Anatomy of the levator claviculae, with an overview and a literature survey

Abstract

We report here an anatomical study of the levator claviculae discovered during an anatomical dissection course for medical students. The muscle was identified on the left side, and followed a typical topography to previous detections, originating from the transverse process of the fourth cervical vertebra and attaching to the upper facet of the middle part of the clavicle. Innervation to this muscle came from both the third and fourth rami of the cervical spinal nerves. Blood supply to the muscle could not be identified clearly. In this report, we undertook a comprehensive literature survey of this muscle dating back ca. 170 years, and attempted to ascertain the phylogenic and ontogenetic explanations for the development of this muscle.

Levator claviculae muscle: Anatomic variation found during neck dissection

“…When the LC muscle is present only on one side, it seems to be more frequent on the left side, as observed in our case. A recent review considered the anatomical variability of LC muscle origin, and reported that it can originate at the level of one or more transverse processes of the cervical vertebrae, between C1 and C6. From its origin, the LC muscle runs inferiorly, coursing laterally to the scalene muscles and medial to the sternocleidomastoid muscle.…”

“…In the present case, it originated from the transverse process of the C2‐C3 vertebrae, even if an origin at the level of C1‐C2 cannot be excluded, because we did not skeletonize the transverse processes of the upper cervical vertebrae during surgery so as not to injure anatomic structures that did not require any dissection. The point of insertion was found at the level of the middle portion of the clavicle, as reported in the literature . The pattern of innervation of the LC is still unclear; nevertheless, the anterior branches of the cervical plexus seem to guarantee nerve supply of the muscle.…”

“…The embryological origin of the LC muscle is controversial. Odate et al reviewed the literature, reporting different theories on the embryological origin of the LC muscle having the same or similar development as sternocleidomastoid, trapezius, anterior scalene, or longus colli muscles …”

“…The point of insertion was found at the level of the middle portion of the clavicle, as reported in the literature. 3 The pattern of innervation of the LC is still unclear; nevertheless, the anterior branches of the cervical plexus seem to guarantee nerve supply of the muscle. In the present case, the LC muscle was innervated by a short branch of the medial supraclavicular nerve, a ventral ramus of the C2-C3 spinal nerves.…”

“…The LC is more often unilateral than bilateral. Some authors reported a left‐sided predominance, which remains unconfirmed by others . The LC muscle is usually found during routine cadaveric neck dissection or radiological diagnosis as an incidental finding…”