James Montgomery, DVMSeptember 27, 2010

Cranial Vascular Anatomy

Major VesselsArterial Supply

Internal carotidBasilar

Venous ReturnSinuses of the dura mater (though not confined to the dura in

dogs)Dorsal set

Unpaired: Dorsal sagittal and straight sinusesPaired: transverse sinus

Ventral setDouble, unpaired intercavernous sinusPaired cavernous, signoid, basilar, and dorsal and ventral petrosal

sinuses

Major arterial supply – Internal Carotid

Marks termination of common carotid

Carotid body: chemoreceptorHighly sensitive to O2

concentrationAlso sensitive to CO2

and pH

Major arterial supply – Internal CarotidEnters petro-occipital fissure and traverses

the carotid canalThen passes ventrally through the foramen

lacerum, forms a loop, and re-enters the cranial cavity through the same foramen.

Major arterial supply – Internal CarotidPerforates one layer of the dura mater and

runs through the blood filled cavernous sinus that separates the dura into two layers

Major arterial supply – Internal CarotidPerforates second layer of dura and the

arachnoid, and comes to lie in the subarachnoid space

Trifurcates:Middle CerebralRostral CerebralCaudal Cerebral

Circle of WillisFormed by the right and left internal carotid arteries and

basilar arteryCaudal communicating artery

Leaves the internal carotid after it enters the subarachnoid space and forms the lateral and caudal thirds of the arterial circle before anastomosing with the basilar artery

Rostral, Middle, and Caudal cerebral arteries supply cerebrum

Rostral, and Caudal Cerebellar arteries supply the cerebellum; pontine and medullary branches of the basilar supply the pons and medulla oblongata.

Ensures the maintenance of constant blood pressure in the terminal arteries and provides alternate routes by which blood can reach the brain

Circle of Willis

Circle of Willis

Venous ReturnPaired: Transverse, Cavernous, Sigmoid,

Basilar, and dorsal and ventral petrosal sinuses

Unpaired: Dorsal sagittal, Straight, Intercavernous

Sinuses empty into venous system via multiple routesMaxillary veinBasilar sinusVertebral veinInternal jugular vein