Trapezius Muscle, Posterior View

Description

Across the posterior cervicothoracic region, the paired trapezius muscles form a broad kite-shaped sheet spanning from the superior nuchal line and external occipital protuberance down the midline to the spinous processes of the lower cervical and thoracic vertebrae (classically C7 to T12). Laterally, the fibers converge onto the lateral third of the clavicle, the acromion, and the spine of the scapula, with superior fibers running inferolaterally, middle fibers coursing transversely, and inferior fibers ascending superolaterally. The right and left muscles meet at the median raphe over the vertebral column, framing the posterior neck superiorly and the interscapular region inferiorly. Fiber direction is the story here. A posterior view clarifies how trapezius drives scapulothoracic mechanics: upper fibers elevate, middle fibers retract, and lower fibers assist depression and upward rotation, coordinating with serratus anterior for overhead elevation. That alignment matters when you teach spinal accessory nerve (CN XI) palsy after posterior triangle trauma or neck dissection, where denervation produces shoulder droop, impaired abduction above 90 degrees due to loss of upward rotation, and lateral scapular winging distinct from long thoracic nerve injury. Palpation and needling targets also rely on these borders, since trapezius trigger points commonly refer pain to the occiput and temporal region in tension-type headache patterns. Use this asset in gross anatomy and kinesiology modules on the dorsum and shoulder girdle, in surgical atlases illustrating posterior cervical exposure and lymph node dissection risk zones, or in rehabilitation texts explaining scapular dyskinesis and accessory nerve assessment. Anatomical accuracy verified by SciePro's Medical Advisory Board.