The median nerve enters the posterior compartment of the upper arm through an osteofibrous tunnel .
The latter is formed by:
- the medial intermuscular septum
- a fibrous expansion of the coracobrachialis muscle
- a part of the insertion of the 'Struthers Arcade'.
The nerve may suffer external compression in a narrowed osteofibrous tunnel.
At the level of the cubitus the nerve first courses between the olecranon and the lateral epicondyle and then under the fibrous arch that connects the two heads of the flexor carpi ulnaris.
- ulnar nerve
- median nerve
- Struthers arcade
- medial intermuscular septum
- medial epicondyle
- olecranon
- humeral and ulnar (olecranon) origin of the flexor carpi ulnaris