European Journal of Cardiovascular Medicine

Median nerve is also known as laborer’s nerve. Because, it supplies flexor muscles of forearm and thenar muscles & lateral two lumbricals of hand.  Hence, its variations may be of utmost clinical important1. Median nerve originates from medial and lateral cords of brachial plexus, With root value of C5, C6, C7, C8 &T1 spinal nerves2. The two roots (lateral root from lateral cord and medial root of medial cord of brachial plexus) joins anterior to third part of the axillary artery to form a trunk of the median nerve. During its further course, the median nerve accompanies medial to the brachial artery in flexor compartment of arm without any branches and extends into the cubital fossa medial to the brachial artery and leaving the cubital fossa between the two heads of the pronator teres into the forearm between the flexor digitorum profundus and flexor digitorum superficialis. Next, the median nerve descends deep to flexor retinaculum in wrist and in the hand it gives out its terminal branches, which include the palmar digital branches on the medial side and recurrent motor branches on the lateral side. The aim of this anatomical study is to report the origin, number of anatomical root variations among cadavers.

Data collection was carried out through the dissections of 45 anatomical bodies of both the genders, out of which 34 are male and 11 are female analyzed at the department of Anatomy, in Gayatri Vidya Parishad Institute of Health Care & Medical Technology, Marikavalasa, Visakhapatnam. A descriptive cross sectional study was carried out to report during the time period between 2023-2026. Present study describing findings on dissected limbs according to Cunningham’s manual of dissection 3.  Upper limbs fixed in 10% formalin. The axilla and anterior region of the arm in both right and left extremities was exposed in order to observe the detailed study of the median nerve formation. 

We observed the following variations in routine dissections of upper limb.

The communication between median nerve and musculocutaneous nerve

Normally there is no communication between median nerve and musculocutaneous nerve. Musculocutaneous nerve pierces the coracobrachialis and supplies the muscles of front of arm, which are the flexors of elbow joint2.

In the present study MCN is terminal branch of lateral cord of brachial plexus had a communication with the median nerve in the upper 1/3rd of the arm with no change in the distribution.

Formation of median nerve by 3 roots, with the absence of musculocutaneous nerve

In this case median nerve is formed by 3 roots with the absence of musculocutaneous nerve. The muscles of front of arm – coracobrachialis, biceps brachii, brachialis are innervated by median nerve.

In this variation injury or compression of median nerve causes weakness in flexion of elbow and supination along with sensory deficit along lateral aspect of forearm.

Median nerve is one of the terminal branches of brachial plexuses formed by two roots in front of third part of axillary artery. Formation of median nerve by more than two roots might increase the risk of median nerve injury in surgical operation of axilla. It may lessen the blood supply of upper extremity by compressing the vessels due to very close course of two roots of median nerve to the axillary artery4. Damage of median nerve in the axillary region may leads to paralysis of flexor compartment muscles of arm motor disability of elbow joint and sensory deficit in the lateral aspect of forearm.

As per Le Minor Communication between musculocutaneous nerve and median nerve classification5:

Type 1: No communication

Type 2: Fibres from lateral root of median nerve pass through MCN, joining it in the middle of arm

Type 3: Fibres from MCN form the lateral root of median nerve

Type 4: The MCN arises from the median nerve

Type 5: MCN is absent and MN supplies muscles of the arm.

Neurological, anomalous root contributions could leads variations in axonal supply, which may predispose individuals to atypical patterns of weakness or sensory disturbance in muscles and skin regions innervated by median nerve 6,7. Embryologically, these anomalies can be attributed signaling during limb bud development 8. Molecular cues and transcription factors guide axonal growth into the upper limb; disturbances in these processes may lead to duplication or splitting of roots, thereby accounting for the observed variation 8,9.

The present study insights the rare variation pays an importance in explanation that, how the flexion of elbow is affected by the injury of median nerve in the axilla or in upper arm as it is supplying the flexor muscles of elbow instead of normally they were supplied by musculocutaneous nerve.

1.      Kumar A, Sinha BK. Study of surgical importance of variations and branching pattern of median nerve at carpal tunnel. Eur J Mol ClinMed.2021;8(4):2236-2243

2.      Grays anatomy 2000. The Anatomical Basis of Medicine and Surgery .38th Edition Edinburgh, London, New york, Philadelphia, Sydney, Toronto: Churchill Livingstone. pp.1266-1272.

3.      Romans J. Cunningham’s Manual of Practical Anatomy. Vol 2, 1998

4.      Chrysikos, D.; Papapostolou, S.; Samolis, A.; Antonopoulos, I.; Troupis, T. Anatomical variation of a trifid (trifurcation) lateral root origin of the median nerve. Folia Morphol. 2020, 79, 860–862. [Google Scholar] [CrossRef]

5.      Le Minor JM.[A rare variation of the median and musculocutaneous nerve in man]. Arch Anat Histol Embryol. 1990; 73: 33-42, doi 10.5580/2429, indexed in pubmed: 1669679.

6.      Bozhikova E, NovakovS, Petleshkova T, Harizanova Z, Uzunov N: Variations in the terminal branches of the brachial plexus in the axillary fossa. Biomed Res Int.2025, 2025;5547451.

7.      Soubeyrand M, Melhem R, Protais M, Artuso M, Creze M: Anatomy of the median nerve and its clinical applications. Hand Surg Rehabil. 2020, 39: 2-18.

8.      Saddler TW: Langman’s medical embryology. Lippincott Williams & Wilkins , Philadelphia (PA); 2006.

9.      Encarnacion M, Nurmukhametov R, Barrientos RE, et al.: Anatomical variations of the median nerve: a cadaveric study . Neurol Int. 2022, 14:664-72.