Trigeminal Lecture Flashcards

1
Q

What is chemesthesis?

What is an example of this?

A

The idea that free nerve endings can have a chemical sensitivity
An example of this would be eating something spicy or minty

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2
Q

What sensations is the trigeminal nerve responsible for?

A

Pain
Touch
Temperature
Proprioception

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3
Q

What is stereognosis?

A

The 3 dimensionality of something- size, texture, hardness

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4
Q

What is Flavour?

A

Taste, olfaction, texture, temperature, and chemesthesis

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5
Q

What are the three branches of the trigeminal nerve and what do they each contain?

A

Ophthalmic- sensory
Maxillary- sensory
Mandibular- sensory and motor

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6
Q

What are 2 other names for the trigeminal ganglion?

A

Gasserian ganglion

Semilunar ganglion

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7
Q

The afferent pathway of the trigeminal ganglion that is responsible for mostly touch end s on which nucleus in the brain?

A

The principal (main or chief) sensory nucleus

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8
Q

The spinal trigeminal nucleus has three parts- oralis, interpolaris, and caudalis. What generally is found in each?

A

Oralis- mostly touch
Interpolaris- temperature and touch
Caudalis- pain

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9
Q

A-beta fibers are responsible for what time of perception?

A

Touch

Proprioception

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10
Q

A-delta fibers are responsible for what type of perception?

A

Touch
Temperature
Chemesthesis
Sharp pain

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11
Q

C fibers are responsible for what type of perception?

A

Temperature
Chemesthesis
Dull and burning pain

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12
Q

Meisnner corpuscles measure what?

A

Light touch/spatial discrimination

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13
Q

Merkel receptors measure what?

A

Pressure

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14
Q

Ruffini corpuscles measure what?

A

Skin strethc

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15
Q

Pacinian corpuscles measure what?

A

Vibration

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16
Q

The response properties of mechanoreceptors are influence by several sources. What are they? (3)

A

Degree of myelination
The location of the receptor (superficial or deep)
The structure of the nerve ending (Meissner, Ruffini etc)

17
Q

What happens with stretch or mechanical contact?

A

Cation channels open

18
Q

What are the three mechanisms of mechanotransduction?

A
ENaC (epithelial Na+ channels)
TRP channels (transient receptor potentials)
Piezo1 and Piezo2
19
Q

How are Merkel cells activated?

A
  1. Pressure sensitive transduction by Piezo2 leads to depolarization
  2. Voltage gated Ca++ channels open
  3. Neurotransmitter released into synaptic cleft (glutamate)
  4. Postsynaptic response leads to action potentials
20
Q

Is there a synapse involved Merkel cell activation?

A

Yes

21
Q

Is there a synapse involved in Pacinian corpuscle activation?

A

No- it’s right on the nerve ending

22
Q

Pacinian corpuscles- how do they work?

A

The nerve ending is surrounded by lamellae. These lamella, when compressed, only allow the initial impact of the stimulus to make it to the transduction site. When the force is removed, the compressed part of the lamellae give and off-response to the receptor resulting in the vibratory sensation.

23
Q

What are Von Frey Hairs?

A

They are instruments that measure touch discrimination using a monofilament that is weighted to bend at a specific pressure.

24
Q

T/F the lateral part of your face has a lower threshold for two-point discrimination than the midline of your face?

A

False! Two point discrimination is achieved far more easily in the midline (specifically the lips) than on the lateral part of your face.

25
Q

In the face, are there Pacinian corpuscles present? What does this mean?

A

Nope

Our face is not designed to detect vibration

26
Q

T/F the tip of the tongue is the highest area of sensitivity of the tongue?

A

True

27
Q

T/F the tongue has both rapidly and slowly adapting mechanoreceptors despite having one kind of ending?

A

True

28
Q

T/F Rapidly adapting receptors have an on/off type of response compared to slowly adapting receptors which seem to taper off?

A

True

29
Q

What are the receptor endings found in the tongue called?

A

Krause end bulbs

30
Q

TMJ mechanoreceptors are innervated by what?

A

The mandibular branch of the trigeminal nerve

31
Q

T/F, you anterior teeth are more sensitive (in PDL) than your posterior teeth?

A

Truth

32
Q

T/F the periodontal ligament mechanoreceptor is rate sensitive- i.e. fewer action potentials form as the stimulus is applied more slowly?

A

Truuuth!

33
Q

PDL mechanoreceptors have _______ sensitivity. Give an example.

A

Directional

i.e. more sensitive to labial and distal force than lingual or mesial force

34
Q

Denture and implant patients have trouble controlling their biting force (if asked to hold something like a peanut between their teeth without breaking it) because why?

A

Because they have no periodontal ligament and thats where the information comes from to do that correctly.

35
Q

Are PDL mechanoreceptors helpful with stereognosis?

A

Absolutley- they help you feel what the shape of something is in your mouth

36
Q

For warm stimuli, which part of mouth is most sensitive?

A

The tip of the tongue

37
Q

Temperature transduction is mediated by what type of channels?

A

TRP channels