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Dural Venous Sinuses

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INTRODUCTIONINTRODUCTION

The venous sinuses of the The venous sinuses of the cranial cavity are blood-cranial cavity are blood-filled spaces situated filled spaces situated between the layers of the between the layers of the dura mater.dura mater.

They are lined by They are lined by endothelium. endothelium.

Their walls are thick and Their walls are thick and composed of fibrous tissue; composed of fibrous tissue; they have no muscular they have no muscular tissuetissue..

The sinuses The sinuses have no valveshave no valves.. They receive tributaries They receive tributaries

from the brain, the diploe of from the brain, the diploe of the skull, the orbit, and the the skull, the orbit, and the internal ear.internal ear.

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Dural Venous SinusesSuperior Sagittal SinusInferior Sagittal SinusStraight SinusTransverse SinusesSigmoid SinusesOccipital SinusCavernous SinusSuperior & Inf. Petrosal Sinuses

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SUPERIOR SAGITTAL SINUSSUPERIOR SAGITTAL SINUS The The superior sagittal superior sagittal

sinussinus occupies the upper occupies the upper fixed border of the falx fixed border of the falx cerebri. cerebri.

It begins in front at the It begins in front at the Crista GelliCrista Gelli

It runs backward, It runs backward, grooving the vault of the grooving the vault of the skull, and at the internal skull, and at the internal occipital protuberance it occipital protuberance it deviates to one or the deviates to one or the other side (usually the other side (usually the right) and becomes right) and becomes continuous with the continuous with the corresponding corresponding transverse sinus.transverse sinus.

Numerous arachnoid villi Numerous arachnoid villi and granulations project and granulations project into it. into it.

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SUPERIOR SAGITTAL SINUSSUPERIOR SAGITTAL SINUS The superior The superior

sagittal sinus sagittal sinus receives in its receives in its course the course the superior cerebral superior cerebral veinsveins

At the internal At the internal occipital occipital protuberance it is protuberance it is dilated to form the dilated to form the confluence of the confluence of the sinusessinuses

Here, the superior Here, the superior sagittal sinus sagittal sinus usually becomes usually becomes continuous with continuous with the right transverse the right transverse sinus; it is sinus; it is connected to the connected to the opposite transverse opposite transverse sinus and receives sinus and receives the the occipital sinusoccipital sinus

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INFERIOR SAGITTAL SINUSINFERIOR SAGITTAL SINUS The inferior sagittal The inferior sagittal

sinus occupies the free sinus occupies the free lower margin of the lower margin of the falx cerebri. falx cerebri.

It runs backward and It runs backward and joins the great joins the great cerebral vein at the cerebral vein at the free margin of the free margin of the tentorium cerebelli to tentorium cerebelli to form the form the straight straight sinus.sinus.

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STRAIGHT SINUSSTRAIGHT SINUS

The straight sinus The straight sinus occupies the line of occupies the line of junction of the falx junction of the falx cerebri with the cerebri with the tentorium cerebelli. tentorium cerebelli.

It is formed by the union It is formed by the union of the inferior sagittal of the inferior sagittal sinus with the great sinus with the great cerebral vein. cerebral vein.

It ends by turning to the It ends by turning to the left (sometimes to the left (sometimes to the right) to form the right) to form the transverse sinus.btransverse sinus.b

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TRANSVERSE SINUSESTRANSVERSE SINUSES The transverse sinusesThe transverse sinuses are are

pairedpaired structures and structures and begin at the internal begin at the internal occipital protuberance. occipital protuberance.

The The right sinusright sinus is is usually continuous with usually continuous with the superior sagittal the superior sagittal sinus. sinus.

TheThe left left sinussinus is is continuous with the continuous with the straight sinus.straight sinus.

Each sinus occupies the Each sinus occupies the attached margin of the attached margin of the tentorium cerebelli, tentorium cerebelli, grooving the occipital grooving the occipital bone and the bone and the posteroinferior angle of posteroinferior angle of the parietal bone.the parietal bone.

They receive: They receive: Superior petrosal sinuses,Superior petrosal sinuses,

They end by turning They end by turning downward as the downward as the sigmoid sigmoid sinuses.sinuses.

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SIGMOID SINUSESSIGMOID SINUSES

The sigmoid The sigmoid sinusessinuses are a are a direct direct continuation of continuation of the transverse the transverse sinuses.sinuses.

The sinus then The sinus then turns downward turns downward through the through the jugular foramen jugular foramen to become to become internal jugular internal jugular vein. vein.

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OCCIPITAL SINUSOCCIPITAL SINUS

The occipital sinusThe occipital sinus is a small sinus is a small sinus occupying the occupying the attached margin of attached margin of the falx cerebelli. the falx cerebelli.

It commences near It commences near the foramen the foramen magnum, where it magnum, where it communicates with communicates with the vertebral veins the vertebral veins and drains and drains superiorly into the superiorly into the confluence of confluence of sinuses.sinuses.

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CAVERNOUS SINUSESCAVERNOUS SINUSES

The internal carotid artery, The internal carotid artery, surrounded by its surrounded by its sympathetic nerve plexus, sympathetic nerve plexus, runs forward through the runs forward through the sinus. sinus.

The abducent nerve also The abducent nerve also passes through the sinus. passes through the sinus.

The internal carotid artery The internal carotid artery and the nerves are separated and the nerves are separated from the blood by an from the blood by an endothelial covering.endothelial covering.

The third and fourth cranial The third and fourth cranial nerves, and the ophthalmic nerves, and the ophthalmic and maxillary divisions of and maxillary divisions of the trigeminal nerve run the trigeminal nerve run forward in the lateral wall of forward in the lateral wall of the sinus. the sinus.

They lie between the They lie between the endothelial lining and the endothelial lining and the dura mater.dura mater.• The cavernous sinuses are situated in

the middle cranial fossa on each side of the body of the sphenoid bone. • Each sinus extends from the superior orbital fissure in front to the apex of the petrous part of the temporal bone behind.

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SUPERIOR AND INFERIOR PETROSAL SINUSESSUPERIOR AND INFERIOR PETROSAL SINUSES

The superior and The superior and inferior petrosal inferior petrosal sinusessinuses are small are small sinuses situated on the sinuses situated on the superior and inferior superior and inferior borders of the petrous borders of the petrous part of the temporal part of the temporal bone on each side.bone on each side.

Each Each superior sinussuperior sinus drains the cavernous drains the cavernous sinus into the sinus into the transverse sinustransverse sinus..

Each Each inferior sinusinferior sinus drains the cavernous drains the cavernous sinus into the sinus into the internal internal jugular veinjugular vein..

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