Muscular Branch of Musculocutaneous Nerve to Brachialis

Origin

The muscular branch to brachialis muscle arises from the musculocutaneous nerve (C5—C7).

Course

Following its origin from the lateral cord of the brachial plexus, the musculocutaneous nerve leaves the axilla and enters the anterior compartment of the arm by piercing the coracobrachialis muscle. In the arm, it runs downwards and laterally between the biceps brachii superficially and brachialis deeper to reach the lateral side of the tendon of the biceps.

As the nerve descends between the two muscles, the muscular branches to biceps brachii are given off from the main nerve at a mean distance of 19–31 cm from the acromial process.

Different patterns of innervation of the brachialis muscle have been recorded. In the first pattern. In the more common first pattern (Type 1), only one primary motor branch emerges from the musculocutaneous nerve and splits into two or three secondary branches that entered the muscle. In the second branching pattern (Type 2), the muscle is innervated by two primary branches with different origins on the main nerve trunk and each branch makes its own way to a different part of the brachialis muscle (Pacha Vicente et al., 2005).

Branches

There are no named branches.

Supplied Structures

Muscular branches from the musculocutaneous nerve provide motor innervation to the flexor muscles of the anterior arm, including the brachialis muscle.

References

Pacha Vicente, D., Forcada Calvet, P., Carrera Burgaya, A. and Llusá Pérez, M. (2005) 'Innervation of biceps brachii and brachialis: Anatomical and surgical approach', Clin Anat, 18(3), pp. 186-94.