Posterior Forearm Muscles | Deep Layer

This video tutorial explores the deep layer of muscles in the posterior compartment of the forearm, focusing on the abductor pollicis longus, extensor indicus, extensor pollicis longus and brevis, and the supinator muscle. It covers their origins, insertions, functions, and innervations, providing a detailed understanding of their roles in thumb and finger movements.

Which muscle is responsible for abducting the thumb?

• Extensor Pollicis Brevis

• Supinator

• Abductor Pollicis Longus

• Extensor Indicus

What is the origin of the abductor pollicis longus muscle?

• Anterior surface of the radius

• Posterior surface of the ulna, radius, and interosseous membrane

• Lateral epicondyle of the humerus

• Medial epicondyle of the humerus

Which nerve innervates the extensor indicus muscle?

• Posterior interosseous nerve

• Ulnar nerve

• Median nerve

• Deep branch of the radial nerve

What is the primary action of the extensor indicus muscle?

• Supination of the forearm

• Flexion of the index finger

• Extension of the index finger

• Abduction of the thumb

Where does the extensor pollicis longus muscle insert?

• Base of the first metacarpal

• Base of the distal phalanx of the thumb

• Base of the proximal phalanx of the thumb

• Base of the second metacarpal

Which muscle is synergistic with the biceps brachii in supination?

• Extensor Indicus

• Supinator

• Extensor Pollicis Brevis

• Abductor Pollicis Longus

What is the innervation of the supinator muscle?

• Ulnar nerve

• Median nerve

• Deep branch of the radial nerve

• Posterior interosseous nerve