The cavernous sinus is the name given to a dilated venous space within the meninges. It is one of the cerebral blood vessels.
What is the cavernous sinus?
The cavernous sinus is a venous blood conductor of the human brain. The name sinus cavernosus comes from Latin. Thus, sinus translates to German as “innermost,” “pocket,” or “sac.” The term cavernosus is derived from the Latin word cavus (cavity or hollow). The cavernous sinus is part of the cerebral blood vessels (sinus durae matris). These provide for the outflow of blood from the brain region. Various diseases can occur in the area of the cavernous sinus.
Anatomy and structure
The cavernous sinus is found on both sides of the sella turcica (Turkish saddle), which is located on the inside of the sphenoid bone (Os sphenoidale). This bone structure divides the middle cranial fossa in the median plane. The cerebral blood vessel is located at the anterior base of the skull, where it represents a venous space within the hard meninges (dura mater). In the cavernous sinus, inflow occurs from the inferior orbital vein (inferior ophthalmic vein), superior orbital vein (superior ophthalmic vein), and sphenoparietal sinus. Sometimes the sylvian vein (vena media superficialis cerebri) is also included by the venous space. Outflow from the cavernous sinus into the superior jugular vein bulb occurs through the inferior petrosal sinus. Several cranial nerves are located in the lateral wall of the dilated venous space. These are the 3rd cranial nerve (oculomotor nerve), the 4th cranial nerve (trochlear nerve), the ophthalmic nerve (ophthalmic nerve), the maxillary nerve (maxillary nerve), and the internal carotid artery (ACI). The 6th cranial nerve, also known as the abducens nerve, passes directly through the cavernous sinus.
Function and Tasks
The cavernous sinus fulfills the function of providing direct passage for several important cranial nerves as well as the internal carotid artery, allowing them to innervate various areas of the organism. Furthermore, the cavernous sinus transports blood from the facial area back towards the heart. In addition, it participates in the fact that released hormones from the adenohypophysis cross the venous space and in this way enter the circulation of the human body. This enables them to develop effectively. The hormones of the adenohypophysis (anterior pituitary gland) include glandotropic and non-glandotropic hormones. While glandotropic hormones have a stimulatory effect on downstream endocrine glands, non-glandotropic hormones exert a direct effect on their target organs. Non-glandotropic hormones include prolactin and the growth hormone somatotropin (STH). Surrounding the cavernous sinus are the cranial nerves that control the movements of the human eyes. They also sense sensations from parts of the facial region.
Diseases
The cavernous sinus can be affected by several diseases and conditions. These include fractures of the skull, tumor formation, Tolosa-Hunt syndrome, and basal meningitis. However, one of the most common problems of the venous space is the development of a carotid sinus cavernosus fistula. This is an abnormal connection that occurs between the cavernous sinus as well as a carotid artery. The internal and external carotid arteries provide blood to the brain. However, in some people, a tear sometimes forms on the arteries. If this process takes place near the cavernous sinus, there is a risk of a canal forming. Such an unnatural channel is called a fistula by physicians. Through this fistula, blood that normally flows through the artery is diverted into the vein. It is not uncommon for the fistula to provide increased pressure within the cavernous sinus. As a result, the affected nerves become compressed and suffer loss of function. The veins leading away from the eye may also be affected by the increase in pressure. This becomes noticeable through visual disturbances and swollen eyes. Doctors distinguish between a direct and an indirect carotid sinus-cavernous fistula. In a direct carotid sinus-cavernosal fistula, there is a connection between parts of the internal carotid artery and the veins within the cavernous sinus.This form occurs most frequently and is characterized by increased blood flow velocity. Indirect carotid sinus-cavernosus fistula is when the unnatural connection between the sinus-cavernosus veins as well as the branches within the carotid artery forms in the membranes surrounding the brain. This is noticeable by a low blood flow velocity in the fistula. Responsible for the development of a direct carotid sinus-cavernosus fistula are injuries caused by accidents or brawls as well as surgery. In contrast, the cause of an indirect fistula is unknown to date. Another disease of the venous plexus is the sinus cavernosus syndrome. In this case, the eyes of the affected persons suffer from multiple signs of paralysis. In addition, there is loss of sensitivity of the upper facial segments and the cornea, as well as significant headaches. Responsible for the sinus cavernosus syndrome is a pressure damage in the sinus cavernosus, which results in a partial or complete loss of various cranial nerves. Causes include thrombosis, tumors, hemorrhage, trauma, or aneurysms on the nerves. Sinus cavernosus thrombosis is one of the most serious diseases of the sinus cavernosus. It can have life-threatening consequences. The thrombosis is caused by the spread of a bacterial inflammation, which in turn arises from a sinusitis. There is also a risk of soft tissue inflammation spreading from the upper facial region. Sinus cavernosus thrombosis is noticeable by headache, seizures, facial numbness, chills, fever, vomiting, eye muscle paralysis, and double vision.
