Anatomy of elbow + cubital fossa

Question 1

the anterior (flexor) compartment of the arm is innervated by what nerve of the brachial plexus

Answer 1

The anterior (flexor) compartment of the arm is primarily innervated by the MUSCULOCUTANEOUS NERVE, which is a branch of the brachial plexus. This nerve arises from the lateral cord of the brachial plexus, carrying fibers predominantly from the C5, C6, and sometimes C7 nerve roots.

The musculocutaneous nerve is responsible for innervating key muscles in the anterior compartment of the arm, including the biceps brachii, brachialis, and coracobrachialis, facilitating their primary functions of flexion at the elbow and, in the case of the biceps brachii, supination of the forearm.

Question 2

the posterior (extensor) compartment of the arm is innervated by what nerve of the brachial plexus

Answer 2

The posterior (extensor) compartment of the arm is primarily innervated by the RADIAL NERVE, which is a major branch of the brachial plexus. The radial nerve originates from the posterior cord of the brachial plexus, carrying fibers from the C5 to T1 nerve roots.

In the posterior compartment of the arm, the radial nerve is responsible for innervating the triceps brachii, which is the primary extensor of the elbow, and the anconeus muscle. This innervation allows for the extension of the forearm at the elbow joint, a key function of the muscles in the posterior compartment of the arm.

Question 3

what are the muscles of the anterior compartment of the arm

Answer 3

• biceps brachii (flexor at shoulder + elbow, powerful supinator)
• brachialis (flexes elbow in all positions)
• coracobrachialis (flexes + adducts shoulder+ resists dislocation)
  (BBC)

*innervated by musculocutaneous nerve
* C5,C6,C7

• biceps reflex= C5,6

Question 4

is the radius twisted during supination or pronation

Answer 4

the radius is twisted during pronation

Question 5

what muscle of the upper limb flexes the elbow in all positions

Answer 5

brachialis flexes the elbow in all positions

Question 6

the radial nerve runs in the _________ compartment of the arm, the ulnar nerve runs in the _______ compartment of the arm

Answer 6

the radial nerve runs in the POSTERIOR compartment of the arm, the ulnar nerve runs in the ANTERIOR compartment of the arm

Question 7

what nerve runs behind medial epicondyle of elbow

Answer 7

ulnar nerve runs behind medial epicondyle of elbow

Question 8

a) what are the 2 muscles of pronation
b) 2 muscles of supination

Answer 8

a) pronation= pronator teres + pronator quadratus

b) supination= biceps brachii + supinator