What anatomy is involved in ulnar neuropathy?

Updated: Jun 08, 2018
  • Author: Charles F Guardia, III, MD; Chief Editor: Nicholas Lorenzo, MD, MHA, CPE  more...
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The ulnar nerve is the terminal branch of the medial cord of the brachial plexus and contains fibers from C8, T1, and, occasionally, C7. [9, 10] It enters the arm with the axillary artery and passes posterior and medial to the brachial artery, traveling between the brachial artery and the brachial vein.

At the level of the insertion of the coracobrachialis in the middle third of the arm, the ulnar nerve pierces the medial intermuscular septum to enter the posterior compartment of the arm. [11, 12] Here, the nerve lies on the anterior aspect of the medial head of the triceps, where it is joined by the superior ulnar collateral artery. The medial intermuscular septum extends from the coracobrachialis proximally, where it is a thin and weak structure, to the medial humeral epicondyle, where it is a thick, distinct structure.

The next important site along the course of the ulnar nerve is the arcade of Struthers. This structure is found in 70% of patients, 8 cm proximal to the medial epicondyle, and extends from the medial intermuscular septum to the medial head of the triceps. The arcade of Struthers is formed by the attachments of the internal brachial ligament (a fascial extension of the coracobrachialis tendon), the fascia and superficial muscular fibers of the medial head of the triceps, and the medial intermuscular septum.

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