Plexus anesthesia: Interscalene, Subclavian and Axillary Perivascular Techniques

Abstract

The single-injection techniques developed to provide anesthesia for the upper extremities are based on the fact that all of the nerves to the arm are contained in a tubular sheath of fascia. [8,9,11] The anterior scalene muscle arises from the anterior tubercles of the transverse processes of the third, fourth, fifth, and sixth cervical vertebrae and inserts on the scalene tubercle of the first rib, separating the subclavian vein from the subclavian artery, which lies posterior to this insertion. The middle scalene muscle arises from the posterior tubercles of the transverse processes of the lower six cervical vertebrae. Its insertion is separated from that of the anterior scalene muscle by the subclavian groove, through which the artery passes. Thus, since the roots of the nerves comprising the brachial plexus travel in the groove between the anterior and posterior tubercles of the transverse processes of the cervical vertebrae, they emerge from the “gutters” of the cervical processes to descend toward the first rib between the two walls of fascia covering the anterior and middle scalene muscles (i.e., they enter the interscalene space). As the roots pass down through this space, they converge to form the trunks of the brachial plexus, which together with the subclavian artery invaginate the scalene fascia to form a subclavian perivascular sheath, which in turn becomes the axillary sheath as it passes under the clavicle.