Trapezius Muscle Under the Skin, Posterior View

Description

Spanning the posterior neck and upper thorax, the trapezius sits immediately deep to the skin and superficial fascia as a broad diamond with right and left halves meeting along the median line. Superior fibers arise from the external occipital protuberance and medial superior nuchal line, blending with the ligamentum nuchae, then course inferolaterally toward the lateral third of the clavicle. Middle fibers run transversely from the spinous processes of C7 through the upper thoracic vertebrae to the acromion and spine of the scapula, while inferior fibers ascend from lower thoracic spinous processes to the medial end of the scapular spine; laterally, its border frames the posterior shoulder over the deltoid, with deeper rhomboids and levator scapulae implied along the medial scapular margin. Fiber direction matters here because each region of trapezius drives a different scapular motion: elevation, retraction, and upward rotation, coordinated with serratus anterior during overhead reach. Injury to the spinal accessory nerve (CN XI), often after posterior triangle lymph node biopsy or radical neck dissection, produces trapezius weakness with shoulder droop, limited abduction above 90 degrees, and lateral scapular winging that differs from long thoracic nerve palsy. Palpable trigger points and myofascial pain commonly localize along the superior fibers near the neck and along the medial scapular spine. A clean posterior superficial view makes those landmarks easy to teach. Use this asset for gross anatomy labs covering the dorsum and shoulder girdle, kinesiology modules on scapulothoracic rhythm, and surgical texts discussing the posterior cervical triangle and accessory nerve risk. It also fits rehabilitation handouts for trapezius strengthening and posture correction where surface anatomy cues guide palpation. Anatomical accuracy verified by SciePro's Medical Advisory Board.