Dural Venous Sinuses

DURAL VENOUS SINUSES

definition 1.Venous spaces present between the two layers of dura 2.Lined by endothelium 3.Devoid of valves

definition 4.Do not have muscle coat in their tunica adventitia. 5.Contain CSF

Classification Paired and unpaired

Paired are: Cavernous sinuses J Petrosal sinuses H,I Transverse sinuses G Sigmoid sinuses C Sphenoparietal sinuses A

unpaired are: Superior sagittal sinus Inferior sagittal sinus Straight sinus Occipital sinus Basilar plexus of sinuses

Dural Venous Sinuses: Lateral View A. Superior Sagittal Sinus B. Great Cerebral Vein C. Ophthalmic Veins D. Facial Vein E. Cavernous Sinus F. Inferior Petrosal Sinus G. Jugular Vein H. Sigmoid Sinus I. Superior Petrosal Sinus J. Transverse Sinus K. Straight Sinus

Cavernous sinus Situated on either side of the body of sphenoid Extends from superior orbital fissure To the apex of petrous temporal

Relations Medially related to pituitary gland and sphenoidal air sinus Lateral wall contains III,IV,V1,V2 nerves

Passing through the sinus are ICA and Abducent nerve

Connections It receives tributaries from brain bones(skull),pterygoid plexus, orbit and the eye(central vein of retina)

Superior and inferior ophthalmic veins (from the orbit) are regarded as emissary veins as they do not have valves.

Ophthalmic veins also have communication with the facial vein(c&d) so the infections from the ‘dangerous area’ of face can spread to Cavernous sinus causing thrombosis.

drainage

Applied anatomy 1.infections from face, orbit,shenoid sinus can cause thrombosis. 2.III,IV,V1,V2,VI can be involved resulting in various diplopias 3.rupture of ICA can cause pulsatile exophthalmos

Caput medusae in cavernous sinus thrombosis

MR image at the level of the pituitary stalk shows bilateral involvement of the cavernous sinuses with narrowing of the right internal carotid artery due to infiltration of the lesion (arrows).

Superior sagittal sinus Situated along the upper margin of the falx cerebri Begins at the foramen caecum near crista galli (by the union of small veins from the nasal cavity) enlarges as it passes posterior

Usually turns to the right side and forms the right transverse sinus

Superior sagittal sinus Presents gaps called “lacunae laterales” which are Three on each side usually. Arachnoid villi project into these playing important role in CSF circulation

Arachnoid villi projecting into the sinus

Arachnoid foveae

Tributaries of sup.sagittal sinus 1.superior cerebral veins from brain 2.emissary veins from the scalp 3.diploic veins and nose

1.infections can spread from scalp,nasal cavity causing thrombosis. 2. It can be used to draw venous blood/ fluid administration through the anterior fontanelle

Transverse sinuses

Grooving the inner aspect of occipital bone

Transverse sinuses receive the cavernous sinuses through superior petrosal sinuses.

Right transverse sinus is usually larger than the left because it is the continuation of superior sagittal sinus(!)

Left transverse sinus is formed by the continuation of straight sinus. Straight sinus is formed by union of inferior sagittal sinus and great cerebral vein ( of Galen)

Straight sinus

Sigmoid sinuses

Continuations of transverse sinuses Groove the inner aspect of posteroinferior angle of parietal bone(mastoid angle) Pass into jugular foramina and continue as Internal jugular veins(IJV)

Groove for sigmoid sinus

P

T

asterion O

Close relation of sigmoid sinus with the mastoid process

Sigmoid sinus

Mastoid process

Sigmoid sinus thrombosis can occur as a complication of otitis media (middle ear infection)

Identify

A

B