Sphenoparietal, Sphenobasilar And Sphenopetrosal Sinuses

Table of Contents

Transverse Sigmoid Sinuses

Superior Petrosal Sinus

Inferior Petrosal Sinus

A vestibule may form when two or three meningeal sins join together to reach the superior sagittal. It is possible for veins from the anterior frontal or posterior parietal regions to merge to form a meningeal sinus in a dura mater lateral the superior sagittal. Most veins coming from the posterior parietal and frontal regions tend to dip below the vessels lacunae, and then pass directly to superior sagittal. The veins that originate from the medial hemisphere reach the inferior border of a sinus, or laterally turn onto the superior margin.

The segment of sagittal sinus superior in the frontal zone above the corpus genus receives fewer veins than other areas, with the exception of the 4-6 cm proximal and the torcular sheophili. Bridging veins rarely enter superior sagittal sin.

The inferior sagittal Sinus (Fig 2) is located at the inferior edge the falx (16).

It is located above the anterior part of the corpus Callosum. As it runs posteriorly, it joins the straight sinus.

It results from the union between veins from adjacent parts of the falx and corpus callosum. The junction between the veins of cingulate Gyrus and corpus Callosum often forms an acute hook shape, with the apex facing forward.

The anterior pericallosal and inferior sagittal veins are the largest tributaries.

The superior and inferior sagittal sins might communicate via a vein in the falx. In rare cases, this connection can be so strong that the superior sinus drains predominantly to the straight and inferior sagittal sinuses.

Direct Sinus

The straight sinus (Fig 5) is located behind the corpus callosum’s selenium at the union between the inferior sagittal and great veins. (16)

It continues laterally and downwards at the junction between the falx & tentorium.

It can drain into either of the transverse sinuses but is more likely to drain into left transverse.

Transverse Sigmoid Sinuses

The right- and left transverse sinuses begin at the herophili. They travel laterally from there to the internal Occipital Protuberance. (16)

The transverse Sinus exits the tentorial attachments, becoming the sigmoid Sinus at the site just after the petrous Rim, where the superior and transverse petrosal Sinuses meet.

The superior sagittal nasal sinus can drain equally to the transverse sinuses on either side or predominantly to one side. However, the transverse sinus is larger and receives most of the drainage from superior sagittal.

The left transverse sinus, which is typically smaller, receives a lot of drainage from the straight sinus. The right transverse sinus and right sigmoid are blood vessels that drain blood from the superficial brain parts. However, the left transverse and left sigmoid sins and right jugular blood vessels contain blood from the deeper brain parts.

The drainage patterns of each side are what explain the different symptoms. Cortical blood vessels from the temporal and lateral surfaces may drain into transverse sinuses. However, they will often pass medially under the hemisphere to join a narrow sinus in its tentorium. The tentorium runs for approximately 1cm before draining into transverse sinus’ terminal part.

The lateral tentorial sinus is formed by the cortical vessels that run from the base of the temporal lobes and occipital. Labbe’s vein often ends in the transverse. However, it can curve around inferior margins of the hemisphere and join the lateral camporial sinus. Transverse sinus communication may be possible through the extracranial and emissary vessels in the occipital bones.

The smallest cranial sinus is the occipital. (fig. 7). It is found in the attached margin, or falx cerebelli. Occasionally, it may be two.

It starts at the foramen Magnum’s margin and connects to the terminal portion of the transverse sin. (21)

Two venous channels run through the tentorium, one for each half. They are often symmetrical but not always constant.

The medial

Lateral tentorial Sinuses (16)

The medial-tentorial sinuses are formed when veins from above the cerebellum condense.

Convergence of veins of the basal, lateral surfaces and temporal lobes results in the formation of the lateral tentorial sinuses. The lateral tractorial sinuses form within the tentorium.

The paired cavernous sinuses are located on each side the sella turkeyica. They are connected across midline by the posterior and anterior intercavernous Sinuses. They run through the junction of diaphragma soldae and dura lining sella. (16)

Anteriorly the cavernous sinuses communicate with each other and with the sphenoparietal or ophthalmic nerves.

Its middle portion connects to the pterygoidplexus through a small vein that passes through the ovale.

Posteriorly, it opens directly into a basilar sinus that sits on the ground. It connects via the superior petrosal nasal junction with the transverse-sigmoid sinuses, and the inferior petrosal and sigmoid cavities.

Superior Petrosal Sinus

The superior petrosal nasal sinus (fig 12), is found within the attachment between the tentorium (16) and the petrous-ridge (16).

It connects to cavernous sinus’s posterior end at its medial tip. Its lateral tip joins the junction between the transverse sinus and the sigmoid.

It is the brainstem and cerebellum that usually produce the bridging veins connecting it.

The sinus may extend over, below, or around trigeminal root posterior roots.

The superficial sinus veins of the sylvian can drain into an infrequently occurring tributary called the sphenopetrosal.

Inferior Petrosal Sinus

Inferior Petrosal Sinuses (fig. 12) are small sinuses on either side of each petrous bone (16).

Each inferior petrosal nasal drains the cavity into the inner jugular vein.

The inferior petrosal sinus can be found in the inferior petrosal. It is formed at the junction of petrous bone and basilar bone.

It starts in the posteroinferior cavernous sin and then passes through the anterior foramen of the jugular.

The inferior petrosal sin receives the inner auditory veins as well as veins from medulla, pons, under surface and cerebellum.

The largest meningeal channel that runs alongside the meningeal veins is the sphenoparietal. Fig (9)

It is attached to an anterior branch, above the level pterion, of the middlemeningeal artery. It leaves the artery below this level and runs through the dura mater to the Cavernous sinus anterior. Its upper part communicates via the meningeal veins to the superior-sagittal sinus. The sinus running along the sphenoid roof may go inferiorly, reaching the floor at the middle cranial Fossa. It can then run posteriorly to empty into the lateral extension or sphenoidal veins on the greater side of the cavernous cavity. It may also pass farther posteriorly to join lateral or superior petrosal sinuses.

The sphenobasal variant is where the sinus exits from the skull by joining the veins of the sphenoidal and pterygoid.

The sphenopetrosal nasal variant is one in which the sinus flows further posteriorly along with the floor of middle fossa to drain into the superior and lateral sinuses.

The sphenoparietal cavity is commonly reached by the superficial and deep sylvian blood vessels. The sphenoparietal sinus may not be present or well developed. In this case, the sylvian vessels may drain into the cavernous sinus.