Venous sinuses

Dr.Saeed Mustafa

Cranial Meninges

3

Meninges of the Spinal Cord

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Spinal cord

Spinal cord

Pia mater

Arachnoid mater

Dura mater

Dorsal root

Dorsal root

Spinal nerve

Epidural space

(a) (b)

Ventral root

Dorsal rootganglion

Thoracicvertebra

Spinalnerve

Dorsal rootganglion

Subarachnoidspace

Dorsal branch(dorsal ramus)

Ventral branch(ventral ramus)

Ventral root

Epiduralspace

Body ofvertebra

CRANIAL MENINGES

• Dura:– an inner (meningeal) layer and outer (periosteal) layer– Most of the dura’s venous sinuses lie between the dural layers– Dural layers are generally fused, except where they separate to

provide space for the venous sinuses and where the inner layer forms septa between the brain portions

– Outer layer firmly attached to inner surface of cranial bones; inner layer continuous with spinal dura

Meninges: Dura Mater

• Reflections:Falx cerebri:

Midline fold of dura mater extending between two cerebral hemispheres.

Tentorium cerebelli:Dural fold located between

cerebellum and occipital lobes of cerebral hemispheres.

Meninges: Dura Mater

• Reflections:Falx cerebelli:

Dural fold between two cerebellar hemispheres.

Diaphragma sellaeDural fold over hypophyseal

fossa.

CRANIAL MENINGES

CRANIAL MENINGES• Arachnoid:

– Delicate avascular membrane covers the subarachnoid space

– Between the arachnoid and dura mater lies the subdural space

– Arachnoid granulations project into the superior sagittal sinus

• Arachnoid granulations－ project into sinuses of dura mater, serve as

sites where cerebrospinal fluid diffuses into bloodstream

Circulation of cerebrospinal fluidCSF drains from lateral ventricle interventricular foramina third ventricle

mesencephalic aqueduct fourth ventricle median and two lateral apertures

subarachnoid space arachnoid granulations superior sagittal sinus vein

CRANIAL MENINGES

• Pia:– Thin connective tissue membrane that covers the brain

surface and extends into sulci and fissures and around blood vessels throughout the brain

– Beyond the end of the spinal cord continues as the filum terminale

Dural Nerve Supply

• Branches of trigeminal,vagus and 1st 3 cervical nerves• Sensitive to streching which produces the sensation

of headache

Dural arterial supply

Int. carotid arteryMaxillaryAscending pharyngealOccipitalVertebral*Middle meningeal artery

Intra cranial hemorrhage

1.Extra dural (middle meningeal artery) 2.Subdural (sup.cerebral vein) 3.Subarachnoid (the circle of willis)

Blood stained csf 4.Cerebral (lenticulostriate artery)

VENOUS DRAINAGE

• Venous drainage of the brain and coverings includes veins of the brain itself, dural venous sinuses, dura’s meningeal veins, and diploic veins

• Eventual cerebral venous drainage is the internal jugular vein

• Cerebral veins contain no valves

Vasculature: Venous Sinuses

Dural venous sinuses

• :Superior sagittal sinus:

Lies along superior margin of falx cerebri.

receives in its course the sup.cerebral vein

Inferior sagittal sinus:Lies along inferior margin of falx cerebri.

joins great cerebral vein

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Meninges: Dura Mater

• Dural venous sinuses:Straight sinus:

Lies at intersection of falx cerebri and tentorium cerebelli.

Confluence of sinuses:Common confluence of superior sagittal sinus and straight sinus.

Venous sinuses

Meninges: Dura Mater

• Dural venous sinuses:Transverse:

Begins at confluence of sinuses.Extends along edges of tentorium

cerebelli.Right receives blood from superior

sagittal sinus.Left receives blood from straight sinus.

receives sup.petrosal sinus,inf.cerebral n cerebellar veins n diploic veins

Meninges: Dura Mater

• Dural venous sinuses:Sigmoid:

Continuation of straight sinus.“S”-shaped.Ends at jugular foramen:

Joins internal jugular vein.

• Superior n inferior petrosal sinuses• Petrous part of temporal bone• Sup.petrosal sinus drains the cavernous sinus

into transverse sinus• Inf.petrosal sinus drains the cavernous sinus

into IJV

Vasculature: Venus Sinuses

The flowing of the blood in dural sinus

Sup. sagittal sinus

Inf. sagittal sinus Straight sinus Confluence of sinus Transverse sinus

Cavernous sinus

Sup. petrosal sinus

Inf. petrosal sinus Internal jugular vein

Sigmoid sinus

Cavernous sinus

• Middle cranial fossa• Extends from Sup.orbital fissure to petrous part of

temporal bone• Tributaries • Sup.n inf.ophthalmic veins,cerebral veins,the

sphenoparietal sinus n the central vein of retina• Drains Posteriorly into sup n inf petrosal sinuses

and inferiorly into pterygoid venous plexus

Cavernous sinus

• Position: lies on each side of sella turcica• Relations of cavernous sinus:

– Internal carotid artery and abducent nerve run through the sinus – Oculomotor and trochlear nerves and ophthalmic and maxillary

divisions of trigeminal nerve lie in the lateral wall of the sinus

Veins of brainSuperficial cerebral veins • Drain blood from cortex

and subcortical medullary substance and empty into adjacent sinuses of dura mater

Veins of brain

• Deep cerebral veins: drain deeper parts of hemispheres, basal nuclei, internal capsule, diencephalon and choroid plexus, ultimately form great cerebral vein which enter straight sinus

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