A cadaveric study in the Indian population of the brachialis muscle innervation by the radial nerve.

Radial nerve innervation to the brachialis muscle has been studied previously by different authors in Caucasian, Chinese, and Thai population. Present study was aimed to describe the radial nerve and musculocutaneous nerve contribution to the brachialis muscle and to elucidate racial differences between Indian and other populations. Hundred-forty superior extremities of 70 embalmed cadavers including 29 female and 41 male cadavers were dissected to study the innervation of brachialis muscle by musculocutaneous nerve and branch from the radial nerve. All the specimens were studied for site of penetration, level of distribution and nature of course and pathway of the branch of the radial nerve to the brachialis muscle. The musculocutaneous nerve innervated the brachialis muscle in 100% specimens, whereas the radial nerve in 72.14% specimens. The radial nerve branch to brachialis pierced the muscle in the lower one third of the humerus in 65.71% specimens; on the other hand in the middle one third in 34.29% specimens. The radial nerve branch to brachialis in 50.71% specimens had relatively straighter course before penetration into the muscle, whereas in 49.29% specimens the nerve had relatively curved course and pathway. Aforementioned results regarding brachialis innervation by radial nerve in Indian population is different from studies reported in other populations. These anatomical facts are important for humeral surgery including both the anterior and posterior approaches especially for orthopedic interventions on the Indian population.