Posterior Scalene Muscle

Description

Posteriorly in the lateral neck, the posterior scalene (scalenus posterior) forms a narrow muscular column running inferolaterally from the transverse processes of the lower cervical vertebrae (typically C4 to C6) to the external surface of the second rib. Lateral to it, the levator scapulae and splenius muscles would be expected to frame the posterior cervical triangle, while the middle scalene lies anterior and slightly medial, separated by a fascial plane that guides the brachial plexus roots. Superiorly, the muscle approaches the cervical vertebral column; inferiorly, its fibers converge toward the rib cage deep to the clavicular region. Orientation matters. Clear depiction of the posterior scalene’s vertebral attachments helps in teaching interscalene anatomy, where small differences in muscular bulk or fascial bands can alter the corridor used for regional anesthesia. Clinically, this muscle is a recognized contributor to neurogenic thoracic outlet syndrome and to cervical myofascial pain patterns that refer into the shoulder girdle, and its relationship to the brachial plexus and subclavian vessels explains why scalene hypertrophy or spasm can mimic radiculopathy. For surgeons and pain specialists, identifying the posterior scalene relative to the middle scalene is also relevant when planning botulinum toxin injection or selective scalenectomy, where misidentification risks incomplete decompression. Anatomy faculty will find this asset suited to head and neck modules, regional anesthesia teaching sets, and dissection-lab atlases that emphasize the posterior triangle and first and second rib landmarks. Publishers can also pair it with thoracic outlet syndrome or interscalene block content in orthopedic, vascular, and anesthesiology references. Anatomical accuracy verified by SciePro's Medical Advisory Board.