Ulnar Nerve Flashcards
What are the nerve roots?
Spinal roots: C8-T1.
What are the motor functions?
Innervates the muscles of the hand (apart from the thenar muscles and two lateral lumbricals), flexor carpi ulnaris and medial half of flexor digitorum profundus.
What are the sensory functions?
Innervates the anterior and posterior surfaces of the medial one and half fingers, and the associated palm area.
What is the anatomical course?
The ulnar nerve is derived from the brachial plexus. It is a continuation of the medial cord, containing fibres from spinal roots C8 and T1.
After arising from the brachial plexus, the ulnar nerve descends down the medial side of the upper arm. At the elbow, it passes posterior to the medial epicondyle of the humerus, entering the forearm. At the medial epicondyle, the nerve is easily palpable and vulnerable to injury.
In the forearm, the ulnar nerve pierces the two heads of the flexor carpi ulnaris, and travels alongside the ulna. Three branches arise in the forearm:
Muscular branch: innervates some muscles in the anterior compartment of the forearm.
Palmar cutaneous branch: innervates the skin of the medial half of the palm.
Dorsal cutaneous branch: innervates the skin of the medial 1 and 1/2 fingers, and the associated palm area.
At the wrist, the ulnar nerve travels superficially to the flexor retinaculum. It enters the hand via the ulnar canal (or Guyon’s canal). In the hand the nerve terminates by giving rise to superficial and deep branches.
