Internal carotid artery

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 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. 

• It ascends vertically in the neck from its origin to the base of skull to reach the lower end of the carotid canal.
• 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.
• Its initial part shows slight dilation, carotid sinus, which acts as a baroreceptor.

Branches:

1. Caroticotympanic– enter middle ear & anastomose with ant. & post. Tympanic branches
2. Artery of the Pterygoid Canal–  anastomose with greater palatine artery

3. Cavernous Part

• Within the Cavernous Sinus

1. Cavernous branch
2. Superior & inferior Hypophyseal artery
3. Meningeal branch

4. Cerebral Part-

Branches:

1. Ophthalmic Artery
2. Anterior Cerebral Artery
3. Middle Cerebral Artery
4. Posterior Communicating Artery
5. Anterior choroidal Artery

• Branch from cerebral part of ICA.
• It enters orbit through optic canal lying inferolateral to optic nerve.
• Both artery & nerve lie in a common dural sheath.
• It gives following branches:

1. Lateral palpebral branch
2. Zygomaticotenporal
3. Zygomaticofacial 
4. Recurrent meningeal
5. Meningeal
6. Ciliary
7. Anterior ethmoidal → Supplies anterior ethmoidal sinus
8. Posterior ethmoidal
9. Medial palpebral
10. Supratrochlear
11. Supraorbital
12. Dorsal nasal