C: Ascending sensory pathways 2 Flashcards Preview

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Flashcards in C: Ascending sensory pathways 2 Deck (31)
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1
Q

Where are cranial nerve nuclei located?

A

Within the brainstem

2
Q

The trigeminal nerve is a major carrier of sensory info from where?

A

1) Face
2) Nose
3) Scalp
4) Dura

3
Q

The facial nerve carries general sensory info from where?

A

The external ear

4
Q

The glossopharyngeal nerve carries general sensory info from where?

A

1) Posterior 1/3 of tongue
2) Pharynx
3) Middle ear

5
Q

The vagus nerve carries general sensory info from where?

A

1) Auditory canal
2) Larynx
3) Pharynx
4) Oesophagus

6
Q

General sensory info from the head is carried in which central pathway?

A

Trigeminal sensory pathway

7
Q

Sensory fibres from the cranial nerves in the trigeminal sensory pathway run within which nucleus in the brain stem?

A

Trigeminal nucleus

8
Q

What 3 parts can the trigeminal nucleus be divided into?

A
Mesencephalic nucleus (extends into midbrain)
Pontine/chief sensory nucleus (bulbous part in pons)
Spinal nucleus (extends down into medulla towards spinal cord)
9
Q

Where does the motor nuclei of the trigeminal lie in relation to the sensory nuclei?

A

Motor nuclei is medial to the sensory nuclei

10
Q

How many trigeminal sensory nuclei are there within the brainstem?

A

2 - one on each side

11
Q

Somaesthetic inputs from the trigeminal sensory nucleus travel to which region of the post central gyrus?

A

Inferior post central gyrus mainly

12
Q

Pain and temperature info from the face travels to what part of the trigeminal nucleus?

A

Caudal part of the spinal nucleus

13
Q

Simple touch and pressure from the face travels to what part of the trigeminal nucleus?

A

Rostral part of the spinal nucleus

14
Q

Where are the cell bodies of the primary neurones in the trigeminal sensory pathway located?

A

In ganglia outside of the brainstem

eg. primary cell bodies of CNV in trigeminal ganglion, CN7,9,10 all have their own ganglion

15
Q

Where are the cell bodies of the secondary neurones in the trigeminal sensory pathways located?

A

(generally) in the trigeminal nucleus within the brainstem

16
Q

Pain and temperature info from the face is carried by what kind of nerve fibre?

A

Thin, slow fibre

17
Q

Do primary neurones in the TSP (trigeminal sensory pathway) enter the ipsilateral or contralateral trigeminal nucleus?

A

Ipsilateral

18
Q

Which neurone in the TSP crosses the midline?

A

The secondary neurone

19
Q

What would be the course of neurones carrying pain and temperature info from the face?

A

For example, carried by the trigeminal nerve:

1) Cell body of primary neurone in the trigeminal ganglion
2) Primary axon enters brain stem and travels caudally in the spinal tract of the trigeminal (which is quite superficial)
3) Enters the trigeminal nucleus at the caudal end and where it synapses with the secondary neurone
4) Secondary axon crosses the midline and ascends in the trigeminothalamic tract (lies deep within the brainstem) to the thalamus

20
Q

What would be the course of a neurone carrying touch and pressure information from the face?

A

In the case of the face info is carried in trigeminal nerve

1) Primary cell body in trigeminal ganglion
2) Primary axon enters brainstem and travels caudally in the spinal tract of trigeminal but enters the spinal nucleus more rostrally than a fibre carrying pain and temp info
3) Primary and secondary neurones synapse in the spinal nucleus
4) Secondary axon crosses the midline and ascends to thalamus in trigeminothalamic tract

21
Q

What would be the consequence of a lesion affecting the superficial lateral medulla - in terms of sensation from the face and sensation from the body?

A

1) Loss of pain, temp, touch and pressure on ipisilateral side of face (primary axons carrying this info descend on in the spinal tract which lies superficially in the lateral medulla)
2) Loss of pain, temp, touch and pressure on the contralateral side of the body - spinal lemniscus (spinothalamic tract in medulla) lies superficially in the medulla which carries this info from the lateral side of the body

22
Q

Neurones carrying discriminative touch information travel to which part of the trigeminal nucleus?

A

Pontine nucleus

23
Q

Neurones carrying proprioception travel to which part of the trigeminal nucleus?

A

Mesencephalic nucleus

24
Q

How does the pathway of neurones carrying proprioception info from the face differ slightly to the pathway of other neurones in the trigeminal sensory pathway in terms of cell body position?

A

Primary neuron cell bodies (first order cell bodies) don’t lie in a peripheral ganglion - they lie within the mesencephalic nucleus
Secondary cell bodies lie just outside the trigeminal nucleus thus the primary and secondary axons synapse outside of the trigeminal nucleus

25
Q

What would be the course of neurones carrying discriminative touch info from the face?

A

In this case the info would be carried in the trigeminal nerve

1) Primary cell body in the trigeminal ganglion
2) Primary axon enters the brainstem and passes striagh into the pontine nucleus
3) Secondary cell body located in pontine nucleus where primary and secondary neurone synapse
4) Secondary axon crosses the midline and ascends to the thalamus in the trigeminothalamic tract

26
Q

Does the trigeminothalamic tract carry info from the contralateral or ipsilateral side of the head?

A

Contralateral

27
Q

Which neuron in the trigeminal sensory pathway crosses the midline?

A

Secondary neuron axon

28
Q

What kind of fibres carry discriminatory touch info from the head?

A

Fat, fast fibres

29
Q

What 2 groups do somaesthetic modalities from the head fall into?

A

1) Modalities that are essential to survival - pain, temp, some touch and pressure
2) Modalities that increase detail - discriminative touch: 2 point discrimination and vibration, proprioception

30
Q

What would be the course of neurones carrying proprioceptive information from the muscles of mastication?

A

Info would be carried in the trigeminal nerve

1) Primary neuron cell body within the mesencephalic nucleus - gives off 2 axons
2) One axon synapses with a secondary sensory neurone just outside of the mesencephalic nucleus - the axon of which then ascends to the thalamus in the trigeminothalamic tract
3) The other axon travels to the motor trigeminal nucleus where it synapses with the cell body of a motor neurone
4) Axon of the motor neurone then travels to the muscles of mastication

31
Q

Proprioceptive information from the head travels to which part of the trigeminal nucleus?

A

Mesencephalic nucleus