Scalenes
Musculi scaleni
Three paired lateral neck muscles (anterior, middle, posterior) that laterally flex the neck and act as accessory muscles of inspiration by elevating the upper ribs. The brachial plexus and subclavian artery pass through the scalene hiatus between the anterior and middle scalenes, making these muscles clinically important in thoracic outlet syndrome; for lifters they assist labored breathing under heavy loads and contribute to lateral neck stability.
- Actions
- Elevation of the 1st rib (anterior, middle) and 2nd rib (posterior) in forced inspiration, Ipsilateral cervical lateral flexion (unilateral), Cervical flexion (bilateral, anterior scalene)
- Origin
- Anterior/posterior tubercles of the transverse processes of the cervical vertebrae (anterior: C3-C6; middle: C2-C7; posterior: C5-C7).
- Insertion
- Anterior and middle scalenes onto the 1st rib; posterior scalene onto the 2nd rib.
- Innervation
- Anterior rami of the cervical spinal nerves (C3-C8).
- Blood supply
- Ascending cervical artery and inferior thyroid artery.
- Heads
- Scalenus anterior, Scalenus medius, Scalenus posterior