Anterior Scalenes, Lateral View

Description

Arising from the anterior tubercles of the transverse processes of C3 to C6, the anterior scalene descends obliquely inferolaterally to its insertion on the scalene tubercle of the first rib, just posterior to the medial clavicle. From a lateral neck perspective, the muscle sits deep to the sternocleidomastoid and anterior to the brachial plexus and middle scalene, forming the anteromedial border of the interscalene interval. The subclavian artery runs posterior to the anterior scalene within that interval, while the subclavian vein courses anterior to it, separated by the muscle and the first rib. Bony landmarks likely included in this view are the mandible, cervical vertebrae, clavicle, first ribs, and the superior thoracic cage. That artery vein split matters. During central venous access, the subclavian vein’s anterior relationship to the anterior scalene and first rib explains both the target and the hazard, since an overly posterior needle trajectory can cross the muscle and enter the subclavian artery or pleura. Thoracic outlet syndrome also lives here, most often neurogenic from brachial plexus irritation in the interscalene triangle, but arterial compression can occur where the subclavian artery passes between anterior and middle scalene. A small space, big consequences. Use this lateral anatomy for gross anatomy teaching on the cervical root of the neck, for anesthesia training in interscalene block planning, or for surgical and radiology publications discussing thoracic outlet decompression, cervical rib variants, and subclavian line complications. It also reads well in patient education materials that need clear spatial logic without excessive dissection detail. Anatomical accuracy verified by SciePro's Medical Advisory Board.