Brainstem Anatomy & CNS Trauma

Question 1

What section of the spinal cord is this?

Answer 1

Lumbar

• lower down
• big anterior horn

Question 2

What section of the spinal cord is this?

Answer 2

Thoracic

• upper
• small anterior horn

Question 3

What section of the spinal cord is this?

Answer 3

Cervical

• big anterior horn
• uneven ratio
• looks like a C

Question 4

How does the touch pathway ascend in the spinal cord?

Answer 4

Ipsilaterally (same side)

Question 5

How does the pain and temperature pathways ascend in the spinal cord?

Answer 5

Contralateral

Question 6

What is the brainstem made up of? What are its main functions?

Answer 6

Brainstem = midbrain, pons, medulla 
Main functions 
-Receive most cranial nerves
- Throughway for ascending sensory tracts and descending motor tracts
-Reticular formation

Question 7

What is the role of the medulla?

Answer 7

Vestibular control/ controls respiration & heart rate

Question 8

What is the role of the midbrain?

Answer 8

Contains superior & inferior colliculi, and substantia nigra. Regulates consciousness

Question 9

Where are sensory and motor neurons located in the spinal cord and brainstem?

Answer 9

Sensory = lateral 
Motor = medial

Question 10

What is the cellular response to injury in the PNS?

Answer 10

Neurons of the PNS regenerate quite well because Schwann cells stimulates growth factors

Question 11

What is the cellular response to injury in the CNS?

Answer 11

CNS neurons do not regenerate well. Oligodendrocytes release NogoA that causes the collapse of growth cones and inhibits growth. Astrocytes form a glial scar

Question 12

How does assessment of TBI using the Glasgow Coma Scale (3-15) work?

Answer 12

Lower number is worse condition

Question 13

What happens to the BBB after TBI?

Answer 13

Becomes damaged causing fluid leakage and excitotoxcity

Question 14

What does damage at C5-C6 cause? Damage in T or L regions?

Answer 14

C5/6 = quadriplegic 
T/L= Paraplegic

Question 15

What is axonal shearing?

Answer 15

Because white matter is on the outside in spinal cord and due to the segmented bone in the spinal cord, SCI often causes shearing of axons and demyelination

Question 16

What is the difference between active transporters and ion channels?

Answer 16

Active transporters:
-change shape
-need energy source
-move selected ions against concentration gradient
Ion Channels:
-no energy needed
-allow ions to diffuse down concentration gradient

Question 17

What is the electrochemical equilibrium?

Answer 17

When the electrical gradient opposes the concentration gradient (K+ at resting potential)

Question 18

Describe the phases of an action potential

Answer 18

Question 19

What does myelin do?

Answer 19

Myelin wraps around the axon between nodes and prevents leakage of ions thus increasing the passive conductance and ensuring enough depolarization reaches the next node

Question 20

What is a channelopathie?

Answer 20

Diseases that can affect channels

Question 21

What are the postsynaptic responses mediated by ionotrophic glutamate receptors - NMDA & AMPA?

Answer 21

Ionotrophic AMPA receptors open faster than NMDA receptors, allowing Na+ influx which depolarizes the membrane. This causes Mg2+ to be released from the NMDA channel and then NMDA receptors allow cations to flow

Question 22

What can moderate head injuries cause?

Answer 22

Moderate head injuries can cause extracellular amyloid beta deposits and/or intracellular Tau deposits which may be linked to Alzheimer’s

Question 23

What is MRI-DT good for?

Answer 23

MRI-DT is a great new technique to image long axons.

Question 24

How does CSF protect the brain against injury?

Answer 24

CSF protects the brain and spinal cord by reducing the effective mass by a factor of ~30 so the resulting force of trauma on neurons is also reduced.