Anterior Scalenes

Description

Running deep to the sternocleidomastoid, the anterior scalene (musculus scalenus anterior) is shown on a lateral view of the male neck, descending from the anterior tubercles of the transverse processes of C3 to C6 to its insertion on the scalene tubercle of the first rib. Anterior to the muscle lies the clavicular head of sternocleidomastoid and the prevertebral fascia, while posterior and slightly lateral sit the middle scalene and the interscalene interval. Superiorly, the muscle approaches the cervical vertebrae and skull base landmarks; inferiorly it anchors to the superior surface of rib 1, adjacent to the costoclavicular space. Depth is the point. This view matters because the anterior scalene is a gatekeeper for neurovascular anatomy entering the upper limb. The brachial plexus trunks and subclavian artery pass posterior to it between the anterior and middle scalenes, whereas the subclavian vein runs anterior to it, a relationship that explains the pattern of symptoms in thoracic outlet syndrome and the risks of low neck dissection. It also frames common procedures: palpation and injection in suspected scalene myofascial pain, ultrasound guided supraclavicular brachial plexus block, and central venous access where a misread anterior scalene can put the phrenic nerve and pleura at risk. Use this plate in gross anatomy and head and neck modules to teach prevertebral compartment layering, in anesthesia and pain medicine materials covering scalene blocks, and in surgical atlases discussing supraclavicular approaches and first rib decompression. It also fits radiology teaching files when correlating lateral neck anatomy with CT or MRI of the lower cervical region and thoracic inlet. Anatomical accuracy verified by SciePro's Medical Advisory Board.