Morphometric Study of the Shoulder and Subclavicular Innervation by the Intermediate and Lateral Branches of Supraclavicular Nerves

Background: The supraclavicular (intermediate) and supra-acromial (lateral) branches of supraclavicular nerves contribute to the innervation of the thorax, shoulder, and neck. Despite their clinical and surgical interest, they are not often considered for descriptive anatomy. The goal of this work was to clarify the morphometric knowledge of these two branches and to discuss the clinical relevance of the anatomical features.

Methods: Intermediate and lateral branches of supraclavicular nerves of 14 necks (8 embalmed cadavers) were dissected using magnifying glasses. Macroscopic parameters were measured and nerve relationships were recorded.

Results: In 12 cases, the intermediate and lateral branches arose from a common trunk behind the posterior border of the sternocleidomastoideus muscle, at a mean distance of 96 mm (70-137) from the sternal angle. The intermediate branch divided into two or three secondary rami. Its most internal ramus crossed the middle third of the clavicle and its most external ramus crossed the second lateral quarter of the bone. The distance between the two farthest nerve endings of this branch was at mean of 98 mm (85-125). The mean distance of the most distal nerve ending from the clavicle was 46 mm (30-63). The lateral branch divided into two or three rami in eight cases and did not divide in six cases. Its most anterior rami crossed the trapezius muscle at a mean distance from the clavicular insertion of 17 mm (12-24). In 13 cases, these rami ended posteriorly or at the level of the anterior border of the acromion process and in 12 cases, they ended laterally or at the level of the acromion process with a mean distance 10.4 mm (0-24).

Conclusion: In case of deficiency of these nerves, pain or sensitive deficit can occur without motor trouble. The factors of acute or chronic injury are direct compression, nerve stretching, repetitive stresses, and direct wound. Moreover, several neck or shoulder surgical approaches are dangerous for these nerves.