Muscles of Wrist, Flexors and Extensors

Human hand possess a complicated structure and anatomy. Wrist consists of a variety of joints, intrinsic and extrinsic muscles, tendons and ligaments. Muscles of Wrist play key role in flexion, extension, medial and lateral rotation of hand and forearm. Let’s discuss flexors and extensors of wrist.

MUSCLES OF WRISTFLEXORS

wrist flexors
wrist muscle pain

Flexor carpi radialis

Origin: Medial epicondyle via common flexor tendon.
Insertion: Front of base of second and third metacarpals.
Nerve: Median (C6, C7).
Action: Flexes and abducts wrist.

Flexor carpi ulnaris

Origin: Humeral head: Medial epicondyle via common flexor tendon. Ulnar head: Medial border of olecranon and upper 2/3rd of border of ulna.
Insertion: Pisiform, hook of hamate and base of fifth metacarpal.
Nerve: Ulnar nerve (C7–T1).
Action: Flexes and adducts wrist.

Palmaris longus

Origin: Medial epicondyl via common flexor tendon.
Insertion: Flexor retinaculum, palmar aponeurosis.
Nerve: Median (C7, C8).
Action: Flexes wrist.

Flexor digitorum superficialis

Origin: Humero-ulnar head—humerus (medial epicondyle via common flexion tendon). Ulna (medial collateral ligament of elbow joint); coronoid process (medial side). Intermuscular septum. Radial head—radius (oblique line on anterior shaft).
Insertion: Four tendon arranged in two pairs: Superficial pair—middle and ring fingers (side of the middle phalanges). Deep pair—index and little fingers (side of middle phalanges).
Nerve: Median (C8, T1).
Action: Flexes fingers and wrist.

Flexor digitorum profundus

Origin: Ulna (proximal 3/4th of anterior and medial shaft, medial coracoid process), interosseous membrane (ulnar).
Insertion: Four tendons to digits 2–5 (distal phalanges, at the base of palmar surface).
Nerve: Medial part—ulnar nerve (C8, T1). Lateral part—anterior interosseous branch of median nerve (C8,T1).
Action: Flexes fingers and wrist.

EXTENSORS

wrist extensors

Extensor carpi radialis brevis

Origin: Lateral epicondyle via common extensor tendon.
Insertion: Posterior surface of base of third metacarpal.
Nerve: Posterior interosseous branch of radial nerve (C7, C8).
Action: Extends and abducts wrist.

Extensor carpi radialis longus

Origin: Lower third of lateral supracondylar ridge of humerus, intermuscular septa.
Insertion: Posterior surface of base of second metacarpal.
Nerve: Radial nerve (C6, C7).
Action: Extends and abducts wrist.

Extensor carpi ulnaris

Origin: Lateral epicondyle via common extension tendon.
Insertion: Medial side of fifth metacarpal base.
Nerve: Posterior interosseous nerve (C7, C8).
Action: Extends and adducts wrist.

Extensor digitorum

Origin: Lateral epicondyle via common extensor tendon, intermuscular septa.
Insertion: Lateral and dorsal surface of second to fifth digits.
Nerve: Posterior interosseous branch of radial nerve (C7, C8).
Action: Extends fingers and wrist.

Extensor digiti minimi

Origin: Lateral epicondyle via common extensor tendon, intermuscular septa.
Insertion: Dorsal digital expansion of fifth digit.
Nerve: Posterior interosseous nerve (C7, C8).
Action: Extends fifth digit and wrist.

Extensor pollicis longus

Origin: Ulna (middle 3rd of posterior surface), interosseous membrane.
Insertion: Dorsal surface of distal phalanx of thumb.
Nerve: Posterior interosseous nerve (C7, C8).
Action: Extends thumb and wrist, abducts wrist.

Extensor pollicis brevis

Origin: Radius (posterior surface), interosseous membrane.
Insertion: Dorsolateral base of maximal phalanx of thumb.
Nerve: Posterior interosseous nerve (C7, C8).
Action: Extends thumb and wrist, abducts wrist.

Extensor indicis

Origin: Lower part of posterior surface of ulna, interosseous membrane.
Insertion: Dorsal digital expansion on back of proximal phalanx of index finger.
Nerve: Posterior interosseous nerve (C7, C8).
Action: Extends index finger and wrist.