1. The Meninges of Brain and Spinal Cord
DR. S. H. KHAN

2. The Meninges of Brain and Spinal Cord
The spinal cord and brain are surrounded by three membranes, the meninges. Named from the outside~ inward they are the dura mater, arachnoid, and pia mater.
DURA MATER
SUB-DURAL SPACE (filled with thin film of fluid)
ARACHNOID MATER
SUB-ARACHNOID SPACE (filled with CSF)
PIA MATER

3. The meninges of spinal cord
Spinal Dura mater
Spinal Arachnoid mater
Spinal Pia mater

4. Spinal dura mater Characters Dense, strong, fibrous membrane
Encloses the sp. Cord & cauda equina
Continuous above foramen magnum with the meningeal layer of Dura mater of brain
Below, becomes thinner & ends at lower border of S2
invests filum terminale to attach at back of coccyx

5. Epidural space Subdural space: potential space
Position: lies between spinal dura mater and periosteum & ligaments of
vertebral canal
Contents: loose connective tissue, semi liquid fat, spinal arteries, vertebral venous plexus, lymphatics and, the spinal nerves on each side pass through the epidural space which is applicable for block anesthesia
Subdural space: potential space

6. Spinal arachnoid mater
Characters
A thin, delicate, tubular membrane loosely investing spinal cord
Above, it is continuous with cerebral arachnoid mater
Inferiorly extends as Dura ( lower border of S2)

7. Subarachnoid space
Position: lies between pia and arachnoid maters containing cerebrospinal fluid. Extends upto low. Border of S2
Terminal cistern : the largest part of subarachnoid space extending from termination of spinal cord (low. Border of L1) to level of S2, where it is occupied by nerves of cauda equina, so it is the best site for a lumbar puncture

8. Lumbar puncture (spinal tap)
Bet. L3 & L4 (adult), L4 & L5 (child)

9. Spinal pia mater
A delicate vascular membrane that closely invests the spinal cord
Denticulate ligament:
consist of 21 pairs triangular ligaments extending from spinal cord on each side between anterior and posterior roots of spinal nerves to spinal dura mater; these ligaments help to fix position of spinal cord.
Filum terminale: an extension of pia beyond conus medullaris

10. The Meninges of Brain Cerebral Dura mater (Pachymeninx)
Cerebral Arachnoid mater
Cerebral Pia mater
Leptomeninges

11. Cerebral Dura mater Characters A thick and dense inelastic membrane
Composed of two layers, an inner - meningeal and outer - endosteal
Cranial venous sinuses lie between 2 layers

12. Endosteal layer of Cerebral Dura mater
Lies just below the skull bone -Epidural Hge
Continuous outside at sutures & foramina with the periosteum of skull bones
Most strongly adherent to the bones over base of skull
Meningeal layer of Cerebral Dura mater
(Dura mater proper)
Dense, strong fibrous membrane
Continuous through the foramina magnum as Dura mater of Spinal cord
Forms 4 septa which divide the cranial cavity

13. Falx cerebri Tentorium cerebri Falx cerebelli Diaphragma sellae
Four septa of Dura mater Proper
Falx cerebri
－ Lies in between the cerebral hemispheres.
Tentorium cerebri
－ Roof over the posterior cranial fossa.
－ covers the upper surface of cerebellum .
Falx cerebelli
－ Lies between the cerebellar hemispheres.
Diaphragma sellae
－ Forms roof of the sellar/ hypophyseal fossa

14. Dural Artery Supply ICA Vertebral A. ECA Maxillary a.
Middle meningeal artery (clinically important -Epidural hge)
Ascending pharyngeal a.
Occipital a.

15. Venous Sinuses of duramater Function: To receive blood from brain through cerebral veins To receive CSF from SA space through Arachnoid villi
Superior sagittal sinus
Inferior sagittal sinus
Straight sinus
Confluence of sinus

16. Transverse sinus
Sigmoid sinus
Superior petrosal sinuses
inferior petrosal sinuses

17. Position: lies on each side of sella turcica (hypophyseal fossa)
Cavernous sinus
Position: lies on each side of sella turcica (hypophyseal fossa)
Relations of cavernous sinus:
Internal carotid artery and abducent nerve run through the sinus
Oculomotor and trochlear nerves and ophthalmic & maxillary divisions of trigeminal nerve lie in the lateral wall of the sinus
MCA
Occul n.
Pituitary gland
Troch n.
ICA
Abducent n.
Optha n.
Maxil n.
Sphenoid air sinus

18. The flowing of the blood in dural sinus
Sup. sagittal sinus
Inf. sagittal sinus
Straight sinus
Confluence of sinus
Transverse sinus
Sup. petrosal sinus
Sigmoid sinus
Cavernous sinus
Inf. petrosal sinus
Internal jugular vein

19. Cerebral Arachnoid mater
Characters:
A delicate membrane covering brain loosely,
Passing over sulci and entering only cerebral longitudinal and transverse fissures.
Separated from Dura by potential Subdural space
Separated from Pia by the Subarachnoid space

20. Arachnoid villi :
In certain areas arachnoid projects into venous sinuses to form arachnoid villi
Most numerous along the sup. Sagital sinus
serve as sites where CSF diffuses into bloodstream
Aggregations of arachnoid villi called archnoid granulations,
May give rise to Brain tumour (Meningioma)

21. Cerebral pia mater Thin vascular membrane
Closely invests brain surface,
Covers the gyri and descends into the sulci
Folds of Pia mater enclosing tufts of capillaries form the Telachoroidea. Such pia mater lined by secretory ependyma form the Choroid plexuses

22. Tela choroidea and choroid plexus
Capillaries
Pia
Ependyma

23. Sub Arachnoid Space (SAS)
Interval between Arachnoid & Pia mater
Contains :
－ CSF, large blood vessels of brain & cranial nerves
Extension:
－ Along the olfactory n. to the mucoperiosteum of nose
－ Along the cerebral bl. Vessels, till they become an arteriole or venule
－ Beyond the lower end of spinal cord, ends between S2 & S3
Around the base of the brain the SAS expands to form SA cisterns

24. Subarachnoid cisterns
In certain situations the Arachnoid & Pia are widely separated to form the SA cisterns
Has free comunication with one another and with remainder SA Space
Cerebellomedullary cistern /
Cisterna magna
(Bet. Inf. Surface of cerebellum and the medulla)
Interpeduncular cistern
(contain circle of Willi’s)
Pre Pontine cistern
(contain vert. & basillar a.)
Quadrigaminal cistern / Cisterna ambiens
(contain the great cerebral vein of Galen)

25. Cerebellomedullary cistern
CISTERNAL PUNCTURE

26. Cerebrospinal fluid (CSF)
Clear colorless fluid,
Contained in the ventricular system & SA space
Replaces lymph in the CNS
Function:
－ Cushions & protects the CNS.
－ Nourishment of CNS.
－ Removes metabolites from CNS
Production:
－ By the choroids plexuses within the lateral ventricle mainly and, third and fourth ventricles also
Absorption: By arachnoid villi
Amount: 150ml
Rate of production: 0.5ml/min
Density of brain is slightly greater than that of CSF.

27. Circulation of cerebrospinal fluid
interventricular foramina
CSF drains from lateral ventricle
third ventricle
mesencephalic aqueduct
median and two lateral apertures
fourth ventricle
arachnoid granulations
subarachnoid space
superior sagittal sinus
vein

28. Ventricular System
Lateral (L&R)
Cerebral Aqueduct
3rd
4th

29. The Blood vessels of Brain and Spinal Cord

30. Arteries of brain Two sources
Internal carotid artery: supplies anterior 2/3 of cerebral hemisphere and parts of diencephalon.
Divides into ant. & mid. Cerebral arteries.
Vertebral artery: supplies posterior 1/3 of cerebral hemisphere and parts of diencephalon, brain stem and cerebellum
At lower border of pons two VA join to form the basilar artery

31. Internal carotid artery
Anterior cerebral artery
Middle cerebral artery
Anterior choroidal artery
Posterior communicating artery
ICA
ACA
MCA
AChA
PComA

32. Anterior cerebral artery
Terminal br. Of ICA
Joins the fellow of the opposite side by the anterior communicating artery
supply all medial surface of the cerebral cortex up to the parietooccipital sulcus
ACA

33. Middle cerebral artery
Largest br. Of ICA
Cortical branches:
supply entire lateral surface of cerebral hemisphere, except occipital pole and inferolateral surface which is supplied by PCA
Central branches: supply lentiform and caudate nuclei, internal capsule

34. Posterior communicating artery
runs backward to join posterior
cerebral artery

35. Vertebral artery Cranial branches Branches of basilar artery
Anterior and posterior spinal arteries
Posterior inferior cerebellar artery
Branches of basilar artery
Anterior inferior cerebral artery
Labyrinthine artery
Pontine arteries
Superior cerebellar artery
Posterior cerebral artery

36. Posterior cerebral artery
Cortical branches: supply medial and inferolateral surfaces of temporal lobe and lat. & medial surfaces of occipital lobe
Central branches: supply dorsal thalamus, midbrain, medial and lateral geniculate bodies,

37. Cerebral arterial circle ( circle of Willis )
Concept:
－ Arterial anastomosis.
－ Distribute blood to any part of the cerebral hemisphere.
－ Equalizes pressure in the arteries of the two sides of brain.
Position:
－ lies in the interpeduncular fossa at the base of the brain.

38. Formation: Anteriorly: － Ant
Formation: Anteriorly: － Ant. communicating artery Posteriorly: － Basilar artery that divides into posterior cerebral arteries On each side: － Anterior cerebral arteries, － Internal carotid arteries, － Posterior communicating arts, － Posterior cerebral arteries

39. VENOUS DRAINAGE － very thin wall － no valves 1.External cerebral veins
－ lie in the subarachnoid space
－ drain into the cranial venous sinuses
－ ultimately drain into internal jugular vein
1.External cerebral veins
2.Internal cerebral veins

40. Veins of brain External cerebral veins
Drain blood from cortex and subcortical medullary substance and empty into adjacent sinuses of dura mater

41. Veins of brain Internal cerebral veins: Two veins
drain deeper parts of hemispheres, basal nuclei, internal capsule, diencephalon and choroid plexus, ultimately two ICV form great cerebral vein of Galen which enter straight sinus

42. Blood vessels of spinal cord
Arteries of spinal cord
Two sources
One Anterior and two posterior spinal arteries
Branches of segmental arteries:
ASA
PSA

43. Blood vessels of spinal cord
Spinal veins: drain into internal vertebral venous plexus
Post. Sp. A.
Segmental sp. A.
Ant. Spinal artery

44. Optic/visual pathway Light falling on the cornea.
Traverse the refractive medias of the eye.
Stimulates the rods and cones of retina.
Optic nerve ( nasal & temporal fibers)
Optic chaisma ( nasal fibers cross)
Optic tract
Lateral geniculate body
Optic radiation
Visual cortex