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BDS 3 Sem 1 > Orofacial sensation > Flashcards

Orofacial sensation Flashcards

1
Q

How do we perceive the world around us?

A

Through sensory stimuli.

The sensations can be preceve through general and special sensations

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2
Q

What are the importance of sensory preception?

A
  1. Sensation
  2. Control of movement
  3. Maintaining arousal/cortical consiousness - e.g. maintaining arousal when there is pain
  4. Safety - e.g. smell
  5. For future reference - brain recognition
  6. Emotions - e.g. self explanation
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3
Q

What are the main types of sensory receptor in the body?

A
  1. Photoreceptors - light
  2. Chemoreceptors - taste, smell, pH
  3. Thermoreceptors - temperature
  4. Mechanoreceptors - mechanical forces like touch, pressure, sound
  5. Nociceptors - pain
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4
Q

What are some of classification of sensory receptors based on speed of adaptation?

A
  1. Slowly adapting - slowly adapting receptors are related to nociception - think about tooth ache, the stimulus is continuous but also the receptor will be affected continuously - think about ongoing tooth ache
  2. Rapidly adapting - example is a mechanoreceptors relating to light touch - the response is quick but the touch perception is reduced quick - the sensation occurs only due to intial stimulus and reduction of stimulus
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5
Q

What are some of classification of sensory receptors based on speed of adaptation?

A
  1. Slowly adapting - slowly adapting receptors are related to nociception - think about tooth ache, the stimulus is continuous but also the receptor will be affected continuously - think about ongoing tooth ache
  2. Rapidly adapting - example is a mechanoreceptors relating to light touch - the response is quick but the touch perception is reduced quick - the sensation occurs only due to intial stimulus and reduction of stimulus
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6
Q

What are the classification of sensory receptors based on the source of the stimuli?

A
  1. Exteroceptors - provide information from the external environment - e.g. touch, pressure, temperature
  2. Enteroreceptos - provide information from the internal environment - blood pressure, plasma osmolality, blood pH
  3. Proprioceptors - provide information from the musculoskeletal system (position sense) - muscles, tendons and the joints
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7
Q

What is kinaesthesia?

A

It is the awareness of the position and movement of the parts of the body by means of sensory organs (proprioceptors) in the muscles and joints.

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8
Q

What are the essential receptors for kinaesthesia?

A
  1. Exteroceptors: in eye, ear and skin
  2. Proprioceptors: in muscles, tendons and joints
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9
Q

What are some of exteroceptors located in the oral cavity?

A
  1. Receptors in the PDL
  2. Receptors in alveolar mucosa
  3. Receptors in gingiva
  4. Receptors in periosteum of the jaw bone

They inform about the external loading when for example we chew

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10
Q

What are some of the proprioceptors in the oral cavity?

A
  1. Muscle spindles in mastictory muscles
  2. TMJ spindles
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11
Q

What is the basic pathway pf sensory processing in the brain?

A

The simple model is:
1. Sensory input - stimuli
2. Integration - understanding of stimuli
3. Perception - feeling of a certain sense
4. Motor response

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12
Q

What is the basic pathway of the stimulus to the somatic sensory area in the brain?

A
  1. Stimulus detected by receptors
  2. The signal is propogated via the sensory nerve by ascending sensory pathway
  3. The stimulus reaches the somatic sensory area in the brain
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13
Q

How does the sensory information travel from the teeth?

A

The information from the teeth and supporting structures transmitted to the brain via the trigeminal nerve.

In certain situations, the infromation transmitted from different teeth may converge into the same secondary neruon from the primary neuron thus the brain may process the pain sensation as non-localised thus localisation of pain could be a clinical problem .

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14
Q

Please explain the pain and temperature pathway of the spinal trigeminal tract?

A
  1. Intial stimulus occurs
  2. Primary neuron caries the signal from the sensory ogran to the trigeminal ganglion
  3. From the trigeminal ganglion, primary neuron carries it below to the spinal trigeminal nucleus where a cross over occurs and the signal it transducted to the secondary nucleus
  4. The secondary neuron through the ventral trigeminal leminscus and crus cerebri
  5. The final transduction to the ventral posteromedial nuceleus and later the signal is transducted to postcentral gyrus
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15
Q

Please explain the touch pathway of the sensory trigeminal tract?

A
  1. Initial stimulus occurs
  2. Primary neuron caries the signal to the trigemina ganglion
  3. After, the primary neruon caries the signal to the main sensory trigeminal nucleus where transductio of the signal occurs to the secondary neuron
  4. The secondary neuron propogates the signal through the crus cerebri towars the intralaminar nuclei
  5. The final transduction to the intralaminar nuclei and later the signal is transducted to postcentral gyrus
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16
Q

Why is the oral cavity one of the most densely innervated parts of the body?

A
  1. It is linked to the key role of oral sensorimotor control of the oral motor functions
  2. Mouth contains a large range of different tissue types in close proximity and constant interaction
  3. Oral sensations provide an important interface experience: internal and external surface of the body
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17
Q

What are the types of principal somatosensory receptors that are innervating the oral tissues?

A
  1. Mechanoreceptors that detect touch - mostly A-beta receptors but sometimes also C type receptors
  2. Nociceptors that detect pain and temperature changes - A-delta and C receptors
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18
Q

What is the importance of periodontal mechanoreceptors in clinical prectice?

A

They enable patients to detect new restoration which are high in occlusion

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19
Q

What is the purpose of TMJ receptors?

A

They function as pain receptors and proprioceptors. They may act as velocity detectors and static-position of the TMJ detectors.

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20
Q

How do we know that the tongue is so sensitive?

A

Because during two-point discrimination test, the tongue can detect 2 distinct points at around 1.4mm distance between them.

This sensitivity is related to tongue function and can be damped with local anaesthetics.

Tongue is also very very sensitive to temperature changes especially o n the dorsum area.

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21
Q

What is osseoperception?

A

It is a type of perception that occurs int eh absence of a functional periodontal mechanoreceptive input.

The mechanoreceptors are derived from TMJ, muscles or periosteal mechanoreceptors.

They provide mechanosensory infromation for oral kinaesthetic sensibility in relation to the jaw function and the contacts of artificial teeth.

22
Q

What is oral stereognosis?

A

It is the ability to recognise and discriminate forms. Oral stereognosis is the ability to feel depth and understanding of 3 dimentions of objects.

Oral stereognosis can be used to measure oral functions.

Oral stereognosis is influences by forms, size and surface characteristics of the test piece.

Oral steregnosis is associated with health.

Oral stergnosis is HIGHLY DEPENDENT ON PERIODONTAL MECHANO RECEPTORS.

PULP IS NOT INVOLVED

23
Q

What is pain?

A

An unpleasant sensory and emotional experience associated with, or resembling that associated with, actual or potential tissue damage.

24
Q

What is somatic pain?

A

It is pain that can usually be attributed to one area of the body.

The somatic pain can be separated into superficial pain (usually related to skin stimuli or musculoskeletal stimuli) and deep pain (usually derived from damage to the deep organs.

25
Q

What are the factors that affect pain preception?

A
  1. Intensity of the stimulation or tissue damage
  2. Emotions
  3. Past experience and memories of pain
  4. Other concomitant sensory experiences
  5. Sex, ethnicity and age
  6. Placebo effect
26
Q

What are the two different types of pain and WHAT FIBRES are responsible for them?

A
  1. Fast pain - sharp pain that is well localised and has a short duration - facilitate by A-delta fibres
  2. Slow pain - aching, burning pain that is poorly localised and is long in duration - involves unmyelinated C fibres
27
Q

What causes pain?

A
  1. First there is injury or tissue damage
  2. That leads to a release in chemicals
  3. Some chemicals are able to actuallly activate nociceptors - like potassium
  4. Other are able to sensitise the nociceptors making them more excitable - like prostaglandins
28
Q

What is antidromic activation of nociceptors? Explain how it relates to the ‘hot pulp’ syndrome.

A

it is belied that in some cases, injury that is detected by the receptor through orhodromic means, meaning due to the injury itself, may cause propogation of the action potential to other receptors thus causing the pain to intensify through Substance P release.

Hot pulps:

  1. In ‘hot pulps’ the pain from the lesion is able to causes antidromic activation though the stimulus thus releasing substance P and Calcitonin gene related peptide (CGRP)
  2. Substance P is able to induce oedema formation through plasma extravasation
    and also cause mast cells degranulation, releasing histamines which activate more nociceptors
  3. CGRP are able to cause aditional oedema through dilation of peripheral blood vessels
  4. The increase in oedema causes an additional release of bradykinin which activates more nociceptors
  5. Through this multi step process, patient has a large number of nociceptors released thus causing hyperlgesia meaning the action potential threshold is considerably lower
29
Q

How does some patient adapt so quickly to dental occlusal change or rehabilitative procedures?

A

It relates to central sensitisation and neuroplasticity.

Central sensitisation is process of shifting of the sensation by the central nervous system due to new stimuli.

Neuroplasticity is a process in which the central nervous system may change it’s ability to detect different stimuli.

The adaptation to the new stimuli occurs first to central sensitisation and lead to the changes to the face sensorimotor cortex due to neuroplastic changes.

30
Q

What are the two main characteristics of central sensitisation?

A
  1. Allodynia - pain due to a stimulus that does not normally provoke pain
  2. Hyperalgesia - increased pain form a stimulus that normally provokes pain
31
Q

Of what 3 parts is the spinal nucleus of the trigeminal system composed of?

A
  1. Oralis
  2. Interpolaris
  3. Caudalis

The first order A-delta and C fiber neuron will always go through the Caudalis

32
Q

What is the main theory which is used to explain pain and pain perception?

A

Nerumatrix theory.

It states that pain is a multifactorial feeling thus multiple factors regulate it like:
1. Cognitive-related to brain
2. Sensory signaling systems
3. Emotions-related brain area
4. Pain preception
5.Action programs
6.Stress-regulation programs

33
Q

What is referred pain?

A

It is the pain from internal organs is felt as pain in more superficial region of the body due to visceral cross-over

34
Q

What are neuralgias?

A

It is pain that relates to nerve pathways.

In the dental senario it could be due to compression of the trigeminal sensory root or due to degenerative changes in myelinanted fibres in the ganglion

35
Q

What is phantom pain?

A

It is a sensation that can occur in a part of the body that have been amputated or extracted (e.g. wisdom teeth).

This occurs due to hyperactivity of the neurons in spinal cord or trigeminal nucleus

36
Q

What nerve fibres are present in the pulp?

A

A-beta
A-delta
C unmyelinated fibres - close to the pulp

37
Q

What are some of the factors that influence susceptibility of nerve fibre to LA?

A
  1. Size of nerve fibre - smallest to largest: C, A-delta, A-beta
  2. State of myelination
  3. Rate of firing
38
Q

What is the importance of taste and smell?

A
  1. Protective/survival function
  2. Elicit physiological responses
  3. Modulate masticatory movement and initiation of the swallowing reflex
39
Q

What are the factors that affect taste?

A
  1. Age
  2. Hunger
  3. Smoking
  4. Obesity
  5. Pregnancy
  6. Disease
  7. Taste adaptation
40
Q

What are the primary taste sensations?

A
  1. Sour
  2. Salty
  3. Sweet
  4. Bitter
  5. Umami
41
Q

What are the papilla involved in taste?

A
  1. Vallate papilla
  2. Foliate
  3. Fungiform
42
Q

What is the design of the taste buds?

A

Taste buds were designed to recognise toxins in the food - that is why the threshold to bitter taste is considerably lower than to something sweet.

They look like onions with microvili exposed to the chemical stimuli and taste afferent on the conter side.

42
Q

What are the 3 areas of the body that are able to detect taste and what nerves are able to carry the action potential form those areas?

A
  1. Anterior 2/3 of the tongue - nerve supply: Chorda tympani - VII
  2. Posterior 1/3 of the tongue nd pharynx - nerve supply: Glossopharyngeal - IX
  3. Anterior epiglotis and larynx - nerve supply: Vagus - X
43
Q

What are some of the common taste disorders?

A
  1. Ageusia - total loss of taste
  2. Dysgeusia - taste distortion
  3. Hypergeusia - increased sensitivity
  4. Hypogeusia - decreased sensativity
  5. Phantom Taste Perception
44
Q

How can we separate the aeitology of taste disorders?

A
  1. Due to transport loss - interfere with access of a tastant to the taste bud - associated with xerostomia
  2. Due to sensory loss - Injury to the receptor cells - could be due to drugs, inflammatory disease or other
  3. Due to neural loss - damage to the gustatory afferent nerves and the central gustatory pathways - for example after third molar extractions or neoplasma in the oral area
45
Q

In which space does smell reception occur?

A

The smell reception occurs in the area known as the olfactory membrane - which is a pigmented yellowish-brown membrane that is located in the mucosa of each of the nostrils. It is an areas that sit in between the cribiform plate.

The epithelium ahs bipolar nerve that carry the stimuli from the receptors to the olfactory bulb.

Before being transported, the chemical of smell are first desolved in mucos released by the bowman gland.

46
Q

What conditions must the chemical meet in order to become detected and cause an olfactory stimulus?

A
  1. Must be volatile
  2. Must have sufficient water solubility
  3. Must be lipid soluble

]4. Must have a minimal concentration and minimal time of exposure to be detected

47
Q

What are the common olfactory disorders?

A
  1. Anosmia - total loss
  2. Dysosmia - distortion of taste
  3. Hyperosmia - increased in smell sensitivity
  4. Hyposmia - decrease in smell sensitivity
  5. Presbyosmia - loss of smell due to aging
48
Q

What is the aetiology of smell related disorders?

A
  1. Transport loss - loss in interference between the odorant to the olfactory epithelium - e.g. in swollen nasal mucuous
  2. Sensory loss - injury to receptor cells - e.g. after exposure to toxic chemicals
  3. Neural loss - due to damage in the olfactory afferent nerve and the central olfactory pathways - e.g. due to neoplasms
49
Q

What are some of the possible oral sources of smell and taste disorders in the elderly?

A
  1. Oral trauma - burns, lacerations etc.
  2. Oral diseases and symptoms - dental caries, periodontal diseases, NG, NPD etc
  3. Treatment of oral and systemic diseases - Chlorexedine use and other
50
Q

What are peridontal mechanoreceptors, what is their function and what is their make up and ability?

A

Periodontal mechanoreceptors are ruffini type receptors that are within periodontal ligament.

They regulate the forces applied by the teeth in occlusion and mastication.

Response of the receptors vary ith the force applied to the tooth, but there is greater sensativity at low force levels.

This allows the mechanoreceptors to aid patient with finding high spots on restorations

BDS 3 Sem 1 (21 decks)

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