Scalenus Anterior

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  • key muscle in understanding root of neck
  • deeply placed
  • ascends almost vertically from vertebral column to first rib

Origin

  • anterior tubercles of 3rd-6th cervical vertebrae

Insertion

  • scalene tubercle on inner border first rib
  • ridge on upper surface first rib

Nerve Supply

  • anterior rami of 4th-6th cervical nerves

Action

  • assists in elevating first rib
  • laterally flexes and rotates cervical spine

Relations

  • Anteriorly
    • prevertebral layer of deep cervical fascia
      • binds phrenic nerve to muscle
    • superficial cervical artery
    • suprascapular artery
    • internal jugular vein
    • subclavian vein
  • Posteriorly
    • subclavian artery
    • brachial plexus
    • cervical dome of pleura
  • Medially
    • vertebral artery and vein
    • inferior thyroid artery
    • thyrocervical trunk
    • sympathetic trunk
    • thoracic duct (on left side)
  • Laterally
    • union of roots of phrenic nerve 
      • at level of cricoid cartilage
    • emerging laterally to enter posterior triangle
      • roots of brachial plexus
      • subclavian artery
 

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