Dural venous sinuses

One of the meninges of the human brain, namely the dura mater, has cavities filled with venous blood between its sheaths. Such cavities or spaces are called dural venous sinuses.

On the cross section, their lumina are triangular and do not collapse. It is this structure that ensures constant circulation and venous outflow from the veins of the brain, which maintains constant pressure in these veins. There are no valves in their walls, and venous blood flows freely from the skull area into the internal jugular vein (vena jugularis interna).

Internal jugular vein (vena jugularis interna)

There are the following dural venous sinuses (sinus durae matris):

The superior sagittal sinus (sinus sagittalis superior) is located in the superior part of the cerebral falx.

It begins from the crista galli of the ethmoidal bone and ends at the internal occipital crest.

The anterior parts of the sinus anastomose with the veins of the nasal cavity. In the middle part, this sinus communicates with the diploic veins and the superficial veins of the calvaria through the parietal emissary veins. The posterior part of the sinus ends by the confluence of sinuses (confluens sinuum), which is located at the level of the internal occipital protuberance.

Confluence of sinuses (confluens sinuum)

There are lateral lacunae (lacunae laterales) to the right and left of the superior sagittal sinus.

Adjacent to the lacunae are arachnoid (pacchionian) granulations (granulationes arachnoidales), which drain venous blood from the dura mater and regulate intracranial pressure.

The inferior sagittal sinus (sinus sagittalis inferior) is located in the inferior border of the cerebral falx.

It passes into the straight sinus in the area of the cerebellar tentorium.

Some veins of the corpus callosum, part of the veins of the cerebral falx, and the veins of the medial surface of the hemispheres end by this sinus.

The straight sinus (sinus rectus) passes in the schindylesis of the cerebellar tentorium in the area of attachment of the cerebral falx to it.

The straight sinus communicates the posterior ends of the superior and inferior sagittal sinuses. The great cerebral vein, the inferior sagittal sinus, the veins of the cerebellar tentorium, and the inferior vein of the vermis end by the anterior part of the straight sinus. From behind, the straight sinus ends by the transverse sinus in the area of the confluence of the sinus.

The transverse sinus (sinus transversus) is located in the area where the cerebellar tentorium arises from the dura mater.

On the internal surface of the occipital bone, the transverse sinus passes in a wide groove. On the right and left, the transverse sinus continues into the right and left sigmoid sinuses. Two emissary veins end by the transverse sinus. The transverse sinus has the already mentioned widening called the confluence of the sinus (confluens sinuum).

Confluence of the sinus (confluens sinuum)

The occipital sinus (sinus occipitalis) passes at the base of the cerebellar falx and in the area of the internal occipital crest, it reaches the posterior border of the foramen magnum.

Here, the occipital sinus divides into two branches that circumflex the foramen magnum bilaterally. These branches end by the corresponding sigmoid sinuses. The superior part of the occipital sinus ends by the transverse sinus.

The right and left sigmoid sinuses (sinus sigmoideus) are located in the groove of the same name on the internal surface of the cranium. The sinus is S-shaped. In the area of the jugular foramen, it passes into the internal jugular vein.

The cavernous sinus (sinus cavernosus) is located in the area of the base of the cranium to the side of the sella turcica.

This sinus consists of many cavernous cavities communicating with each other. The right and left cavernous sinuses communicate with each other by means of anastomoses, which are called anterior and posterior intercavernous sinuses (sinus intercavernosi). The internal carotid artery and several cranial nerves pass through the cavernous sinus. The sphenoparietal sinus and the superior ophtalmic vein end by the anterior part of the cavernous sinus.

Posterior intercavernous sinuses (sinus intercavernosi)

The sphenoparietal sinus (sinus sphenoparietalis) passes along the border of the lesser wing of the sphenoidal bone. This is a paired sinus that communicates with the cavernous sinus on the right and left.

The superior and inferior petrosal sinuses (sinus petrosus superior et sinus petrosus inferior) lie along the superior and posterior borders of the petrous part of the temporal bone. These sinuses are involved in the outflow of venous blood from the cavernous sinus to the sigmoid sinus. In the area of the body of the occipital bone, the right and left lower petrous sinuses communicate by venous anastomoses, forming the basilar plexus. The basilar plexus exits through the foramen magnum and communicates with the internal vertebral venous plexus.

Superior petrosal sinuses (sinus petrosus superior)

Inferior petrosal sinuses (sinus petrosus inferior)

The marginal sinus (sinus marginalis) passes along the edge of the foramen magnum. The posterior part communicates with the occipital sinus, and the anterior part communicates with the basilar plexus and the venous plexus of the hypoglossal canal. The veins of the medulla oblongata and cerebellum partially end by the marginal sinus.

The basilar venous plexus (plexus basilaris) is formed from the veins of the spongy bone of the base of the cranium and communicates the cavernous sinus with the marginal sinus and the inferior marginal sinuses with each other. It is located on the clivus of the occipital bone and surrounds the basilar artery. The basilar venous plexus ends by the cavernous and petrosal sinuses.

The atlantooccipital sinus (sinus atlantooccipitalis) lies between the posterior edge of the foramen magnum and the posterior arch of the atlas and is also limited by the atlantooccipital membrane and the spinal dura mater. This sinus communicates with the jugular vein, basilar plexus, and internal venous vertebral plexus. The vertebral vein and the deep veins of the neck arise from the atlantooccipital sinus.

The movement of blood in this sinus can be bidirectional and depends on the pulsation of the vertebral artery.

In addition to the sinuses, there are three venous plexuses in the venous system of the head. These include:

The venous plexus of the internal carotid artery (plexus venosus caroticus internus) and the venous plexus of the foramen ovale (plexus venosus foraminis ovalis) communicates with the cavernous sinus and the pterygoid plexus (plexus venosus pterygoideus).
Venous plexus of the internal carotid artery (plexus venosus foraminis ovalis)
The venous plexus of the hypoglossal canal (plexus venosus canalis hypoglossi) communicates the marginal sinus with the internal jugular vein.

Venous plexus of the hypoglossal canal (plexus venosus canalis nervi hypoglossi)

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