Orofacial sensation + mastication Flashcards
(98 cards)
1
Q
What are the TWO speeds of adaptation and their examples?
A
- Tonic (slowly adapting e.g. nociceptors, muscle stretch receptors, joint prioprioceptors)
- Phasic (fast adapting e.g. touch, temperature)
2
Q
What are the THREE types of receptors based on location of detection?
A
- Teleceptors (external environment at a distance e.g. sight, hearing)
- Exteroceptors (external environment nearby e.g. smell, also sight and hearing)
- Interoceptors (internal environment e.g. chemoreceptors, proprioceptors)
3
Q
What exteroceptors and interoceptors are involved in kinaesthesia?
A
Exteroceptors: eye, ear, skin
Interoceptors: muscles, tendons, joints
4
Q
In terms of kinaesthesia, why might a patient panic after sudden lowering of the dental chair?
A
It takes time for the pt to reorientate using extero/interocepters.
5
Q
What are the exteroceptors and interoceptors related to the oral cavity?
A
Exteroceptors: PDL, alveolar mucosa, gingiva, periosteum
Interoceptors: proprioceptors (muscle spindles, TMJ receptors)
6
Q
Sensory information is coded with what FOUR aspects?
A
- Modality (type of energy e.g. light, heat, odour)
- Location
- Intensity
- Duration
7
Q
What sensation travels in the spinothalamic tract?
A
- Pain
- Temperature
- Crude touch and pressure
- Tickle/itch
- Sexual sensations
8
Q
What sensation travels via the dorsal column-medial lemniscal pathway?
A
- Fine touch, fine pressure
- Proprioception
- Vibration
9
Q
What information do A-alpha fibres carry and where are the cell body and synapse of the first order neuron?
A
- Proprioception
First order neuron
- cell body: mesencephalic nucleus (midbrain)
- synapse: motor nucleus (pons)
10
Q
What information do A-beta, A-delta/C fibres carry and where are the cell body and synapse of the first order neuron?
A
A-beta (touch)
- synapse: Chief sensory nucleus (pons)
A-delta/C (pain, temp)
- synapse: Spinal nucleus (medulla)
- Both cell body: trigeminal ganglion
11
Q
What FOUR types of receptors can mechanoreceptors in the mouth have, and are they slow or fast adapting?
A
- Merkel cell (slow)
- Ruffini endings (slow)
- Meissner corpsuscles (fast)
- Pacinian corpuscles (fast)
12
Q
What type of receptors do a-delta and C fibres have?
A
Free nerve endings
13
Q
True of false: Lower touch threshold mean higher two-point discrimination.
A
True
my rationale: the more receptors activated, the more information and therefore discrimination there is.
14
Q
What THREE areas of the oral cavity have no sensitivity to hot/warm?
A
Gingiva, Buccal mucosa, Hard/soft palate
15
Q
Which is more superficial and has more receptors: warm or cold receptors?
A
Cold receptors.
16
Q
What type of receptor endings do hot/cold receptors in the mouth have?
A
Free nerve endings.
17
Q
What type of receptor endings do periodontal mechanoreceptors in the PDL have?
A
Ruffini type endings.
18
Q
What is fremitus?
A
It is the slight movement that can be felt on a tooth when the opposing tooth bites on it (e.g. the finger will be placed on the buccal surface where you might feel the tooth having a ‘flex’ movement when occluding)
19
Q
What THREE types of nerve endings are found in the TMJ, and what do they sense?
A
- Free nerve endings (pain)
- Ruffini endings + GTO (static mechanorecetor - jaw position)
- Pacini corpsucles (dynamic mechanoreceptor - extremes of joint displacement ie. opening, protrusion, lateral excursion)
20
Q
What do rapidly adapting and slowly adapting proprioceptors in the TMJ detect?
A
- Rapidly adapting (velocity)
- Slowly adapting (static position)
21
Q
What is oral stereognostic ability (OSA)?
A
The ability of the mouth to discern shape, size and surface characteristics of an object placed in the mouth.
22
Q
What FOUR factors may decrease OSA?
A
- Age (older = lower OSA)
- Teeth (edentulous = lower OSA)
- Severe periodontitis
- Duschenne muscular dystrophy (reduced muscle spindle function - affects interocclusal 5mm discrimination)
23
Q
What parts of the oral cavity are involved with OSA?
A
Mainly the tongue mucosa and palate
- To a lesser extent: Teeth with their PDL (periodontal mechanoreceptor [PMR])
24
Q
Above what thickness do TMJ receptors and jaw muscle receptors detect things interocclusally?
A
5mm or more to detect something.
25
In an edentulous patient, what are TWO things that may increase OSA?
- Dentures
| - Oral implants
26
True of false: RCT decreases PMR sensation?
False, it has no effect on periodontal mechanoreceptors.
27
What are FOUR functions of oral stereognosis?
- Denture adaptation
- Mastication
- Swallowing
- Speech
28
What is Burning Mouth Syndrome?
Chronic idiopathic oral mucosal pain with no clinical lesions nor systemic disease.
Not due to psychological factors alone but neuropathic pain may cause psychological effects.
29
What is Stomatodynia? (also, break up the meaning of the prefix and suffix)
```
Stomatodynia = Burning Mouth Syndrome
Stomato = mouth
Dynia = pain
```
30
What is Allodynia?
Pain due to stimulus that does not normally provoke pain (e.g. light touch)
31
What is the difference between unimodal and polymodal nociceptors?
Polymodal responds to many stimuli.
32
What TWO things can sleeping/silent nociceptors cause?
- Hyperalgesia (increased pain to painful stimuli)
| - Allodynia (pain to non-painful stimuli)
33
What is meant by 'Double pain sensation'?
Fast pain (a-delta fibres) with slow pain (C fibres).
34
What are FIVE differences of fast pain vs. slow pain?
Fast / Slow
- A-delta / C fibres
- sharp pain / dull, aching, burning pain
- well localised / poorly localised
- short / long duration
- thermal and mechanical nociceptors / polymodal nociceptors
35
Name FOUR physiological chemicals that can activate nociceptors (different to sensitising them) and where they come from.
- Potassium (from damaged cells)
- Bradykinin (damaged vessels)
- Serotonin (damaged endothelial cells and platelets)
- Histamine (degranulated mast cells)
36
Name TWO physiological chemicals that can sensitise nociceptors (different to activating them) and where they come from.
- Prostaglandins (damaged cells)
| - Substance P (primary afferent neurons)
37
What is the difference between antidromic and orthodromic activation of nociceptors?
Orthodromic activation is the normal direction of nociceptor conduction (e.g. skin to CNS)
Antidromic activation is opposite (e.g. CNS to nociceptors in skin -> can release substance P -> sensitise the nociceptors)
38
What is one dentally related condition that is caused by antidromic activation of nociceptors?
Hot pulp
- Substance P causes mast cells to degranulate -> histamine activates nociceptors
- Substance P causes inflammation -> bradykinin release activates nociceptors
39
True of false: antidromic stimulation can lead to peripheral sensitisation.
True
40
Why might we want to give pre-emptive analgesia to treat post-op pain (e.g. LA used for someone under GA during an extraction)?
Pre-emptive analgesia aims to prevent establishment of central sensitisation.
41
Describe the synapses of the Spinothalamic tract and where it crosses the midline.
1. synapse: dorsal horn
2. crosses midline
3. synapse: thalamus
42
2nd order neurons can either be nociceptive or WDR neurons. What is the difference between the two?
- Nociceptive neurons: respond only to noxious stimuli
| - Wide Dynamic Range Neurons (WDR): reponds to noxious and non-noxious (e.g. light touch, temp, proprioception)
43
Describe the SEVEN steps of the trigeminal pain pathway starting from the trigeminal ganglion.
1. 1st order neurons carry nociceptive information from orofacial region to brainstem
2. Entering the pons, fibres descend (forming spinal tract of V)
3. Synapse at the spinal nucleus of V
4. Cross midline
5. 2nd order neuron travels to thalamus (trigeminothalamic tract)
6. Synapse in thalamus
7. 3rd order neurons travel from thalamus to cortex (corona radiata)
44
What are the FIVE theories of pain?
- Specificity (response only to specific noxious stimuli)
- Intensity (increased response with increased intensity)
- Pattern (each stimuli ellicit different pattern of response)
- Gate control (large fibres that detect non-nociceptive stimuli [e.g. touch] activate pain inhibitory pathways "close the gate" so if this is high, pain is low - occurs via presynaptic inhibition in the substantia gelatinosa)
- Neuromatrix (matrix of neurons can generate pain even in absence of signals - can explain phantom limb pain)
45
What is referred pain and why does it occur?
Pain from internal organs (viscera) is felt as pain in more superficial region of body
- Occurs due to convergence of pain pathways
e. g. pain from teeth felt elsewhere on the face and vice versa (like muscles of mastication)
e. g. heart attack felt in left arm and into jaw.
46
What is the transduction theory of dentinal sensitivity?
The neuron is in close proximity to the odontoblast and/or it's process (acts as transducer of stimuli)
47
Following hydrodynamic theory of intratubular nerves responding to fluid flow, what are FOUR stimuli for outward flow of dentinal fluid and ONE for inward flow?
Outward
- Air
- Drilling
- Probing
- Osmotic
Inward
- Hot liquid
48
How does fluid move in or out of the dentinal tubules to cause dentinal sensitivity?
Due to pressure differences in the surrounding tissues
49
True or false: people who are insensitive to pain in their teeth can still have tactile sensation from their teeth.
True
| e.g. left and right mandibular block done at the same time reduces OSA by 20%, not 100%.
50
What is barodontalgia and what is one activity that can cause this?
In barodontalgia, tooth damage occurs due to ambient pressure changes.
e.g. deep sea divers (pressure can increase many fold)
51
Order the following fibres in terms of when LA would affect them:
- A-delta fibres (temperature and sharp pain)
- A-beta fibres (touch)
- C fibres (burning pain)
LA works in this order:
1. C fibres (burning pain)
2. A-delta fibres (temperature and sharp pain)
3. A-beta fibres (touch)
52
What chemical causes sour taste?
Acids (H+)
53
What chemical causes bitter taste?
Organic substances
- can contain nitrogen
- Alkaloids (quinine, caffeine, nicotine)
54
What chemical causes umami taste?
L-Glutamate
55
What are the FOUR types of papillae found on the tongue and which ones have taste buds?
Has taste:
- Fungiform
- Circumvallate
- Foliate
Does not have taste:
- Filiform
56
What FOUR areas can extra-lingual taste papillae be found?
- Soft/Hard palate
- Pharynx
- Epiglottis
- Larynx
57
What are TWO ways to measure taste acuity?
- Detection threshold (single drop on dried tongue or 5-10mL moved around tongue)
- Recognition threshold (conc at which particular taste can be distinguished (e.g. sweet, sour etc)
58
Of all the taste types, which has the lowest threshold and why?
Bitter, because a lot of poisons are bitter.
59
What are TWO cell types in a taste bud and what is the lifespan of the active cell?
- Taste cell and sustentacular cell
| - Taste cell life span: 1-2wks
60
How might smoking, taste and blood pressure be linked?
Smoking kills taste buds -> threshold to salt increased 7 times -> increased BP
61
How might taste receptors and obesity be linked?
1. Obese individuals have less taste receptors in taste buds
2. Compromised fat sensing system for both oral cavity and GI tract -> attenuated oral signals to brain
3. Delayed satiety response -> excessive food intake.
62
What THREE cranial nerves are involved with taste and where do they innervate?
- VII facial nerve (Chorda Tympani) = ant 2/3 tongue
- IX glossopharyngeal = post 1/3 tongue
- X Vagus = ant epiglottis
63
What is ageusia?
Total loss of taste
64
What are THREE mechanisms for taste/smell disorders?
- Transport loss (interfere with access of tastant to taste bud)
- Sensory loss (injury to receptor cells)
- Neural loss (injury to afferent/central nerves)
65
What is an example of transport loss? (taste)
- Poor OH
- Xerostomia
- Inflammation of the oral cavity
66
What is an example cause of sensory loss? (taste)
- Antineoplastic agents
- Radiation therapy
- Antithyroid medication
NOTE: sensory loss is caused by injury to the receptor cells
67
What are FIVE things that can cause taste disorders in clinical dentistry? (not necessarily iatrogenic)
- LA
- Intraoral infections (candida, gingivitis, periodontitis)
- Autoimmune (oral lichen planus, burning mouth syndrome)
- Chlorhexidine mouthwash
- Metallic restorations
68
Define haematinic.
| What are FOUR examples?
Nutrient that is required for blood cell development.
- Folate
- B12
- Iron
- Zinc
69
What oral manifestation might occur with low haematinics?
Loss of filiform papillae > red 'bald' appearance of tongue ("glossy tongue")
70
What glands are found in circumvallate papillae and what type of secretion do they secrete?
Von ebner's glands
| - Serous secretion
71
Where is the most high risk area for oral cancer on the tongue?
Where the foliate papillae are.
72
What type of first order neurons exist for olfaction?
Bipolar neurons
73
Describe the cell body location bone it travels through and synapse location of the first order neurons for olfaction.
1. Bipolar neuron cell body in olfactory mucosa
2. Travel through cribriform plate
3. Synapse at glomeruli in olfactory bulb
74
What roles do glomeruli and mitral cells have in olfaction?
- Glomeruli code for different smells
| - Mitral cells further refine/distinguish the smell
75
What secretes the thin layer of mucus on the olfactory epithelium?
Bowman's glands
76
What are FOUR requirements that must be met for an olfactory stimulus to be detected?
- Volatile
- Sufficiently water soluble (dissolve into mucus)
- Lipid soluble (cross neuron membrane)
- Sufficient numbers and duration
77
What are THREE types of dysosmia?
Dysosmia = distortion
- Parosmia (altered perception of smell in presence of smell)
- Phantosmia (perception of smell without presence of smell)
- Agnosia (inability to classify/contrast smells)
78
What is dual processing? (in terms of the human senses)
| - Give an example.
Senses have both conscious and unconscious components.
| E.g. Blind sight (half blind person still able to detect movement or location of object on their blind side)
79
What is the vomeronasal organ (VNO)?
| Where is it located?
- Auxillary sense organ associated with CN-N (cranial nerve zero) = pheromone sensing.
- It is located near the vomer and nasal bones.
80
What is the formula for flavour?
Taste + smell + texture + temperature + experience + hunger = flavour
81
List the FOUR stages of the masticatory cycle (closing and opening phases)
1. Fast closing
2. Slow closing (occlusal phase)
3. Slow opening
4. Fast opening
82
In terms of tooth loss, when is there considered an impairment in the chewing ability of an individual?
When <20 well-distributed teeth are present.
83
Which masticatory muscles are used for crushing vs. grinding?
```
Crushing
- Temporalis
- Masseter
Grinding
- Lateral pterygoid
- Medial pterygoid
```
84
Define a motor unit.
Several muscle fibres innervated by a single motorneuron.
85
True or false: a high axon:muscle fibre innervation ratio allows for finer movements.
True. (e.g. 1:2 = laryngeal muscles, 1:640 = masseter, 1:936 = temporalis)
86
True of false: gamma and alpha motor neurons innervate intrafusal and extrafusal muscle fibres respectively.
True
87
True or false: there are way more muscle spindles in jaw closers than there are in jaw openers.
True
88
What is the function of Golgi Tendon Organs (GTO)?
GTO produce reflex inhibition of the corresponding muscle when there is increased stress on the tendons.
89
What are the FIVE components of a reflex arc?
1. Receptor
2. Sensory neuron
3. Integration centre (in spinal cord)
4. Motor neuron
5. Effector (muscle/gland)
90
What receptor type is responsible for jaw closing/jerk reflex?
What are TWO functions?
- Muscle spindles
| - Maintaining rest position (excitatory) and unloading reflex (inhibitory - biting through a nut)
91
What receptor types are responsible for jaw opening reflex?
| What is the function?
- Mechanoreceptors/Nociceptors
| - Inhibit jaw closers upon stimulus by pressure/pain (e.g. fishbone in gingiva)
92
What occurs during the periodontal reflex?
- Rapid increase in load on tooth (detected by PDL) evokes reflex inhibition of jaw-closers
93
True or false: Weak pressure on a tooth evokes reflex excitation of jaw-closer muscles
True, although paradoxical. This may play a role in helping jaw muscles keep food between teeth.
94
Define curarized.
Anaesthetised.
95
What are the THREE aspects of the currently accepted theory for mastication?
- Peripheral input (reflex theory)
- Central Pattern Generator (CPG - pattern generator theory)
- Cortical input (conscious control)
96
What are the FOUR phases of swallowing?
1. Preparatory/Masticatory phase (voluntary)
2. Oral/Buccal phase (voluntary)
3. Pharyngeal phase (involuntary)
4. Oesophageal phase (involuntary)
97
Where is the swallowing centre found?
The brainstem.
98
What is the difference between peripheral and central sensitisation?
- Peripheral sensitisation occurs at the nerve endings (via primary afferent neuron secretion of substance P)
- Central sensitisation occurs at the synapses of primary/secondary/tertiary neurons (via C-fibre activation causing protein kinase activation -> altered secondary messengers at synapse -> increased excitability at synapse)
