Colliscalene triangle

The colliscalene triangle is an important anatomical region of the neck, situated medial to the scalenus anterior muscle.

It should not be confused with the scalene triangle which is located posterior to the scalenus anterior muscle.

Gross anatomy

Boundaries

• medial: lateral border of longus colli
• lateral: medial border of scalenus anterior
• inferior: first part of the subclavian artery
• apex: carotid tubercle (Chassaignac tubercle)
• roof: deep investing layer of cervical fascia

Contents

• arterial
  • thyrocervical trunk
  • inferior thyroid artery: arching over apex of triangle
  • first part of vertebral artery
• venous
  • vertebral vein
• nervous
  • inferior cervical (stellate) ganglion
  • middle cervical ganglion
  • ansa subclavia
• lymphatic
  • thoracic duct (on left)
  • right lymphatic duct (on right)

Variant anatomy

• additional vertebral vein passing through foramen transversarium of C7
• vertebral artery entering at C7