Medical Gross Anatomy: Muscles of the Upper Limb

This set of vocabulary flashcards covers the muscles of the upper limb, documenting their primary actions, unique anatomical notes, and nerve associations based on the MedCharts Anatomy tables.

abductor digiti minimi (hand)

A muscle in the hypothenar compartment of the hand that originates at the pisiform and abducts the $5$th digit; innervated by the deep branch of the ulnar nerve.

abductor pollicis brevis

A muscle in the thenar compartment of the hand that originates from the flexor retinaculum, scaphoid, and trapezium and abducts the thumb.

abductor pollicis longus

A forearm muscle whose tendon forms the lateral border of the anatomical snuffbox; it abducts the thumb at the carpometacarpal joint and is innervated by the radial nerve.

adductor pollicis

A muscle in the adductor-interosseous compartment that adducts the thumb; the deep palmar arch and deep ulnar nerve pass between its oblique and transverse heads.

anconeus

A muscle originating from the lateral epicondyle of the humerus that extends the forearm.

biceps brachii

A professional muscle with a short head ($tip of the coracoid process$) and long head ($supraglenoid tubercle$) that flexes the forearm, flexes the arm, and acts as a powerful supinator when the elbow is flexed.

brachialis

A powerful flexor of the forearm originating from the anterior surface of the lower one-half of the humerus; innervated by the musculocutaneous nerve ($C5, 6$).

brachioradialis

A muscle innervated by the radial nerve that flexes the elbow; its neutral position is half way between supination and pronation.

coracobrachialis

A muscle that flexes and adducts the arm; it is uniquely notable because the musculocutaneous nerve passes through it.

deltoid

The principal abductor of the arm; anterior fibers flex and medially rotate the arm, while posterior fibers extend and laterally rotate the arm; innervated by the axillary nerve ($C5, 6$).

dorsal interosseous (hand)

Four bipennate muscles that flex the MCP joints and abduct digits $2$-$4$; remembered by the mnemonic DAB (Dorsal ABduct).

extensor carpi radialis longus

A muscle that extends the wrist and abducts the hand; it originates at the lower one-third of the lateral supracondylar ridge of the humerus.

extensor carpi ulnaris

A muscle that extends the wrist and adducts the hand; it originates from the common extensor tendon and the middle one-half of the posterior border of the ulna.

extensor digiti minimi

An extensor muscle that appears to be the ulnar-most portion of the extensor digitorum and extends the joints of the $5$th digit.

extensor digitorum

A muscle that extends the metacarpophalangeal, proximal interphalangeal, and distal interphalangeal joints of digits $2$-$5$ and extends the wrist.

extensor indicis

A deep forearm extensor that extends the index finger at the MCP, PIP, and DIP joints; its tendon joins that of the extensor digitorum.

extensor pollicis brevis

A muscle that extends the thumb at the MCP joint; its tendon forms part of the lateral border of the anatomical snuffbox.

extensor pollicis longus

A muscle that extends the thumb at the interphalangeal joint and hooks around the dorsal radial tubercle to form the medial border of the anatomical snuffbox.

flexor carpi radialis

A muscle originating from the medial epicondyle that flexes the wrist and abducts the hand; innervated by the median nerve.

flexor carpi ulnaris

A muscle that flexes the wrist and adducts the hand; the ulnar nerve passes between its two heads of origin.

flexor digitorum profundus

A muscle that flexes the MCP, PIP, and DIP joints; the portion acting on digits $4$ and $5$ is innervated by the ulnar nerve, while the portion for digits $2$ and $3$ is innervated by the median nerve.

flexor digitorum superficialis

A muscle that flexes the MCP and PIP joints; the median nerve travels distally in the forearm on its deep surface.

flexor pollicis longus

A muscle that flexes the MCP and IP joints of the thumb; its tendon passes through the carpal tunnel.

rotator cuff muscles

A group of four muscles: infraspinatus, supraspinatus, teres minor, and subscapularis.

latissimus dorsi

A muscle originating from the vertebral spines ($T7$ to sacrum) that extends and medially rotates the arm; innervated by the thoracodorsal nerve ($C7, 8$).

lumbrical (hand)

Worm-like muscles arising from the profundus tendons that flex MCP joints and extend IP joints; they follow the same innervation pattern as flexor digitorum profundus.

opponens pollicis

A thenar muscle that performs a rotational movement of the $1$st metacarpal to oppose the thumb.

palmar interosseous

Unipennate muscles that flex the MCP, extend IP joints, and adduct digits $1$, $2$, $4$, and $5$; remembered by the mnemonic PAD (Palmar ADduct).

palmaris longus

A muscle that flexes the wrist; it is notably absent in approximately $13\%$ of forearms.

pectoralis minor

A muscle that draws the scapula forward and downward; its fibers are usually pierced by the medial pectoral nerve.

pronator quadratus

The deepest muscle in the distal forearm; it pronates the forearm and is innervated by the anterior interosseous nerve.

serratus anterior

A muscle originating from ribs $1$-$8$ or $9$ that draws the scapula forward; a lesion of its long thoracic nerve supply causes winging of the scapula.

subclavius

A muscle that draws the clavicle down and forward and cushions the subclavian vessels during clavicular fractures.

supraspinatus

A rotator cuff muscle that initiates abduction of the arm before the deltoid completes the action.

teres major

A muscle that adducts and medially rotates the arm; it inserts at the crest of the lesser tubercle beside the latissimus dorsi.

trapezius

A muscle that elevates, depresses, and retracts the scapula; its motor supply is the spinal accessory nerve ($XI$).

triceps brachii

A three-headed muscle that extends the forearm; its long head originates at the infraglenoid tubercle and separates the triangular and quadrangular spaces.