9.1 Posterior Compartment of the Forearm and Dorsum of Hand

Question 1

Identify the muscles of the posterior compartment of the forearm:

a. Brachioradialis
b. Extensor carpi radialis longus
c. Extensor carpi radialis brevis
d. Extensor digitorum
e. Extensor digiti minimi
f. Extensor carpi ulnaris

a. Abductor pollicis longus
b. Extensor pollicis brevis
c. Extensor pollicis longus
d. Extensor indicis
e. Supinator

By what nerve are these muscles innervated?
What are the primary functions of the muscles of the posterior forearm?

Answer 1

• Innervated by radial nerve (C5-C8)
• Posterior forearm muscles work as extensors and supinators of the forearm and hand. (Brachioradialis is a weak flexor at the elbow)

Question 2

Identify the posterior interosseus nerve.

From what proximal nerve does this branch? Describe its course.

Answer 2

the termination of the deep radial nerve as it emerges from the supinator

Question 3

Identify the posterior interosseus artery.

From what proximal artery does this branch? Describe its course

Answer 3

Branch from common interosseous (from Ulnar).

Runs along posterior aspect of interosseous membrane.

Question 4

Identify the radial artery and describe its course.

Answer 4

Branches from brachial aa. Travels along lateral aspect of forearm.

Question 5

Locate the region of the anatomical snuffbox:

What structures are involved in this?

Answer 5

Abductor pollicis longus tendon.
Extensor pollicis brevis tenon.
Extensor pollicis longus tendon.
Radial artery.

Question 6

Locate the dorsal interossei.

Describe their attachments, function, and innervation.

Answer 6

originate from the metacarpal bones and insert onto the proximal phalanx between 2 fingers.

Question 7

Identify the extensor (dorsal digital) expansion.

Answer 7

present on the dorsum of each digit. It serves as the distal attachment for the lumbricals and interossei muscles of the palm and facilitates extension of the interphalangeal joints.