The Anterior Triangle and Root of Neck

The Carotid Triangle




Superomedially Posterior belly of the digastric
Laterally: Anterior border of the .sternocleidomastoid muscle
Inferomedially: superior belly of omohyoid




The carotid sheath:

Location: Longitudinal interval between cervical viscera (pharynx, esophagus, larynx, trachea and thyroid gland) medially, and prevertebral muscles posteriorly


  • Prevertebral fascia behind
  • Pretracheal fascia medially



Contents of carotid sheath

  • Common and Internal Carotid arteries medially.
  • Internal jugular vein laterally.
  • Vagus nerve posteriorly and between the above two.
  • Ansa cervicalis embedded in the carotid sheath(anteriorly).
  • Deep cervical lymph nodes.


1) Common carotid artery divides at superior border of thyroid gland (C3,4).

2) The carotid sinus (the baroreceptor) is a slight dilatation at the proximal part of the internal carotid artery. It is innervated by:

  • Carotid sinus nerve, a branch of glossopharyngeal.
  • A branch of vagus nerve.
  • Sympathetic division of ANS.

3) The carotid body, is a small reddish brown, ovoid mass of tissue located at the carotid bifurcation. The same nerves that go to the carotid sinus innervate it.


Common carotid artery



Brachio cephalic trunk- behind right sternoclavicular joint


Aortic arch – behind manubrium sterni


  • Extends from sternoclavicular joint to upper border of thyroid gland c3/ c4

  • Anterolateral neck in the carotid sheath lateral to trachea/ esophagus and larynx/ pharynx

  • Palpable between sternocleidomastoid and angle of the mandible

  • Divides in the carotid triangle into internal and external carotid arteries


    • Parasympathetic: Submandibular ganglion
    • Sympathetic: superior cervical ganglion


From the ventral side: From the dorsal side:

Terminates by dividing into:


  • Superior thyroid artery. [5]

  • Lingual artery. [4]

  • Facial artery. [3]

  • Ascending pharyngeal (may form from medial side).


  • Occipital artery. [7]

  • Posterior auricular. [6]


  • Superficial temporal artery [1]

  • Maxillary artery. [2]
Internal jugular vein


  • Union of sigmoid and inferior petrosal sinuses


  • Base of skull to sternoclavicular joint


  • Between sternal and clavicular heads of sterno cleido mastoid muscles


  • Pharyngeal veins
  • Lingual
  • Common facial
  • Superior thyroid
  • Middle thyroid

Joins subclavian vein to form brachio-cephalic vein

Vagus Nerve


  • Emerges through jugular foramen

  • Two ganglia- superior and inferior cervical ganglia

  • Runs straight down in the carotid sheath

  • Between and behind carotid artery and internal jugular veins

  • At the root of the neck, it passes infront of the subclavian artery to enter mediastinum

  • Branches and distribution




  • Dura of posterior cranial fossa


  • Postero inferior quadrant of external surface of tympanic membrane
  • Floor of external auditory meatus
  • Skin on the cranial auricular canal

Carotid body branch

  • Carotid body
  • Carotid sinus

Pharyngeal branch

  • Muscles of pharynx except stylopharyngeus
  • Muscles of soft palate except tensor palate

Superior laryngeal


External Laryngeal

  • Cricothyroid muscle
  • Inferior pharyngeal constrictors

Internal  Laryngeal

  • Pharyngeal mucosa
  • Laryngeal mucosa above vocal folds

Recurrent Laryngeal

  • Trachea and Esophagus
  • Cricopharyngeus
  • Laryngeal muscles except  cricothyroid
  • Laryngeal mucosa below vocal folds

Cardiac branches

  • Heart