Anterior Scalene Muscle

Description

Running anteroinferiorly from the transverse processes of the mid cervical vertebrae, the anterior scalene (musculus scalenus anterior) is presented on a male neck with the cervical spine and upper thoracic skeleton as deep landmarks. Its muscle belly lies deep to the sternocleidomastoid and lateral to the cervical vertebral bodies, tapering inferiorly toward the first rib. The clavicle and superior thoracic aperture frame the inferior extent of the field, with the upper ribs and proximal humerus establishing the shoulder girdle context. Clean bony references. Clinically, the anterior scalene defines the anterior boundary of the interscalene triangle, a corridor that matters when you are thinking about neurovascular compression at the thoracic outlet. The subclavian artery and brachial plexus pass between anterior and middle scalenes, while the subclavian vein courses anterior to the anterior scalene, a relationship that explains why hypertrophy or spasm of scalenus anterior can contribute to neurogenic thoracic outlet syndrome yet spare venous flow until more anterior structures are involved. Anesthetic techniques also depend on this anatomy, since the interscalene brachial plexus block is performed at the level of C6 near the scalene groove, where needle trajectory must respect the phrenic nerve running on the anterior surface of the anterior scalene. Faculty can drop this plate into gross anatomy and clinical anatomy teaching to anchor attachments to C3 to C6 transverse processes and the first rib, and to clarify why a cervical rib or fibrous band can change the space available to the plexus. It also reads well in surgical education materials for supraclavicular exposure and in radiology teaching when correlating scalene morphology on ultrasound or CT in thoracic outlet workups. Anatomical accuracy verified by SciePro's Medical Advisory Board.