The posterior compartment of the arm - nerves (dave's notes)

Question 1

List the nerves found in the posterior compartment of the arm

Answer 1

Radial and ulnar nerves

Question 2

What is the origin of the radial nerve?

Answer 2

It is a continuation of the posterior cord - the largest branch

Question 3

What is the course of the radial nerve?

Answer 3

Originates from the posterior cord, crosses the lower border of the posterior axillary wall then passes down through the triangular space. Spirals obliquely downwards behind the humerus (medial to lateral) behind the uppermost fibres of triceps (hence is separated from the bone). At the lateral edge the nerve comes into contact with periosteum in the lower end of the spiral groove.
The nerve then pierces the lateral intermuscular septum to enter the anterior compartment in the cubital fossa, under the cover of brachioradialis

Question 4

What is found with the radial nerve?

Answer 4

The radial nerve accompanies the profunda brachii vessels

Question 5

What covers the radial nerve in the cubital fossa?

Answer 5

brachioradialis

Question 6

Where does the radial nerve come into contact with periosteum?

Answer 6

At the lateral edge of triceps, in the lower end of the spiral groove

Question 7

How many branches does the radial nerve give off in the posterior compartment?

Answer 7

four branches to triceps - long, medial, lateral and (Med???)

Question 8

Do the posterior compartment branches of the radial nerve come off early or late relative to their target tissue?

Answer 8

Characteristically come off considerably proximal to the part to be innervated.

Question 9

Other than supplying triceps in the posterior compartment of the arm, what branches does the radial nerve give off?

Answer 9

lower lateral cutaneous nerve of the arm and the posterior cutaneous nerve of the forearm

Question 10

How is the ulnar nerve related to the posterior compartment of the arm?

Answer 10

It passes through the lower part of the extensor compartment, then disappears by passing through humeral and ulnar heads into forearm.

Question 11

Where is the ulnar nerve in contact with the humerus? What does it supply in this region?

Answer 11

In contact with the bone in the groove behind the medial epicondyle, gives a twig to the elbow joint.