Tellus Colli: An Anomalous Muscle Located at the Posterolateral Aspect of the Neck-A Case Report

This report presents the case of the first author, an asymptomatic 31-year-old physiotherapy professor who explored himself using panoramic B-mode ultrasound imaging to prepare instructional materials for neck ultrasound-guided invasive interventions. The sonographic exploration demonstrated the unilateral presence of a nondescribed muscle in the posterolateral aspect of the neck, proposed to name this variant as "tellus colli" by the authors. To our knowledge, the presence of this muscle has not been previously described. This muscle arises from the external occipital tubercle and the nuchal ligament. It courses superficially to the upper trapezius and slides laterally as it approaches its insertion onto the anterolateral surface of the second rib (passing in the most superficial layer over the levator scapulae in this region). In accordance with the anatomical course of the muscle and the electromyographic findings, this muscle seems to contribute to forced inspiration and specific neck movements (contralateral rotation and neck extension). The presence of this accessory muscle is a casual finding which is not related to neck or neuropathic symptoms.