Anterior Scalene Muscle Beneath the Skin, Lateral View

Description

Positioned deep to the sternocleidomastoid on the lateral neck, the anterior scalene (scalenus anterior) descends from the anterior tubercles of the transverse processes of C3 to C6 to its inferior attachment on the scalene tubercle of the first rib. Posterior to it, the middle scalene (scalenus medius) forms the next muscular plane, while the trapezius lies more posterior and superficial over the shoulder girdle. Along the anterior border of scalenus anterior, the phrenic nerve typically courses inferiorly toward the thorax, and the internal jugular vein and common carotid artery sit anteromedially within the carotid sheath. Layering is the point. A lateral, beneath-the-skin rendering makes the scalene interval easy to teach: the brachial plexus trunks and subclavian artery pass between the anterior and middle scalenes, while the subclavian vein runs anterior to scalenus anterior, a relationship that frames both thoracic outlet syndrome patterns and safe needle trajectories. For clinicians performing an interscalene brachial plexus block, distinguishing scalenus anterior from scalenus medius and appreciating their depth relative to sternocleidomastoid reduces the risk of phrenic nerve palsy and unintended vascular puncture. The first rib serves as a palpable and procedural landmark. Neck anatomy courses, anesthesia training modules, and surgical atlases covering supraclavicular exposure or central venous access will benefit from this view, since it ties surface muscular contours to deeper neurovascular corridors without flattening the spatial relationships. It also fits well in patient education materials on cervical rib and scalene-related thoracic outlet compression. Anatomical accuracy verified by SciePro's Medical Advisory Board.