13.2 Protection and support of the brain Flashcards
What is the pia mater made of?
Areolar Connective tissue- this follows every contour of the brains surface.
What is the arachnoid mater made of?
Collagen and elastin fibers
What is immediately deep to the arachnoid mater?
What does it contain?
Subdurachnoid
CSF
What are the two layers of the dura mater?
Menigeal layer- immediately superficial to the arachnoid
Periosteal layer- more superficial layer, forms the periosteal layer on the internal surface of the cranial bones.
these two layers are usually fused in most places.
Dural venous sinuses
Areas between the menigeal slyer and the periosteal layer where blood fills large space.
Usually triangular and don’t have valves to regulate blood flow.
Epidural space
A space between the dura mater and the bones of the skull.- This contains the arteries and veins that nourishments the meninges and bones of the cranium.
Subdural space
Positioned between the arachnoid mater and the overlying dura mater.
Are the epidural and subdural spaces real?
Only if blood leaks into them. Otherwise this is just potential space.
Cranial dura septa
Layers of the meningeal layer of the dura mater that extend into the cranial cavity.
What are the four cranial dura septa?
falx cerebri, tentorium cerebelli, falx cerebelli, and diaphragm sellae.
Falx cerebri
Larges of the gory dura septa.
Vertical fold of dura mater that projects though the midsagittal planed into the logitudinal fissures between the left and right cerebral hemispheres.
Anteriorly, its inferior portion attaches to the crista galli of the ethmoid bone.
Inferior portion attaches to the internal occipital crest.
What are the two venous sinuses in the falx cerebri?
Superior sagittal sinus
Inferior sagital sinus
Tentorium Cerebelli
What sinuses are in it?
Horizontally oriented dura mater
Separates the occipital and temporal lobes from the cerebellum.
Forms a dural tent over the cerebellum.
Tentorial notch
hole in the anterior surface of the tentorium cerebelli for the entrance of the brain stem.
Diaphram sellae
smallest dura septa
forms roof over sella turcica
Infundibulum
small stalk that that exits and attaches to the pituitary gland at the base of the hypothalamus
Ventricles
Cavities or expansions within the brain derived from the neural canal (the lumen of the embryonic neural tube)
All ventricles are lined with ependymal cells and contain CSF.
All ventricle are connected with each other and the central canal of the spinal cord.
What separates the two lateral ventricles?
The septum pellucidum
Where is the third ventricle located?
In the diencephalon
Where is the fourth ventricle located?
Between the ponds, cerebellum, and medulla oblongata.
What are the functions of CSF?
Buoyancy- keeps the brain floating and from crushing itself
Protection- liquid cushion.
Environmental stability- transports nutrients and chemical messengers to the brain and removes waste. Also protects nerve tissue from chemical fluctuations.
What brain structure produces CSF and how much does it make?
Choroid plexus
500 mL per day.
Where is CSF re-absorbed?
Arachnoid villi- finger like extension of the arachnoid mater that poke through the meningeal layer of the dura mater into the main flow of the CSF where they can re-absorb it when CSF pressures cause increase in ICP. Note that the arachnoid villi don’t project through the periosteal layer of the arachnoid mater.
form a conduit to return CSF to the dural venous sinuses.
Arachnoid granulation
Collection of arachnoid villi
