Internal Carotid Artery Segments

Branches 

C1

Cervical

None

C2

Petrous

Vidian

Caroticotympanic

Anastomose with Vidian branch of Internal maxillary of ECA

Anastomose with Inferior tympanic branch of ECA

Both get enlarged in cases of aberrant ICA(congenital absence of C1 of ICA, ECA > Caroticotympanic/Vidian > C2 of ICA)

C3

Lacerum

None

C4

Cavernous

Meningeohypophyseal

Inferolateral trunk

Gives: inferior hypophyseal – Dorsal meningeal – Tentorial artery (Called Bernasconi a. which may supply some dAVFs) 

Supplies cranial nerves in the cavernous sinus and meninges.

Meningeal branches anastomose with middle meningeal artery (help in ICA stenosis)

C5

Clinoid

None

C6

Ophthalmic (supraclinoid)

Ophthalmic

Superior hypophyseal

Gives: Central retinal – Anterior ciliary – Posterior ciliary

Supplies optic nerve, chiasm, pituitary gland

C7

Communicating (terminal)

Posterior communicating

Anterior choroidal

Thalamoperforators: supply anteromedial thalamus, hypothalamus, mamillary

Premamillary: hypothalamus, mamillary

Medial Posterior Choroidal: medial thalamus, hippocampus

Lateral Posterior Choroidal: lateral thalamus, LGB

Posterior limb of internal capsule, lateral thalamus, LGB, hippocampus, parahippocampus, lateral midbrain, optic tract, choroid plexus.

Branch Occlusion

Occlusion syndrome

Complete ICA Occlusion

Contralateral hemiplegia, hemi-sensory loss, ipsilateral gaze deviation, hemianopia, aphasia if dominant, neglect if non-dominant.

Ophthalmic Artery

Loss of vision with no cherry red spot (worse than CRAO)

Central retinal artery

CRAO: sudden, acute, and painless loss of vision in one eye. Fundus with cherry red spot (pale retina)

Prognosis: 65% will lose vision (worse than 20/400) – only 15% will regain their vision (better than 20/40)

Posterior Ciliary

AION: ischemia of optic nerve head due to decrease blood flow in circle of Zinn (made by medial & lateral post ciliary arteries around optic nerve head). Manifests as altitudinal field defect (commonly inferior). GCA is a major cause of AION (median age 72, more in women, 50% of patients have PMR).

Posterior Communicating

Uncommon

Anterior Choroidal Artery

Hemiparesis, hypothesia, hemianopia. Sometimes mutism which is considered a form of neglect