Internal Carotid Artery

INTRODUCTION:
  • On angiogram internal carotid show ‘S’ shaped figure ( carotid siphon )
  • The internal carotid artery is a major paired artery, one on each side of the head and neck, in human anatomy. 
  • They arise from the common carotid arteries where these bifurcate into the internal and external carotid arteries at cervical vertebral level 3 or 4 
  • Internal carotid artery at the bifurcation from the common carotid is Lateral to the external carotid
  • The internal carotid artery supplies the brain, while the external carotid nourishes other portions of the head, such as face, scalp, skull, and meninges.
  • Supplies duramater 
  • Internal carotid artery lies in close relation of the optic nerve
ORIGIN:
  • It is one of the terminal branch of common carotid artery originates with external carotid artery at the upper border of thyroid cartilage at the disk of third and fourth cervical vertebra.
BRANCHES:
  • Cervical part in the neck
  • Petrous part in the petrous temporal bone
  • Cavernous part in the cavernous sinus
  • Cerebral part in relation to base of brain
COURSE:
  • Cervical Part
  1. It ascends vertically in the neck from its origin to the base of skull to reach the lower end of the carotid canal.
  2. This part is enclosed in carotid sheath along with internal jugular and vagus nerve. No branches arises from the internal carotid artery in the neck.
  3. Its initial part shows slight dilation, carotid sinus. Which acts as a baroreceptor.
  • Petrous Part
  1. Within the petrous part of the temporal bone,in the carotid canal runs upward forward & medially at rt. Angle.
  2. Branches
  3. Caroticotympanic- enter middle ear & anastomose with ant. & post. Tympanic branches
  4. Artery of the Pterygoid Canal- anastomose with greater palatine artery
  • Cavernous Part
  1. Within the Cavernous Sinus
  2. Branches
  3. Artery to trigeminal ganglion
  4. Superior & inferior Hypophyseal artery
  • Cerebral Part
  1. Lies at the base of the brain after emerging from the cavernous sinus
  2. Branches
  3. Ophthalmic.
  4. Anterior Cerebral.
  5. Middle Cerebral.
  6. Posterior Communicating.
  7. Ant. choroidal

Exam Question
  • Posterior communicating artery arises from internal carotid artery.
  • Branch of cavernous part of internal carotid artery Artery to trigeminal ganglion, Superior & inferior Hypophyseal artery
  • Branches of cerebral part of the internal carotid artery are Ophthalmic,Anterior Cerebral,Middle Cerebral,Posterior Communicating,Ant. choroidal
  • Anterior choroidal artery is a branch of internal carotid artery
  • Ophthalmic artery is the branch of cerebral part of internal carotid artery
  • Internal carotid artery Supplies duramater 
  • Internal carotid artery lies in close relation of the optic nerve
  • Internal carotid artery at the bifurcation from the common carotid is Lateral to the external carotid

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