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Chapter 8Chapter 8

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22

Overview of the SkeletonOverview of the Skeleton

Regions of the skeletonRegions of the skeleton• axial skeleton = central axisaxial skeleton = central axis• appendicular skeleton = limbs and appendicular skeleton = limbs and

girdlesgirdles Number of bonesNumber of bones

• 206 in typical adult skeleton206 in typical adult skeleton varies with development of sesamoid bones varies with development of sesamoid bones

(patella)(patella) Classification of ossicles on the earClassification of ossicles on the ear

33

Surface Features of BonesSurface Features of Bones

44

Axial and Appendicular SkeletonAxial and Appendicular Skeleton

Axial skeleton in Axial skeleton in tantan• skull, vertebrae, skull, vertebrae,

sternum, ribs, sternum, ribs, sacrum and hyoidsacrum and hyoid

Appendicular Appendicular skeleton in greenskeleton in green• pectoral girdlepectoral girdle• upper extremityupper extremity• pelvic girdlepelvic girdle• lower extremitylower extremity

55

Major Skull CavitiesMajor Skull Cavities

66

The SkullThe Skull

22 bones joined together by sutures22 bones joined together by sutures Cranial bones surround cranial cavityCranial bones surround cranial cavity

Facial bones support teeth and form Facial bones support teeth and form nasal cavity and orbitnasal cavity and orbit

77

Cranial FossaCranial Fossa

3 basins that comprise the cranial floor or base3 basins that comprise the cranial floor or base• anterior fossa holds the frontal lobe of the brainanterior fossa holds the frontal lobe of the brain• middle fossa holds the temporal lobes of the middle fossa holds the temporal lobes of the

brainbrain• posterior fossa contains the cerebellumposterior fossa contains the cerebellum

88

Frontal BoneFrontal Bone Forms forehead and Forms forehead and

part of the roof of part of the roof of the craniumthe cranium

Forms roof of the Forms roof of the orbitorbit

Contains frontal Contains frontal sinussinus

99

Parietal BoneParietal Bone

Cranial roof and part Cranial roof and part of its lateral wallsof its lateral walls

Bordered by 4 Bordered by 4 suturessutures

Temporal lines of Temporal lines of temporalis muscletemporalis muscleTemporal lines

1010

Temporal BoneTemporal Bone Lateral wall and part Lateral wall and part

of floor of cranial of floor of cranial cavitycavity

zygomatic processzygomatic process mandibular fossa and mandibular fossa and

TMJTMJ

external auditory external auditory meatusmeatus

styloid processstyloid process mastoid processmastoid process

1111

Petrous Portion of Temporal BonePetrous Portion of Temporal Bone

Part of cranial floorPart of cranial floor

Houses middle and Houses middle and inner ear cavitiesinner ear cavities

• internal auditory meatusinternal auditory meatus

1212

Right Temporal Bone Right Temporal Bone

1313

Openings in Temporal BoneOpenings in Temporal Bone

Carotid canalCarotid canal

Jugular foramenJugular foramen• Created by temporal Created by temporal

and occipital bone and occipital bone “joint”“joint”

1414

Occipital BoneOccipital Bone

Foramen magnum holds Foramen magnum holds spinal cordspinal cord

Skull rests on atlas at Skull rests on atlas at occipital condylesoccipital condyles

External occipital External occipital protuberance for nuchal protuberance for nuchal ligamentligament

Nuchal lines mark neck Nuchal lines mark neck musclesmuscles

1515

Sphenoid BoneSphenoid Bone

Lesser wingLesser wing Greater wingGreater wing Body of sphenoidBody of sphenoid Medial and lateral Medial and lateral

pterygoid processespterygoid processes

1616

Sphenoid BoneSphenoid Bone Body of the sphenoidBody of the sphenoid

• sella turcica contains sella turcica contains hypophyseal fossahypophyseal fossa

• houses pituitary glandhouses pituitary gland Lesser wingLesser wing

• optic foramen optic foramen Greater wing Greater wing

Foramen ovaleForamen ovale

1717

Sphenoid BoneSphenoid Bone

Sphenoid sinusSphenoid sinus

1818

Ethmoid BoneEthmoid Bone

Lateral walls and roof nasal Lateral walls and roof nasal cavitycavity

Cribriform plate and crista galliCribriform plate and crista galli Ethmoid air cells form ethmoid Ethmoid air cells form ethmoid

sinussinus Perpendicular plate forms part Perpendicular plate forms part

of nasal septumof nasal septum Concha (turbinates) on lateral Concha (turbinates) on lateral

wallwall

1919

Ethmoid BoneEthmoid Bone

Superior and middle conchaSuperior and middle concha

Perpendicular plate of Perpendicular plate of nasal septumnasal septum

2020

Maxillary BonesMaxillary Bones

Forms upper jawForms upper jaw• alveolar processes are bony pointsalveolar processes are bony points

between teethbetween teeth• alveolar sockets hold teethalveolar sockets hold teeth

Forms inferomedial wall of orbitForms inferomedial wall of orbit• infraorbital forameninfraorbital foramen

Forms anterior 2/3’sForms anterior 2/3’sof hard palateof hard palate• incisive foramenincisive foramen• cleft palate cleft palate

2121

Locations of Paranasal SinusesLocations of Paranasal Sinuses

Maxillary sinus fills maxillae boneMaxillary sinus fills maxillae bone Other bones containing sinuses are frontal, Other bones containing sinuses are frontal,

ethmoid and sphenoid.ethmoid and sphenoid.

2222

Palatine BonesPalatine Bones

L-shaped boneL-shaped bone Posterior 1/3 of the Posterior 1/3 of the

hard palate hard palate Part of lateral nasal Part of lateral nasal

wallwall Part of the orbital Part of the orbital

floorfloor

2323

Zygomatic BonesZygomatic Bones

Forms angles of the Forms angles of the cheekbones and part cheekbones and part of lateral orbital wallof lateral orbital wall

Zygomatic arch is Zygomatic arch is formed from formed from temporal process of temporal process of zygomatic bone and zygomatic bone and zygomatic process of zygomatic process of temporal bonetemporal bone

2424

Lacrimal BonesLacrimal Bones

Form part of medial Form part of medial wall of each orbitwall of each orbit

Lacrimal fossaLacrimal fossa

2525

Nasal BonesNasal Bones

Forms bridge of Forms bridge of nose and supports nose and supports cartilages of nosecartilages of nose

Often fractured by Often fractured by blow to the noseblow to the nose

2626

Inferior Nasal ConchaeInferior Nasal Conchae

A separate boneA separate bone Not part of ethmoid Not part of ethmoid

like the superior and like the superior and middle concha or middle concha or turbinatesturbinates

2727

VomerVomer

Inferior half of the Inferior half of the nasal septumnasal septum

Supports cartilage Supports cartilage of nasal septumof nasal septum

2828

Only movable bone Only movable bone • TMJ joint between mandibular fossaTMJ joint between mandibular fossa

and condyloid processand condyloid process Attachment of muscles of Attachment of muscles of

masticationmastication

Mandibular foramenMandibular foramen Mental foramenMental foramen

MandibleMandible

2929

Ramus, Angle and Body of Ramus, Angle and Body of MandibleMandible

3030

Auditory ossiclesAuditory ossicles• malleus, incus, and malleus, incus, and

stapesstapes Hyoid boneHyoid bone

• suspended from suspended from styloid process of styloid process of skull by muscle skull by muscle and ligamentand ligament

Bones Associated With SkullBones Associated With Skull

3131

Skull in Infancy and ChildhoodSkull in Infancy and Childhood

Spaces between Spaces between unfused bones called unfused bones called fontanelsfontanels• filled with fibrous filled with fibrous

membranemembrane• allow shifting of bones allow shifting of bones

during birth and growth during birth and growth of brain of brain

Skull reaches adult size Skull reaches adult size by 8 or 9by 8 or 9

3232

The Vertebral ColumnThe Vertebral Column

33 vertebrae and 33 vertebrae and intervertebral discs of intervertebral discs of fibrocartilagefibrocartilage

Five vertebral groupsFive vertebral groups

• 7 cervical in the neck7 cervical in the neck• 12 thoracic in the chest12 thoracic in the chest• 5 lumbar in lower back5 lumbar in lower back• 5 fused sacral 5 fused sacral • 4 fused coccygeal 4 fused coccygeal

3333

Newborn Spinal CurvatureNewborn Spinal Curvature

Spine exhibits one Spine exhibits one continuous C-continuous C-shaped curveshaped curve

Known as primary Known as primary curvature curvature

3434

Adult Spinal CurvaturesAdult Spinal Curvatures

S-shaped vertebral S-shaped vertebral column with 4 column with 4 curvaturescurvatures

Secondary curvatures Secondary curvatures develop after birthdevelop after birth• lifting head as it begins lifting head as it begins

to crawl develops to crawl develops cervical curvaturecervical curvature

• walking upright walking upright develops lumbar develops lumbar curvaturecurvature

3535

Abnormal Spinal CurvaturesAbnormal Spinal Curvatures From disease, From disease,

posture, paralysis posture, paralysis or congenital defector congenital defect

Scoliosis from lack Scoliosis from lack of proper of proper development of one development of one vertebraevertebrae

Kyphosis is from Kyphosis is from osteoporosisosteoporosis

Lordosis is from Lordosis is from weak abdominal weak abdominal musclesmuscles

3636

General Structure of VertebraGeneral Structure of Vertebra

Body Body Vertebral foramen Vertebral foramen

form vertebral canalform vertebral canal Neural arch Neural arch

• 2 lamina2 lamina• 2 pedicles2 pedicles

ProcessesProcesses• spinous, transverse spinous, transverse

and articularand articular

3737

Intervertebral Foramen and DiscsIntervertebral Foramen and Discs Intervertebral Intervertebral

foramenforamen• passageway for nervespassageway for nerves

Intervertebral discsIntervertebral discs• bind vertebrae bind vertebrae

togethertogether• absorb shockabsorb shock• gelatinous nucleus gelatinous nucleus

pulposus surrounded pulposus surrounded by anulus fibrosus (ring by anulus fibrosus (ring of fibrocartilage)of fibrocartilage)

3838

Typical Cervical VertebraeTypical Cervical Vertebrae

Small body and larger vertebral foramenSmall body and larger vertebral foramen Transverse process short with transverse Transverse process short with transverse

foramen for protection of vertebral arteriesforamen for protection of vertebral arteries Bifid or forked spinous process in C2 to C6Bifid or forked spinous process in C2 to C6

3939

The Unique Atlas and AxisThe Unique Atlas and Axis Atlas (C1) supports the Atlas (C1) supports the

skullskull• ring surrounding large ring surrounding large

vertebral foramenvertebral foramen anterior and posterior archanterior and posterior arch no vertebral bodyno vertebral body

Axis (C2)Axis (C2)• dens or odontoid process is dens or odontoid process is

held in place inside the held in place inside the vertebral foramen of the vertebral foramen of the atlas by ligamentsatlas by ligaments

4040

Atlas and Axis ArticulationAtlas and Axis Articulation

4141

Typical Thoracic VertebraeTypical Thoracic Vertebrae

Larger body than cervical but smaller than lumbarLarger body than cervical but smaller than lumbar Spinous processes pointed and angled downwardSpinous processes pointed and angled downward

Rib attachmentRib attachment• costal facets on vertebral body and at ends of transverse costal facets on vertebral body and at ends of transverse

processes for articulation of ribsprocesses for articulation of ribs

4242

Lumbar VertebraeLumbar Vertebrae

Thick, stout body and blunt, squarish Thick, stout body and blunt, squarish spinous processspinous process

Superior articular processes face mediallySuperior articular processes face medially• lumbar region resistant to twisting movementslumbar region resistant to twisting movements

4343

Sacrum (Anterior View)Sacrum (Anterior View)

5 sacral vertebrae 5 sacral vertebrae fuse by age 26fuse by age 26

Ala and Sacral Ala and Sacral prominenceprominence

4444

Sacrum (Posterior View)Sacrum (Posterior View)

Median sacral crestMedian sacral crest Lateral sacral crestLateral sacral crest Posterior sacral Posterior sacral

foraminaforamina

4545

CoccyxCoccyx

Single, small boneSingle, small bone• 4 vertebrae fused by 304 vertebrae fused by 30• Co1 to Co4Co1 to Co4

Fractured by fall or Fractured by fall or during childbirthduring childbirth

4646

Thoracic CageThoracic Cage

Consists of thoracic Consists of thoracic vertebrae, sternum and vertebrae, sternum and ribsribs

Protects many organsProtects many organs Rhythmically expanded Rhythmically expanded

by respiratory muscles by respiratory muscles to draw air into the to draw air into the lungslungs

4747

Rib StructureRib Structure Flat blade called a shaftFlat blade called a shaft

• inferior margin has costal inferior margin has costal groove for nerves and vesselsgroove for nerves and vessels

Proximal head and tubercle Proximal head and tubercle are connected by neckare connected by neck

ArticulationArticulation• head with body of vertebraehead with body of vertebrae• tubercle with transverse tubercle with transverse

processprocess

Tubercle Head

4848

Numbered Rib ArticulationsNumbered Rib Articulations

4949

True and False RibsTrue and False Ribs

True ribs (1 to 7) True ribs (1 to 7) attach to sternum attach to sternum with hyaline with hyaline cartilage cartilage

False ribs (8-12)False ribs (8-12)• 11-12 are floating 11-12 are floating

and not attached to and not attached to sternumsternum

12 pairs of ribs in 12 pairs of ribs in both sexesboth sexes

5050

Pectoral GirdlePectoral Girdle Attaches upper extremity to the bodyAttaches upper extremity to the body Scapula and clavicleScapula and clavicle Clavicle attaches medially to the Clavicle attaches medially to the

sternum and laterally to the scapulasternum and laterally to the scapula• sternoclavicular jointsternoclavicular joint• acromioclavicular jointacromioclavicular joint

Scapula articulates with the humerusScapula articulates with the humerus• humeroscapular or shoulder jointhumeroscapular or shoulder joint• easily dislocated due to loose attachmenteasily dislocated due to loose attachment

5151

ClavicleClavicle

S-shaped bone, flattened dorsoventrally S-shaped bone, flattened dorsoventrally Sternal end rounded -- acromial end flattenedSternal end rounded -- acromial end flattened

5252

ScapulaScapula

Coracoid process = muscle attachmentCoracoid process = muscle attachment Subscapular, infraspinous and supraspinous fossaSubscapular, infraspinous and supraspinous fossa Glenoid fossa = socket for head of humerusGlenoid fossa = socket for head of humerus

5353

Scapular FeaturesScapular Features

5454

Upper LimbUpper Limb

Brachium (arm) = humerusBrachium (arm) = humerus Antebrachium (forearm) = radius and Antebrachium (forearm) = radius and

ulna (radius on thumb side)ulna (radius on thumb side) Carpus (wrist) = 8 small bones(2 rows)Carpus (wrist) = 8 small bones(2 rows) Manus (hand) = 19 bones(2 groups)Manus (hand) = 19 bones(2 groups)

• 5 metacarpals in palm5 metacarpals in palm• 14 phalanges in fingers14 phalanges in fingers

5555

HumerusHumerus

Anatomical neckAnatomical neck Greater and lesser tubercles Greater and lesser tubercles

and deltoid tuberosityand deltoid tuberosity Intertubercular groove holds Intertubercular groove holds

biceps tendonbiceps tendon Trochlea articulates with ulna Trochlea articulates with ulna Olecranon fossa holds Olecranon fossa holds

olecranon process of ulnaolecranon process of ulna Forearm muscles attach to Forearm muscles attach to

medial and lateral medial and lateral epicondyles epicondyles

5656

Ulna and RadiusUlna and Radius RadiusRadius

• head head articulates with capitulum articulates with capitulum

• radial tuberosityradial tuberosity UlnaUlna

• olecranon and trochlear olecranon and trochlear notch notch

Interosseous membraneInterosseous membrane• ligament attaches radius to ligament attaches radius to

ulna along interosseous ulna along interosseous margin of each bonemargin of each bone

5757

Carpal BonesCarpal Bones

Form wristForm wrist

2 rows 2 rows • proximal row = proximal row =

scaphoid, lunate, scaphoid, lunate, triquetrum and triquetrum and pisiformpisiform

• distal row = distal row = trapezium, trapezoid, trapezium, trapezoid, capitate and hamatecapitate and hamate

5858

Metacarpals and PhalangesMetacarpals and Phalanges

Phalanges are Phalanges are bones of the bones of the fingersfingers

Metacarpals are Metacarpals are bones of the palmbones of the palm

5959

Sesamoid BoneSesamoid Bone

6060

Pelvic GirdlePelvic Girdle

Girdle = 2 hip bonesGirdle = 2 hip bones Pelvis = girdle and sacrumPelvis = girdle and sacrum

Anteriorly, pubic bones are Anteriorly, pubic bones are joined by pad of joined by pad of fibrocartilage to form pubic fibrocartilage to form pubic symphysissymphysis

6161

Pelvic Inlet and OutletPelvic Inlet and Outlet

False and true pelvis separated at pelvic False and true pelvis separated at pelvic brimbrim

6262

Os Coxae (Hip Bone)Os Coxae (Hip Bone) Acetabulum is hip joint Acetabulum is hip joint

socketsocket IliumIlium

• iliac crest and iliac fossailiac crest and iliac fossa PubisPubis

• body, superior and inferior body, superior and inferior ramusramus

IschiumIschium• ischial spineischial spine• ischial ramus joins inferior ischial ramus joins inferior

pubic pubic ramusramus

6363

Comparison of Male and Comparison of Male and FemaleFemale

Female lighter, shallower pubic arch( >100 degrees), Female lighter, shallower pubic arch( >100 degrees), and pubic inlet round or ovaland pubic inlet round or oval

Male heavier, upper pelvis nearly vertical, Male heavier, upper pelvis nearly vertical, coccyx more vertical, and pelvic inlet heart-shapedcoccyx more vertical, and pelvic inlet heart-shaped

6464

Femur and Patella (Kneecap)Femur and Patella (Kneecap)

Nearly spherical head and Nearly spherical head and constricted neckconstricted neck• ligament to fovea capitisligament to fovea capitis

Greater and lesser Greater and lesser trochanterstrochanters

Posterior ridge called linea Posterior ridge called linea asperaaspera

Medial and lateral condyles Medial and lateral condyles and epicondyles found and epicondyles found distallydistally

Patella = triangular Patella = triangular sesamoidsesamoid

6565

TibiaTibia

Broad superior head with Broad superior head with 2 flat articular surfaces2 flat articular surfaces

medial and lateral condylesmedial and lateral condyles

• roughened anterior roughened anterior surface palpated below surface palpated below patellapatella(tibial tuberosity)(tibial tuberosity)

• distal expansion = medial distal expansion = medial malleolus malleolus

6666

FibulaFibula

Does not bear any Does not bear any body weightbody weight

Head = proximal Head = proximal endend

Lateral malleolus = Lateral malleolus = distal expansiondistal expansion

Joined to tibia by Joined to tibia by interosseous interosseous membranemembrane

6767

The Ankle and FootThe Ankle and Foot Tarsal bones are shaped and Tarsal bones are shaped and

arranged differently from carpal arranged differently from carpal bones due to load-bearing role of bones due to load-bearing role of the anklethe ankle

Talus is most superior tarsal boneTalus is most superior tarsal bone• forms ankle joint with tibia and forms ankle joint with tibia and

fibulafibula• sits upon calcaneus and articulates sits upon calcaneus and articulates

with navicularwith navicular Calcaneus forms heel (achilles Calcaneus forms heel (achilles

tendon)tendon) Distal row of tarsal bonesDistal row of tarsal bones

• cuboid, medial, intermediate and cuboid, medial, intermediate and lateral cuneiformslateral cuneiforms

6868

The FootThe Foot

Remaining bones of foot Remaining bones of foot are similar in name and are similar in name and arrangement to the handarrangement to the hand

Metatarsal I is proximal to Metatarsal I is proximal to the great toe (hallux)the great toe (hallux)• base, shaft and headbase, shaft and head

PhalangesPhalanges• 2 in great toe2 in great toe

proximal and distalproximal and distal

• 3 in all other toes3 in all other toes proximal, middle and distalproximal, middle and distal