13.2 Protection and support of the brain

Question 1

What is the pia mater made of?

Answer 1

Areolar Connective tissue- this follows every contour of the brains surface.

Question 2

What is the arachnoid mater made of?

Answer 2

Collagen and elastin fibers

Question 3

What is immediately deep to the arachnoid mater?

What does it contain?

Answer 3

Subdurachnoid

CSF

Question 4

What are the two layers of the dura mater?

Answer 4

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.

Question 5

Dural venous sinuses

Answer 5

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.

Question 6

Epidural space

Answer 6

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.

Question 7

Subdural space

Answer 7

Positioned between the arachnoid mater and the overlying dura mater.

Question 8

Are the epidural and subdural spaces real?

Answer 8

Only if blood leaks into them. Otherwise this is just potential space.

Question 9

Cranial dura septa

Answer 9

Layers of the meningeal layer of the dura mater that extend into the cranial cavity.

Question 10

What are the four cranial dura septa?

Answer 10

falx cerebri, tentorium cerebelli, falx cerebelli, and diaphragm sellae.

Question 11

Falx cerebri

Answer 11

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.

Question 12

What are the two venous sinuses in the falx cerebri?

Answer 12

Superior sagittal sinus

Inferior sagital sinus

Question 13

Tentorium Cerebelli

What sinuses are in it?

Answer 13

Horizontally oriented dura mater
Separates the occipital and temporal lobes from the cerebellum.
Forms a dural tent over the cerebellum.

Question 14

Tentorial notch

Answer 14

hole in the anterior surface of the tentorium cerebelli for the entrance of the brain stem.

Question 15

Diaphram sellae

Answer 15

smallest dura septa

forms roof over sella turcica

Question 16

Infundibulum

Answer 16

small stalk that that exits and attaches to the pituitary gland at the base of the hypothalamus

Question 17

Ventricles

Answer 17

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.

Question 18

What separates the two lateral ventricles?

Answer 18

The septum pellucidum

Question 19

Where is the third ventricle located?

Answer 19

In the diencephalon

Question 20

Where is the fourth ventricle located?

Answer 20

Between the ponds, cerebellum, and medulla oblongata.

Question 21

What are the functions of CSF?

Answer 21

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.

Question 22

What brain structure produces CSF and how much does it make?

Answer 22

Choroid plexus

500 mL per day.

Question 23

Where is CSF re-absorbed?

Answer 23

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.

Question 24

Arachnoid granulation

Answer 24

Collection of arachnoid villi

Question 25

Name there significant structural differences in BBB (blood - brain barrier) capillaries.

Answer 25

1) Endothelial cells have tight junctions- preventing the passage of material between cells.
2) Capillary wall has thickened basement membrane that restricts the passage of blood into the brain.
3) Capillaries wrapped in perivascular feet of astrocytes

Question 26

What kind of materials make it past the BBB?

Answer 26

Lipid-soluble molecules like alcohol, nicotine, and some anesthetics.

Question 27

What drugs damage the BBB?

Answer 27

Methamphetamines and cocaine.

Question 28

What are the exceptions to the presence of the BBB? (where is it not present?)

Answer 28

Choroid plexus, hypothalamus, and pineal gland.