Jongwan Kim; Soo-Jung Jung; Yong Wook Jung; Katsuro Tachibana & Jae-Ho Lee

The median nerve (MN) is a peripheral nerve that arises from the brachial plexus. The formation of MN occurs through the fusion of two roots: the lateral root and the medial root, originating from the lateral and medial cord, respectively. MN anatomy including its formation, distribution, and communication was extensively diverse. The present study focused on topography of the MN and its anatomical variation in 112 upper limbs. The lateral and medial cords of the brachial plexus merged at the axillary level in 96.4 % of cadavers and at the brachial level in 3.6 % of cases to form the MN. The MN formation was found at a distance of + 8.71 ± 20.06 mm from the coracoid process, as the reference line. The location of MN formation was more distal in cadavers without COM than those with COM (+13.44 ± 23.77 vs. +2.89 ± 12.76, P = 0.12). Communication branch to the musculocutaneous nerve (COM) was detected in 44.6 % and its position was determined to be at + 43.84 ± 35.90 mm from the reference line. In some case, COM presence formed a small hole, and it was defined as ring formation. The location of COM was different according to the presence of the ring formation (P < 0.001). Understanding these anatomical variations is important for both anatomists and clinicians. Surgeons who conduct procedures related to neoplasms or trauma repair must possess knowledge of these variations.

KEY WORDS: Median nerve; Musculocutaneous nerve; Anatomical variation; Ring form.

KIM, J.; JUNG, S-J.; JUNG, Y.W.; TACHIBAN, K. & LEE, J-H. Topography of the formation of the median nerve and its communication with the musculocutaneous nerve. Int. J. Morphol., 43(5):1478-1482, 2025.