Orofacial Sensations Flashcards
1
Q
List some functions of sensory info
A
Protection/safety Control of movement Future reference Maintain consciousness Emotion
2
Q
How are receptors classified? And what are the different types?
A
By type:
- Mechano (hearing, touch)
- Chemo (taste, smell)
- Photo (light)
- Thermo (temperature)
- Proprio (position)
- Noci (pain)
By range
- Telo (source of stimulus far from target, e.g. sight, sound)
- Extero (source of stimulus must make contact e.g. touch, smell, taste)
- Intero (detect internal conditions e.g. carotid sinus baroreceptors)
By speed of adaptation:
Phasic: fast e.g. touch
Tonic: slow e.g. pain
3
Q
What is kinaesthesia? How is it different from proprioception?
A
Detection of position of body parts, involves use of teloreceptors (sight, sound), internoreceptors (proprioceptors) and exteroreceptors (touch+pressure)
Proprio different in that it only detects muscles/joints–>part of kinaesthesia
4
Q
What are the main types of extero + interoreceptors in the oral cavity and where are they found?
A
Extero: -PMR’s: PDL, gingiva, alveolar mucosa, periosteum
Intero: -TMJ receptors: muscle spindles
5
Q
What is the pre-dominant type of PMR receptor? They are most sensitive to force applied in which direction? Are they more sensitive to high force or low force?
A
- Ruffini endings
- Force applied in labial direction
- Low force
6
Q
What do TMJ receptors mainly consist of? What is their function?
A
- Ruffini endings + GTO’s: Static mechanoreceptors that detect proprioception (slow adapting)
- Nociceptors: Detect pain
- Vater-pacinian corpuscles: Dynamic mechanoreceptors for proprioception (fast adapting)
7
Q
What factors affect conversion of stimulus to a signal/influence properties of signal?
A
Modality
Intensity
Duration
Location
8
Q
What is the distribution of cold receptors relative to warm receptors?
A
-More of cold + cold located more superfically
9
Q
How is referred pain produced?
A
When two primary neurons from different locations converge, resulting in receptor field of secondary neuron encompassing both primary neurons. This results in painful stimulus in one area potentially also causing painful sensations in another location.
10
Q
What can measuring oral stereognosis give an indication of?
A
- Effectiveness of therapy
- Extent of oral dysfunction
- Current oral function
11
Q
What functions does OSA play physiologically?
A
- Control of mastication
- Speech
- Swallowing
- Denture adaptation
(think of this like proprioception)
12
Q
What can affect OSA?
A
Test piece
-Size, shape, order of presentation, texture
Subject:
- Number of teeth present
- All teeth present>dentures>edentulous/no denture
- Age
- Perio breakdown
- Muscle spindle dystrophy
External factors:
-LA reduce OSA
13
Q
What are the types of receptors involved in OSA?
A
- Muscle spindles
- PMR’s
- Tongue + palate mucosal receptors
- TMJ + jaw muscle receptors
14
Q
List 3 different types of abnormal pain response.
A
Allodynia: Non-painful stimulus produce pain
Phantom pain: No stimulus but pain produced
Neuropathic pain: pain due to damage to somatosensory system
15
Q
What are some factors that affect pain intensity?
A
- Race/ethnicity
- Emotions
- Intensity of stimulus/extent of damage
- Concomitant experience
- Placebo
- Memory of experience
16
Q
What is a polymodal nociceptor?
A
Detects pain from multiple sources (i.e. chemical, thermal, mechanical) rather than from just one source type
17
Q
What do nociceptors respond to?
A
Thermal, chemical, mechanical
18
Q
Explain the double pain sensation?
A
A-delta fibres located more superfically and thus stimulated first
Results in initial short, sharp pain sensation that is well localised
C fibres are located deeper and thus are stimulated a short time after, resulting in a dull, throbbing poorly localised sensation (the receptors are polymodal)
19
Q
What chemicals can produce pain and sensitise nociceptors?
A
Produce pain:
- Potassium: damaged cells
- Bradykinin: damaged vessels
- Serotonin: damaged endothelial cells + platelets
- Histamine: mast cells
Sensitise:
- Prostaglandin: From damaged cells
- Substance P: from primary afferent neurons
20
Q
Explain antidromic activation of receptor endings.
A
Rather than nociceptors detecting pain and transmitting signal to CNS, the opposite occurs.
I.e., CNS sends signal to nociceptors to release substances which cause them to become sensitised (e.g. substance P)
21
Q
Describe what occurs in hot pulps.
A
Release of substance P:
- Release of histamine-> increase pain in nociceptors
- Cause increased permeability + extravasation -> edema -> Trigger release of bradykinin
CGRP-> vasoliation->edema->release of bradykinin
-Bradykinin increases pain
22
Q
Explain central sensitisation?
A
- Activation of slow conducting C fibres
- Alters second messengers
- Activation of protein kinases
- Results in increased excitibility and synaptic efficiency
23
Q
What are the effects of P substance?
A
- Vasodilation
- Increased blood flow
- Increased blood pressure
- Increased permeability
- Synthesis of pro-inflammatory cytokines
- Chemotaxis of inflammatory cells
- Increased pain sensitisation
24
Q
What are WDR neurons?
A
-Detect both noxious and non-noxious (touch, pressure, temp,etc.) stimuli (i.e. responsible for both pain and non-painful stimuli)
25
What are the subdivision of the spinal nucleus?
- Oralis
- Interpolaris
- Caudalis
26
Explain the different theories of pain
- Specific: Specific neuron type detects pain
- Intensity: pain is not a sensation but an emotion, detected as pain after it exceeds a certain intensity
- Pattern: neurons produce different patterns which code for different types of pain
- Gate control:
- Small neuron stimulates pain by inhibiting inhibitor neuron and stimulating projection neuron
- Large neuron inhibits pain by stimulating inhibiting neuron and inhibiting projection neuron
Neuromatrix:
- Pain is sensation produced by neurons in the brain
- These neurons can be triggered to fire by signals from the periphery or can fire independantly
27
What are some contributing factors to the neuromatrix?
```
Endocrine, Immune, Autonomic activity
Afferent
Medullary descending inhibition
Pain perception
Pain behaviour
Psychosocial and health factors
Attention
Pathological input
Central nervous system plasticity
```
28
Where are the referred pain areas for the temporalis muscle?
- Supraorbital ridge
- Temporal headache
- Side of face
- Upper jaw + teeth
29
Where are the referred pain areas for the upper part of the masseter?
-Upper + lower jaws and teeth
30
Where are the referred pain areas for the lower part of the masseter?
-Lower jaw
-Supraorbital ridge
(this was the one that made the least sense)
31
Where are the referred pain areas for the lateral pterygoid?
- Cheeks
| - TMJ
32
Where are the referred pain areas for the sternal head of SCM?
- Sternum
- Occipital area
- Top of head
- Side of face
33
Where are the referred pain areas for clavicular head of SCM?
-Ear
-Behind ear
-Forehead
(arrow one)
34
What causes headache during stress?
- Clenching of scalp muscles
- Prevent blood flow to area
- Medications control bloodflow
35
What are some causes for neuralgia?
- Compression of trigeminal ganglion
- Peripheral nerve changes
- Degenerative changes in nerve fibres
36
What are the theories of dentine hypersensitivity?
Direct nerve detection: Stimulus directly detected by nerves in dentine-> disproved as nerves are too deep down + application of pain inducing substances to surface does not illicit pain
Odontoblast transduction: odontoblast detect stimulus/act as receptor and transmit signal to nerves-> disproved as processes do not extend all the way to surface, no evidence of neurotransmitters, odontoblast electrical threshold too low to stimulate nerves
Hydrodynamic theory: movement of water in tubules detected by nerves and interpreted as pain (mainly outward flow e.g. by air drying)
37
What nerves are particularly susceptible to LA? What order do nerves get de-sensitised?
- Smaller nerves
- Myelinated nerves
- Fast conducting nerves
In order first to last:
- C-fibres
- A delta
- A beta (crude touch + pressure)
38
What are the functions of taste?
- Protective: poisons taste bitter/unpleasant
- Stimulate physiological response i.e. digestion and absorption
- Elicit mastication and swallowing
39
What are the factors that affect taste perception?
- Age
- Pregnancy
- Temperature
- Hunger
- Disease
- Smoking
- Adaptation
- Order of eating
- Obesity
40
What are the primary taste sensations and what triggers them?
```
Umami: MSG
Sweet: carbohydrates (poly+disaccharides)
Sour: hydrogen ions
Salty: sodium ions
Bitter: alkaloids + nitrogen
Fat: lipids
```
41
What extra lingual areas can have taste buds?
- Pharynx
- Larynx
- Epiglottis
- Palate
42
How can taste acuity be measured?
Detection threshold: lowest concentration at which substance can be distinguished from de-ionised water but not necessarily recognised
Recognition threshold: minimum concentration of tastant needed to recognise taste type
43
How can damage to taste buds from smoking increase blood pressure?
- Loss of sensitivity to salty taste
| - Take in more sodium->increased BP
44
What is the structure of a taste bud?
- Taste cells
- Sustentacular support cells
- Grouped together in sphere
- Receptors at cell tip
- Life span 1-2 weeks
- Trophic effect: can regenerate
45
How is taste transmitted from the taste bud?
- Tip of receptor cells detect stimulus
- Causes electrical change at base of cell
- Results in release of neurotransmitters that stimulate nerve at base
- Nerve carries signal to brain
46
What is the pathway for taste transmission to brain?
Anterior 2/3 tongue (chorda tympani): cell body geniculate ganglion
Posterior 1/3 (glossopharyngeal): petrosal ganglion
Pharynx/larynx (vagus): Nordose ganglion
All travel to nucleus of the solitary tract to synapse with secondary neuron
Then travel to ventral posterior medial nucleus to synapse with tertiary neuron
Gustatory cortex
47
How can taste disorders cause obesity?
- Decreased sensitivity to fat
| - Results in increased fat intake and delayed satiary response
48
What are the different types of taste disorders?
```
Aguesia: loss of taste
Dysguesia: altered taste
Hyperguesia: Increased taste
Hypoguesia: decreased taste
Phantom taste: taste detected when stimulus not present
```
49
How can taste disorders occur/what mechanism can they occur?
- Transport loss: prevent stimulus from accessing taste bud
- Receptor loss: damage to the taste bud
- Neural loss: damage to nerves making up pathway to gustatory cortex
50
What are the functions of smell?
- Some odours can cause repulsion/nausea
- Connections with amygdala-->elicit emotional response
- Initiate alimentary responses e.g. salivation, gastric secretions
51
Why does sniffing increase smell?
- Causes more air to come in contact with the olfactory epithelium
- As olfactory epithelium is located superiorly normally only 5% of air comes in contact with it
52
What are the requirements a stimulus must have in order to be detected by olfactory epithelium?
- Volatile enough to be carried in air
- Hydrophilic enough to pass through mucous layer
- Hydrophobic enough to pass through cell membrane
- Present in high enough concentration to reach detection threshold
53
What are the types of smell?
- Putrid
- Pungent
- Musky
- Peppermint
- Floral
- Ether
- Camphoraceous
54
How do smell receptors distinguish between different types of smell?
-Different shaped cavities formed by receptor cells correspond to different molecules that have different smells
55
What are some olfactory disorders?
-Anosmia: loss of smell
-Dysosmia: altered smell
-Paraosmia: Altered smell sensation causing odours
to be detected as unpleasant sensation
-Phantosmia: Detection of smell without stimulus
-Agnosia: Unable to discriminate between odours
Hyposmia: decreased smell
Hyperosmia: increased smell
56
What disruptions to pathway can cause smell disorders?
Transport loss
Sensory loss
Neural loss
57
What causes halitosis?
- Volatile and non-volatile sulfur compounds
- Tend to get trapped between tongue papillae or gingival sulcus
Can be caused by:
- Perio disease
- Caries
- Systemic disease: TB, pneumonia, lung infection, tonsilitis
58
What external factors can cause taste/smell abnormalities?
```
Trauma
Anaesthetic
Rem Pros
Tumours
Tumour treatment (e.g. radiotherapy)
-Dry mouth
-Infection
-Stomatitis
-Pain
```
59
What is the vermonasal organ?
- Also receives olfactory information
- Linked to limbic system
- Thought to modulate sexual + social behaviour
60
What constitutes flavour?
Taste + smell + hunger + temperature + texture + emotions/previous experience
61
Which muscle are responsible for grinding and which for crushing?
Grinding:
Medial + lateral pterygoid
Crushing:
Temporalis
Masster
62
What functions do jaw openers/closers have?/ What are they designed to do to help closing + opening?
Jaw opening: force
| Jaw closing: velocity and displacement
63
What is the function of the digastric?
- Opening mouth
| - Raise hyoid bone
64
What is the function of mylohyoid?
- Raise hyoid bone
- Open mouth
- Positions tongue
65
What is the function of temporalis?
- Closing
- Retrusion
- Maintains mandible during rest
66
What is the function of lateral pterygoid?
Inferior head
Opening
Lateral excursion
Protrusion
Superior head:
Similar function +
Hold articular disk in place during closing
67
What is the function of the medial pterygoid?
- Closing
- Protrusion
- Assists lateral pterygoid in lateral excursions
68
What is the function of the masseter?
- Closing
- Some protrusion
- Generation of bite force in different directions
69
What is the difference between the deep and superficial head of the masseter?
- Deep (most active but to a lesser extent in incisal clenching)
- Superficial: less active but active to greater degree during incisal clenching
-Deep has more vertical fibres and shorter sarcomeres (20% shorter)
70
What is a motor unit and what are the different classifications?
-Motor neuron + muscle fibres innervated by it
S: slow contraction, fatigue resistant
Fast resistant: fast contraction, fatigue resistant
Fint: fast contraction, intermediate fatigue
FF: fast fatiguable
71
Which type of tasks are the slow/ fast motor units responsible for?
Slow: postural tasks
Fast: strong/rapid bit tasks
72
List the size/diameter of the motor neurons in ascending order
S, FR, Fint, FF
73
List the order in which motor neurons get activated
S, FR, Fint, FF
74
List the order of strength/speed of contraction of motor units from strongest to weakest
FF, Fint, FR, S
75
What are they myosin chain isotypes found in jaw muscles?
I, IIA, IIX
76
What is the implication of having hybrid fibres in jaw muscles (more than one isoform?)
- Allows fine graduation of movemment
- Allows for some adaptation capacity
- Allows for wide variety of tasks (speech, sing, swallow, mastication, yawn)
77
List in ascending order the rate of firing of neurons in each motor unit type.
S, FR, Fint, FF
78
List, in ascending order, the precision of movement of each motor unit type
FF, Fint, FR, S
79
What can determine the fibre types present in jaw muscles?
- Age
- Food
- Hormones
- Adaptation
- Craniofacial morphology
80
How does age affect myosin chains?
-Few neonatal myosin with age
81
How do dentures influence myosin chain composition?
-Decreased slow fibres and increased hybrid fibres
82
Describe the muscle contraction sequence
1. Ach binds Ach receptors at motor end plate causing opening of sodium channels and depolarisation
2. Depolarisation travels down T tubules causing sarcoplasmic reticulum to release calcium
3. Calcium binds to troponin->causes change to tropomyosin that allows cross links to form
4. This results in muscle contraction
83
What factors affect maximum voluntary bite force?
- Condition of teeth
- Pain threshold
- Strength of muscle contraction
- Rectangular face + deep bite more than narrow face with open bite
- Area of mouth: strongest in first molar region
- Gender: higher in males
84
What do muscle spindles detect?
stretch
85
What are intra/extrafusal fibres innervated by?
Intra: Gamma neuron
Extra: Alpha neuron
86
What is the distribution of muscle spindles like in jaw closers vs jaw openers?
- More in jaw closers than openers
- Jaw closers get stretched on opening
- Jaw opener stretech limited by teeth during closing
87
Why do ends of intrafusal fibres contract simultaneously with extrafusal fibres?
-To keep muscle spindle taunt and preventing slackening, thus allowing it to keep stretch sensitivity
88
What do golgi tendon organs detect and what forces are they sensitive to?
- Tnesion
| - Small forces
89
Where are PMRs most highly concentrated? What do they detect at each region? What is the speed of adaptation of PMR's at each location?
-Most concentrated at mid-root region: detect pain and possibly fine touch (cell bodies in trigeminal ganglion)
(fast adapting)
-At root apex detect proprioception (cell bodies in mesencephalic nucleus)
(slow adapting)
90
How long does it take for PMR's to regenerate?
6 weeks
91
What are the functions of PMR's?
- Efficiency + Control of mastication
- Modulation of jaw reflex
- Adaptation e.g. to prosthesis
92
What situations may require adaptation of muscle length? How long does an adult take to adapt?
- XO
- Ortho
- Surgery
A few weeks
93
What type of pathology can affect motor units?
Poliomyelitis: Destruction of motor neurons in anterior ventral spinal cord
Multiple schlerosis: Autoimmune demyelination of motor neurons
Myasthenia gravis: Prevent binding of Ach at motor end plate
Muscle dystrophy: Decreased contraction of muscles
94
List the masticatory apparatus.
Contain bolus:
Palate
Lips
Cheeks
Move bolus:
Tongue
Muscles
TMJ
Breakdown bolus
Teeth
Salivary glands
95
What are the phases of the masticatory cycle?
Fast close
Slow close
Slow open
Fast open
96
What are the features of carnivore TMJ/masticatory system?
- Sharp teeth
- Cylindrical TMJ (for hinge movements)
- Muscle optimal length at max opening
- Fast muscle action
- Temporalis dominant
Omnivore=mix of herbivore and carnivore
97
What are the features of herbivore TMJ/masticatory system?
- Flat teeth
- Saucer shaped TMJ (grinding movement)
- Slow muscle action
- Masseter dominant
Omnivore=mix of herbivore and carnivore
98
What are the functions of mastication?
1. Digestion (some feeds have absolutle need, partial need, no need)
2. Detect unwanted objects
3. Increase action of salivary enzymes
4. Allows sensation from taste buds
5. Mental satisfaction
6. Has congnitive functions
99
What is masticatory ability/performance? What can affect it? How is it measured?
-Ability to pulverise test food
Affected by:
- Number of teeth in particular <20 teeth
- Efficiency of muscles
- Properties of test food
- Implants
- Dentures
Measured by giving patient 8mmx8mmx8mm cube, get them to chew a preset number of strokes and use sieving procedure to determine distribution of the size of resultant particles
100
What is selection (in terms of mastication)?
| What factors determine this process?
Selection: movement of food between teeth during mastication
Occlusal surface area
Number of teeth
Size of teeth
Shape of teeth
Size of food bolus
Shape of food
Amount of food in mouth
Neuromuscular activity of jaw, tongue and cheeks
101
What is breakage? (in terms of mastication)
Mechanical breaking/pulverisation of food into smaller particles by biting down after selection
102
What are the muscles of mastication?
Primary:
- Masseter
- Temporalis
- Lateral pterygoid
- Medial pterygoid
- Digastric
Accessory:
Suprahyoid:
- Mylohyoid
- Geniohyoid
- Stylohyoid
Infrahyoid:
- Omohyoid
- Thyrohyoid
- Sternohyoid
Others: SCM+trapezius
103
What receptors are used for mastication?
- Muscle spindles
- PMR's
- GTO's (detect low force)
- Mucosal receptors
- TMJ receptors
104
Describe the reflex arc:
1. Peripheral nerve receives signal
2. Signal travels to dorsal root of spinal cord
3. Primary neuron synapses with interneuron, allowing signal to reach integration centre
4. Inteneuron synapses with motor neuron
5. Motor neuron sends a signal to effector organ
6. Effector organ carries out action
105
What is the jaw closing reflex? What is it used for?
Also known as jaw jerk reflex
- Tapping on the chin causes jaw to close (activation of jaw closers)
- Used to maintain jaw rest position, especially while running
Monosynaptic
- Stretch of muscle spindle causes excitatory reflex in muscle of origin
- Receptor type: muscle spindle
- Nerve: muscle spindle afferent fibre
- Cell body: Mesencephalic (proprioception)
To make sense of this: muscle spindles detect jaw closer stretch, picked up by proprioception sense to control posture)
106
What is the unloading reflex?
-Inhibition of jaw closer/jaw jerk reflex when suddenly biting through hard food to adjust for decrease in resistance and avoid damage
107
What is the jaw opening reflex? What is it used for?
-Inhibition of jaw closing muscles, used to prevent injury due to sharp object in food (e.g. fish bone)
Stimulus: mechanical/noxious stimuli
Receptor: Pain/mechanoreceptors
Nerves: Trigeminal sensory nerves
Cell body location: Trigeminal ganglion
Disynaptic
108
What are some periodontal reflex?
- Tapping on tooth or high force causes disynaptic inhibition of jaw closers (similar to jaw opening reflex)
- Weak force on tooth causes excitation of jaw closers
- Also important in guiding teeth into occlusion + coordinating chewing
109
What are the theories of mastication?
Reflex theory:
-Food in oral cavity stimulate oral structures + PMR's
-Activates opening reflex
-Stretch stimulates muscle spindles
-Activates jaw closing reflex
(Not considered appropriate as this would mean rapid mastication)
Pattern generator theory:
- Central pattern generator (CPG) in brain stem sends alternatiing impulses to control jaw closers and openers
- Independant of peripheral input
Peripheral, cortical input + CPG theory
- Combination of CPG, peripheral and cortical imput that determines control of mastication
- CPG sets rhythm
- Peripheral/cortical input influences force, strength, duration
- Allows painful/conscious stimuli to interrupt CPG
- Also allows variation with different hardness
110
What are the stages of swallowing?
1. Masticatory/preparation phase
2. Oral/buccal phase
- Tongue presses itself to the roof of the palate and raises progressively posteriorly, forcing bolus backwards
3. Pharyngeal/laryngeal phase:
- Contact of bolus with pharynx/larynx sends signal to swallowing centre
- Soft palate forms velo pharyngeal seal with passvant's ridges->sealing off nose
- Hyoid bone moves anteriorly and superiorly widening pharynx dimension
- Larynx rises: allows epiglottis to close over the laryngeal inlet + vocal folds approximate sealing larynx and preventing respiration
4. Esophageal phase
- Pharo-esophageal sphincter opens
- Larynx lowers and becomes uncovered
- Soft palate lowers unsealing airway
- Allows respiration to resume
- Hyoid bone returns to rest position
111
What factors contribute to control of swallowing?
-Sensory input from oral cavity, pharynx, larynx, brainstem
-Swallowing centre located in ventral + dorsal region of brain stem
-Motor output: contained in nucleus, ambiguss, facial, trigeminal, glossopharyngeal, hypoglossal, cervical spine
Higher centres: electrical stimulation of motor cortex can stimulate swallowing
112
What is the gag reflex and what can trigger it?
-Unpleasant, abortive, spasmodic action with glottis closed
Triggered by:
- Fauces
- Posterior pharyngeal wall
- Base of tongue
- Soft palate
Patients can gag at sight of tray as easily conditioned reflex, but can be removed with training
