Middle Scalene Muscle, Lateral View

Description

Deep to the sternocleidomastoid on the lateral neck, the middle scalene (scalenus medius) is exposed as a thick, longitudinal cervical muscle running from the posterior tubercles of the transverse processes to its broad insertion on the superior surface of the first rib. Anterior to it, the anterior scalene forms the anterior wall of the interscalene interval, while the posterior scalene lies posterior and slightly inferior as it approaches the second rib. Between anterior and middle scalene, the trunks of the brachial plexus and the subclavian artery course inferolaterally toward the axilla, with the clavicle and the superior thoracic aperture framing the transition into the upper chest. The face and shoulder girdle musculature remain in view for orientation. Clear landmarks. This lateral perspective matters because it aligns with how clinicians conceptualize the scalene triangle during evaluation of neurogenic and arterial thoracic outlet syndrome, where hypertrophy, spasm, or fibrous bands can narrow the interval and reproduce paresthesia or vascular symptoms with arm elevation. It also supports teaching of the interscalene brachial plexus block: local anesthetic is placed at the level of C6 between anterior and middle scalenes, close to the plexus trunks, and the illustration helps you anticipate nearby structures such as the phrenic nerve on the anterior scalene and the pleural dome inferiorly. Use this asset in head and neck anatomy labs, anesthesia and pain medicine training materials, or surgical education covering supraclavicular exposure and the thoracic inlet. It also suits textbook figures on cervical muscle layers and thoracic outlet pathomechanics in a male specimen. Anatomical accuracy verified by SciePro's Medical Advisory Board.