A Novel Variant of the Cleidocervicalis Muscle with Clinical Implications for Nerve Compression/entrapment

Purpose: The cleidocervicalis muscle occurs in approximately 1-3 % of the population that may be confused with pathological neck masses. We describe a novel variant of the muscle and its clinical implications.

Methods: This is a case report of a cleidocervicalis muscle variant identified during routine cadaveric dissection.

Results: The muscle identified originated on the C5 vertebra and inserted on the clavicle medial to the trapezius muscle. Innervation was provided by a C6 spinal nerve branch. Notably, a branch of the supraclavicular nerve was closely associated with the muscle, raising the possibility of compression of this nerve.

Conclusions: Presence of a cleidocervicalis muscle should be considered in cases of shoulder pain consistent with supraclavicular nerve entrapment or compression.