6.1 Central Nervous System

Question 1

Describe embryonic developemnt of the brain

Answer 1

starts as neural tube

• then develops pockets that expand, starts to wrap and get lobes
• then get secondary brain vesicles (telencephalon, diencephalon, mesencephalon, metencephalon and Myelencephalon_
• then develop into adult brain structures

Question 2

What happens in brain development at week 5

Answer 2

2 major flexures form, cause telencephalon and diencephalon to angle toward brain stem

Question 3

what happens to brain development at week 13

Answer 3

Cerebral hemispheres develop & grow posterolaterally (black arrows) to enclose diencephalon & rostral brain stem

Question 4

what happens to brain development at birth

Answer 4

shows adult pattern of structures and convulutions

*lots of dumps and grooves to ince SA

Question 5

What are the regions of the adult brain

Answer 5

1. Cerebral hemispheres (has all the bumps and gorrvs)
2. Diencephalon (middle part)
3. Brain stem (midbrain, pons, and medulla) (brain stem)
4. Cerebellum

Question 6

Orientation words for brain

Answer 6

superior = dorsal

inferior = ventral

anterior = rostral

posterior - caudal

Question 7

What are the five paired lobes of the cerebrum?

Answer 7

frontal, parietal, occipital, temporal

• have a bonus cortex deep to temporal lobe called Gyri of insula

*looks like boxing glove, thumb = temporal lobe

Question 8

What are gyri, sulci and fissues

Answer 8

Gyri: Ridges (sticks up)

Sulci: shallow grooves

Fisue: deep groove

Question 10

what separates teh precentral and postcentral gyrus

Answer 10

central sulcus

Question 11

What separates the temporal from frontal and parietal lobes?

Answer 11

• lateral sulcus/sylvian fissue

*can pull this back to see insular

Question 12

what separates the cerebrum from cerebellum

Answer 12

transverse cerebral fissure

Question 13

what separates left and right hemispheres

Answer 13

longituinal fissue

Question 14

what separates parietal and occipital lobes

Answer 14

• parieto-occipital sulcus

Question 15

what separates the primary visual cortex

Answer 15

calcarine sulcus

Question 16

What protects the brain?

Answer 16

1. SCALP
2. bone (skull)
3. Blood brian barrier
4. Membranes (meninges)
5. Watery cushion (cerebrospinal fluid)

Question 17

what are the layers of the scalp?

Answer 17

S: Skin

C: Connective tissue (dense)

A: Aponeurotic layer

L: Loose connective tissue

P: pericranium

Question 18

What is the blood brain barrier?

Answer 18

• helps maintain a stable environment for brain (doesnt like change, needs stable environment (nervous tissue)
• physically separates neurons from certain bloodborne substances
• Acts as a metabolic barrier (Circulating catecholamines are inactivated by MAO in endothelial cells)

• Surrounds majority of brain tissue -> Absent in some areas (e.g. vomiting centre = area postrema & pituitary)

Question 19

How do brain capillaries compare to most other capillaries?

Answer 19

• both have endothelial cells (simple squamous), pericytes (help support), and basement membrane
• brain cap have Astrocyte feet (wrap around capillaries to help insulate and alter permeability)

*form tight junctions

• these tight junctions between endothelial (epithelial) cells are keey in BBB -> excluse molecules except those that are lipid soluble from rbain tissue

Question 20

what are the different transport routes in the blood brian barrier

Answer 20

1. paracellular aqueous pathway
2. transcellular lipophilic pathway
3. transport proteins
4. efflux pumps (extrude drugs)
5. Receptor mediated transcytosis
6. adsorptive transcytosis
7. cell mediated transcytosis

Question 22

What is the role of the meninges

Answer 22

* membranes

Cover & protect CNS

• Form partitions in skull
• Protect blood vessels & enclose dural venous sinuses
• Contain cerebrospinal fluid (CSF)

Question 23

what are the layers of the meninges

Answer 23

Dura mater (hard mother )

– Arachnoid mater (spider mother)

– Pia mater (soft mother -> think pliable)

*dura = most superficial, pia = deep

Question 25

desribe dura metter

Answer 25

\*most durable - two fused layers of fibrous connective tissue (dense regular) - has periosteal and meningeal layers \*meningeal layer projects down into the longitudiional fissue - has epidural space above and subdural space below \*both potential spaces, want it to be fused but could separate and has potential to create space -\> intracranial bleed

Question 26

What is Dura Mater Septa

Answer 26

two fused layers of meningeal dura metter - Dural septa limits excessive movement of brain - has **flax cerebri** (mid sag, occipital and cerebellum), **tentorium cerebelli** (transverse progections) **Falx cerebelli** (sep left and right cerebellum hemispheres)

Question 27

What is arachnoid matter?

Answer 27

- middle later with weblike extensions - separated from dura metter by subdural space (potential space) **subdural arachnoid space = real space w/ CSF and blood vessels** - Arachnoid villi protude into superior sagittal sinus to reabsorb CSF ^allows body to get rid of CSF thats circulating, can calcify as get older

Question 28

What is Pia matter?

Answer 28

- layer of delicate vascularized connective tissue that clings tightly to brain \*follow bumps and groves

Question 29

Answer 29

Question 30

What is CSF

Answer 30

cerebrospinal fluid * Functions * give buoyancy to brain * protects CNS from blows & trauma (think egg in jar of water, only some protection) * nourishes brain and carries chemical signals * clears wastes \*lined w/ ependymal cells, wastes and unnecessary solutes are absorbed and getfiltrate with glucose, O2, vitamins and ions (Ca, Cl, Mg etc)

Question 31

describe the blood filtrate by coroid plexus

Answer 31

Location: ventricles + subarachnoid space – Produces ~500mL/day – Constant volume (~125-150ml) \*junk in holes are chorid plexus, helps make CSF

Question 32

describe the ventricles of the brain

Answer 32

"holes" - connects to one another and to central canal of psinal chord (tiny hole runs down spinal) - contains cerebrospinal fluid (CSF) - lined by ependymal cells

Question 33

pathway of CSF

Answer 33

Question 34

What are the ventricesl fo the brain

Answer 34

1. Lateral * lateral so not on midline * starts at temporal lobes, loop up and around to midline looks like ram horm * have 2 of them but o not call 1 and 2 bc they are equal \*After lat ventricle CSF goes thru interventricular formaen, that connects lateral and 3rd ven 1. 3rd ventricle * on midline * looks like bird, head is the ventricle \*CSF goes down cerebral aquaduct, connects 3rd to 4th ventricle 1. 4th ventricle * separates ponds and medulla from cerebrellum \*CSF can then go down central canal, exit through med or lateral apetures (ends up in sub arachnoid space) OR central canal of spinal column

Question 35

what do subarachnoid villi do

Answer 35

move CSF into dural venous sinuses

Question 36

Describe the dural venous sinsues

Answer 36

- start with superior sagital sinus (msot superficial margin on falx cerebri) or inferior sagittal sinus - inferior -\> straight sinus \*then joins superior sagittal sinus - both go down transverse sinus (2x -\> no longer midline, travel transversely in superficial margin ) - then does to sigmoid sinus (x2) - sigmoid becomes interanl jugular vein (vein otuside the skull)

Question 37

\*LOOK AT HER VIDEO ON THIS FIGURE PUTS IT ALL TOGETHER