Communications between the Median and Ulnar nerves

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The Median and Ulnar nerves don’t give any branches in the arm. In the forearm and the hand, four communications have been described between them: two in the forearm and two in the hand.

Communications in the Forearm

Communicating branch may rise from:

  1. Median (or anterior interosseous nerve) to Ulnar nerve- Martin-Gruber anastomosis

[ ๐Ÿ’ก Aid to memory: Mโ†’U – Its all in the name!]

Martin-Gruber anastomosis
Martin-Gruber anastomosis [CB– Connecting Branch]
It has an autosomal dominant inheritance pattern. It is more common on the right side and has no sex predilection.

2. Ulnar to Median nerve- Marinacci communication or reversed Martin-Gruber anastomosis.

Marinacci communications
Marinacci communication

It’s rare compared to Martin- Gruber anastomosis.


Communications in the Hand

Communicating branch may rise from:

  1. Median (recurrent branch) to Ulnar (deep branch) nerve- Riche- Cannieu anastomosis, or thenar ansa.
Riche-Cannieu anastomosis
Riche-Cannieu anastomosis

It has an autosomal dominant inheritance pattern. Its incidences is 70- 80% (less frequently present in African Americans)

2. Ulnar to Median nerve (between the common digital nerves arising from them)- Berretini anastomosis, ramus communicans or superficial communicating branch.

 

Berretini anastomosis
Berretini anastomosis

 

Since many investigators found its incidence to be over 80%, the Berretini anastomosis should be considered a normal structure rather than an anatomic variation. It has no age, sex or race predilections.

 

Reference:

  1. Article: Nadire Unver Dogan et al. The communication between the ulnar and median nerves in upper limb. Neuroanatomy 2009-8: 15โ€“19
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