The document describes the cerebral venous sinuses, which are venous spaces located within the dura mater of the brain. There are 8 paired and 7 unpaired venous sinuses that receive blood from the brain, meninges, and bones of the skull. The cavernous sinus is a large venous sinus located on either side of the sphenoid bone. It receives tributaries from the orbit, brain, and meninges and drains into the transverse sinus, internal jugular vein, and pterygoid plexus of veins through emissary veins. The superior and inferior sagittal sinuses are located within the falx cerebri and receive tributaries from cerebral veins and venous lacunae before draining into

1. CEREBRAL VENOUS
SINUSES

2. •Venous spaces, walls are formed by duramater.
•Have an inner lining of endothelium, no muscles in
their wall and have no valves
•Receives venous blood from brain, meanings and bones
of skull.
VENOUS SINUSES OF DURAMATER

3. •Cranial venous sinuses communicates with veins
outside the skull by emissary veins – helps to
keep the pressure of blood in the sinuses
constant
•23 venous sinuses
8paired
7unpaired

4. Paired venous sinuses (one
sinus each on right and left side)
Unpaired venous sinuses
(median in position)
1)Cavernous sinus
2)Superior petrosal sinus
3)Inferior petrosal sinus
4)Transverse sinus
5)Sigmoid sinus
6)Sphenoparietal sinus
7)Petrosquamous sinus
8)Middle meningeal sinus/veins
1)Superior sagittal sinus
2)Inferior sagittal sinus
3)Straight sinus
4)Occipital sinus
5)Anterior intercavernous sinus
6)Posterior intercavernous sinus
7)Basilar plexus of veins

5. CAVERNOUS SINUS
•Large venous sinus situated in the middle cranial fossa on
either side of body of sphenoid bone.
•Interior divided into spaces by trabeculae
•Floor is formed by endosteal duramater
•Lateral wall medial wall and roof is formed by the
meningeal duramater
•Anteriorly- extends up to the medial end of superior orbital
fissure
Posteriorly- up to the petrous temporal bone
•2cm long and 1cm wide

6. RELATIONS
Structures outside the sinus
•Superiorly- optic tract, optic chiasma, olfactory tract, internal
carotid artery and anterior perforated substance.
•Inferiorly- foramen lacerum and the junction of the body and
greater wing of the sphenoid bone

7. •Medially- hypophysis cerebri and sphenoidal air sinus
•Laterally- temporal lobe with uncus
•Anteriorly- superior orbital fissure and the apex of the orbit
•Posteriorly- apex of the petrous temporal and the crus
cerebri of the midbrain

8. Structures in the lateral wall of the sinus, from above
downwards
•Occulomotor nerve
•Trochlear nerve
•Ophthalmic nerve
•Maxillary nerve
•Trigeminal ganglion

9. Structures passing through the center of the sinus
•Internal carotid artery with the venous and sympathetic
plexus around it
•Abducent nerve, inferolateral to the internal carotid artery
The structures in the lateral wall and in the center of the
sinus are separated from blood by the endothelial lining

10. TRIBUTARIES OR INCOMING CHANNELS
•From the orbit
1)Superior ophthalmic vein
2)A branch of inferior ophthalmic vein or sometimes the
vein itself
3)the central vein of the retina may drain either into the
superior ophthalmic vein or into the cavernous sinus.
•From the brain
1)superior middle cerebral vein
2)inferior cerebral veins from the temporal vein

12. •From the meninges
1)sphenoparietal sinus
2)the frontal trunk of middle meningeal vein may
drain either into the pterygoid plexus through the
foramen ovale or into the cavernous sinus.

13. Draining channels and communications
The cavernous sinus drains
•Into the transverse sinus through the superior petrosal sinus
•Into the internal jugular vein through the inferior petrosal sinus and
through the plexus around the internal carotid artery
•Into the pterygoid plexus of veins through the emissary veins passing
through the foramen ovale, the foramen lacerum and the emissary
sphenoidal foramen.

16. •Into the facial vein through the superior ophthalmic vein
•The right and left cavernous sinuses communicate with each other
through the anterior and posterior inter cavernous sinuses and
through the basilar plexus of veins.
•All these communications are valve less and blood can flow through
them in either direction

17. Superior sagittal sinus
•Occupies the upper convex attached margin of the falx cerebri
•Begins anteriorly at the crista gali by the union of tiny meningeal
veins
•Here it communicates with veins of frontal sinus and occasionally
with the veins of nose through foramen caecum.
•As it runs upwards and backwards it becomes progressively larger in
size
•It is triangular in cross section.

18. •It ends near the side
usually the right
transverse sinus and
becomes continues
with it.
•The junction of all
these sinuses is
called the confluence
of sinuses.

19. The interior of sinus shows
•Openings of the superior cerebral veins
•Openings of venous lacunae, usually three on each side
•Arachnoid villi and granulations projecting into the lacunae as well
as into the sinus
•Numerous fibrous bands crossing the inferior angle of the sinus

20. Tributaries
•Superior cerebral sinus which never open into the
venous lacunae
•Parietal emissary veins
•Venous lacunae, usually three on each side which first
receive the diploic and meningeal veins and then open
into the sinus
•Occasionally a vein from the nose opens into the sinus
when the foramen caecum is patent.

21. INFERIOR SAGITTAL SINUS
•The inferior saggital sinus a small channel lies
in the posterior two thirds of the lower, concave
free margin of the falx cerebri.
•It ends by joining the great cerebral vein to
form the straight sinus

23. STRAIGHT SINUS
•Lies in the median plane within the junction of falx
cerebri and the tentorium cerebelli
•It is formed anteriorly by the union of the inferior
sagittal sinus with the great cerebral vein and ends at
the internal occipital protuberance by continuing as the
transverse sinus(usually left).
•Receives a few of the superior cerebellar veins

25. TRANSVERSE SINUS
•Large sinuses –right sinus is larger than left
•Right sinus is situated in the posterior part of the
attached margin of the tentoriun cerebelli
•It is usually a continuation of superior saggital sinus
•Left sinus is a continuation of 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

26. Its tributaries are
•Superior petrosal sinus
•Inferior cerebral veins
•Inferior cerebellar veins
•Diploic (posterior temporal) vein
•Inferior anastomotic vein

28. Sigmoid sinus
•Each sinus right and left is the direct continuation of
the transverse sinus
•S-shaped
•Extends from the posterioinferior angle of the parietal
bone to the posterior part of 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

29. Tributaries are
•The mastoid and condylar emissary veins
•Cerebellar veins
•The internal auditory vein

30. Other sinuses
Occipital sinus
is small and lies in attached margin of the falx cerebri
It begins near the foramen magnum and ends in the confluence of
sinuses
Sphenoparietal sinus
Right and left lies along the free margin of the lesser wing of
sphenoid bone and drain into the anterior part of the cavernous sinus
Each sinus may receive the frontal trunk of the middle meningeal vein
Superior petrosal sinus
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

31. Inferior petrosal sinus
Right and left lie in the corresponding petro occipital fissure, and
drain the cavernous sinus into the superior bulb of the internal
jugular vein
Basilar plexus of veins
Lies over the clivus of the skull. It connects two inferior petrosal
sinuses and communicates with the internal vertebral venous plexus
Middle meningeal veins
Form two main trunks one frontal or anterior and one parietal or
posterior which accompany the two branches of the middle meningeal
artery.

32. Frontal trunk end either in the pterygoid plexus through th foramen
ovale or in sphenoparietal or cavernous sinus
Parietal trunk ends in the pterygoid plexus through the foramen
spinosum
The meningeal veins are nearer to the bone than artries and are
therfore more pliable to injury in fractures of skull
anterior and posterior intercavernous sinuses
They connect the cavernous sinuses