Upper Extremity Anatomy: Shoulder, Elbow, Wrist, and Hand

Comprehensive vocabulary flashcards covering the osteology, arthrology, ligamentous anatomy, musculature, and neural innervation of the shoulder, elbow, forearm, wrist, and hand.

Pectoral Girdle

An incomplete bony ring formed by the clavicles and scapulae that connects the upper limbs to the axial skeleton.

Clavicle

An S-shaped long bone connecting the upper extremity to the axial skeleton; features a medial sternal end, a body (shaft), and a lateral acromial end.

Sternoclavicular (SC) Joint

The articulation between the manubrium of the sternum and the medial end of the clavicle; it is the only direct bony attachment between the upper limb and axial skeleton, containing an articular disc that improves congruency and absorbs shock.

Acromioclavicular (AC) Joint

The gliding joint formed between the acromion process of the scapula and the lateral end of the clavicle, allowing clavicular rotation as the scapula undergoes elevation and depression.

Glenohumeral (GH) Joint

A multi-axial ball-and-socket synovial joint between the glenoid cavity of the scapula and the head of the humerus that sacrifices stability for extensive mobility.

Scapulothoracic Joint

A functional (non-synovial) articulation where the anterior surface of the scapula glides over ribs 2 through 7; lacks a joint capsule and ligaments.

Coracoacromial Ligament

A ligament connecting the coracoid process to the acromion process of the scapula, forming the roof of the coracoacromial arch and providing superior stability to the glenohumeral joint.

Transverse Humeral Ligament

A ligament spanning from the greater tubercle to the lesser tubercle over the intertubercular groove of the humerus, holding the tendon of the long head of the biceps brachii in place.

Rotator Cuff

A musculotendinous group comprising the Supraspinatus, Infraspinatus, Teres Minor, and Subscapularis; functions dynamically to hold the humeral head within the glenoid fossa.

Supraspinatus

A rotator cuff muscle originating in the supraspinous fossa and inserting onto the greater tubercle of the humerus; initiates glenohumeral abduction up to $30^\top$, assists external rotation, and is innervated by the suprascapular nerve.

Infraspinatus

A rotator cuff muscle originating in the infraspinous fossa and inserting onto the greater tubercle of the humerus; externally rotates the humerus and pulls the humeral head into the glenoid cavity; innervated by the suprascapular nerve.

Teres Minor

A rotator cuff muscle originating along the lateral border of the scapula and inserting on the greater tubercle of the humerus; externally rotates the humerus and is innervated by the axillary nerve.

Subscapularis

The anterior rotator cuff muscle originating in the subscapular fossa and inserting onto the lesser tubercle of the humerus; internally rotates and adducts the humerus; innervated by the subscapular nerve.

Teres Major

A non-rotator cuff muscle originating at the inferior angle of the scapula and inserting into the intertubercular groove of the humerus to perform internal rotation, adduction, and extension; innervated by the subscapular nerve.

Serratus Anterior

A muscle originating from the external surfaces of ribs 1 through 8 and inserting along the medial border of the scapula; produces scapular protraction and upward rotation; innervated by the long thoracic nerve.

Trapezius

A large superficial back muscle originating from the occipital bone, ligamentum nuchae, and spinous processes of C7–T12; inserts onto the lateral clavicle and scapular spine to elevate, retract, and depress the scapula; innervated by the spinal accessory nerve (CN XI).

Brachial Plexus

The nerve network supplying the upper extremity formed from the ventral rami of C5–T1, organized into 5 roots, 3 trunks (superior, middle, inferior), 6 divisions (anterior, posterior), 3 cords (lateral, posterior, medial), and 5 terminal branches.

Humeroulnar Joint

The hinge articulation of the elbow formed between the trochlea of the humerus and the trochlear notch of the ulna, permitting flexion and extension.

Humeroradial Joint

The articulation of the elbow formed between the capitulum of the humerus and the head of the radius.

Annular Ligament

A circular ligament surrounding the neck and head of the radius, maintaining its position within the radial notch of the ulna during forearm pronation and supination.

Ulnar Collateral Ligament of the Elbow

A medial elbow ligament with anterior oblique, posterior oblique, and transverse oblique bands running from the medial epicondyle to the coronoid process and olecranon; resists valgus stress.

Radial Collateral Ligament of the Elbow

A lateral elbow ligament complex consisting of the lateral ulnar collateral ligament, radial collateral ligament, and accessory lateral collateral ligament; resists varus stress.

Interosseous Membrane of the Forearm

A dense fibrous sheet spanning between the radius and ulna that binds the bones and distributes compressive loads transmitted from the distal radius throughout the upper limb.

Carrying Angle

The anatomical angle formed between the long axis of the humerus and the ulna in extension; abnormal increases are termed cubitus valgus and abnormal decreases are termed cubitus varus.

Brachialis

A dedicated elbow flexor muscle originating on the anterior lower half of the humerus and inserting onto the coronoid process of the ulna; innervated by the musculocutaneous nerve.

Brachioradialis

A superficial forearm muscle originating from the supracondylar ridge of the humerus and inserting into the lateral styloid process of the radius; flexes the elbow and assists in pronation and supination; innervated by the radial nerve.

Pronator Teres

An anterior forearm muscle originating from the medial epicondyle and coronoid process, inserting onto the middle lateral radius to pronate the forearm and assist in elbow flexion; innervated by the median nerve.

Pronator Quadratus

A deep square-shaped muscle in the distal forearm originating on the anterior distal quarter of the ulna and inserting into the anterior distal quarter of the radius to produce pronation; innervated by the anterior interosseous branch of the median nerve.

Supinator

A deep posterior forearm muscle originating from the lateral epicondyle, radial collateral ligament, annular ligament, and supinator crest of the ulna, inserting on the dorsal and lateral radius to supinate the forearm; innervated by the radial nerve.

Anconeus

A small posterior elbow muscle originating from the lateral epicondyle of the humerus and inserting onto the lateral side of the olecranon process to extend the elbow; innervated by the radial nerve.

Carpal Bones

Eight short wrist bones ordered radial-to-ulnar in proximal (scaphoid, lunate, triquetrum, pisiform) and distal (trapezium, trapezoid, capitate, hamate) rows.

Hook of the Hamate

A distinct bony projection on the palmar aspect of the hamate bone that forms the medial border of the carpal tunnel.

Pisiform

A pea-shaped proximal carpal bone that serves as a sesamoid bone within the distal tendon of the flexor carpi ulnaris.

Radiocarpal Joint

An ellipsoidal synovial joint between the distal radius and the scaphoid and lunate bones, permitting wrist flexion, extension, radial deviation, and ulnar deviation.

1st Carpometacarpal (CMC) Joint

The saddle joint between the trapezium and the base of the first metacarpal, allowing flexion, extension, abduction, adduction, opposition, and reposition of the thumb.

Triangular Fibrocartilage Complex (TFCC)

A triangular fibrocartilaginous and ligamentous structure that suspends the carpals from the ulna, cushions forces through the ulnocarpal axis, and acts as the major stabilizer of the distal radioulnar joint.

Flexor Retinaculum

A fibrous arch (transverse carpal ligament) stretching from the pisiform and hamate medially to the scaphoid and trapezium laterally, forming the roof of the carpal tunnel.

Extensor Retinaculum

A transverse thickening of deep fascia across the dorsal wrist that holds the extensor tendons in place across six separate compartments.

Flexor Digitorum Superficialis (FDS)

An anterior forearm muscle originating from the medial epicondyle, coronoid process, and anterior radius, inserting into the middle phalanges of digits 2–5 to flex the MCP and PIP joints; innervated by the median nerve.

Flexor Digitorum Profundus (FDP)

A deep anterior forearm muscle originating on the ulna and interosseous membrane, inserting on the distal phalanges of digits 2–5 to flex the DIP joints; dually innervated by the median nerve (lateral half) and ulnar nerve (medial half).

Thenar Eminence

The muscular mound at the base of the thumb composed of the abductor pollicis brevis, flexor pollicis brevis, and opponens pollicis; innervated by the median nerve.

Hypothenar Eminence

The muscular mound at the base of the fifth digit composed of the abductor digiti minimi, flexor digiti minimi brevis, and opponens digiti minimi; innervated by the ulnar nerve.

Lumbricals of the Hand

Four intrinsic muscles originating from the tendons of the flexor digitorum profundus that flex the metacarpophalangeal (MCP) joints while extending the interphalangeal (PIP and DIP) joints into a writing position.

Interossei of the Hand

Intrinsic muscles situated between the metacarpals, divided into three palmar interossei (which adduct digits 2, 4, and 5) and four dorsal interossei (which abduct digits 2, 3, and 4); all innervated by the ulnar nerve.

Anatomical Snuffbox

A surface depression on the posterolateral wrist bounded laterally by the abductor pollicis longus and extensor pollicis brevis, and medially by the extensor pollicis longus; contains the radial artery, radial styloid, scaphoid, and trapezium.

Carpal Tunnel

An anatomical space bordered laterally by the scaphoid and trapezium, medially by the pisiform and hamate, and bounded palmarward by the flexor retinaculum; transmits 10 structures: 4 FDS tendons, 4 FDP tendons, 1 FPL tendon, and the median nerve.