Site of Separation of Musculocutaneous Nerve from Axillary Brachial Plexus: Analysis using Ultrasound-Observational Volunteer Study

The axillary approach to brachial plexus blockade provides satisfactory anesthesia for elbow, forearm, and hand surgeries. The use of ultrasound enhances the success of such blocks. The major issue in such a block is the anatomical variation of the musculocutaneous nerve and its possible sparing. The unblocked lateral superficial tissues of forearm and the problem of tourniquet pain will come up if it's spared. Hence in our study we wanted to locate the site of separation of the nerve. In eighty young healthy male volunteers, the scan of the right axillary area showed that the separation was proximal (point C) in 34% of cases to the classical described site (point A) of combined visualisation of conjoint tendon and axillary artery. It was found separating distally (point B) in 59 % of cases. The distance was maximal in the proximal group with 44 mm and in the distal group of 35 mm. It was absent in one individual. With such a large variation in anatomy, it is necessary to identify the musculocutaneous nerve separately and block it for a successful anesthetic journey in axillary approach to blocking brachial plexus.