Skeletal System 3
Honors Anatomyto copy edition
The Appendicular Skeleton
The Pectoral Girdle(Shoulder)
• 2 pectoral girdles• attach bones of upper limbs to
axial skeleton• each: 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 flat• articulates with acromion of the
scapula to form acromialclavicular joint
Clavicle • last bone to stop growing• 1 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 bone• large, triangular, flat bone• in 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
Upper Limb• 6 parts:1. Humerus2. Ulna3. Radius4. Carpals5. Metacarpals 6. Phalanges
• Joints:• Shoulder• Elbow• Wrist• Hand
Humerus • longest & largest bone of upper
limb• articulates proximally with
scapula & distally with ulna & radius
• head: rounded proximal end»articulates with glenoid cavity of scapula to form glenohumeral joint
Humerus• distal end:• capitulum: rounded knob on
lateral aspect that articulates with head of radius
• trochlea: medial to capitulum, spool-shaped, articulates with ulna
Ulna • medial aspect of forearm• longer than radius• proximal 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
places1. interosseous
membrane2. 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
Phalanges • 14 bones of the digits (each
hand)• #’d I to V beginning with thumb• thumb is the pollex has only 2
phalanges, other digits have 3• joints between phalanges called
interphalangeal joints
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 &
inferior3. Ischium • posterior &
inferior
Ilium • largest of the 3 hip bones• distinguishing features:1. Iliac Crest• along superior surface1. Sacroiliac Joint (SI Joint)• between sacrum and ilium
Ischium • ramus of ischium fuses with
pubis• distinguishing features:
1. Ischial Tuberosity• what you feel when someone
sits on your lap
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 & thinner• Pelvis:– false pelvis shallow, widers– pelvic brim larger, more oval– acetabulum smaller & faces
anterior– obturator foramen oval
Lower Limb• 30 bones in each:• 1 femur• 1 patella • 1 tibia• 1 fibula• 7 tarsals• 5 metatarsals• 14 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
Patella (kneecap) • small, triangular, sesamoid bone• develops in tendon of quadriceps
femoris muscle• Parts:• Base: broad, superior end• Apex: pointed, inferior end
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
Tarsals• 7 bones:• 1 calcaneous: heel bone, largest
of the tarsals
Metatarsals
• 5 bones between tarsals & phalanges
• #’d I to V from medial lateral
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 mesoderm
• 1st bone: skull in 4th wk• U/S ~ 24 – 25 wks:
Medical Terminology1. 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 Terminology2. Genu valgum:• knees
abnormally close together with increased space between ankles
• aka “knock-knee”