Anterior Scalene Muscle, Lateral View

Description

Arising from the anterior tubercles of the transverse processes of C3 to C6, the anterior scalene (scalenus anterior) descends obliquely to its insertion on the scalene tubercle and superior surface of the first rib. From a lateral neck perspective, its belly sits deep to the sternocleidomastoid, anterior to the middle scalene, and lateral to the prevertebral fascia overlying the cervical vertebrae. Inferiorly, the muscle forms part of the scalene interval at the root of the neck, with the subclavian artery and trunks of the brachial plexus passing posterior to it, while the subclavian vein courses anterior to its tendinous insertion. Clean landmarks. This relationship matters when you teach or plan procedures around the supraclavicular fossa. An interscalene brachial plexus block targets the plane between anterior and middle scalenes, and poor appreciation of the anterior scalene border increases the risk of unintended phrenic nerve block, since the phrenic nerve typically descends on the anterior surface of scalenus anterior. The same anatomy frames thoracic outlet syndrome, where fibrous bands, hypertrophy, or an accessory cervical rib can narrow the interscalene triangle and provoke neurogenic symptoms. Use this lateral view in head and neck anatomy courses to anchor the layered organization of the lateral cervical region, and in anesthesia or pain medicine materials that illustrate safe needle trajectories for interscalene approaches. It also fits surgical teaching on first rib resection and scalenectomy, where the anterior scalene insertion is a practical landmark for identifying the subclavian vessels. Anatomical accuracy verified by SciePro's Medical Advisory Board.