints allow for varying degrees of movementThree categories of jointsImmovableSlightly movableFreely movable
93Immovable Joints (synarthrosis)Bones are tightly joined and separated by thin fibrous connective tissueNo movement at the jointExample: sutures
Slightly Movable Joints (amphiarthrosis)Bones separated by layer of cartilage or fibrous connective tissueLimited flexibility
Bones separated by layer of cartilage or fibrous connective tissueLimited flexibilityExample: joints between vertebrae
94Freely Movable Joints (diarthrosis)Joints are freely movableStructurally more complexSeveral types of freely movable jointsjoint (articular) capsule: formed of ligamentcf. ligament vs. tendon
95Gliding JointsInvolve sliding of bones across each otherExample: carpal and tarsal bones
96Condyloid JointsAllow movement from side to side and back and forthExample: between carpals and bones of forearm
97Hinge JointsAllow movement in one direction onlyExample: knee and elbow joints
98Saddle JointsEnds of each bone are saddle shapedMovement is side to side and back and forthExample: joint between trapezium and metacarpal of thumb
Example: joint between trapezium and metacarpal of thumb
99Pivot JointsAllow rotational movementExample: atlas on the axis
100Ball-and-Socket JointsA rounded head of one bone fits into a concavity on another boneMovement may be rotational or in any planeExample: hip and shoulder joint
101Movements at Freely Movable JointsMovement is caused by contraction of muscles that span the joint
Movement depends upon joint type and location of muscle(s) involved
102103104105106107 6.8 Disorders of the Skeletal System
Common disorders can be characterized asDisorders of bonesDisorders of joints
OrthopedicsBranch of medicine that specializes in treating skeletal disease and abnormalities
108 Disorders of Bones
Fractures: broken bonesComplete: The break is completely through the bone.Compound: A broken bone pierces the skin.
Complete: The break is completely through the bone.Compound: A broken bone pierces the skin.Simple: A bone does not pierce the skin.Comminuted: The bone is broken into several pieces.Segmental: Only one piece is broken out of the bone.Spiral: The fracture line spirals around the bone.Oblique: The break angles across the bone.Transverse: The break is at right angles to the long axis of the bone.Incomplete: The bone is not broken completely through.Green stick: The break is only on one side of the bone, and the bone is bowed.Fissured: The break is a lengthwise split in the bone.
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OsteomyelitisInflammation of bone and bone marrow due to bacterial infection
OsteoporosisWeakening of bone due to loss of calcium saltsCommon in older people, especially postmenopausal womenCaused by inactivity and decrease in hormone production
111RicketsChildhood diseaseDue to deficiency of calcium salts in bonesDietary deficiency in calcium or Vitamin DChildren have a bowlegged appearance
112 Disorders of Joints
ArthritisCharacterized by inflammation, swelling, and painRheumatoid arthritisMost painful and crippling type
Most painful and crippling typeResult is ossification of joint, making it immovableAuto-immune disorder
OsteoarthritisMost common typeLoss of articular cartilage makes movement restricted and painful
113BursitisInflammation of bursa
DislocationDisplacement of bones forming the joint
Herniated diskIntervertebral disc protrudes out beyond vertebraeCaused by excessive pressureMay apply pressure to nerves
