Posterior Scalene Muscle Beneath the Skin, Lateral View

Description

Seen in lateral profile beneath the superficial coverings, the posterior scalene (musculus scalenus posterior, scalene cervicis) occupies the deep posterolateral neck, running from the posterior tubercles of the midcervical transverse processes to its insertion on the second rib. Anterior to it lie the sternocleidomastoid and, deeper, the middle scalene, while the levator scapulae and upper trapezius sit more posteriorly and superficially as the neck blends into the shoulder. Inferiorly the muscle approaches the thoracic inlet just superior to the clavicle, with the acromioclavicular region and glenohumeral contours providing bony context for cervical and scapular attachments. Color separation distinguishes contractile fibers from surrounding fascia and tendinous junctions. Deep anatomy, clearly staged. This view matters because the posterior scalene helps define the posterior boundary of the scalene interval and frames the space where clinicians mentally map the brachial plexus, subclavian artery, and first rib during evaluation of neurogenic or arterial thoracic outlet syndrome. Its attachment to the second rib links cervical muscle spasm to altered rib mechanics and apical chest wall pain, a pattern that can mimic pleuritic symptoms or C5 to C7 radiculopathy. For anesthetists, distinguishing posterior from middle scalene clarifies needle trajectory for interscalene and supraclavicular blocks, where posterior spread can involve the dorsal scapular or long thoracic nerves and contribute to scapular winging complaints post procedure. Use this illustration in gross anatomy and kinesiology courses to teach layered dissection of the lateral neck, and in surgical anatomy texts discussing supraclavicular approaches, central line surface anatomy, and thoracic outlet decompression planning. It also fits MSK and pain medicine materials on scalene trigger points and rib dysfunction patterns. Anatomical accuracy verified by SciePro's Medical Advisory Board.