Jun 07, 2023
A set of blood vessels called the dural venous sinuses drain the venous blood that circulates in the cranial cavity. To sustain systemic circulation, it collectively pumps deoxygenated blood from the head back to the heart. The superior, inferior, straight, transverse, sigmoid, cavernous, and superior petrosal sinuses are the other six primary dural venous sinuses that are situated in the cranial cavity, specifically between the periosteal and meningeal layer of the dura mater.
Near the falx cerebri and tentorium cerebelli, the majority of these sinuses may be discovered. The most significant dural venous sinus in terms of medicine is the cavernous sinus. For doctors and other healthcare professionals, the distinctive features of venous sinuses are crucial, particularly in situations where infection and thrombosis are potential outcomes.
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Dura mater, a specialized layer of flattened cells present in blood and lymph arteries, lines the walls of the dural venous sinuses. They are distinct from other blood vessels in that they are missing the full complement of vessel layers (such as the tunica media) found in arteries and veins.
It is also devoid of vein valves, with the exception of the placental and pulmonary arteries, which both transport deoxygenated blood in the materno-fetal blood circulation.
The majority of the venous blood that drains into the dural venous sinuses originates from a number of cranial tributaries. The following structures serve as tributaries to the venous sinus flow:
Depending on where they are located within the cranium and the related structures that travel through the sinuses, the major dural venous sinuses have various particular functions. The falx cerebri is inferior to the superior sagittal sinus, which is midsagittal.
It gathers blood from veins in the brain and cerebellum that travel to the intersection of sinuses (torcular herophili). The inferior sagittal sinus links with the great cerebral vein to form the straight sinus, and it is located within the inferior portion of the falx cerebri.
The straight sinus empties into the confluence of sinuses after draining the contents of the great cerebral vein and inferior sagittal sinus. The transverse sinus is another possible outflow for it. The occiput's contents are channeled into the confluence of sinuses through the occipital sinus, which is located in the back of the tentorium cerebelli.
Bilaterally within the tentorium cerebelli are the transverse sinuses. It develops as a connection to the occipital bone and carries venous blood from the sinus apex to the left and right sigmoid sinuses.
The paired sigmoid sinuses are distinguished by their S-shaped sinus and are located posteriorly at the base of the cranial fossa. Venous blood is collectively drained from the left and right sigmoid sinuses into the internal jugular vein, which leaves the body through the jugular foramen.
The cavernous sinus, which drains material from the pterygoid venous plexus (deep face) and ophthalmic veins (orbit), is situated on the hollow of the sphenoid bone around the pituitary gland. Cavernous sinuses also drain inferiorly (into the internal jugular vein) and superiorly (into the sigmoid sinus) into the petrosal sinuses.
Intercavernous sinuses, which connect the left and right cavernous sinuses and are home to cranial nerves III (oculomotor), IV (trochlear), the ophthalmic and maxillary branches of cranial nerve V (trigeminal), and cranial nerve VI (abducens), which is located below the internal carotid artery, are regarded as the most clinically significant venous sinuses.
These explanations are why the cavernous sinus is also referred to as the "anatomic jewel box." The confluence of sinuses, which is located along the occipital bone posteriorly and drains blood from the superior sagittal, straight, and occipital sinuses, transmits venous blood to the left and right transverse sinuses.
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All dural venous sinuses lack valves, which makes it possible for blood to flow forward or backward to other connected structures, allowing pathogens and cancerous cells to spread to other regions of the brain. The medial angle of the eyes, the sides of the nose, and the top lip form a triangle that forms the deadly triangle of the face. This architecture is crucial because it allows viruses to enter the brain through the cavernous sinuses from the face.
Cavernous sinus thrombosis is a disorder in which a thrombus forms due to infection that has spread to the cavernous sinuses from the deep and superficial layers of the face. The swelling of the ankle could develop from this disorder.
The affected sinuses may bulge as a result of this illness, and the related cranial nerves may also sustain harm. Patients may experience internal strabismus due to a lesion in cranial nerve VI, which is typically the first cranial nerve to be impacted.
Thereafter, more movement and sensation of the eyes, skin on the face, and scalp may also be damaged. Other injured cranial nerves may also present as ophthalmoplegia, or eye muscle paralysis. Patients with venous sinus disease may also experience pulsatile proptosis, which is characterized by pulsation and protrusion of the eyeball.
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