Pectoral Girdle & Upper Limb Sarah Derman Irene Park Tom Raday Jenn Suh

Overview Part of the appendicular division -bones of the upper and lower limbs -supporting and connecting bones of the pectoral and pelvic girdles

PECTORAL GIRDLE Two slender, curved clavicles (collarbones) & two broad, flat scapulae Functions: Position the shoulder joint + provide a base for arm movement Surfaces of scapulae and clavicles are sites for muscle attachment -muscles attached to the pectoral girdle help move the arm

Clavicle S-shaped Smooth, superior surface lies just beneath the skin Rough, interior surface of the acromial end has lines and tubules as muscle attachment sites Right clavicle in a superior view Acromial end

Clavicle Only direct connections between the axial skeleton and the pectoral girdle Articulates with the manubrium of the sternum at its strenal end + the acromion (process) of the scapula at its acromial end

Clavicle Small and fragile  fractures are common but heal rapidly without a cast Ex. Simple fall with outstretched arm  fractured clavicle (“broken collarbone”)

Scapula Anterior surface of the body of the scapula forms a triangle bounded by the superior, medial, and lateral borders -Skeletal muscles support and position the scapula by attaching along these borders (scapula has no bony or ligamentous connection to the thoracic cage)

Scapula Right scapula

Scapula Head of scapula at the intersection of the lateral and superior borders forms a process that supports the shallow, cup-shaped glenoid cavity (glenoid fossa) -At the glenoid cavity, the scapula articulates with the proximal end of the humerus to form the shoulder joint

Scapula Right scapula

Scapula Subscapular fossa: Depression in the anterior surface of the body of the scapula -Subscapularis muscle attaches to the subscapular fossa + to the humerus (the proximal bone of the upper limb)

Scapula

UPPER LIMB Skeleton = bones of the… -arm (brachium): from shoulder to elbow; contains a single bone (humerus) that extends from the scapula to the elbow -forearm (radius and ulna) -wrist (carpal bones) -hand (metacarpal bones and phalanges)

Humerus (Arm) TOP Head articulates with the scapula Greater tubercle: rounded projection near the lateral surface of the head -gives shoulder its lateral contour Lesser tubercule: lies more anteriorly; separated from the greater tubercle by a deep intertubercular groove Muscles are attached to both tubercules -large tendon runs along the groove

Humerus (Arm) (damage to axillary nerve and artery causes muscles TOP Anatomical neck: lies between the tubercules and below the surface of the head Surgical neck: lies distal to the tubercles -narrow -common fracture site (damage to axillary nerve and artery causes muscles to malfunction)

Humerus (Arm) MIDDLE Shaft: round in section Deltoid tuberosity: runs along the lateral border of the shaft -deltoid muscle attaches to deltoid tuberosity

BOTTOM Shaft flattens and expands to either side, forming a broad triangle Medial and lateral epicondyles project to either side -surface area for muscle attachment Condyle dominates the inferior surface of the humerus -at condyle: humermus articulates with the bones of the forearm, the radius, and the ulna -two distinct regions 1) trochlea: large medial portion shaped like a spool or pulley 2) capitulum: lateral region of the condyle -radial fossa accepts projection from radius

Ulna (Forearm) Ulna=medial support of the forearm Olecranon: point of the elbow (of ulna) -trochlear notch articulates with the trochlea of the humerus at the elbow joint; -limit of the extension (arm + forearm form a straight line) -limit of flexion (arm + forearm form a V) Radial notch: lateral to the coronoid process; accomdates the head of the radius Styloid process: where the ulna ends -stabilizes the joint by preventing lateral movement of the carpal bones of the wrist

Radius (Forearm) Radius=lateral (thumb) side of the forearm -Fibrous sheet connects the ulna to the radius Narrow neck extends from the head to the radial tuberosity (attachment site of the biceps brachii) -head articulates with the capitulum of the humerus at the elbow joint & with radical notch of the ulna  radius rolls across the ulna (rotating palm movement)

Wrist and Hand Wrist, palm, fingers: 27 bones -8 carpal bones (wrist/carpus): scaphoid, lunate, triquetrum pisiform, trapezium, trapezoid, capitates, hamate -5 metacarpal bones (palm): articulate with the distal carpal bones -14 phalangeal bones (phalange=finger bone): articulate with the metacarpal bones -four fingers have three phalanges each -thumb (pollex) has two phalanges

Upper Limb Upper Limb Disorders (ULDs): affect the arms, from finger to shoulder, and neck Aches, pains, tension, and disorders Problems with muscles, tendons, ligaments Caused or made worse by repetitive, uncomfortable work that involves excessive force Prevention: exercise, breaks, good posture