Ulnar nerve anatomy

1. What nerve roots, trunk, and cord does the ulnar nerve come from?
2. What is the ulnar nerve's anatomical relationship to the triceps?
3. Between what two structures does the ulnar nerve pass in the elbow?
4. What forearm muscles does the ulnar nerve innervate?
5. After the ulnar nerve passes through Guyon's canal in the hand, what are the three branches it gives off and what do they innervate?

Answers:
1. Nerve roots C8-T1, the lower trunk, and the medial cord.
2. The ulnar nerve runs along the medial surface of the medial head of the triceps, with a deep groove of thick fascia called the Arcade of Struthers.
3. Between the medial epicondyle and the olecranon in the retrocondylar groove.
4. It innervates the flexor carpi ulnaris and the flexor digitorum profundus (4th, 5th digits). It also gives off branches as the palmar ulnar cutaneous nerve, the dorsal ulnar cutaneous nerve, and the dorsal digital nerves.
5. The three branches are the Superficial sensory branch (sensory innervation); the hypothenar branch (opponens digiti quinti, abductor digiti quinti, flexor digiti quinti); the deep motor branch (palmaris brevis, dorsal interossei, palmar interossei, lumbricals, adductor pollicis, flexor pollicis brevis (deep head)).