Name

# Scalenes

Pronunciation

(ska-LEEN)

Origin/Proximal Attachment

Anterior: Anterior tubercles of transverse processes of 3rd to6th cervical vertebrae. Middle: Anterior tubercles of transverse processes of 2nd to7th cervical vertebrae. Posterior: Transverse processes of 4th, 5th & 6th cervical

Insertion/Distal Attachment

Anterior: 1st rib - scalene tubercle & cranial crest Middle: 1st rib - between scalene tubercle & groove for subclavian artery Posterior: 2nd rib - outer surface

Action/Relevance

Bilaterally: cervical flexion Unilaterally: lateral flexion to same side, rotation to opposite side

Innervation

Anterior: Cervical nerves (C4, 5,6) Middle: Cervical nerves (C3 –8) Posterior: Cervical nerves- C6, 7,8

Notes

The scalene are lateral vertebral muscles which begin at the first and second ribs and pass up into the sides of the neck. There are three of these muscles. (1) The "scalenus anterior muscle," which, when the neck is fixed, elevates the first rib to aid in breathing or when the rib is fixed, bends the neck forward and sideways and rotates it to the opposite side. (2) The "scalenus medius" is similar to the scalenus anterior and raises the first rib from above or bends to slightly rotates the neck from below. (3) The "scalenus posterior" raises the second rib or bends and slightly rotates the neck. This muscle may be absent or may extend to the third rib. When the scalene muscles are fixed from above, they elevate the first and second ribs to become respiratory muscles for breathing. Acting from below, they bend the spinal column to the same side or, if muscles act on both sides, the spinal column is slightly flexed.