Medical Gross Anatomy: Muscles of the Upper Limb

Complete set of vocabulary flashcards covering the origin, insertion, action, innervation, and clinical notes for muscles of the upper limb as presented in the Medical Gross Anatomy lecture tables.

abductor digiti minimi (hand)

Muscle in the hypothenar compartment of the hand originating from the pisiform and inserting into the base of the proximal phalanx of the 5th digit; abducts the 5th digit and is innervated by the deep branch of the ulnar nerve.

abductor pollicis brevis

Muscle in the thenar compartment of the hand originating from the flexor retinaculum, scaphoid, and trapezium; inserts on the base of the proximal phalanx of the first digit and abducts the thumb; innervated by the recurrent branch of the median nerve.

abductor pollicis longus

Posterior forearm muscle that abducts the thumb at the carpometacarpal joint; its tendons make the lateral border of the anatomical snuffbox; innervated by the deep branch of the radial nerve.

adductor pollicis

Two-headed muscle (oblique and transverse) in the adductor-interosseous compartment that adducts the thumb; the deep palmar arterial arch and deep ulnar nerve pass between its two heads.

anconeus

Muscle originating from the lateral epicondyle of the humerus that extends the forearm; innervated by the nerve to anconeus from the radial nerve.

biceps brachii

Two-headed muscle (short and long head) that flexes and supinates the forearm and flexes the arm; innervated by the musculocutaneous nerve ($C_{5,6}$); a powerful supinator only if the elbow is flexed.

brachialis

Powerful flexor of the forearm originating from the anterior surface of the lower one-half of the humerus; innervated by the musculocutaneous nerve ($C_{5,6}$).

brachioradialis

Muscle of the lateral supracondylar ridge that flexes the elbow; neutral position is halfway between supination and pronation (thumb up); innervated by the radial nerve.

coracobrachialis

Muscle originating from the coracoid process that flexes and adducts the arm; pierced by the musculocutaneous nerve ($C_{5,6}$).

deltoid

Principal abductor of the arm; anterior fibers flex and medially rotate, while posterior fibers extend and laterally rotate; innervated by the axillary nerve ($C_{5,6}$) from the posterior cord.

dorsal interosseous (hand)

Four bipennate muscles that flex the MP joint, extend IP joints, and abduct digits $2-4$; remember DAB: Dorsal interosseous mm. ABduct; innervated by the deep branch of the ulnar nerve.

extensor carpi radialis brevis

Extensor that originates from the common extensor tendon (lateral epicondyle) and inserts on the base of the 3rd metacarpal; extends the wrist and abducts the hand.

extensor carpi radialis longus

Extensor originating from the lateral supracondylar ridge of the humerus that extends the wrist and abducts the hand; works with flexor carpi radialis in abduction.

extensor carpi ulnaris

Extensor originating from the lateral epicondyle and ulna that extends the wrist and adducts the hand; innervated by the deep radial nerve.

extensor digiti minimi

Muscle that appears as the ulnar-most portion of extensor digitorum; extends the joints of the 5th digit; innervated by the deep radial nerve.

extensor digitorum

Muscle that extends digits $2-5$ and the wrist; inserts via a central band on the middle phalanx and lateral/medial slips on the distal phalanx; innervated by the deep radial nerve.

extensor indicis

Deep forearm extensor that extends the index finger ($2nd$ digit) at the MP, PIP, and DIP joints; innervated by the deep radial nerve.

extensor pollicis brevis

Deep forearm extensor that extends the thumb at the metacarpophalangeal joint; forms the lateral border of the anatomical snuffbox where the radial pulse is felt.

extensor pollicis longus

Muscle that hooks around the dorsal radial tubercle and extends the thumb at the interphalangeal joint; forms the medial border of the anatomical snuffbox.

flexor carpi radialis

Muscle that flexes the wrist and abducts the hand; innervated by the median nerve and inserts into the base of the second and third metacarpals.

flexor carpi ulnaris

Muscle that flexes the wrist and adducts the hand; innervated by the ulnar nerve, which passes between its two heads of origin.

flexor digiti minimi brevis (hand)

Muscle in the hypothenar compartment that flexes the CM and MP joints of the 5th digit; innervated by the deep branch of the ulnar nerve.

flexor digitorum profundus

Deep flexor that acts on the MP, PIP, and DIP joints of digits $2-5$; the ulnar half acting on digits $4$ and $5$ is innervated by the ulnar nerve; the radial half is innervated by the median nerve.

flexor digitorum superficialis

Muscle with humeroulnar and radial heads that flexes the MP and PIP joints; the median nerve travels distally on its deep surface.

flexor pollicis brevis

Muscle of the thenar compartment that flexes the CM and MP joints of the thumb; innervated by the recurrent branch of the median nerve.

flexor pollicis longus

Long flexor that passes through the carpal tunnel and flexes the MP and IP joints of the thumb; innervated by the median nerve via the anterior interosseous nerve.

infraspinatus

Rotator cuff muscle that laterally rotates the arm; originates in the infraspinatous fossa and inserts on the middle facet of the greater tubercle; innervated by the suprascapular nerve.

palmar interosseous

Four unipennate muscles that flex the MP joint, extend IP joints, and adduct digits $1, 2, 4,$ and $5$ (PAD: Palmar Adduct); innervated by the deep branch of the ulnar nerve.

latissimus dorsi

Broad muscle that extends and medially rotates the arm; innervated by the thoracodorsal nerve ($C_{7,8}$) from the posterior cord.

levator scapulae

Muscle that elevates the scapula and rotates it inferiorly; originates from transverse processes of $C_1-C_4$ and is innervated by the dorsal scapular nerve ($C_5$).

lumbrical (hand)

'Worm-like' muscles arising from profundus tendons that flex MP joints and extend IP joints of digits $2-5$; same innervation pattern as profundus (radial $2$ by median nerve, ulnar $2$ by ulnar nerve).

opponens digiti minimi

Hypothenar muscle that opposes the 5th digit through rotational movement around its long axis; innervated by the deep branch of the ulnar nerve.

opponens pollicis

Thenar muscle that opposes the thumb through rotational movement of the 1st metacarpal; innervated by the recurrent branch of the median nerve.

palmaris brevis

Superficial muscle that improves grasp by drawing the skin of the ulnar side of the hand toward the center of the palm.

palmaris longus

Wrist flexor absent in approximately $13\%$ of forearms; innervated by the median nerve.

pectoralis major

Muscle that flexes, adducts, and medially rotates the arm; deep fascia on its surface should not be fused to mammary gland fascia (sign of breast disease); innervated by medial and lateral pectoral nerves ($C_5-T_1$).

pectoralis minor

Muscle from ribs $3-5$ that draws the scapula forward, medialward, and downward; usually pierced by the medial pectoral nerve.

pronator quadratus

Deepest muscle in the distal forearm that pronates the forearm; innervated by the median nerve via the anterior interosseous nerve.

pronator teres

Forearm pronator; the median nerve passes between its two heads of origin (common flexor tendon and coronoid process).

rhomboideus major

Rhomboid-shaped muscle originating from spines of $T_2-T_5$ that retracts, elevates, and rotates the scapula inferiorly; innervated by the dorsal scapular nerve ($C_5$).

rhomboideus minor

Muscle originating from the ligamentum nuchae and spines of $C_7$ and $T_1$ that retracts and elevates the scapula.

serratus anterior

Muscle from ribs $1-8/9$ that draws the scapula forward; innervated by the long thoracic nerve (ventral rami $C_5-C_7$); lesion cause 'winging' of the scapula.

serratus posterior inferior

Respiratory muscle originating from $T_{11}-L_2$ that pulls down lower ribs; innervated by ventral primary rami of spinal nerves $T_9-T_{12}$.

serratus posterior superior

Respiratory muscle originating from $C_7-T_3$ that elevates upper ribs; embryonically related to intercostal muscles.

subclavius

Muscle that draws the clavicle down and forward; cushions subclavian vessels from bone fragments in clavicular fractures; innervated by nerve to subclavius ($C_5$).

subscapularis

Rotator cuff muscle that medially rotates and assists in extending the arm; innervated by upper and lower subscapular nerves ($C_{5,6}$).

supinator

Muscle that supinates the forearm; the deep radial nerve passes through it to reach the posterior compartment of the forearm.

supraspinatus

Rotator cuff muscle that initiates abduction of the arm; innervated by the suprascapular nerve from the superior trunk ($C_{5,6}$).

teres major

Muscle that adducts, medially rotates, and extends the arm; inserts into the crest of the lesser tubercle beside the latissimus dorsi tendon.

teres minor

Rotator cuff muscle that laterally rotates the arm and fixes the humeral head in the glenoid fossa; innervated by the axillary nerve ($C_{5,6}$).

trapezius

Large muscle that elevates, depresses, rotates, and retracts the scapula; receives motor innervation from the spinal accessory nerve ($XI$).

triceps brachii

Three-headed muscle (long, lateral, medial) that extends the forearm; the long head separates the triangular and quadrangular spaces and is innervated by the radial nerve.