Marinacci anastomosis, also known as reverse Martin-Gruber anastomosis, describes a rare interneural communication between the ulnar nerve and the median nerve in the distal forearm.
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Gross anatomy
Most commonly, motor fibres from the ulnar nerve cross to join the median nerve in the distal forearm, the opposite to a Martin-Gruber anastomosis (thus 'reverse') 1,2. This is thought to be a very rare variant of the upper limb nerves, with a meta-analysis of cadaveric and electrophysiological studies suggesting a pooled frequency of less than 1% 1.
History and etymology
The anatomical variant was first described by American neurologist Albert A Marinacci in 1964 3.
Clinical importance
The Marinacci anastomosis is generally not of clinical significance. When present, it is often only noted incidentally, usually during upper limb nerve conduction studies, and may confound accurate interpretation in that setting 2.
See also
Martin-Gruber anastomosis: between median nerve or anterior interosseous branch and ulnar nerve, in the forearm
Riche-Cannieu anastomosis: between the recurrent branch of median nerve and deep branch of ulnar nerve, in the hand
Berrettini anastomosis: between digital sensory nerve of ulnar and median nerves
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