Since the median, ulnar, and radial nerves lie in close proximity to the axillary artery in the neurovascular compartment of the axilla, all three nerves are easily and completely blocked by the axillary approach with injection of a moderate volume of anesthetic.
Because of its more proximal origin, however, complete motor and sensory block of the musculocutaneous nerve can be obtained only by the injection of a relatively large volume of local anesthetic into the axillary neurovascular compartment. Block of the distal sensory portion of the musculocutaneous nerve-the lateral antebrachial cutaneous nerve-insures effective analgesia of the lateral forearm, wrist, and hand with a smaller volume and thus a lower total dosage of local anesthetic.
Modified axillary block, providing motor and sensory block of the median, ulnar, and radial nerves and sensory anesthesia of the lateral antebrachial cutaneous nerve, consists of an injection of a moderate volume of anesthetic at the axilla, digital or other compression of the neurovascular compartment distal to the injection site, and a supplementary injection of the lateral antebrachial cutaneous nerve as it emerges from the lateral cleft between the biceps and brachialis muscles at the elbow.
(C) 1965 American Society of Anesthesiologists, Inc.