10. Scalenes

Origin:

• Anterior scalene: Anterior tubercules of TVP of C3-7
• Middle scalene: Posterior tubercules of TVP of C3-7
• Posterior scalene: Posterior tubercules of TVP of C4-6

Insertion:

• Anterior scalene: Anterior aspect of 1st rib
• Middle scalene: Superior surface of 1st rib
• Posterior scalene: External border of 2nd rib (occasionally 1st rib as well)

Action: All are accessory muscles of inspiration as they elevate the first two ribs

• Anterior scalene: Side bend and rotation ipsilaterally
• Middle scalene: Side bend and rotation ipsilaterally
• Posterior scalene: Ipsilateral side bend

Innervation:

• Anterior scalene: C5-7
• Middle scalene: C3-8
• Posterior scalene: C7-8

Needling

Position: Supine, with head in neutral or slightly rotated to opposite side

Palpation: Palpate the posterior triangle of the neck

• • Anterior border: posterior margin of the sternocleidomastoid
  • Posterior border: anterior margin of the trapezius
  • Inferior border: middle 1/3 of clavicle

Technique: Needle very superficially in the posterior triangle of the neck, threading the needle either in a superior-inferior direction or an inferior-superior direction

Caution: High

• • The external jugular vein sits very superficially at the anterior margin of this triangle – It can typically be seen, if not ask the person to hold their breath, bear down, or resist head rotation/side-flexion to make it more visible
  • The roots of the brachial plexus exit between the anterior and middle scalene
  • The internal jugular vein and common carotid artery lie directly underneath these muscles