Anterior Scalene Muscle Beneath the Skin

Description

Running deep to the sternocleidomastoid, the anterior scalene (musculus scalenus anterior) descends from the anterior tubercles of the cervical transverse processes to the superior surface of the first rib. Its fibers course inferiorly and slightly laterally, forming the anterior boundary of the interscalene interval, with scalenus medius positioned posteriorly and the clavicle and first rib defining the inferior root of the neck. Superficial landmarks include the sternocleidomastoid anteriorly and the trapezius posterolaterally, with pectoralis major and the deltoid continuing the contour onto the anterior chest and shoulder. A semi-profile presentation favors the lateral neck, where the scalene column sits medial to the shoulder girdle and deep to the more prominent cervical strap. An anterior scalene focused view matters because it frames the neurovascular corridor entering the upper limb. The brachial plexus trunks and subclavian artery pass between anterior and middle scalenes, while the subclavian vein runs anterior to scalenus anterior, a relationship that explains both venous compression and the target plane for supraclavicular and interscalene blocks. Small distances count here. Hypertrophy, fibrous bands, or anomalous first rib anatomy can narrow the interscalene triangle and contribute to neurogenic thoracic outlet syndrome, and the adjacent phrenic nerve on the anterior scalene is the anatomic basis for hemidiaphragmatic paresis after regional anesthesia. Ideal for gross anatomy teaching of the lateral cervical region and for surgical atlases describing supraclavicular exposure of the thoracic outlet, first rib resection, or scalenectomy, this artwork also supports patient education materials on thoracic outlet syndrome and central venous access planning. Useful in anesthesia references when illustrating needle trajectory relative to sternocleidomastoid and the scalene muscles. Anatomical accuracy verified by SciePro's Medical Advisory Board.