7 terms

Segments & Branches of ICA

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Describe the following segment of the ICA in terms of it's anatomy and branches:
- C1 (cervical)
begins in the neck at carotid bifurcation where the common carotid a. divides into internal & external carotids, travels in carotid sheat w/IJV and vagal n, encircled w/postganglionic sympathetic n's, ending where the ICA enters carotid canal of petrous bone (NO branches)
Describe the following segment of the ICA in terms of it's anatomy and branches:
- C2 (petrous)
still surrounded by PGSNs, ends at the post edge of the foramen lacerum (inferomedial to edge of the Gasserian ganglion in Meckel's cave
3 divisions
vertical segment: ICA ascneds then bends as the posterior loop anterior to cochlea, bends antero-medially becoming the horizontal segment deep and medial to greater and lesser superficial petrosal nerves, ant to tympanic membrane
Describe the following segment of the ICA in terms of it's anatomy and branches:
- C3 (lacerum)
the ICA passes over (but not thru) the f-Lac forming the lateral loop. Ascends in the canalicular portion of the f-Lac to juxtasellar position, piercing the dura as it passes the petrolingual lig to become the cavernous segment.
Branches: (usually not visible angiographically)
caroticotympanic (inconsistent) -> tympanic cavity
pterygoid (vidian) branch - passes thru f-Lac, present in only 30%, may cont as artery of pterygoid canal
Describe the following segment of the ICA in terms of it's anatomy and branches:
- C4 (cavernous)
covered by vascular membrane lining sinus, still surrounded by PGSNs, passes anteriorly then supero-medially, bends posteriorly (medial loop) of ICA, travels horizontally and bends anteriorly (part of anterior loop of ICA) to ant clinoid process, ending at the proximal dural ring
Branches:
Meningohypophyseal trunk
- a. of tentorium (aka artery of Bernasconi & Cassinari)
- dorsal meningeal
- inferior hypophyseal a. (-> post lobe of pituitary

anterior meningeal a.
a. to inferior portion of cavernous sinus (present in 80%)
capsular aa. of McConnell (30%) supplies capsule of pituitary
Describe the following segment of the ICA in terms of it's anatomy and branches:
- C5 (clinoid)
begins at proximal dural ring, ends at distal dural ring where ICA becomes intradural
Describe the following segment of the ICA in terms of it's anatomy and branches:
- C6 (ophthalmic
begins at distal dural ring, ends just prox to p-comm
ophthalmic a - origin from ICA is distal to cavernous sinus in 89% & can vary from 5mm anterior to 7mm posterior to ant clinoid, passes thru the optic canal into the orbit, has characteristic bayonet-like kink on lateral angiogram
superior hypophyseal a. branches -> ant lobe of pituitary & stalk (1st branch of supraclinoid ICA)
Describe the following segment of the ICA in terms of it's anatomy and branches:
- C7 (communicating)
begins just proximal to p-comm origin, travels between CN II & III, terminating just below ant perforated substance where it bifurcates into ACA & MCA
posterior communicating a (p comm)
- few anterior thalamoperforators (-> optic tract, chiasm & post hypothalamus
- plexal segment, enters supracornual recess of temporal horn
- cisternal segment, passes thru curual cistern

anterior choroidal artery - take off 2-4mm distal to p-comm, supplies portion of optic tract, medial globus pallidus, genu of internal capsule, inf 1/2 of post limb of IC, uncus, retrolenticular fibers, lateral geniculate body