Interspinal Muscle Under the Skin

Description

Running in short vertical slips between adjacent spinous processes, the interspinales are shown in the midline of the posterior cervical and upper thoracic spine, immediately deep to the skin and superficial fascia. Each bundle spans from the inferior border of one spinous process to the superior border of the next, lying medial to the multifidus and alongside the interspinous ligaments. Superiorly, the occipital bone frames the upper end of the column, while laterally the scapulae and the proximal humeri sit posterior to the rib cage, giving clear bony context for cervicothoracic alignment. Small as they are, interspinal muscles matter when you are teaching segmental motion and palpation landmarks because they track the exact level-to-level spacing of the spinous processes, the first reference point for counting vertebrae on physical exam and in operative planning. Midline posterior approaches for cervical laminectomy, laminoplasty, or interspinous wiring pass directly through the tissue plane where these bundles and the interspinous ligament are encountered. Their appearance also helps explain why focal tenderness between spinous processes can accompany interspinous bursitis (Baastrup disease) or acute flexion-extension strain, even when larger paraspinal masses look intact. Use this illustration for gross anatomy and surface anatomy modules covering the posterior neck and upper back, or for spine-focused teaching files that pair posterior osseous landmarks with subcutaneous soft tissue. It also supports surgical education materials on posterior midline exposure, level confirmation, and safe dissection planes around the spinous processes and laminae. Anatomical accuracy verified by SciePro's Medical Advisory Board.