The Middle Scalene Muscle Viewed Anteriorly in a Male

Description

Anteriorly, the middle scalene (musculus scalenus medius) appears as a long, slightly curved cervical muscle deep to the sternocleidomastoid and lateral to the prevertebral musculature. Its fibers descend from the transverse processes of the mid to lower cervical vertebrae toward the first rib, where the insertion lies posterior to the subclavian groove and lateral to the anterior scalene’s attachment. Medial to it sit the cervical vertebral column and longus colli, while laterally the muscle blends into the muscular contour of the posterior triangle, approaching the levator scapulae and upper trapezius. The clavicular region and shoulder girdle musculature (deltoid, pectoralis major) provide an external frame of reference for its inferior course. Clinically, the middle scalene defines the posterior boundary of the interscalene triangle, the corridor where the brachial plexus roots and trunks and the subclavian artery travel between the anterior and middle scalenes on their way toward the axilla. This relationship matters in thoracic outlet syndrome, where scalene hypertrophy, spasm, or fibrous bands can narrow the space and provoke neurogenic symptoms, and in anesthetic practice when placing an interscalene brachial plexus block near the C5 to C7 roots. Small errors here have consequences. The anterior view also helps teach why the subclavian vein lies anterior to the anterior scalene and is typically not within the interscalene space. Use this artwork in head and neck anatomy teaching, anesthesia training materials for regional blocks, and surgical atlases discussing supraclavicular exposure and brachial plexus approaches. It also suits patient education sheets explaining scalene-related neck pain patterns and thoracic outlet evaluations. Anatomical accuracy verified by SciePro's Medical Advisory Board.