The Skeletal System Part 2 The Appendicular Skeleton

The Skeletal System Part 2 The Appendicular Skeleton Honors Anatomy & Physiology

The Appendicular Skeleton

� 2 pectoral girdles �attach bones of upper limbs to axial skeleton �each: 1 clavicle � 1 scapula The Pectoral Girdle (Shoulder)

�S-shaped, (medial ½ convex anteriorly, lateral ½ concave anteriorly) slender bone �lies horizontally across anterior thorax superior to 1 st 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 & 2 nd rib) Clavicle

�aka shoulder blade, angel bone �large, triangular, flat bone �in superior part of posterior thorax between levels of 2 nd & 7 th 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

Scapula

� 6 1. 2. 3. 4. 5. 6. parts: Humerus Ulna Radius Carpals Metacarpals Phalanges Upper Limb �Joints: �Shoulder �Elbow �Wrist �Hand

�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

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

Humerus

�medial aspect of forearm �longer than radius �proximal end: olecranon (prominence in elbow) �distal end: head, styloid process (posterior) Ulna

�lateral aspect of forearm �proximal end: head of radius: articulates with capitulum �distal end: styloid process (palpable proximal to thumb) Radius

�connect @ 3 places 1. interosseous membrane 2. proximal end 3. distal end Ulna & Radius

�proximal to the hand, distal to radius & ulna � 8 small bones joined by ligaments �articulations w/each other called intercarpal joints Carpals

Carpal Tunnel

Metacarpals

� 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 Phalanges

Phalanges

� 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 Pelvic Girdle

� 3 bones on each side: 1. Ilium ◦ superior Pubis 2. ◦ anterior & inferior Ischium � posterior & inferior 3. Newborn Pelvis

�largest of the 3 hip bones �distinguishing features: 1. Iliac Crest � along superior surface 1. Sacroiliac Joint (SI Joint) � between sacrum and ilium Ilium

Ilium

�ramus of ischium fuses with pubis �distinguishing features: Ischial Tuberosity � what you feel when someone sits on your lap 1. Ischium

Ischium

�Acetabulum ◦ formed by ilium, ischium, & pubis ◦ is the “socket” half of the hip joint �Pubic Symphysis ◦ joint between the 2 hip bones Pubis

�Pelvic Brim: line that distinguishes between true & false palvis True Pelvis/ False 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 Male Pelvis

�generally bones lighter & thinner �Pelvis: ◦ false pelvis shallow, widers ◦ pelvic brim larger, more oval ◦ acetabulum smaller & faces anterior ◦ obturator foramen oval Female Pelvis

Male or Female?

Male or Female?

� 30 bones in each: � 1 femur � 1 patella � 1 tibia � 1 fibula � 7 tarsals � 5 metatarsals � 14 phalanges Lower Limb

�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 Femur

�small, triangular, sesamoid bone �develops in tendon of quadriceps femoris muscle �Parts: �Base: broad, superior end �Apex: pointed, inferior end Patella (kneecap)

Patella

“shin bone” larger, medial, weight-bearing bone of lower leg proximally articulates with femur & fibula distally articulates with fibula & tarsals Tibia

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

�parallel & lateral to the tibia & considerably smaller �head of fibula on proximal end �lateral malleolus at distal end Fibula

Tibia & Fibula

� 7 bones: � 1 calcaneous: heel bone, largest of the tarsals Tarsals

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

� 14 bones that make up the 5 digits �#’d I to V medial to lateral �Hallux: great or big toe has 2 large heavy phalanges Phalanges

� 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 walking fully developed by age 12 - 13 Arches of the Foot

� 2 longitudinal arches (medial & lateral � 1 Arches of the Foot transverse arch

�all skeletal tissue arises from mesoderm � 1 st bone: skull in 4 th wk �U/S ~ 24 – 25 wks: Development of the Skeletal System

Clubfoot: 1. ◦ ◦ ◦ 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 separated �with lower limbs bowed medially �aka “bowleg” Medical Terminology