Lecture 1

Question 1

Where do cranial nerves sprout from?

Answer 1

The brainstem.

Question 2

Where do spinal nerves sprout from?

Answer 2

The spinal cord.

Question 3

Cells found in the nervous system can be grouped into two categories. What are the categories and what types of cells they?

Answer 3

Excitable cells (neurons) and support cells (glia) (see page 6 of Lecture 1 for image).

Question 4

Name the three types of neurons and describe where they can be found.

Answer 4

Multipolar (which are commonly found throughout the body), pseudounipolar (which are found in the spinal ganglia), and bipolar (which are found in the retinas) (see Page 7 of Lecture 1 for image).

Question 5

Name the six types of glia.

Answer 5

Astrocytes, oligodendrocytes, neurolemmocytes (a.k.a. Schwann cells), microglia, polydendrocytes, and ependymal cells (see page 6 of Lecture 1 for image).

Question 6

What are astrocytes and what do they do?

Answer 6

Astrocytes are glial cells that support and nurture neurons by providing nutrients and removing waste. They remove excess neurotransmitters from synaptic clefts and form the blood-brain barrier (see page 12 of Lecture 1 for image).

Question 7

What are oligodendrocytes and what do they do?

Answer 7

Oligodendrocytes are glial cells that myelinate neurons in the central nervous system. They can wrap around and insulate/propogate more than one axon at a time (see page 9 of Lecture 1).

Question 8

What are neurolemmocytes and what do they do?

Answer 8

Neurolemmocytes, also known as Schwann cells, are glial cells that myelinate neurons in the peripheral nervous system. Unlike oligodendrocytes, they cannot serve more than one axon at a time.

Question 9

What are microglia, what do they do, and why are they different than other glial cells?

Answer 9

Microglia are small glial cells that serve and function as immune cells. During an inflammation of the central nervous system, the number of microglia is increased. They are different than other glial cells because they originate from yolk-sac progenitors instead of ectodermal tissue like other glial cells (see page 11 of Lecture 1).

Question 10

What are polydendrocytes and what do they do?

Answer 10

Polydendrocytes are glial cells that act as stem cells, meaning they can turn into other types of glial cells (see page 9 of Lecture 1).

Question 11

What are ependymal cells and what do they do?

Answer 11

Ependymal cells are glial cells that line the ventricles of the brain and produce/control cerebrospinal fluid (see page 9 of Lecture 1).

Question 12

What is anterograde transport and retrograde transport?

Answer 12

Anterograde transport is when proteins, neurotransmitters, and hormones produced in the cell body are transported via the microtubules down through the axon to the synapse. Retrograde transport is when trophic factors from a neuron’s target is shuttled up from the synapse, through the axon, and into the cell body. This is important for neurons to survive (see page 8 of Lecture 1).

Question 13

What substances are able to diffuse through the blood-brain barrier? How do substances without this ability cross the barrier.

Answer 13

Small lipophilic molecules such as water and gases can diffuse through the barrier. Other substances require active transport (see page 12 of Lecture 1).

Question 14

How is an action potential generated?

Answer 14

An action potential is generated through the voltage-gated Na+ channels opening. The channels open when the stimulus is strong enough to reach the threshold value (see page 13 of Lecture 1).

Question 15

What are the characteristics of an action potential?

Answer 15

The action potential must be:
1. Unidirectional
2. Fast (myelin and an increased axon diameter helps)
3. Efficient (action potentials are generated only at the nodes of Ranvier. The reason why myelin facilitates the speed of action potentials is because it allows the action potentials to skip across the neuron).
(See page 14 of Lecture 1).

Question 16

There are five spinal cord segments. Which segment has a different number of spinal nerves than vertebrae and why?

Answer 16

The cervical segment has 8 spinal nerves and 7 vertebrae. All of the other segments have corresponding numbers of spinal nerves and vertebrae. The reason why the cervical segment has 8 nerves is because while the other segments have the corresponding nerve located under the vertebrae (nerve T1 is other vertebrae T1

Question 16

There are five spinal cord segments. Which segment has a different number of spinal nerves than vertebrae and why?

Answer 16

The cervical segment has 8 spinal nerves and 7 vertebrae. All of the other segments have corresponding numbers of spinal nerves and vertebrae. The reason why the cervical segment has 8 nerves is because while the other segments have corresponding nerves located under the vertebrae (e.g. nerve T1 is under vertebrae T1), nerve C1 has to be located above the C1 vertebrae, otherwise there would be no innervation in that area (see page 15 of Lecture 1).

Question 17

How long is the spinal cord and what does this have to do with epidurals?

Answer 17

The spinal cord extends from the foramen magnum (the hole in the skull) down to L1-L2. Epidurals are safe because they are administered under L1-L2, meaning they don’t come in contact with the spinal cord (see page 16 of Lecture 1).

Question 18

Which spinal nerves form the cauda equina?

Answer 18

The lumbar, sacral, and coccygeal spinal nerves (see page 16 of Lecture 1).

Question 19

List the three layers of meninges starting from the innermost layer.

Answer 19

The pia mater, the arachnoid mater, and the dura mater (see page 17 of Lecture 1).

Question 20

Which two meninge layers does cerebrospinal fluid flow through?

Answer 20

The pia mater and the arachnoid mater (see page 17 of Lecture 1`).

Question 21

What is the connection between the dura mater and spinal nerves?

Answer 21

The dura mater extends through the intervertebral foramen to become the epineurium (the external sleeve) of the spinal nerves (see page 17 of Lecture 1).

Question 22

How can a person distinguish between the anterior side and posterior side of the spinal cord using blood vessels?

Answer 22

The anterior side of the spinal cord only has one spinal artery and vein, while the posterior side has two spinal arteries and veins.

Question 23

What is the mixed spinal nerve comprised of and where is it located?

Answer 23

The mixed spinal nerve is comprised of anterior (motor) and posterior (sensory) roots. It is located in the intervertebral foramen so if the intervertebral discs herniate posterolaterally, the nerve will become entrapped, causing a lot of pain (see page 18).

Question 24

Describe what a nerve plexus is and give two examples.

Answer 24

A nerve plexus is a network of fibres from multiple nerve roots that come together/merged/rearrange to form more individual nerves. Two examples are the brachial plexus and the lumbosacral plexus (see page 19 of Lecture 19).