Posterior Scalene Muscle, Lateral View

Description

Seen from the left lateral aspect of the neck, the posterior scalene muscle is highlighted deep to the superficial cervical fascia, running inferolaterally from the transverse processes of the lower cervical vertebrae toward its insertion on the second rib. Anterior and slightly medial to it lie the anterior and middle scalenes, creating the familiar stepped scalene interval against the cervical spine. Superiorly, the muscle belly sits inferior to the mastoid region of the temporal bone and posterior to the mandibular ramus, while inferiorly it approaches the thoracic inlet beside the first ribs, clavicle, and superior border of the scapula. For teaching and clinical correlation, this lateral view clarifies why the posterior scalene is often discussed in thoracic outlet mechanics even though the brachial plexus and subclavian artery pass between the anterior and middle scalenes, not behind them. The posterior scalene’s pull on rib 2 can contribute to elevated upper ribs and altered first and second rib kinematics, a pattern commonly seen with chronic accessory breathing and some neck pain syndromes. Palpation and injection planning also benefit from appreciating its depth and its proximity to the cervical transverse processes and costovertebral region. A small but telling muscle. Use this artwork in gross anatomy or regional neck modules to distinguish the three scalene muscles by their attachments and to anchor discussions of the thoracic inlet, cervical ribs, and scalene-related myofascial pain. It also fits well in physiotherapy texts and interventional pain or anesthesia references when outlining landmark-based approaches around the lateral cervical spine and upper ribs. Anatomical accuracy verified by SciePro's Medical Advisory Board.