Basic Structure of the CNS

Question 1

Name 2 categories of cells found in the CNS?

Answer 1

Neurons (the communicators)
Glial cells (support cells)

Question 2

Name the 4 major types of glial cell?

Answer 2

Astrocytes
Oligodendrocytes
Microglia
Ependymal cells

Question 3

What cells are more numerous in the CNS, glial cells or neurons?

Answer 3

Glial cells

These are 10 x more numerous!

Question 4

Describe astrocytes?

Answer 4

These have many numerous processes (often star-shaped). Roles in support, maintaining the blood-brain barrier, environmental homeostasis. Support is important as there is no connective tissue in the CNS.

Question 5

Describe oligodendrocytes?

Answer 5

Cells that produce myelin in the CNS

not in the PNS

Question 6

Describe microglia?

Answer 6

Cells of similar lineage to macrophages (i.e. hemopoietic origin). Involved in immune monitoring and antigen presentation

Question 7

Describe ependymal cells?

Answer 7

Ciliated cuboidal/columnar epithelium that lines the ventricles.

Question 8

Why is the brain thought to be bumpy as opposed to smooth?

Answer 8

To increase SA

Question 9

What are gyri (gyrus), sulci (sulcus) and fissures?

Answer 9

A gyrus is the raised ridge
A sulcus is the groove
Where a sulcus is particularly deep it is called a fissure

Question 10

Grey matter is on the ____1____ of the brain. It is where the ____2____ are found

White matter is found on the ___3____ of the brain. It contains ____4______ this contains NO neurons,

There is the presence of __5_____ grey matter structures e.g. ____6____

Answer 10

1) outside
2) neurons
3) inside
4) no neurons but instead glial cells and myelinated axons
5) deep
6) thalamus

Question 11

Describe where white and grey matter are found in the spinal cord?

Answer 11

White matter is found on the outside and grey matter in a H shape in the inside

Question 12

What are the three layers of the meninges from superficial to deep?

Answer 12

Dura mater
Arachnoid mater
Pia mater

Question 13

What space contains the CSF?

Answer 13

The subarachnoid space and the ventricles

Question 14

How are the lateral ventricles connected and separated?

Answer 14

The septum pellucidum separates the two ventricles from one another so they are only connected by the third ventricle

The third ventricle attaches to both of the lateral ventricles separately through interventricular foramen

Question 15

What connects the third ventricle to the fourth ventricle?

Answer 15

The cerebral aqueduct

Question 16

What is CSF produced by?

Answer 16

the secretory epithelium of the choroid plexus

Question 17

What are the two main arteries of the body that supply the brain?

Answer 17

the internal carotids and the vertebral arteries

Question 18

What are the vertebral arteries usually a branch of?

Answer 18

subclavian arteries

Question 19

The vertebral arteries are major arteries of the neck. Typically, the vertebral arteries originate from the ________1________. Each vessel courses superiorly along each side of the neck, merging within the skull to form the _____2________

Answer 19

1) subclavian arteries

2) single, midline basilar artery

Question 20

In the brain what does the internal carotid arteries branch into?

Answer 20

The anterior and middle cerebral arteries (left and right)

Question 21

What does the basilar artery branch into?

Answer 21

the left and right posterior cerebral arteries

Question 22

Blood from the brain drains into a system of _______ which drain into _________

Answer 22

dural venous sinuses

the internal jugular vein

Question 23

What arteries make up the circle of willis?

Answer 23

the internal carotid arteries, anterior cerebral arteries, anterior communicating arteries, posterior communicating arteries, posterior cerebral arteries, and basilar arteries

Question 24

The spinal cord terminates in a tapered cone-shape called the ____1______ which in turn, continues as a thin connective tissue cord called the ___2_____ which is anchored to the ______3_________

Answer 24

1) conus medullaris
2) filum terminale
3) dorsum of the coccyx

Question 25

The spinal meninges are continuous with the cranial meninges via the foramen magnum. And include all 3 layers, ____________1_____________

The spinal cord is suspended in the canal by a ribbon of tissue on the lateral aspects of the cord called the ______2______.

This ligament is formed of _____3______ and attaches to the ____4___ at points along the length of the cord.

Note that just as with the brain, the subarachnoid space is filled with ___5___

Answer 25

1) the dura mater, arachnoid mater and pia mater.
2) denticulate ligament
3) pial and arachnoid tissue
4) dura
5) CSF

Question 26

What is the denticulate ligament?

Answer 26

triangular shaped ligaments that anchor the spinal cord along its length, at each side, to the dura mater

Question 27

Describe the make up of white and grey matter in the spinal cord and what each one consists of?

Answer 27

The spinal cord is made up of an outer layer of white matter and an inner, ‘H’ shaped core of grey matter. The white matter consists of longitudinally oriented nerve fibres (axons), glial cells and blood vessels. The grey matter contains neuronal soma, cell processes, synapses, glia and blood vessels.

Question 28

Describe the blood supply to the spinal cord?

Answer 28

Three major longitudinal arteries: one anterior and two posterior that originate from the vertebral arteries. These run the length of the cord.
Segmental arteries derived from vertebral, intercostal and lumbar arteries.
Radicular arteries that travel along the dorsal and ventral roots.

Question 29

Describe the difference between the relationship between dura and bone in the spinal cord vs in the brain?

Answer 29

Unlike the dura in the cranial cavity, which is attached to the periosteum, in the spinal canal there is a space between the dura and the bone, termed the epidural space, which contains adipose tissue and the anterior and posterior epidural venus plexuses. This space is utilized in epidural anaesethesic.

Question 30

What is the cortex of the brain?

Answer 30

cerebral cortex is the outermost layer of the brain, made up primarily of grey matter

Question 31

Define saltatory conduction?

Answer 31

Saltatory conduction is the propagation of action potentials along myelinated axons from one node of Ranvier to the next node, increasing the conduction velocity of action potentials.