INTERNAL CAROTID ARTERY

• 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.

• They arise from the common carotid arteries where these bifurcate into the internal and external carotid arteries at cervical vertebral levels 3 or 4.

• The 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 the face, scalp, skull, and meninges.

• Supplies dura mater 

• The internal carotid artery lies in close relation to the optic nerve.

• It ascends vertically in the neck from its origin to the base of the skull to reach the lower end of the carotid canal.

• This part is enclosed in the carotid sheath along with the internal jugular and vagus nerve. 

• No branches arise from the internal carotid artery in the neck.

• Its initial part shows slight dilation, carotid sinus, which acts as a baroreceptor.

Branches:

• Caroticotympanic– enter middle ear & anastomose with ant. & post. Tympanic branches

• Artery of the Pterygoid Canal–  anastomose with greater palatine artery

3. Cavernous Part

• Within the Cavernous Sinus

• Cavernous branch

• Superior & inferior Hypophyseal artery

• Meningeal branch

4. Cerebral Part-

Branches:

• Ophthalmic Artery

• Anterior Cerebral Artery

• Middle Cerebral Artery

• Posterior Communicating Artery

• Anterior choroidal Artery

• A branch from the cerebral part of ICA.

• It enters the orbit through optic canal lying inferolateral to the optic nerve.

• Both artery & nerve lie in a common dural sheath.

It gives the following branches: 

1. Central artery of retina → an end artery

2. Lacrimal artery: It gives the following branches-

• Lateral palpebral branch

• Zygomaticotenporal

• Zygomaticofacial 

• Recurrent meningeal

• Meningeal

• Ciliary

• Anterior ethmoidal → Supplies anterior ethmoidal sinus

• Posterior ethmoidal

• Medial palpebral

• Supratrochlear

• Supraorbital

• Dorsal nasal