The meninges are composed of three layers - the dura mater, arachnoid, and pia mater. The dura mater has two layers and is composed of dense connective tissue. It lines the inner skull and provides protection to the brain and spinal cord. Between the arachnoid and pia mater is the subarachnoid space, filled with cerebrospinal fluid. The pia mater is the innermost layer and closely adheres to the brain and spinal cord. The ventricles are fluid-filled cavities within the brain that include the two lateral ventricles, third ventricle, and fourth ventricle.

1. NEURO HISTO
GROUP 4

2. MENINGES
• Are composed of connective tissues
• Has three layers: Dura mater(or Pachymeninx), Arachnoid and
Pia mater
• Neurons and Macroglia – are of ectodermal origin
• Blood vessels of the CNS – are of mesenchymal origin
• Arachnoid + Pia Mater = Leptomeninges

5. DURA MATER
• Inner surface is lined by SQUAMOUS CELLS
• Connected to the spinal cord on each side by Denticulate
Ligaments

6. DURA MATER OF THE BRAIN
• has two layers
• closely joined in adults
• both consist of collagenous fibers and elongated fibroblasts
• NO distinct border between the two layers
• small blood vessels are present in both layers
• only some differences in organization

7. DURA MATER OF THE BRAIN
PERIOSTEAL DURA
• outer layer
• adheres loosely to the inner aspect
of the skull except at Cranial
Sutures where it
is more firmly adherent
• functions as a periosteum
• richer in cells
• contain many blood vessels
• collagen fibers organized in distinct
bundles
MENINGEAL DURA
• inner layer
• almost continuous sheet of fine fibers
• fibers coursing upward and backward
from the frontal region
• fibers oriented at an angle to the
outer layer
• fibroblasts have darker cytoplasm,
elongated processes, ovoid nuclei,
more condensed chromatin

8. BORDER CELL LAYER
• internal to the inner dura
• modified, flattened fibroblasts w/ long sinous processes that intermingle with
neighboring cells
• have usual organelles
• processes are attached at occasional desmosomes and gap junctions (are lacking on the
cells of the meningeal dura)
• distinctive features: dark highly branched fibroblasts, amorphous intercellular material,
absence of connective tissue fibers
• transitional zone between the border cell layer and the meningeal dura, flocculent
intercellular material is found, together with small collagen fibers

9. INTERCELLULAR SPACES
• are occupied by flocculent
material (polysaccharide in
nature)

10. SPINAL DURA
• collagenous fibers are oriented
longitudinally
• The inner surface of the dura is
lined by squamous cells is firmly
connected to the spinal cord
along each side by a series of
denticulate ligaments
• fewer elastic fibers than cerebral
dura

12. INNER SURFACE OF VERTEBRAL CANAL
• lined by its own periosteal layer of connective tissue while the

13. SPINAL CORD
• enclosed by a separate loose cylindrical dural membrane

14. EPIDURAL SPACE
• wide space between the periosteum and the dura
• contains loose connective tissue, adipose cells and the
EPIDURAL VENOUS PLEXUS

15. ARACHNOID
ARACHNOID BARRIER LAYER
• layer of closely apposed cells
• separated by little or no
extracellular space
• attached to one another by many
desmosomes and tight junctions
ARACHNOID TRABECULAR
CELLS
• inner layer of very loosely associated
cells
• perpendicluar to the arachnoid barrier
layer
• traverses the subarachnoid space
• are modified fibroblasts w/ long
processes
• attached to the cells of the barrier layer
by desmosomes and gap junctions

17. PIA MATER
• closely adherent to the brain and spinal cord
• composed of flattened modified fibroblasts that conforms to the
contours of the brain
• may for a single layer or overlap one another
• resembles cells of the arachnoid trabeculae
• numerous blood vessels that are often surrounded by trabecular cells
• fine collagenous and elastic fibers are interposed in between this
layer and the brain

18. • macrophages are also found between the pial cells and the glial
basement membrane around the pial blood vessels
• in humans, often contain yellow pigments that reacts positively
to iron
• mast cells and lymphocytes (may increase in number during a
pathologic condition) may be found along pial vessels
• melanocytes (variable in number) can be found on pia covering
the ventral surface of medulla oblongata

20. MENINGEAL SPACES

21. SUBDURAL SPACE
• normally no such space between dura and arachnoid
• when present, it is an artefact of specimen preparation
• subdural hematoma commonly follows head injuries is not
beneath the dura but blood accumulation within the dural
border cell layer, intradural (the dural border cell layer has
many intercellular spaces, is a weak plane, extravagation of
blood or fluids enlarges the spaces, disrupts cell junctions or
tears off process creating a larger space where none normally
exists)

22. SUBARACHNOID SPACE
• between arachnoid barrier cell layer and pia mater
• truly occurring, traversed by arachnoid trabeculae and normally
filled with large amount of cerebrospinal fluid
• narrow in the convolutions of the brain, wide and deep in sulci
between cerebral hemispheres
• wide throughout the spinal cord
• greatly enlarged is some places in the brain called cisternae

23. • cisternae magna (largest cisternae), lies above the medulla
oblongata and below the posterior border of the cerebellum. 4th
ventricle communicates with it through 3
• openings in tela choroidea (1 medial foramen of Magendie and
2 lateral foramina of Luschka)
• communicates with the ventricles of the brain where CSF is
produced

24. NERVES OF THE MENINGES
• The dura and pia mater are richly supplied with nerves
• All vessels of the pia, and of the choroid plexus, are
surrounded by extensive nerve plexuses in their adventitia
• The axons, belonging to the sympathetic system, originate in
certain cranial nerves and in the carotid and vertebral plexuses.
Non-encapsulated sensory nerve terminations, and even single
nerve cells, are also present in the adventitia of the blood
vessels.

25. • In addition to the nerves to the vessels, the cerebral dura
contains many sensory nerve endings
• The pia also contains extensive nerve plexuses, most abundant
in the tela choroidea of the third ventricle
• The axons end either in large pear-shaped or bulbous
expansions or in spiral convolutions like those of Meissner’s
corpuscles

26. • In the spinal pia, the vessels receive their nerves from the
plexuses following the larger spinal blood vessels. Afferent
nerve endings are also present, but these are unevenly
distributed.
• Both myelinated and unmyelinated nerve fibers accompany the
blood vessels into the substance of the spinal cord and the
brain, ending on the smooth muscle cells of the vessel walls

27. INNERVATION
• The dominant nerve supplying most of the supratenotrial dura
is the tentorial nerve (a branch of the ophthalmic nerve (CN Va)
which supplies the falx, calvarial dura and superior surface of
the tentorium.

28. ANTERIOR CRANIAL FOSSA
• meningeal branches from the anterior and posterior ethmoidal
nerves, off the nasociliary nerve from the ophthalmic division
of the trigeminal nerve
• meningeal branches from the maxillary nerve (CN Vb)

29. MIDDLE CRANIAL FOSSA
• meningeal branches of ophthalmic, maxillary and mandibular
divisions of trigeminal nerve
• middle meningeal nerve (a branch off the maxillary nerve (CN
Vb) supplies the anterior parts of the fossa
• meningeal branch of the mandibular nerve (CN Vc) supplies the
posterior parts of the fossa

30. POSTERIOR CRANIAL FOSSA
• sensory meningeal branches from the vagus nerve (CN
X) and glossopharyngeal nerve (CN IX) supply the inferior
surface of the tentorium and dura of the posterior fossa
• small sensory branches of the C1 to C3 dorsal rami supply
around the foramen magnum

32. VENTRICLES
• CNS develops from the embryonic neural tube
• Remains a hollow organ in the adult
• Form a continuous channel for the flow of CSF
• If part of this channel will be occluded by disease preventing free
circulation of fluid, intracerebral pressure increases, resulting in
hydrocephalus and other serious consequences
• Central canal of the spinal cord is minute in the adult and may be
obliterated.
• The ventricular cavity is divided into four regions:

33. VENTRICLES
2 LATERAL
VENTRICLES
• in the medial wall of the
cerebral hemispheres
THIRD VENTRICLE
• in the roof of the diencephalon
between the two thalami;
caudal to the nondilated
cerebral aqueduct traversing
the midbrain.
FOURTH VENTRICLE
• Roof of the Pons and Rostral
Medulla Oblongata
• Choroid Plexuses develop in all
four regions
• Most of the fluids is from the
blood vessels of these plexuses