The Skeletal SystemPart 2

The Appendicular SkeletonHonors Anatomy & Physiology

The Appendicular Skeleton

The Pectoral Girdle(Shoulder)

2 pectoral girdlesattach bones of upper limbs to axial

skeletoneach: 1 clavicle 1 scapula

Clavicle

S-shaped, (medial ½ convex anteriorly, lateral ½ concave anteriorly) slender bone

lies horizontally across anterior thorax superior to 1st rib

Clavicle

medial end = sternal end is rounded & articulates with the manubrium @ sternoclavicular joint

Clavicle

lateral end = acromial end is flatarticulates with acromion of the

scapula to form acromialclavicular joint

Clavicle

last bone to stop growing1 of most frequently fx’d bones (2

curves) usually from fall on outstretched arm

or see compression fx in auto accidents from shoulder strap which can cause damage to median n. (between clavicle & 2nd rib)

Scapula

aka shoulder blade, angel bonelarge, triangular, flat bonein superior part of posterior thorax

between levels of 2nd & 7th ribs

spine: prominent ridge that runs diagonally across posterior surface

Scapula

lateral edge: acromion a flattened expanded process, easily felt as hi pt of shoulder (tailors use it as landmark to measure length of arm)

glenoid cavity: inferior to acromion, smooth, shallow depression that accepts head of humerus in shoulder joint

Scapula

Upper Limb

6 parts:1. Humerus2. Ulna3. Radius4. Carpals5. Metacarpals 6. Phalanges

Joints:ShoulderElbowWristHand

Humerus

longest & largest bone of upper limbarticulates proximally with scapula &

distally with ulna & radiushead: rounded proximal end

articulates with glenoid cavity of scapula to form glenohumeral joint

Humerus

Humerus

distal end:capitulum: rounded knob on lateral

aspect that articulates with head of radius

trochlea: medial to capitulum, spool-shaped, articulates with ulna

Humerus

Ulna

medial aspect of forearmlonger than radiusproximal end: olecranon (prominence

in elbow)distal end: head, styloid process

(posterior)

Radius

lateral aspect of forearm

proximal end: head of radius: articulates with capitulum

distal end: styloid process (palpable proximal to thumb)

Ulna & Radius

connect @ 3 places

1. interosseous membrane

2. proximal end3. distal end

Carpals

proximal to the hand, distal to radius & ulna

8 small bones joined by ligaments

articulations w/each other called intercarpal joints

Carpal Tunnel

Metacarpals

Phalanges

14 bones of the digits (each hand)#’d I to V beginning with thumbthumb is the pollex has only 2

phalanges, other digits have 3joints between phalanges called

interphalangeal joints

Phalanges

Pelvic Girdle

2 hip bones (os coxa) which unite anteriorly at pubic symphysis and posteriorly with the sacrum @ sacroiliac joint

Pelvic Girdle

Functions:provides sturdy

support for vertebral column

connects lower limb to axial skeleton

Newborn Pelvis

3 bones on each side:

1. Ilium◦ superior

2. Pubis◦ anterior &

inferior

3. Ischium posterior &

inferior

Ilium

largest of the 3 hip bonesdistinguishing features:1. Iliac Crest along superior surface1. Sacroiliac Joint (SI Joint) between sacrum and ilium

Ilium

Ischium

ramus of ischium fuses with pubisdistinguishing features:

1. Ischial Tuberosity what you feel when someone sits on

your lap

Ischium

Pubis

Acetabulum ◦formed by ilium, ischium, & pubis◦is the “socket” half of the hip joint

Pubic Symphysis◦joint between the 2 hip bones

True Pelvis/ False Pelvis

Pelvic Brim: line that distinguishes between true & false palvis

Male Pelvis

generally male bone heavier & stronger & have larger surface marker (because larger muscles attach)

Pelvis:◦deeper false pelvis, smaller, narrower◦pelvic brim heart-shaped◦acetabulum larger, faces posterior◦obturator foramen round

Female Pelvis

generally bones lighter & thinnerPelvis:

◦false pelvis shallow, widers◦pelvic brim larger, more oval◦acetabulum smaller & faces anterior◦obturator foramen oval

Male or Female?

Male or Female?

Lower Limb

30 bones in each:1 femur1 patella 1 tibia1 fibula7 tarsals5 metatarsals14 phalanges

Femur

longest, heaviest, & strongest bone in the body

proximally articulates with the acetabulum to form hip joint◦Head of the Femur: “ball” part of joint

small, central depression: fovea capitis◦Greater Trochanter

prominence felt & seen @ side of hip

Femur

Femur

distally articulates with:◦Patella◦Tibia

Patella (kneecap)

small, triangular, sesamoid bonedevelops in tendon of quadriceps

femoris muscleParts:Base: broad, superior endApex: pointed, inferior end

Patella

Tibia

“shin bone”larger, medial, weight-bearing bone of

lower legproximally articulates with femur &

fibuladistally articulates with fibula &

tarsals

Tibia

medial malleolus forms prominence that is palpable & visible on medial ankle

Fibula

parallel & lateral to the tibia & considerably smaller

head of fibula on proximal end

lateral malleolus at distal end

Tibia & Fibula

Tarsals

7 bones:1 calcaneous: heel bone, largest of

the tarsals

Metatarsals

5 bones between tarsals & phalanges#’d I to V from medial lateral

Phalanges

14 bones that make up the 5 digits#’d I to V medial to lateralHallux: great or big toe has 2 large

heavy phalanges

Arches of the Foot

2 arches in foot: 1. allows the foot to support weight of

body by distributing weight over the soft & hard tissues

2. provide leverage while walkingfully developed by age 12 - 13

Arches of the Foot

2 longitudinal arches (medial & lateral

1 transverse arch

Development of the Skeletal System

all skeletal tissue arises from mesoderm1st bone: skull in 4th wkU/S ~ 24 – 25 wks:

Medical Terminology

1. Clubfoot:◦ inherited deformity in which baby is born with

foot twisted inferiorly & medially◦ 1/1000 births◦ tx: casts or wraps, surgery may be indicated

Medical Terminology

2. Genu valgum: knees

abnormally close together with increased space between ankles

aka “knock-knee”

Medical Terminology

3. Genu varum:knees abnormally

separatedwith lower limbs

bowed mediallyaka “bowleg”