Middle Scalene

Description

Framed from a posterior neck and upper back perspective, the middle scalene (scalenus medius) runs inferolaterally from the posterior tubercles of the cervical transverse processes, typically C2 to C7, toward its broad insertion on the superior surface of the first rib posterior to the subclavian groove. Medial to it sit the cervical vertebrae with prominent spinous processes and the occipital bone superiorly, while lateral landmarks include the scapular spine and the clavicular region at the shoulder girdle. Deep paraspinal bundles such as semispinalis capitis and cervicis occupy the paramedian gutter, helping orient the scalene plane against the posterior elements of the cervical spine. Upper thoracic ribs and their vertebral articulations provide the inferior boundary. Scale matters here. The middle scalene forms the posterior wall of the interscalene triangle, where the roots and trunks of the brachial plexus and the subclavian artery pass between anterior and middle scalene on their way to the axilla, and the dorsal scapular nerve commonly pierces scalenus medius on its course to levator scapulae and rhomboids. This anatomy underpins thoracic outlet syndrome patterns and explains why scalene hypertrophy or spasm can reproduce neurogenic symptoms, while also guiding needle trajectory and depth expectations for interscalene brachial plexus blockade. A clear posterior relationship to the transverse processes helps when teaching segmental muscle attachments and when correlating focal tenderness with cervical level. Use this artwork for gross anatomy labs covering the posterior cervical triangle, for anesthesia education on interscalene and supraclavicular regional techniques, and for rehab or sports medicine materials addressing scalene-related neck pain and brachial plexus irritation. It also reads well in surgical anatomy chapters that orient the cervical spine, first rib, and shoulder girdle as a single functional unit. Anatomical accuracy verified by SciePro's Medical Advisory Board.