Berrettini anastomosis is a common sensory interneural communication between the ulnar nerve and the median nerve in the palmar surface of the hand.
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Gross anatomy
The Berrettini anastomosis is a purely sensory anastomosis between the common palmar digital nerves that arise from the median and ulnar nerve 1,2. While there are at least four patterns (or types) of anastomosis, most commonly, it forms between the fourth common palmar digital nerve (from the ulnar nerve) joining the third common palmar digital nerve (from the median nerve) 1,2. The anastomosis occurs in close proximity to the flexor retinaculum 1,2.
This is thought to be a very common variant of the upper limb nerves, with a meta-analysis of cadaveric and electrophysiological studies suggesting a pooled frequency of approximately 60% 1. It is, in fact, so common that many authors consider it to be a normal structure 2,3.
History and etymology
This anastomosis was first illustrated by Berrettini in 1741 1.
Clinical importance
The Berrettini anastomosis is usually not of significance to the physical examination or in routine upper limb nerve conduction studies. However, due to its proximity to the flexor retinaculum, it may be at risk of iatrogenic injury during carpal tunnel release surgery, leading to a small region of digital sensory loss 1,2.
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
Marinacci anastomosis: a reverse Martin-Gruber anastomosis, between the ulnar nerve and median nerve
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