Paired Dural Venous Sinuses - Transverse | Sigmoid | Superior Petrosal | Inferior Petrosal | Others скачать в хорошем качестве

Paired Dural Venous Sinuses - Transverse | Sigmoid | Superior Petrosal | Inferior Petrosal | Others

Transverse Sinus The transverse sinuses are large sinuses. The right sinus usually larger than the left, is situated in the posterior part of the attached margin of the tentorium cerebelli. The right transverse sinus is usually a continuation of the superior sagittal sinus, and the left sinus a continuation of the straight sinus. Each sinus extends from the internal occipital protuberance to the posteroinferior angle of the parietal bone at the base of mastoid process where it bends downwards and becomes the sigmoid sinus. Its tributaries are: 1. Superior petrosal sinus 2. Inferior cerebral veins 3. Inferior cerebellar veins 4. Diploic (posterior temporal) vein 5. Inferior anastomotic vein. Sigmoid Sinus Each sinus right or left is the direct continuation of the transverse sinus. It is S-shaped: hence the name. It extends from the posteroinferior angle of the parietal bone to the posterior part of the jugular foramen where it becomes the superior bulb of the internal jugular vein. It grooves the mastoid part of the temporal bone, where it is separated anteriorly from the mastoid antrum and mastoid air cells by only a thin plate of bone. Its tributaries are: 1. The mastoid and condylar emissary veins. 2. Cerebellar veins. 3. The internal auditory vein. Clinical Anatomy 1. Thrombosis of the sigmoid sinus is always secondary to infection in the middle ear or otitis media, or in the mastoid process called mastoiditis. 2. During operations on the mastoid process, one should be careful about the sigmoid sinus, so that it is not exposed. 3. Spread of infection or thrombosis from the sigmoid and transverse sinuses to the superior sagittal sinus may cause impaired CSF drainage into the latter and may, therefore, lead to the development of hydrocephalus. Such a hydrocephalus associated with sinus thrombosis following ear infection is known as otitic hydrocephalus. Other Sinuses 1. The occipital sinus is small, and lies in the attached margin of the falx cerebelli. • It begins near the foramen magnum and ends in the confluence of sinuses 2. The sphenoparietal sinuses, right and left lie along the posterior free margin of the lesser wing of the sphenoid bone, and drain into the anterior part of the cavernous sinus. • Each sinus may receive the frontal trunk of the middle meningeal vein 3. The superior petrosal sinuses lie in the anterior part of the attached margin of the tentorium cerebelli along the upper border of the petrous temporal bone. • It drains the cavernous sinus into the transverse sinus. 4. The inferior petrosal sinuses right and left lie in the corresponding petro-occipital fissure, and drain the cavernous sinus into the superior bulb of the internal jugular vein. 5. The basilar plexus of veins lies over the clivus of the skull. • It connects the two inferior petrosal sinuses and communicates with the internal vertebral venous plexus. 6. The middle meningeal veins form two main trurks, one frontal or anterior and one parietal or posterior, which accompany the two branches of the middle meningeal artery. • The frontal trunk may end either in the pterygoid plexus through the foramen ovale, or in the sphenoparietal or cavernous sinus. • The parietal trunk usually ends in the pterygoid plexus through the foramen spinosum. • The meningeal veins are nearer to the bone than the arteries, and are, therefore, more liable to injury in fractures of the skull. 7.The anterior and posterior intercavernous sinuses connect the cavernous sinuses. • They pass through the diaphragma sellae, one in front and the other behind the infundibulum Follow me in blogspot - https://human-anatomylessons.blogspot... _________________________________________________________________________________________________________________ Visit my blogs - https://humananatomyonline.in/ Contact me @ https://t.me/humananatomylessons