This document summarizes the dural sinuses, ventricles, and cerebrospinal fluid (CSF) systems. It describes the anatomy and flow of blood within the dural sinuses, located between the layers of the dura mater, and lists the various sinuses. It also outlines the anatomy and structures of the four ventricles - lateral, third, fourth, and their interconnections via the cerebral aqueduct. Finally, it discusses CSF production, circulation from the ventricles to subarachnoid space, reabsorption into dural sinuses, and conditions like hydrocephalus.

1. Dural Sinuses and Ventricles
Dr. Anudeep Singh
MBBS MD

2. Dural VenousSinuses
They are blood-filled spaces situated between the layers of the dura
mater.
• Has bidirectional flow.
• They are lined by endothelium.
• They have no valves.
They receive tributaries from:
• The brain
• The diploic veins of the skull;
• The orbit and
• The internal ear.
• Also from CSF.
Finally drain into the internal jugular vein.

6. DURAMATER
2 parts:
1. Outer endosteal layer and
2. Inner meningeal layer
Four Processes:
1. Falx cerebri
2. Falx cerebelli
3. Tentorium cerebelli
4. Diaphragma sellae

7. Group of sinuses
Upper group:
1. Superior sagittal sinus
2. Inferior sagittal sinus
3. Straight sinus
4. Confluence of sinuses
5. Transverse sinus
Lower group:
1. Cavernous sinus
2. Anterior intercavernous sinus
3. Posterior intercavernous sinus
4. Superior petrosal sinus
5. Inferior petrosal sinus

10. • Inferior sagittal sinus: Occupies the free lower margin of the falx cerebri. It runs
backward and joins the great cerebral vein to form the straight sinus.
• Superior sagittal sinus: Occupies the upper fixed border of the falx cerebri. It runs
backward, at the internal occipital protuberance it deviates to one side (usually the
right ) and becomes continuous with the transverse sinus.
• Straight sinus: Present at the line of junction of the falx cerebri with the tentorium
cerebelli. It ends by turning to the left (sometimes to the right) to form the
transverse sinus.
• Occipital Sinus: Occupies attached margin of the falx cerebelli. Superiorly it drains
into the confluence of sinuses.
• Transverse Sinus: They are paired and begin at the internal occipital protuberance.
Each sinus occupies the attached margin of the tentorium cerebelli , grooving the
occipital bone and posteroinferior angle of the parietal bone. They end by turning
downward as the sigmoid sinuses.

11. • Superior and inferior petrosal sinuses: Are small and situated on the superior
and inferior borders of the petrous part of the temporal bone on each side.
Each superior sinus drains the cavernous sinus into the transverse sinus. Each
inferior sinus drains the cavernous sinus into the internal jugular vein.
• Confluence of sinuses: Present at internal occipital protuberance, is a junction
of occipital sinus, superior sagittal sinus and straight sinus.
• Sigmoid sinus: bilateral continuation of transverse sinus and drains into
internal jugular vein.

12. Cavernoussinus
Situation: in the middle cranial fossa on
each side of the body of the sphenoid
bone.
Extent:
In front: from the superior orbital fissure
Behind: to the apex of the petrous part of
the temporal bone.
It receives:
• Superior and inferior Ophthalmic
veins,
• Cerebral veins
• Sphenoparietal sinus.
Communicate with each other with
anterior and posterior inercavernous
sinuses.

13. 1. 3rd and 4th cranial nerves and
2. Abducent nerve.
3. The ophthalmic & maxillary
divisions of the trigeminal
nerve.
4. The internal carotid artery with
sympathetic plexus.
Drains into:
Superior and inferior petrosal sinuses

14. Ventricular System

15. Consists Of:
1. Lateral ventricles (pair)
2. Third ventricle
3. Fourth ventricle
4. Cerebral aqueduct.

17. Fourth ventricle
Location:
Present between the brain stem (pons and medulla) anteriorly and cerebellum
posteriorly.
Roof:
Rostral part: Formed by the superior cerebellar peduncle and superior
medullary velum.
Caudal part: formed by piamater and ependyma.
Communicates with subarachnoid space through a
Median aperture ( foramen of magendie) and
Two lateral apertures (foramen of luschka).

19. FLOOR OF THE
FOURTH VENTRICLE

20. Boundaries:
Anterior wall: Lamina terminalis.
Posterior wall: Opening of cerebral aqueduct, posterior comissure,
pineal recess, habenular comissure.
Floor: optic chaisma, tuber cinerium, infundibulum of the pituitary and
mamillary bodies.

21. Third Ventricle
• It is interthalamic space lined by ependyma.
– Bounded laterally on both sides by the thalamus and hypothalamus.
– Communicates with lateral ventricle through interventricular foramen
(foramen of monro)

22. Lateral ventricle
• C- shaped cavity.
• Lined by ependymal cells.
Parts:
Body
3 horns:
Anterior
Posterior
Inferior

23. • Boundaries:
Anterior horn: Lies in frontal lobe
Floor: Head of caudate nucleus,
Roof: Under surface of Corpus
callosum.
Medially: Septum pellucidum.
Body: Lies in parietal lobe
Floor: Thalamus and body of caudate
nucleus.
Roof: Corpus callosum
medially: Septum pellucidum
Inferior horn: Lies in the temporal lobe
Floor: Hippocampus
Roof: Tail of caudate nucleus.
Posterior horn: Lies in occipital lobe.
Roof and lateral wall: Corpus callosum.
Medial wall: bulb of posterior horn
and swelling of calcar avis.

24. CC
CN
Hippocampus
Anterior horn Body
Inferior horn

25. CSF
• Produced by choroid plexus.
• Choroid plexus is formed by the invagination of vascular piamater into
ventricular lumen.
• Formation: Both by active secretion and passive diffusion.
• Volume: 150 mL.
• Circulation:
Lateral ventricle ------- through interventricular foramen ---------to 3rd ventricle -
------- through aqueduct ------ to 4th ventricle -------- leaves through the
apertures of the fourth ventricle and enters the subarachnoid space.
• Reabsorption: Into the dural venous sinuses.
The absorption occurs in the arachnoid villi.

28. Hydrocephalus
• Excessive accumulation of CSF.
1. External: Excess fluid in
subarachnoid space.
2. Internal: Due to blockage in
normal passage leading to
enlargement of ventricles.

29. References
• Grays anatomy for students 2nd edition