Meninges

arachnoid mater

#2 -"spider web" -transparent membrane that consists of arachnoid membrane (epithelial membrane that contacts the Dura Mater) and trabeculae (collagen and elastic fibers that span the subarachnoid space and attach to the Pia Mater)

tentorium cerebelli

#4 -extends horizontally into the transverse fissure between the cerebellum and the cerebrum -transverse sinus runs along its posterior border and the straight sinus runs along the midsagittal plane -its anterior surface has the tentorial notch which contains the brainstem

falx cerebelli

#5 -inferior to the tentorium, runs along the vermis of the cerebellum -separates the right and left halves of the cerebellum on the inferior side -the occipital sinus funs in its posterior vertical border

pia mater

#7 -"tender" -thin delicate areolar connective tissue anchored to the brain by processes of astrocytes -adheres to brain surfaces and extends into every fold and fissure, and accompanies the branches of the cerebral blood vessels as they penetrate the surface of the brain -usually only visible with a microscope

dura mater

-2 layers: periosteal layer and meningeal layer -the tough outermost membrane enveloping the brain and spinal cord

Cerebrospinal Fluid (CSF)

-clear, colorless liquid that fills the ventricles and canals of the CNS and bathes its external surface. -CSF has more sodium and chloride than blood plasma, but less potassium, calcium, and glucose and very little protein.

meningeal layer

-dura mater -inner layer -continues into the vertebral canal where it forms the dural sac around the spinal cord -extends to the cranial cavity and forms cranial dural folds that support and stabilize the brain -there are 4 cranial folds: falx cerebri, tentorium cerebelli, falx cerebelli and diaphram sellae

periosteal layer

-dura mater -outer most layer -forms the periosteum of the internal surface of the bone -NO epidural space, potential space -contains blood vessels

arachnoid villi

-fingerlike projections extend through the Dura Mater into the superior sagittal sinus -a collection of them forms an arachnoid granulation

straight sinus

-it forms from the confluence of the inferior sagittal sinus and great cerebral vein

Meninges

-pia mater, arachnoid, and dura mater -cerebrospinal fluid (CSF) -protect the central nervous system

subdural space

-potential space between the arachnoid and the Dura Mater -become an actual space if fluid accumulates there

transverse sinus

-runs horizontally from the rear of the head toward each ear -ultimately empty into the inter- nal jugular veins of the neck

falx cerebri in longitudinal fissure

-sickle shaped fold -dips into the longitudinal fissure between the cranial hemispheres to attach to the crista galli of the ethmoid bone of the skull -contains the superior and inferior sagittal sinuses -intersects the tentorium cerebelli posteriorly -there is no fusion of the dura mater here

choroid plexus

-small capillary nots hanging from the roof of the ventricles of the brain. -produce about 30% CSF

interventricular foramina

-the CSF secreted in the lateral ventricles flows through this foramina into the third ventricle.

hydrocephalus

-the abnormal accumulation of CSF in the brain, usually resulting from a blockage in its route of flow and reabsorption. Such obstructions occur most commonly in the interventricular fora- men, cerebral aqueduct, and apertures of the fourth ventricle.

superior sagittal sinus

-the cavity created at the point of the falx cerebri dipping into the longitudinal fissure -collects blood draining from the brain tissue

subarachnoid space

-the space between the arachnoid and pia maters filed with CSF -the arachnoid trabeculae and the CSF support the cerebral arteries and veins within the subarachnoid space