Orofacial sensation + mastication Flashcards
What are the TWO speeds of adaptation and their examples?
- Tonic (slowly adapting e.g. nociceptors, muscle stretch receptors, joint prioprioceptors)
- Phasic (fast adapting e.g. touch, temperature)
What are the THREE types of receptors based on location of detection?
- 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)
What exteroceptors and interoceptors are involved in kinaesthesia?
Exteroceptors: eye, ear, skin
Interoceptors: muscles, tendons, joints
In terms of kinaesthesia, why might a patient panic after sudden lowering of the dental chair?
It takes time for the pt to reorientate using extero/interocepters.
What are the exteroceptors and interoceptors related to the oral cavity?
Exteroceptors: PDL, alveolar mucosa, gingiva, periosteum
Interoceptors: proprioceptors (muscle spindles, TMJ receptors)
Sensory information is coded with what FOUR aspects?
- Modality (type of energy e.g. light, heat, odour)
- Location
- Intensity
- Duration
What sensation travels in the spinothalamic tract?
- Pain
- Temperature
- Crude touch and pressure
- Tickle/itch
- Sexual sensations
What sensation travels via the dorsal column-medial lemniscal pathway?
- Fine touch, fine pressure
- Proprioception
- Vibration
What information do A-alpha fibres carry and where are the cell body and synapse of the first order neuron?
- Proprioception
First order neuron
- cell body: mesencephalic nucleus (midbrain)
- synapse: motor nucleus (pons)
What information do A-beta, A-delta/C fibres carry and where are the cell body and synapse of the first order neuron?
A-beta (touch)
- synapse: Chief sensory nucleus (pons)
A-delta/C (pain, temp)
- synapse: Spinal nucleus (medulla)
- Both cell body: trigeminal ganglion
What FOUR types of receptors can mechanoreceptors in the mouth have, and are they slow or fast adapting?
- Merkel cell (slow)
- Ruffini endings (slow)
- Meissner corpsuscles (fast)
- Pacinian corpuscles (fast)
What type of receptors do a-delta and C fibres have?
Free nerve endings
True of false: Lower touch threshold mean higher two-point discrimination.
True
my rationale: the more receptors activated, the more information and therefore discrimination there is.
What THREE areas of the oral cavity have no sensitivity to hot/warm?
Gingiva, Buccal mucosa, Hard/soft palate
Which is more superficial and has more receptors: warm or cold receptors?
Cold receptors.
What type of receptor endings do hot/cold receptors in the mouth have?
Free nerve endings.
What type of receptor endings do periodontal mechanoreceptors in the PDL have?
Ruffini type endings.
What is fremitus?
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)
What THREE types of nerve endings are found in the TMJ, and what do they sense?
- Free nerve endings (pain)
- Ruffini endings + GTO (static mechanorecetor - jaw position)
- Pacini corpsucles (dynamic mechanoreceptor - extremes of joint displacement ie. opening, protrusion, lateral excursion)
What do rapidly adapting and slowly adapting proprioceptors in the TMJ detect?
- Rapidly adapting (velocity)
- Slowly adapting (static position)
What is oral stereognostic ability (OSA)?
The ability of the mouth to discern shape, size and surface characteristics of an object placed in the mouth.
What FOUR factors may decrease OSA?
- Age (older = lower OSA)
- Teeth (edentulous = lower OSA)
- Severe periodontitis
- Duschenne muscular dystrophy (reduced muscle spindle function - affects interocclusal 5mm discrimination)
What parts of the oral cavity are involved with OSA?
Mainly the tongue mucosa and palate
- To a lesser extent: Teeth with their PDL (periodontal mechanoreceptor [PMR])
Above what thickness do TMJ receptors and jaw muscle receptors detect things interocclusally?
5mm or more to detect something.
In an edentulous patient, what are TWO things that may increase OSA?
- Dentures
- Oral implants
True of false: RCT decreases PMR sensation?
False, it has no effect on periodontal mechanoreceptors.
What are FOUR functions of oral stereognosis?
- Denture adaptation
- Mastication
- Swallowing
- Speech
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.
What is Stomatodynia? (also, break up the meaning of the prefix and suffix)
Stomatodynia = Burning Mouth Syndrome Stomato = mouth Dynia = pain
What is Allodynia?
Pain due to stimulus that does not normally provoke pain (e.g. light touch)
What is the difference between unimodal and polymodal nociceptors?
Polymodal responds to many stimuli.
What TWO things can sleeping/silent nociceptors cause?
- Hyperalgesia (increased pain to painful stimuli)
- Allodynia (pain to non-painful stimuli)
What is meant by ‘Double pain sensation’?
Fast pain (a-delta fibres) with slow pain (C fibres).
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
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)
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)
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)
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
True of false: antidromic stimulation can lead to peripheral sensitisation.
True