Dual Innervation of Human Brachialis Muscle

Brachialis muscle anatomy and its innervation has been studied previously by many authors. There have been inconsistent description of the brachialis muscle anatomy in literature. In the present study 40 upper limbs of twenty embalmed Indian cadavers were dissected and found that all specimens of the brachialis had 2 heads, superficial and deep. The larger, superficial head had more proximal origin and distal insertion than deep head. In all specimens, brachialis was supplied by musculocutaneous nerve while only 70% (28/40) cases received branch from radial nerve. All specimens of superficial head and 20% (8/40) specimens of deep head were supplied by branches from musculocutaneous nerve entering in their upper third part only. Branches from the radial nerve were observed to enter in 5% (2/40) specimens of superficial head in upper third part and 65% (26/40) specimens of deep head in lower two-third part. These anatomical facts have implications for humeral surgery including both anterior and anterolateral approaches.