Ulnar Nerve Anatomy
Section snippets
Anatomy of ulnar nerve at elbow
In the upper arm, the ulnar nerve lies posteromedial to the brachial artery. It then traverses the medial intermuscular septum posteriorly, passing through the arcade of Struthers approximately 8 cm proximal to the medial epicondyle (Fig. 1) [1]. This arcade comprises a band of deep brachial fascia that attaches to the intermuscular septum, has a V-shaped opening, and covers the ulnar nerve for an average length of 5.7 cm [2]. As shown both anatomically and electrophysiologically, the arcade of
Anatomy of the ulnar nerve in the forearm
The ulnar nerve descends down the arm, deep to the FCU on the surface of the flexor digitorum profundus. At the junction of the middle and distal third of the forearm, the ulnar nerve passes ulnar to the ulnar artery and both lie subjacent to the FCU. The palmar cutaneous branch of the ulnar nerve, also termed the “nerve of Henle,” is referenced sparingly in most anatomic textbooks (Fig. 3) [22]. McCabe and Kleinert [23] described the nerve of Henle most typically to originate 16 cm proximal to
Anatomy of the ulnar nerve at the wrist and hand
The main or volar trunk of the ulnar nerve continues subjacent to the FCU and becomes relatively superficial, covered by fascia and skin. The ulnar nerve and artery enter Guyon's canal, which is a fibro-osseous tunnel formed between the pisiform and hamate hook (Fig. 4). The floor of the canal is formed by the pisohamate ligament, and the roof is the superficial volar carpal ligament. Within Guyon's canal, the ulnar nerve bifurcates into superficial and deep branches. The ulnar artery lies
Ulnar nerve anastomoses
Two commonly mentioned nerve variations must be recognized because they are apt to confuse the diagnosis of ulnar nerve dysfunction, resulting in delayed or erroneous treatment. The first is the Martin-Gruber anastomosis in the forearm. With this anomaly, there is a communication between the ulnar nerve and the median nerve in the forearm. The point of connection can be anywhere from 3 to 10 cm distal to the medial epicondyle [48]. With a typical Martin-Gruber anastomosis, the motor nerves that
Summary
The anatomy of the ulnar nerve in the upper extremity is complex because of its passage through various confined spaces. Knowledge of the local, often variable, anatomy is essential for accurate diagnosis and successful treatment of ulnar nerve dysfunction. Surgical management requires a thorough exploration and complete release of all potential sites of compression when treating neuropathies of the upper extremity. Particular attention should be directed toward identifying and addressing
Acknowledgment
The authors thank Jill K. Gregory, MFA, CMI, medical illustrator, and Dori Kelly, MA, senior editor.
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