subclavian artery

The subclavian arteries are asymmetric paired arteries that supply blood to the posterior cerebrum, cerebellum, posterior neck, upper limbs and the superior and anterior chest wall.

Gross anatomy

Origin

Right and left subclavian arteries classically have different origins:

Course

The subclavian artery exits the thorax via the superior thoracic aperture between the anterior and middle scalene muscles before passing between the first rib and clavicle. At the lateral border of the first rib it continues as the axillary artery.

Parts

The vessel can be split into three parts (first, second, third) depending on the position of the vessel in relation to scalenus anterior:

  • first part: from its origin to the medial border of scalenus anterior
  • second part: posterior to scalenus anterior
  • third part: from the lateral border of scalenus anterior to the lateral border of the first rib
Branches

The vessel branches relate to the part of the vessel :

Memorable mnemonics for these branches include:

  • Very Indignant Tired Individuals Sip Strong Coffee Served Double Daily
  • VIT C, D (as in vitamins C and D).
Relations
  • first part
    • anterior
      • common carotid artery
      • internal jugular and vertebral vein
      • vagus and phrenic (left side only) nerve, cardiac branches of vagus and sympathetic trunk, and ansa cervicalis (encircling)
      • sternocleidomastoid, sternohyoid and sternothyroid muscles 
      • thoracic duct (left)
    • posterior
      • apex of lung
      • lower trunk of the brachial plexus 
      • scalenus medius muscle
  • second part
    • anterior:
      • scalenus anterior
      • phrenic nerve (right side only)
      • sternocleidomastoid 
    • posterior:
      • apex of lung
      • lower trunk of the brachial plexus 
      • scalenus medius muscle
  • third part
    • anterior:
      • suprascapular and transverse cervical vessels 
      • subclavian and anterior jugular vein
    • posterior:
      • apex of lung
      • lower trunk of the brachial plexus
      • scalenus medius muscle

Variant anatomy

The subclavian vessels may arise from aberrant locations if there is failure of the normal embryological aortic arch development.

The most common variant is the aberrant right subclavian artery which results in a vessel that arises distal to the left subclavian artery and courses posteriorly between the trachea and esophagus where it may cause compression resulting in breathing difficulties or dysphagia. An aberrant left subclavian artery may arise with a right aortic arch.

Other variations occur with branching patterns. If the inferior thyroid artery arises from it (instead of the normal origin of from the thyrocervical trunk), it is known as the accessory inferior thyroid artery.

Related pathology