keeping in mind the medical and surgical aspects , the nerve supply of arm is very important .
the brachial plexus is the network formed by the communication between the anterior rami of the fifth to eighth cervical nerve roots and first thoracic nerve root .
almost every muscle of the upper limb is supplied by nerves derived from the brachial plexus , as is most of its overlying skin .
the radial nerve is a terminal branch of the posterior cord of the brachial plexus .
it is the largest branch of the plexus , supplying majority of the posterior and extensor components of the arm and forearm .
the medial cutaneous nerve of forearm arises from the medial cord of the brachial plexus , initially lying between the axillary artery and vein .
travelling distally , it lies medial to the brachial artery , and pierces the deep fascia at the midpoint of the upper arm adjacent to the basalic vein . here
it divides into two branches - the anterior branch passes anterior to the median cubital vein , lays anteromedially in the forearm and supplies skin to the wrist .
the posterior branch has an oblique course anteriorly , lying medial to the basalic vein , becoming posterior distal to the medial epicondyle of the humerus to descend on the posteromedial border of the forearm towards the wrist ; it supplies a smaller area of the posteromedial forearm .
although communication between the nerves in the arm are rare , communication between median nerve and musculocutaneous nerve is being described since the 19 century .
anatomical variations of peripheral nerves are important to medical personnel , especially to orthopedic surgeons , neurophysicians , physiotherapist and radiologists .
the present variation was observed during routine dissection at the anatomy department of medical college and rural hospital .
in a 58-year - old male cadaver , the brachial plexus was exposed after excising pectoralis major and pectoralis minor muscles .
a communication between the radial and medial cutaneous nerves of forearm on left side was found [ figure 1 ] .
the communicating nerve was found to be arising from the medial cutaneous nerve of forearm .
the communicating nerve was seen crossing the third part of the axillary artery on its medial side and running downward backward , laterally , to join the radial nerve .
this nerve was related medially with the axillary vein and laterally to the axillary artery and ulnar nerve .
the dissection was continued to expose the entire brachial plexus from the origin and was found to be normal .
( aa : axillary artery ; bbr : biceps brachii ; cbr : coracobrachialis ; ld : latissimus dorsi ; mc : medial cord ; mcn : musculocutaneous nerve ; mn : median nerve ; rn : radial nerve ; sc : subscapularis muscle ; un : ulnar nerve ; communication between radial nerve and medial cutaneous nerve of forearm ; 1 : medial cutaneous nerve of forearm ; 2 : nerve to latissimus dorsi ; 3 : lower subscapular nerve ; 5 : subscapular region )
in the present case report , we report the communication between the radial and medial cutaneous nerves of forearm on the left side in an adult male cadaver .
the surgeon should keep such variations in mind as while performing operations of the region of axilla ( specifically constructive shoulder arthroplasty and treating shoulder dislocations ) .
report communication between the radial and axillary nerve in eight of the 602 brachial plexus .
report the presence of communication between the radial and ulnar nerves on the dorsal surface of the hand .
das s and paul s report an unusual communication between ulnar and medial cutaneous nerves of the forearm .
the existence of this variation , described in our case report , may be attributed to the random factors influencing the mechanism of formation of limb muscles and the peripheral nerves during embryonic life . in the context that ontogeny recapitulates phylogeny ; it is possible that the variation seen in the current study is the result of developmental anomaly . in human beings ,
forelimb muscles develop from the mesenchyme of paraxial mesoderm in the fifth week of intrauterine life .
the radial extensor muscles of the forearm have a different origin from other extensor muscles of the forearm . regional expression of five hox d ( hox d 1 to hox d 5 ) genes is responsible for upper limb development .
the motor axons arrive at the base of limb bud ; they mix to form brachial plexus in upper limb .
the guidance of the developing axons is regulated by the expression of chemo - attractants and chemo - repulsant in highly coordinated sight specific fission .
the tropic substances attract the correct growth cones or support the viability of the growth cones that happen to take the right path .
tropic substances include brain - derived neurotropic growth factor , c - kit ligand , neutrin-1 , neutrin-2 etc .
significant variations in nerve pattern may be result of altered signaling between mesenchymal cells and neuronal growth cones or circulatory factors at the time of fission of brachial plexus cords . meticulous knowledge of possible variations of medial cutaneous nerve of the forearm and the radial nerve may provide valuable help in the management of traumatology of shoulder joint and arm ; help the surgeon in circumventing iatrogenic damage during repair operations of these regions .
meticulous knowledge of possible variations of medial cutaneous nerve of the forearm and the radial nerve may provide valuable help in the management of traumatology of shoulder joint and arm ; help the surgeon in circumventing iatrogenic damage during repair operations of these regions .
 radial nerve is usually a branch of the posterior cord of the brachial plexus . 
 it innervates triceps , anconeous , brachialis , brachioradialis , extensor carpi radialis longus muscles and gives the posterior cutaneous nerve of the arm , lower lateral cutaneous nerve of arm , posterior cutaneous nerve of forearm ; without exhibiting any communication with the medial cutaneous nerve of forearm or any other nerve . 
 we report communication between the radial nerve and medial cutaneous nerve of forearm on the left side in a 58-year - old male cadaver . 
 the right sided structures were found to be normal . 
 neurosurgeons should keep such variations in mind while performing the surgeries of axilla and upper arm . 
Introduction
Case Report
Discussion
Clinical significance