Nervous System

Question 1

What is the parasympathetic supply to the enteric system?

Answer 1

The enteric nervous system contains preganglionic cholinergic vagal fibres

Question 2

In the enteric nervous system, are vagal fibres post-ganglionic?

Answer 2

No, pre-ganglionic

Question 3

In the enteric nervous system, does it contain post-ganglionic sympathetic fibres?

Answer 3

Yes.

The sympathetic supply is post ganglionic but may end on cholinergic neurones or smooth muscle fibres directly.

Question 4

Where does the enteric nervous systems sympathetic fibres end on?

Answer 4

Cholinergic neurones or intestinal smooth muscle fibres directly

Question 5

Which type of nerve fibres are the fastest?

Answer 5

A and B fibres are myelinated and conduct via saltatory conduction, so have fast conduction velocities

Question 6

Are C-fibres myelinated?

Answer 6

No

Question 7

What speed do A-alpha fibres conduct at?

Answer 7

70 - 120m/s

Question 8

What type of fibres supply motor supply to muscle spindles?

Answer 8

A-gamma fibres

Question 9

What does Brown-Sequard syndrome cause?

Answer 9

This is hemisection of spinal cord.

Causes:

• ipsilateral paralysis
• ipsilateral loss of proprioception
• ipsilateral touch + vibration sensation
• contralateral loss of pain
• contralateral loss of temperature sensation

Question 10

How big is the synaptic cleft?

Answer 10

30-50 nm wide

Question 11

What type of summation do excitatory postsynaptic potentials exhibit?

Answer 11

Temporal or spatial

Question 12

How long is synaptic delay?

Answer 12

0.5ms

Question 13

What are IPSPs? (inhibitory post synpatic potentials)

Answer 13

Hyperpolarising

Question 14

What are EPSPs? (excitatory post synaptic potential)

Answer 14

Depolarising

Question 15

How many synapses does the knee jerk reflex have?

Answer 15

It is monosynaptic

Question 16

What is the synaptic transmitter at the knee jerk reflex?

Answer 16

Glutamate

Question 17

What is the sensory organ in the knee jerk reflex?

Answer 17

The muscle spindle

Question 18

What spinal roots does the knee jerk reflex involve?

Answer 18

L2,3,4

Question 19

How does the knee jerk reflex work?

Answer 19

The sensory organ is the muscle spindle, which when stretched sends signals to the CNS where a single synapse occurs with the motor supply to the muscle. In addition the Ia fibre from the muscle spindle synapses with an inhibitory interneurone (golgi bottle neurone) which releases inhibitory glycine at the motor neurone to the antagonistic muscle - known as reciprocal innervation.

Question 20

What happens to fibres in the antagonistic muscles in the knee jerk reflex?

Answer 20

Glycine inhibition

The Ia fibre from the muscle spindle synapses with an inhibitory interneurone (golgi bottle neurone) which releases inhibitory glycine at the motor neurone to the antagonistic muscle. Reciprocal innervation.

Question 21

What do optic tract lesions cause?

Answer 21

Homonymous hemianopia

(optic tract carries fibres that supply the same field (ie left or right) from both eyes)

Question 22

What do optic chiasm lesions cause?

Answer 22

Bitemporal hemianopia

(at the optic chiasm temporal fibres cross the midline)

Question 23

Why do occipital lesions spare the macula?

Answer 23

The macula fibres are separated from the rest of the cortex subserving vision

Question 24

What do optic nerve lesions cause?

Answer 24

Unilateral loss of vision

Question 25

What do visual field defects start as?

Answer 25

Scotomas - small areas of visual loss

Question 26

Where are the cell bodies of the A-delta fibres?

Answer 26

Dorsal root ganglia

Question 27

Where do A-delta fibres synapse?

Answer 27

With cells in laminae I and V of the dorsal horn

Question 28

Where do C fibres synapse?

Answer 28

Cells in laminae II and III in the dorsal horn

Question 29

Which column are most ascending neurones in?

Answer 29

The anterolateral columns (spinothalamic tract)

Most second order neurones cross within a few segments and ascend in the anterlateral columns.

Question 30

What does the substantia gelatinosa do?

Answer 30

It does not project directly to higher levels but contains multiple interneurones involved in pain modification.

Question 31

What are Meissners corpuscles associated with?

Answer 31

Touch

Question 32

What are Ruffini corpuscles associated with?

Answer 32

Proprioception

Question 33

What are Pacinian corpuscles associated with?

Answer 33

Vibration and proprioception

Question 34

What are free nerve endings associated with?

Answer 34

Nociception

Question 35

What cranial nerve supplies taste sensation?

Answer 35

The posterior 1/3 of tongue is glossopharyngeal (IX) and the rest is the chorda tympani accompanying the facial nerve (VII)

Question 36

What does the trigeminal nerve supply?

Answer 36

Muscles of mastication and sensation to forehead and face in distribution of opthalmic, maxillary and mandibular branches.

Includes sensation from cornea.

Question 37

What muscle does cranial nerve IV (trochlear) innervate?

Answer 37

The superior oblique muscle

Question 38

Which cranial nerve is responsible for most eye movements? Which nerves do the rest?

Answer 38

Cranial nerve III.

IV (trochlear - superior oblique- look down and inward) and VI (abducens - lateral rectus- abduction)

Question 39

What does XII (hypoglossal nerve) innervate?

Answer 39

ALL tongue muscles EXCEPT palatoglossus - which is innervated by the vagus nerve (X)

Question 40

When are delta waves present on the EEG?

Answer 40

They are abnormal 4Hz waves - but can be normal in sleep or in children

Question 41

When are alpha waves prominent on the EEG?

Answer 41

On closing the eyes or with increased cortical activity

Question 42

When are beta waves prominent in the EEG?

Answer 42

Over the frontal area