Levator claviculae muscle: Anatomic variation found during neck dissection.

The levator claviculae muscle is a variant of the anatomy of the posterior triangle of the neck. It is reported in 2% to 3% of all humans. All previous articles described this muscle as an incidental finding during cadaveric or radiological examinations. We report here, for the first time, a case discovering this muscle variation intraoperatively during a modified radical neck dissection. The muscle was identified on the left side, originating from the transverse processes of the upper cervical vertebrae (C2-C3), attached to the upper aspect of the middle part of the clavicle. This muscle was innervated by the supraclavicular nerve, coming from the third and fourth rami of the cervical spinal nerves. Blood supply to the muscle could not be identified clearly during the surgical procedure. Surgeons and radiologists should be aware of the presence of this rare variant muscle so as not to misinterpret the anatomy. Laryngoscope, 129:634-636, 2019.