Muscles of the Forearm: Anterior and Posterior Compartments

Comprehensive vocabulary flashcards covering the anatomical origins, insertions, innervations, and actions of the muscles of the anterior and posterior compartments of the forearm.

Muşchiul rotund pronator (Pronator teres muscle)

A cylindrical forearm muscle originating by two heads (humeral and ulnar) and inserting on the pronator tuberosity in the middle $\frac{1}{2}$ of the lateral surface of the radius; innervated by the median nerve, it acts primarily as a pronator of the forearm and secondarily as a flexor of the forearm on the arm.

Caput humerale of Muşchiul rotund pronator

The superficial head of the pronator teres muscle that originates on the medial epicondyle of the humerus.

Caput ulnare of Muşchiul rotund pronator

The deep head of the pronator teres muscle that originates on the coronoid process of the ulna; the median nerve passes between this head and the humeral head.

Muşchiul flexor radial al carpului (Flexor carpi radialis muscle)

A fusiform muscle originating on the medial epicondyle of the humerus whose insertion tendon passes under the flexor retinaculum to insert onto the base of metacarpal II; innervated by the median nerve, it flexes the hand on the forearm, flexes the forearm on the arm, and secondarily abducts the hand.

Muşchiul palmarul lung (Palmaris longus muscle)

A superficial and sometimes absent muscle originating on the medial epicondyle of the humerus and inserting onto the flexor retinaculum and palmar aponeurosis; innervated by the median nerve, it acts as a weak flexor of the hand on the forearm.

Muşchiul flexor ulnar al carpului (Flexor carpi ulnaris muscle)

A fusiform muscle with two heads (humeral head from the medial epicondyle; ulnar head from the olecranon and upper $\frac{3}{5}$ of the posterior border of the ulna) inserting onto the pisiform bone and via ligaments to metacarpal V and the hook of the hamate; innervated exceptionally by the ulnar nerve, it flexes and adducts the hand.

Partea profundă (Pars profunda) of the anterior compartment

The deep division of the anterior forearm flexors located in layers II and III, comprising the flexor digitorum superficialis, flexor digitorum profundus, flexor pollicis longus, and pronator quadratus, whose tendons pass deep to the flexor retinaculum.

Muşchiul flexor superficial al degetelor (Flexor digitorum superficialis muscle)

A layer II muscle arising via a humeroulnar head and a radial head (between which passes the ulnar artery and median nerve) and inserting via four bifurcated tendons onto the middle phalanx of digits II–V; innervated by the median nerve, it flexes the middle phalanx, digits II–V, and the palm.

Chiazma tendinoasă (Chiasma tendinum)

The tendinous crossing formed by the tendons of digits III and II of the flexor digitorum superficialis muscle before they pass deep to the flexor retinaculum.

Tendon arrangement of Muşchiul flexor superficial al degetelor

The mediolateral sequence of flexor digitorum superficialis tendons in the inferior $\frac{1}{4}$ of the forearm, ordered from lateral to medial as III, II, IV, and V.

Muşchiul flexor profund al degetelor (Flexor digitorum profundus muscle)

A layer III muscle originating on the upper approximately $\frac{2}{3}$ of the anterior surface of the ulna and adjacent interosseous membrane, inserting via four tendons on the distal phalanges of digits II–V by passing through the bifurcated tendons of the superficial flexor; innervated by the median nerve (II–III) and ulnar nerve (IV–V).

Muşchiul flexor lung al policelui (Flexor pollicis longus muscle)

A deep (layer III) semipennate muscle originating on the middle $\frac{1}{3}$ of the anterior surface of the radius and inserting onto the distal phalanx of the pollex (thumb); innervated by the anterior interosseous nerve of the median nerve, it flexes the distal phalanx, the pollex, and the palm.

Muşchiul pătratul pronator (Pronator quadratus muscle)

A deep (layer III) muscle located in the lower forearm, originating on the inferior $\frac{1}{4}$ of the anterior surface of the ulna and inserting on the inferior $\frac{1}{4}$ of the anterior surface of the radius; innervated by the anterior interosseous nerve of the median nerve, it acts to pronate the forearm.

Compartimentul posterior al antebraţului (Posterior compartment of the forearm)

The extensor compartment of the forearm containing the anconeus, extensor digitorum, extensor indicis, extensor digiti minimi, extensor carpi ulnaris, supinator, abductor pollicis longus, extensor pollicis brevis, and extensor pollicis longus, all covered by the extensor retinaculum.

Partea laterală sau radială (Pars lateralis/radialis)

A distinct subdivision of the posterior compartment of the forearm that comprises the brachioradialis, extensor carpi radialis longus, and extensor carpi radialis brevis muscles.

Muşchiul anconeu (Anconeus muscle)

A superficial, triangular muscle situated posterior to the elbow joint, originating on the lateral epicondyle of the humerus and inserting onto the olecranon and posterior surface of the ulna; innervated by the radial nerve, it extends the forearm and slightly abducts the ulna during pronation.

Muşchiul extensor al degetelor (Extensor digitorum muscle)

A superficial lateral epicondylar muscle originating on the lower part of the lateral epicondyle of the humerus and inserting via four flattened, interconnected tendons onto the base of the middle and distal phalanges of digits II–V.