BIO 210 LabInstructor: Dr. Rebecca Clarke

Chapter 8:The Appendicular Skeleton

Appendicular Skeleton Allows us to move and manipulate objectsIncludes all bones besides axial skeleton:

the limbs the supportive girdles

Pectoral (shoulder)Pelvic

Appendicular Skeleton

Figure 8–1

Pectoral Girdle Also called the shoulder girdlePositions shoulder jointsConnects the arms to the body Provides base for muscle attachmentHelps move upper limbs

Pectoral Girdle

Figure 8–2a

Pectoral Girdle Consists of:

2 clavicles 2 scapulae

Connects with axial skeleton only at the manubrium (clavicle articulations)

ClavicleAlso called collarboneLong, S-shaped boneOriginates at manubrium (sternal end)Articulates with scapula (acromial end)Relatively fragile so fractures common

ClavicleSternal End:

Square, flat surfaceArticulates with

manubrium; only ones between axial skeleton and pectoral girdle

Acromial End:Flatter, broader

endArticulates with

acromion of scapula

Figure 8–2b, c

Scapula Also called shoulder bladeBroad, flat triangleArticulates with arm and collarboneSkeletal muscles support/position

Extreme mobilityNot much strength

Scapula: Posterior SurfaceBody

Broad, flat, triangular area

Has 3 borders/ marginsSuperiorMedialLateral

Figure 8–3c

Scapula: Posterior Surface

SpineLarge ridge across

posterior surfaceShoulder blade

Supraspinous fossaDepression superior to

spineInfraspinous fossa

Depression inferior to spine

Figure 8–3c

Scapula: Posterior SurfaceAcromion

Large, posterior extension at lateral end of spine

Articulates with clavicle (acromial end)

Figure 8–3c

Scapula: Lateral ViewGlenoid fossa (cavity)

Cup-shaped, lateral depression

Articulates with humerus

Forms shoulder joint

Figure 8–3c

Scapula: Lateral ViewCoracoid process

Smaller, anterior projection superior to glenoid cavity

Near clavicle vs coronoid process on mandible near nose)

Figure 8–3c

Scapula: Anterior SurfaceSubscapular fossa

Depression on smooth, anterior side of body

Figure 8–3a

Bones of the Upper LimbsBrachium (arm)Antebrachium (forearm)

UlnaRadius

Carpals (wrist)Metacarpals (hand)Phalanges (fingers)

HumerusOnly bone in brachium (arm)Extends from scapula to elbowArticulates with pectoral girdle

on proximal end (head) – with glenoid fossa of scapula

on distal end – with radius and ulna (bones of antebrachium)

Humerus

HeadLarge, ball-shaped

structure on proximal endGreater tubercle

Larger, rounded projection on lateral/posterior surface of epiphysis

Lesser tubercleSmaller projection on

medial/anterior surfaceIntertubercular groove

Separates tubercles

Figure 8–4

Humerus

Anatomical neckNarrow groove between

base of head and tuberclesMargin of joint capsule

Surgical neckAt metaphysisWhere fractures often occur

Deltoid tuberosityRough ridge on-anterior

surface of shaftWhere deltoid muscle

attaches

Figure 8–4

Humerus

Condyle= rounded projection for

muscle attachmentDistal epiphysis where

humerus articulates with radius and ulna

“Knuckles” on anterior surface of humerus

Figure 8–4

Humerus

Lateral epicondyleMedial epicondyle

More prominent than lateral one

Trochlea (“pulley” or “spool”)In center of condyle (middle

“knuckle)Where trochlear notch of ulna

rotates during forearm flexionCapitulum

Forms a “cap” over the radius

Figure 8–4

Humerus

Coronoid fossaOn anterior surfaceArticulates with coronoid

process of ulnaOlecranon fossa

On posterior surfaceArticulates with

olecranon of ulna

Figure 8–4

Antebrachium (Forearm)

Consists of 2 long bones:Ulna (medial)Radius (lateral)

“Rotates”Site of radial pulse

Figure 8–5

Ulna

Olecranon (process)Large, curved

projection (like cobra head) on proximal end

“U” for ulnaArticulates in

olecranon fossa of humerus

Superior lip of trochlear notch

Point of elbow

Figure 8–5

Ulna

Trochlear notchAnterior curved surface

of proximal epiphysisArticulates with trochlea

of humerusCoronoid process

Inferior lip of trochlear notch

Articulates in coronoid fossa of humerus

Figure 8–5

Ulna

HeadMuch smaller, distal

epiphysis (near wrist)Articulates with radium

and carpal (wrist) bonesStyloid process

Medial pointed extension at distal epiphysis

On posterior, lateral surface of head

Figure 8–5

Ulna: Articulations with the HumerusForearm extended:

Olecranon enters olecranon fossa Forearm flexed:

Coronoid process enters coronoid fossa

Radius

HeadDisc-shaped proximal

epiphysisArticulates with humerus

NeckNarrow region between

head and tuberosityRadial tuberosity

Structure at proximal end of diaphysis below neck

Marks attachment site of biceps brachii muscle

Figure 8–5

Radius

ShaftCurves and

broadensDistal portion much

larger than distal portion of ulna

Styloid processLateral pointed

extension at distal epiphysis

Stabilizes wrist joint

Figure 8–5

Carpal Bones Allow wrist to bend and twist

8 bones“Sam likes to push the toy car hard.”

Carpal BonesScaphoidLunateTriquetrumPisiform

TrapeziumTrapezoidCapitateHamate

Wrist and Hand Bones

Figure 8–6

Metacarpal Bones5 long bones of the hand Numbered I–V from lateral (thumb) to

medialArticulate with proximal phalanges

Phalanges (Phalanx=singular)Finger bones

I (lateral)Pollex (thumb):2 phalanges (proximal, distal)

II - V3 phalanges (proximal, medial or middle, distal)

Pelvic GirdleFunctions

Weight-bearingLocomotion

Bones more massive than those of pectoral girdle

Strong to bear body weight

Pelvic GirdleMade up of 2 hip bones (coxal bones or

pelvic bones)Each hip bone is made up of 3 fused bones:

Ilium (articulates with sacrum)IschiumPubis

Pelvic Girdle

Figure 8–7

Pelvic Girdle: Ilium

Largest hip boneSuperior part of

coxaeFused to ischium

(posteriorly) and pubis (anteriorly)

Articulates with sacrum – attaches pelvic girdle to axial skeleton

Figure 8–7

Pelvic Girdle: Ilium

Iliac crestSuperior border

Anterior superior iliac spine (ASIS)

Anterior inferior iliac spine (AIIS)

Posterior superior iliac spine (PSIS)

Posterior inferior iliac spine (PIIS)

Figure 8–7

Pelvic Girdle: Ilium

Iliac fossaDepression on anterior

aspectSacroiliac joint

Between posterior superior and inferior spines; where ilium and sacrum articulate

Greater sciatic notchInferior to PIISPassageway for large

sciatic nerve

Figure 8–7

Pelvic Girdle: Ischium

Posterior-inferior part of coxae

Ischial spineInferior to greater

sciatic notchAt posterior-superior

end Lesser sciatic notch

Inferior to ischial spine Ischial tuberosity

Thickened posterior-inferior part

Bears body weight when seated (“sit bone”)

Figure 8–7

Pelvic Girdle: Pubis

Anterior-inferior part of coxae

Pubic symphysisJoint where anterior

medial surfaces of pubic bones are interconnect by fibrocartilage pad

Limits movement between pubic bones of left and right hipbones

Figure 8–7

Pelvic Girdle: Acetabulum

Also called the hip socket

Large, concave socket on lateral surface of os coxae

Meeting point of ilium, ischium, and pubis

Articulates with head of femur

Figure 8–7

Pelvic Girdle: Obturator Foramen

Large space encircled by pubis and ischium

Closed by sheet of collagen fibers

Provides base for hip muscles

Figure 8–7

PelvisConsists of:

2 hip bonesSacrumCoccyx (of axial skeleton)

Stabilized by ligaments of pelvic girdle, sacrum, and lumbar vertebrae

Pelvis

Figure 8–8

Pelvic OpeningsPelvic inlet – (anterior) space enclosed by

pelvic brim Pelvic outlet – opening bounded by coccyx and

ischial tuberosities

Figure 8–9

Pubic AngleInferior angle between pubic bones

Figure 8–10

Bones of the Lower LimbsFemur (thigh)Patella (kneecap)Tibia and fibula (leg)Tarsals (ankle)Metatarsals (foot)Phalanges (toes)

Femur

Longest, heaviest boneTransfers body weight

to groundArticulates with:

coxae at acetabulumtibia at knee joint

Figure 8–11

Femur

HeadLarge, round proximal endArticulates at acetabulum

NeckNarrow connector between

head and shaftJoins shaft at angle

Figure 8–11

Femur

Greater trochanterLarge process at superior

end of shaftLesser trochanter

Smaller process inferior to neck on medial /posterior side

Figure 8–11

Femur

Lateral condyleLarge, rounded, lateral

projection at distal epiphysis

Articulates with lateral condyle of tibia

Medial condyleLarge, rounded, medial

projection at distal epiphysis

Articulates with medial condyle of tibia

Figure 8–11

Femur

Intercondylar fossaDepression between

condyles on posterior side

Figure 8–11

Femur

Patellar surfaceFlattened area between

condyles on anterior side

Figure 8–11

PatellaLarge sesamoid boneForms within tendon of quadriceps femoris

(extends/straightens the knee)

Figure 8–12

TibiaLarger, medial bone; supports body weightAlso called the shinbone

Figure 8–13

Tibia

Lateral condyleLateral projection at

proximal epiphysisArticulates with lateral

condyle of femurMedial condyle

Medial projection at proximal epiphysis

Articulates with medial condyle of femur

Figure 8–13

Tibia

Tibial tuberosityRoughened area on

anterior surfaceInferior to condylesAttachment for

patellar ligament

Figure 8–13

Tibia

Anterior marginRidge that begins at

tibial tuberosity and extends distally along anterior surface (“shin bone”)

Medial malleolus (“little mallet”)Projection on medial

side at distal epiphysis

Figure 8–13

FibulaSlender, lateral bone of lower leg

Figure 8–13

Fibula

HeadArticulates with

proximal tibiaLateral malleolus

Projection on lateral side at distal epiphysis

Articulates with distal tibia

Provides lateral stability to ankle

Figure 8–13

Tarsal Bones Allow ankle to bend and twist

7 bones

Ankle and Foot Bones

Figure 8–14a

Tarsal BonesTalusCalcaneousNavicularCuboid

Cuneiforms (3)

Note: movement more restricted than wrist/hand

Metatarsal Bones5 long bones of the foot Numbered I–V from medial (big toe) to

lateralArticulate with proximal phalanges

PhalangesToe bones

I (lateral)Hallus (big toe):2 phalanges (proximal, distal)

II - V3 phalanges (proximal, medial or middle, distal)