1d - Muscles of the Anterior Forearm

Question 1

Pronator teres - Origin, Insertion, Action and Innervation

Answer 1

Origin: First head [medial epicondyle of humerus] second head [coronoid process of ulna]
Insertion: By common tendon into lateral radius midshaft
Primary action: Pronates forearm. Acts with Pronator Quadratus muscle.
Other action: Weak flexor of forearm.
Innervation: Median

Question 2

Flexor carpi radialis - Origin, Insertion, Action and Innervation

Answer 2

Origin: Medial epicondyle of humerus.
Insertion: Base of second and third metacarpals.
Primary action: Flexor of hand.
Other actions: Abducts hand. Weak synergist of forearm flexion.
Innervation: Median

Question 3

Palmaris longus - Origin, Insertion, Action and Innervation

Answer 3

Origin: Medial epicondyle of humerus.
Insertion: Fascia of palm (palmar aponeurosis).
Primary action: Tenses skin and fascia of palm during hand movements.
Other actions: Weak hand flexor and synergist of forearm flexion.
Innervation: Median

Question 4

Flexor carpi ulnaris - Origin, Insertion, Action and Innervation

Answer 4

Origin: Humeral head [Medial epicondyle of humerus], ulnar head [olecranon and posterior surface of ulna]
Insertion: Pisiform, hamate, and base of fifth metacarpal.
Primary action: Flexes and adducts hand.
Other action(s): Stabilizes wrist during finger extension.
Innervation: Ulnar

Question 5

Flexor digitorum superficialis - Origin, Insertion, Action and Innervation

Answer 5

Origin: Humeroulnar head [Medial epicondyle of humerus and coronoid process of ulna], Radial head [Superior 1/2 of anterior border of radius]
Insertion: Bodies of middle phalanges of fingers II-V
Primary action: Flexes hand and middle phalanges of fingers II-V.
Innervation: Median

Question 6

Flexor pollicis longus - Origin, Insertion, Action and Innervation

Answer 6

Origin: Anterior surface of radius and interosseous membrane
Insertion: Distal phalanx of thumb
Primary action: Flexes distal phalanx of thumb.
Innervation: Anterior interosseous

Question 7

Flexor digitorum profundus - Origin, Insertion, Action and Innervation

Answer 7

Origin: Anteromedial surface of ulna and interosseous membrane
Insertion: By four tendons into distal phalanges of fingers II-V
Primary action: Flexes distal interphalangeal joints.
Other action(s): Slow-acting flexor of fingers and assists in hand flexion.
Innervation: Anterior interosseous

Question 8

Pronator quadratus - Origin, Insertion, Action and Innervation

Answer 8

Origin: Distal portion of anterior ulnar shaft.
Insertion: Distal portion of anterior distal shaft.
Primary action: Prime mover of forearm pronation. Acts with Pronator Teres.
Other action: Helps hold radius and ulna together
Innervation: Anterior interosseous

Question 9

What is the flexor retinaculum and what does it do?

Answer 9

It is a transverse carpal ligament distal to the radial joint. It spans the carpal bones and forms a tunnel for flexor tendons and the median nerve to pass through.
Prevents bowstringing of tendons during contraction.

Question 10

What is carpal tunnel syndrome?

Answer 10

Caused by inflammation of tendons in the carpal tunnel.

The inflammation squeezes the median nerve and causes numbness and a dull pain in regions supplied by the median nerve.