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1 MENINGEAL ARTERIES: RELATIONSHIP TO SKULL AND DURA

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Vasculature



77



Left middle meningeal artery



Right and Ieft middle cerebral arteries



Right and Ieft posterior

cerebral arteries



Right and Ieft anterior cerebral arteries

Anterior communicating artery



Right and Ieft superior

cerebellar arteries



Right ophthalmic artery

Right posterior

communicating artery



Basilar artery



Cavernous sinus



Mastoid branch of

Ieft occipital artery

Left interior auditory

(labyrinthine) artery



Right deep temporal artery



Posterior meningeal branch

of Ieft ascending

pharyngeal artery



Right maxillary artery

Right middle meningeal artery



Right and Ieft anterior

inferior cerebellar arteries



Right superficial temporal artery



Right and Ieft posterior

inferior cerebellar arteries



Right exterior carotid artery



Posterior meningeal branches

of right and Ieft vertebral arteries

Anterior meningeal branch

of right vertebral artery

Right posterior auricular artery

Right occipital artery

Right interior carotid artery

Right ascending pharyngeal artery

Right carotid sinus



Right facial artery

Right lingual artery

Carotid body

Right superior laryngeal artery

Right superior thyroid artery

Thyroid cartilage

Right common carotid artery



Right vertebral artery



Right inferior thyroid artery



Transverse process of C6



Right interior thoracic artery



Right deep cervical artery

Right thyrocervical trunk



Brachiocephalic trunk



Right costocervical trunk

Right subclavian artery



7.2  ARTERIAL SUPPLY TO THE BRAIN

AND �MENINGES

The internal carotid artery )>>ICA) and the vertebral artery ascend through the neck and enter the skull to supply the brain

with blood. The tortuous bends and sites of branching )>>such

as the bifurcation of the common carotid artery into the internal and external carotids) produce turbulence of blood flow

and are sites where atherosclerosis can occur. The bifurcation

of the common carotid is particularly vulnerable to plaque

formation and occlusion, threatening the major anterior part

of the brain with ischemia, which would result in a stroke. The

ICA passes through the cavernous sinus, a site where carotidcavernous fistulae can occur, resulting in damage to the extraocular and trigeminal cranial nerves, which also pass through

this sinus. Studies of blood flow through these arteries are important diagnostic tools. Magnetic resonance arteriography

and Doppler flow studies have, for most purposes, replaced

the older dye studies for performing cerebral angiography.



CLINICAL POINT

The paired carotid arteries and vertebral arteries supply the brain and

part of the spinal cord with blood. The carotids supply the anterior

circulation, including most of the forebrain except for the occipital

lobe and inferior surface of the temporal lobe. The bifurcation of

the common carotid artery is a common site of plaque formation in

atherosclerosis, leading to gradual occlusion of blood flow to the forebrain on the ipsilateral side. Early warnings can be seen in the form of

transient ischemic attacks, forerunners of a full-blown stroke. The best

treatment is prevention, with exercise, proper diet and weight control,

careful regulation of lipid levels and other contributing factors such as

inflammatory mediators. In cases in which severe and symptomatic

occlusion has occurred as the result of atherosclerotic plaque, carotid

endarterectomy can be performed to remove the plaque and attempt

to open up more robust flow to the anterior circulation. Carefully

performed controlled studies have established criteria that determine

which patients can best benefit from this surgical procedure as opposed to more conservative medical treatment. Current studies are

investigating the use of carotid stents to enhance blood flow to the

brain.



78



Overview of the Nervous System



Vidian nerve



Lateral View



Carotid plexus



Cavernous sinus



Ophthalmic artery



Internal carotid artery

Maxillary nerve



Great superficial petrosal nerve

Nervus intermedius

Facial nerve



Internal carotid artery

Carotid nerve

Superior cervical ganglion



Spheno-palatine

ganglion



7.3  INTERNAL CAROTID AND OPHTHALMIC

�ARTERY COURSE

The ophthalmic artery is the first major branch of the ICA. It

supplies the eyeball, ocular muscles, and adjacent structures.

This artery is commonly involved in the first phases of clinical

recognition of cerebrovascular disease. Because of its position



as the first branch of the ICA, emboli from atherosclerotic

arteries that are found at sites such as the bifurcation of the

common carotid artery travel through the ophthalmic artery,

resulting in a transient ischemic attack with the symptom of

fleeting blindness in the affected eye.



Vasculature



79



Anterior communicating artery

Anterior cerebral artery



Circle of Willis



Recurrent artery (of Heubner)

Internal carotid artery

Medial and lateral lenticulostriate arteries

Middle cerebral artery

Lateral orbitofrontal artery

Ascending frontal (candelabra) branch

Anterior choroidal artery

Posterior communicating artery

Posterior cerebral artery

Superior cerebellar artery

Basilar artery and pontine branches

Internal auditory (labyrinthine) artery

Anterior inferior cerebellar artery

Vertebral artery

Anterior spinal artery

Posterior inferior cerebellar artery

Posterior spinal artery



7.4  ARTERIAL DISTRIBUTION TO THE BRAIN:

BASAL VIEW

The anterior circulation )>>middle and anterior cerebral �arteries;

MCAs, ACAs) and the posterior circulation )>>the vertebrobasilar system and its end branch, the posterior cerebral artery;

PCA) and their major branches are shown. The right temporal

pole is removed to show the course of the MCA through the

lateral fissure. The circle of Willis )>>the paired ACAs, MCAs,

and PCAs and the anterior and two posterior communicating

arteries) surrounds the basal hypothalamic area. The circle of

Willis appears to allow free flow of blood around the anterior

and posterior circulation of both sides, but usually it is not

sufficiently patent to allow bypass of an occluded zone.



CLINICAL POINT

The vertebrobasilar system supplies the posterior circulation of the

brain, including most of the brain stem, part of the diencephalons,

and the occipital and inferior temporal lobes of the forebrain. The

paired PCAs are the end arteries of the vertebrobasilar system. An infarct in the PCAs )>>top of the basilar infarct) results in damage to the

ipsilateral occipital lobe, including both the upper and lower banks of

the calcarine fissure. Functionally, this infarct results in contralateral

blindness, called contralateral homonymous hemianopia. There may

be macular sparing if the MCA has some anastomoses with the posterior cerebral circulation.



80



Overview of the Nervous System



Anterior communicating artery

Recurrent artery (of Heubner)

Anterior cerebral artery

Middle cerebral artery

Posterior communicating artery

Anterior choroidal artery

Optic tract

Cerebral peduncle

Lateral geniculate body

Posterior medial choroidal artery

Posterior lateral choroidal artery

Choroid plexus of lateral ventricle

Medial geniculate body

Pulvinar

Lateral ventricle



7.5  ARTERIAL DISTRIBUTION TO THE BRAIN:

CUTAWAY BASAL VIEW SHOWING THE

CIRCLE OF WILLIS

The circle of Willis and the course of the choroidal arteries

are shown. The arteries supplying the brain are end arteries

and do not have sufficient anastomotic channels with other

arteries to sustain blood flow in the face of disruption. The occlusion of an artery supplying a specific territory of the brain

results in functional damage that affects the performance of

structures deprived of adequate blood flow.



CLINICAL POINT

Obstruction of the MCA near its origin is relatively unusual compared

with obstruction or infarcts in selected branches, but it demonstrates

the full range of blood supply of this critical artery. Obstruction near

the origin usually results from embolization, not from atherosclerotic

or thrombotic lesions. It causes contralateral hemiplegia )>>resolving to

spastic), contralateral central facial palsy )>>lower face), contralateral

hemianesthesia, contralateral homonymous hemianopia, and global

aphasia if the left hemisphere is involved. Additional problems with

anosognosia )>>inability to recognize a physical disability), contralateral

neglect, and spatial disorientation may occur.



Vasculature



81



Frontal View with Hemispheres Retracted, Tilted for a View of the Ventral Brain Stem

Paracentral artery



Corpus callosum

Medial and lateral

lenticulostriate arteries



Frontal branches



Lateral orbitofrontal artery



Pericallosal artery

Callosomarginal artery



Ascending frontal

(candelabra) branch



Frontopolar artery

Anterior and posterior

parietal branches

Anterior cerebral

arteries



Precentral

(prerolandic)

and central

(rolandic)

branches



Medial orbitofrontal artery

Recurrent artery

(of Heubner)



Angular branch

Temporal branches

(posterior, middle,

anterior)



Interior carotid

artery



I



Middle cerebral

artery and branches,

deep in lateral

cerebral (sylvian) fissure



Anterior choroidal

artery



II



III



Anterior communicating artery



IV



Posterior cerebral

artery



V

VII

VIII



Posterior communicating artery



XII



Superior cerebellar artery



Basilar artery

Interior auditory

(labyrinthine) artery



IX

X



Anterior inferior cerebellar artery

Posterior spinal artery



VI



Vertebral artery

Posterior inferior cerebellar artery



XI



7.6  ARTERIAL DISTRIBUTION TO THE BRAIN:

FRONTAL VIEW WITH HEMISPHERES

�RETRACTED

With the hemispheres retracted, the course of the ACAs and their

distribution along the midline are visible. This artery supplies

blood to the medial zones of the sensory and motor cortex, which

are associated with the contralateral lower extremity; an ACA

stroke thus affects the contralateral lower limb. With the lateral

fissure opened up, the MCA is seen to course laterally and to give

branches to the entire convexity of the hemisphere. End-branch

infarcts of the MCA affect the contralateral upper extremity and,

if on the left, also affect language function. More proximal MCA

infarcts affecting the MCA distribution to the internal capsule

can cause full contralateral hemiplegia with drooping of the contralateral lower face; this results from damage to corticospinal

and other corticomotor fibers traveling in the posterior limb of



Anterior spinal artery



the internal capsule and damage to corticobulbar fibers traveling

in the genu of the internal capsule.

CLINICAL POINT

The ACA branches from the internal carotid as it splits from the middle cerebral artery. It supplies a medial strip of the forebrain with

blood. ACA occlusion is usually caused by embolization, although an

anterior communicating artery aneurysm, vasospasm resulting from

a subarachnoid hemorrhage, or subfalcial herniation can occlude this

artery. If the ACA is occluded distal to the recurrent artery of Heubner, it results in contralateral spastic paresis and sensory loss in the

lower extremity. A more proximal lesion involving the recurrent artery of Heubner may involve the upper body and limb as well. In addition, there may be internal sphincter weakness of the urinary bladder,

frontal release signs, and conjugate deviation of the eyes toward the

side of the lesion )>>damage to frontal eye fields with unopposed deviation from the intact side).



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