Vascular Anatomy Flashcards
Brain circulation
Anterior: carotid artery distribution -> ICA, ACA, MCA
Posterior: vertebral and basilar artery distribution -> PCA
Anterior circulation - carotid artery
Carotid arteries
> Left: direct from aorta
> Right: from brachiocephalic artery
Common carotid arteries divides to external and internal carotid arteries
Division of internal carotid artery:
1. Cervical: bifurcation of common carotid to carotid canal within petrous portion of temporal bone
- Behind has superior cervical ganglion of sympathetic trunk and superior laryngeal nerve
> Carotid dissection -> unilateral Horner’s syndrome
- Petrous - petrous bone into skull cavity
- Surrounded by carotid plexus (sympathetic fibres) - Cavernous - through cavernous sinus
- Surrounded by sympathetic fibres
- Close to CN 3, CN 4, CN 5a 5b, and CN 6
- Branches to ophthalmic artery -> amaurosis fugax in carotid stenosis - Cerebral - penetrates dura mater and passes between CN 2 and CN 6
- Terminal branches: ACA, MCA, PcommA, anterior choroidal artery
Anterior cerebral artery (ACA)
Branches:
1. Anteromedial ganglionic branches
- Supplies: corpus callosum, head of caudate
- Inferior branches
- Supplies: orbital surface of frontal lobe, olfactory lobe - Anterior branches
- Supplies: part of superior frontal gyrus
- Twigs over edge of hemisphere to superior and middle frontal gyri, upper part of anterior central gyrus - Middle branches
- Supplies: corpus callosum, cingulate gyrus, medial surface of superior frontal and upper part of anterior central gyrus - Posterior branches
Linkage:
- Acomm connects 2 ACAs, length about 4mm
Middle cerebral artery (MCA)
(largest branch)
Runs laterally in Sylvian fissure into insula and divides over lateral surface of hemisphere
Branches:
1. Lenticulostriate branches
- Supplies: basal ganglia, internal capsule, thalamus
- Inferior lateral frontal
- Supplies: inferior frontal gyrus (Broca area) - Ascending frontal
- Supplies: anterior central gyrus - Ascending parietal
- Supplies: posterior frontal and superior parietal lobule - Parietotemporal
- Supplies: supramarginal and angular gyri, posterior parts of superior and middle temporal gyri - Temporal branches (2 or 3)
- Supplies: temporal lobe
PComm and anterior choroidal artery
PCommA - connects ICA to PCA
- Usually larger on one side
- Gives off a few small branches
Anterior choroidal artery - small branch near PCommA
- Supplies: choroid plexus, hippocampus
Posterior circulation - vertebral -> basilar artery
Vertebrobasilar circulation
- Two vertebral arteries join to form basilar artery
- Basilar artery terminates in 2 PCA
Anterior and posterior circulations joined by Circle of Willis
Course of vertebral artery
Vertebral artery
Origin: first branch of subclavian artery
Ascends through foramina in transverse processes of upper 6th cervical vertebrae
Winds behind atlas
Enters skull through foramen magnum
Termination: at lower border of pons - meets with vessel of opposite side to form basilar artery
Vertebral artery is divided into 4 parts
Division of vertebral artery
Extracranial - V1-V3
1. V1 - runs upward and backward behind internal jugular and in front of transverse process of C7
- V2 - runs upward through foramina in transverse process of C6 until transverse process of C1
- ## V3 - exits foramen of C1 and curves backward behind C1 and enters vertebral canal by passing beneath posterior atlanto-occipital membraneIntracranial - V4
- V4 - pierces dura mater and inclines to front of medulla oblongata, unites with vessel of opposite side at lower border of pons to form basilar artery
Asymmetry of vertebral arteries
15% population have hypoplastic or atretic single vertebral artery (<2mm in diameter)
May be clinically significant if dominant vessel becomes diseased
Posterior cerebral artery
Supplies: occipital lobe, median temporal lobes
