The brachial plexus supplies all the motor and most of the sensory functions of the shoulder, with the exception of the cephalad cutaneous areas of the shoulder.
- The cephalad cutaneous areas of the shoulder are innervated by the supraclavicular nerves which originate from the superficial cervical plexus (C3-C4).
The terminal branches of the brachial plexus that supply the majority of the shoulder innervation are the axillary and suprascapular nerves.
- The axillary nerve originates from C5-C6 nerve roots, with occasional contribution from C4. It is derived from the posterior cord of the brachial plexus.
- The suprascapular nerve supplies sensory innervation to the subacromial bursa, acromioclavicular joint, coracoclavicular ligament, and 70% of the shoulder joint capsule. This nerve arises from the superior trunk of the brachial plexus, C5-C6 and possibly C4.
This block has been considered a “spinal” of the upper extremity.
The supraclavicular regional block anesthetizes the trunks and divisions of the brachial plexus, resulting in analgesia or surgical anesthesia of the entire upper extremity with the exception of the superficial, upper medial portion of the arm which is supplied by the intercostobrachial nerve that is derived from the T2 ventral rami nerve.
Motor blockade of the upper extremity will require that a patient utilizes a support sling to minimize injury until the regional block resolves.