Anatomy of the cavernous sinus.

                  Cavernous Sinus 

                Cavernous sinus is a dural venous sinus situated in the middle cranial fossa between the two layers of Dura mater. There are two sinuses on either side of the body of the sphenoid bone. They are connected to each other via anterior and posterior inter cavernous sinuses running on either side of the pituitary stalk on the diaphragma sellae. The inside of the sinus is divided into spaces by trabaculae. Each sinus extends from the superior orbital fissure to the apex of the petrous part of temporal bone. Internal carotid artery surrounded by sympathetic nervous plexus and the abducent nerve runs through the middle of the sinus. Abducent nerve is inferolateral to the artery. They are separated from the blood by the endothelial lining of the sinus.

                            Optic nerve, Trochlear nerve, Ophthalmic nerve and Mandibular nerve run in the lateral wall of the sinus from top to bottom in order. They lie between the endothelial ling and the Dura mater.

                             Superior and inferior ophthalmic veins, inferior cerebral veins, the sphenoparietal sinus and the central vein of the retina drain into it. The cavernous sinus posterior drains into superior and inferior petrosal sinuses and inferiorly in to pterygoid venous plexus through emissary veins.

                               Cavernous sinus is superiorly related to optic tract, optic chiasma, internal carotid artery and olfactory tract. It is medially related to pituitary gland and sphenoidal air sinus. It is inferiorly related to foramen lacerum and laterally related to temporal lobe.

Cavernous sinus

Clinicals

👀 Thrombosis of cavernous sinus

               - Caused by sepsis in dangerous area of face, nasal cavities, paranasal air sinuses                 - Nervous symptoms – Severe pain in eye and forehead (ophthalmic nerve)                              Paralysis of ocular muscles (3rd, 4th and 6th cranial nerves)

               - Venous symptoms – Oedema of eyelids, cornea, root of nose Exophthalmos

👀 Pulsating exophthalmos

               - In head injury, a communication between cavernous sinus and internal carotid                   artery may occur.

              - Eyeball protrudes and pulsates with each heartbeat.

Venous sinuses

*  Lie between the inner meningeal and outer endosteal layers of dura mater – except inferior sagittal & straight sinuses (between inner layers)

*  Receives all the blood from the Brain, Meninges, Bones of skull

 *  Communicates with diploe veins of the skull and veins of scalp via emissary veins

 *  Lined interiorly by endothelium 

*  Do not contain valves 

*  No muscle tissue in walls

1.Superior sagittal sinus

  Inferior sagittal sinus

2. Straight sinus

3. Transverse sinus

4. Sigmoid Sinus

5. Occipital sinus

6. Basilar plexus

7. Cavernous sinus