The Brain

Question 0

What are the primary brain vesicles?

Answer 0

Prosencephalon (forebrain)
Mesencephalon
Rhombencephalon (hindbrain)

Question 1

What germinal later does the CNS derive from?

Answer 1

Ectoderm

Question 2

What does the prosencephalon develop into?

Answer 2

Telencephalon

Diencephalon

Question 3

What does the mesencephalon (1°) develop into?

Answer 3

Mesencephalon (psych!)

Question 4

What does the rhombencephalon develop into?

Answer 4

Metencephalon

Myelencephalon

Question 5

What does the telecephalon develop into?

Answer 5

Cerebrum and lateral vesicles

Question 6

What does the diencephalon develop into?

Answer 6

Thalamus, hypothalamus, Epithalamus and third ventricle

Question 7

What does the mesencephalon (2°) develop into?

Answer 7

Midbrain

Aqueduct of midbrain (cerebral aqueduct)

Question 8

What does the metencephalon develop into?

Answer 8

Pons
Cerebellum
Upper 4th ventricle

Question 9

What does the Myelencephalon develop into?

Answer 9

Medulla oblongata

Lower 4th ventricle

Question 10

What does the brain stem contain?

Answer 10

Continuous with spinal cord

Contains medulla oblongata, pins and midbrain

Question 11

Largest part of brain

Answer 11

Cerebrum

Question 12

Three layers of cranial meninges

Answer 12

Dura mater
Arachnoid mater
Pia mater

Question 13

Two layers of dura mater

Answer 13

Periosteal (external)

Meningeal (internal)

Question 14

The two layers of dura mater are fused except for where

Answer 14

Dural venous sinus

Question 15

Dural venous sinus

Answer 15

Endothelial lined venous channel

Drain blood from brain and deliver to internal jugular veins

Question 16

What are the three extensions of dura mater?

Answer 16

Falx cerebri
Falx cerebelli
Tentorium cerebelli

Question 17

Falx cerebri

Answer 17

Extension of dura mater

Separates two hemispheres of the cerebrum

Question 18

Falx cerebelli

Answer 18

Extension of dura mater

Separates two hemisphere if cerebellum

Question 19

Tentorium cerebelli

Answer 19

Extension of dura mater

Separates cerebrum from cerebellum

Question 20

Blood enters the brain via

Answer 20

Internal carotid and vertebral arteries

Question 21

Blood exits brain via:

Answer 21

Dural venous sinuses which drain into internal jugular veins.

Question 22

Brain makes up what percent of total body weight but uses what percent of O2 and glucose?

Answer 22

2 and 20

Question 23

What cells make up the blood brain barrier?

Answer 23

Astrocytes + endothelial cells connected by tight junctions.

Question 24

What is the blood brain barrier

Answer 24

Semi-permeable covering encasing capillaries of the brain. Doesn't cover the roof of third and fourth ventricle, posterior pituitary gland, pineal gland, the median eminence of the hypothalamus and the area postrema.

Question 25

What is the blood brain barrier permeable to?

Answer 25

H2O-soluble substances (ie glucose) by active transport Creatine, urea, ions cross slowly. Fat soluble substances : O2, CO2, alcohol, anesthetic agents cross passively Not proteins, bacteria

Question 26

Cerebral spinal fluid

Answer 26

Protect CNS from chemical and physical injury Mainly water, plus O2, glucose and other stuff (glucose, proteins, lactic acid, cations, anions, WBC)

Question 27

Where does CSF circulate?

Answer 27

Subarachnoid space

Question 28

Average total volume of CSF?

Answer 28

80-150 ml

Question 29

What cavities are filled with CSF?

Answer 29

``` 2 lateral ventricles (on each side of cerebrum) Third ventricles (midline) Fourth ventricles (between brain stem and cerebellum) ```

Question 30

Septum pellucidum

Answer 30

Thin triangular membrane separating anterior horns of left and right ventricles.

Question 31

The CSF from 4th ventricle flows into

Answer 31

Subarachnoid space and central canal

Question 32

Functions of CSF

Answer 32

1. Mechanical protection 2. Homeostatic function (pH affects pulmonary ventilation and cerebral blood flow) 3. Circulation

Question 33

Where is most of the CSF made?

Answer 33

Chroroid plexuses

Question 34

Ependymal cells

Answer 34

Special glial cells in choroid plexuses that filter substances from blood and secrete them into CSF

Question 35

Choroid plexuses

Answer 35

Networks of blood capillaries in walls of ventricles. Location of CSF production.

Question 36

Blood-CSF barrier

Answer 36

More tight junctions between ependymal cells. Protect CNS from harmful blood borne substances.

Question 37

Interventricular foramina

Answer 37

Opening between lateral and 3rd ventricles

Question 39

Cerebral aqueduct

Answer 39

Connect 3rd and 4th ventricle

Question 40

CSF Circulation

Answer 40

Lateral ventricle --[interventricular foramina]--> Third ventricle --[cerebral aquaduct]--> Fourth ventricle --[lateral and median apertures] --> subarachnoid space & central canal --> (absorbed into) Arachnoid Villi of dural venous sinuses --> venous blood --> heart and lungs --> arterial blood --> Choroid plexuses of the lateral, third and fourth ventricles

Question 41

Arachnoid granulation

Answer 41

Cluster of arachnoid villi

Question 42

Arachnoid villi

Answer 42

Fingerlike extensions of the arachnoid mater that projects into the dural venous sinuses (esp. the superiors sagittal sinus) Where reabsorption of CSF into blood stream occurs.