AGM Flashcards
1
Q
Where does the trigeminal system connect to the brainstem at?
A
Pons
2
Q
Name the 4 components of the trigeminal sensory nuclear complex
A
- Trigeminal main sensory nucleus
- Nucleus oralis
- Nucleus caudalis
- Nucleus interpolaris
3
Q
What makes up the trigeminal spinal nucleus?
A
- Nucleus oralis
- Nucleus interpolaris
- Nucleus caudalis
4
Q
Where is the trigeminal ganglion located?
A
In the trigeminal fossa of the temporal bone in the middle cranial fossa
5
Q
What neurons does the trigeminal ganglion contain?
A
1st order neurons for the trigeminothalamic tracts (pseudounipolar)
6
Q
Function of trigeminal main sensory nucleus
A
Site for synapse for touch
7
Q
Function of nucleus oralis
A
Receives nociceptive inputs, esp. from teeth –> essential for oral and dental pain (reflexes > sensation)
8
Q
Function of nucleus caudalis
A
Site for synapse for facial pain, hot & cold
9
Q
What does tractotomy at the nucleus caudalis result in?
A
Loss of ipsilateral facial pain, hot/cold; but can still feel touch
10
Q
Name structures which help in the identification of the nucleus caudalis
A
foramen magnum; end of IVth ventricle
11
Q
What do efferents of the motor root of peripheral trigeminal nerve supply?
A
Muscles of mastication
12
Q
Where are the primary afferent cell bodies of the peripheral trigeminal nerve found?
A
In the trigeminal mesencephalic nucleus
13
Q
What is unique about the motor root of the peripheral trigeminal nerve?
A
Primary afferent cell bodies are within the CNS
14
Q
Define ganglion
A
A collection of nerve cell bodies in the PNS
15
Q
Where in the brainstem is the motor nucleus located?
A
Pons
16
Q
Is the motor nucleus located medially or distally w.r.t the main sensory nucleus?
A
Medially
17
Q
What do afferents from the motor root of CN Vc supply?
A
From all muscle spindles and some peridontal ligament mechanoreceptors (PDLM)
18
Q
Role of the mesencephalic nucleus
A
Carries the primary afferent cell bodies of CN Vc
19
Q
Role of the motor nucleus
A
Site of synapse of the primary afferents of CN Vc
NOT IN TRIGEMINAL MESENCEPHALIC NUCLEUS
20
Q
Define pain
A
An unpleasant sensory and emotional experience that is associated with actual or potential tissue damage.
21
Q
Define nociception
A
The activation of neural pathways by stimuli that damage or threaten to damage tissues
22
Q
Describe the anatomy of a nociceptor
A
Free nerve ending at one terminal; with C-fibre or Ad-fibre
23
Q
Name the 2 types of fibre that could be present in a nociceptor
A
- C fibre
2. Ad-fibre (A-delta)
24
Q
Which nerve fibre gives slow, burning pain?
A
C fibre
25
Which nerve fibre gives fast, sharp pain?
Ad-fibre
26
Which nerve fibre has a faster conduction velocity?
Ad-fibre (5-30m/s)
| [vs C fibre - 0.2-2m/s]
27
Which nerve fibre has the smallest diameter size?
C fibre (0.2 - 1.5um)
28
Name 2 effects of substance P
1. Vasodilatation of arteries
| 2. Stimulates mast cells, which releases histamine and serotonin, which sensitizes nociceptors
29
Describe the axon reflex
When a noxious stimulus is applied to a cell, instead of travelling to the CNS, the action potential goes in the other way, up another branch, resulting in the release of Substance P.
30
Name some algogenic substances (7)
- H+
- Serotonin
- ATP
- K+
- Prostaglandins
- Histamine
- Bradykinin
31
Define the term "allodynia"
Allodynia refers to pain produced by a stimulus that would not normally produce pain
32
What results in allodynia?
Sensitization of nociceptors by the effects of an axon reflex, which lowers the threshold potential
33
Site of 1st synapse of the trigeminal sensory pathway
Trigeminal sensory nucleus
34
Site of 1st synapse of pain pathways
Trigeminal nucleus caudalis (+ oralis?)
35
What type of drugs are simple analgesics?
COX inhibitors / Non-steroidal anti-inflammatory drugs
36
Describe hyperalgeria
When a noxious stimulus is applied on Area X, the primary afferent neurone diverges and synapses, sensitizing the 2nd order neurone of Y. Hence, it takes a less than normal noxious stimulus to reach threshold of Area Y, causing increased pain from a stimulus that normally provokes pain.
37
Describe discrete pain
When a noxious stimulus is applied on Area X, the primary afferent neurone diverges and synapses, but it is insufficient to reach the threshold potential to excite 2nd order neurone of Y. Hence, pain is felt only in Area X.
38
Describe radiating pain
When a noxious stimulus is applied on Area X, the primary afferent neurone diverges and synapses, resulting in pain felt in both Areas X and Y. (Pain appears to spread beyond the area affected)
39
Describe "referred" pain
Pain appears originate from an area that is different to the injured area.
(usually from a deep to superficial structure/tissue that produces sensory activity e.g. maxillary sinus to teeth / heart to left arm)
40
Where in the primary somatosensory cortex does the pain neurones terminate?
Cingulate gyrus of the insula
41
List excitatory neurotransmitters
- Calcitonin gene related peptide
- Substance P
- Glutamate
42
List inhibitory neurotransmitters
- Endogenous opiods
- Glycine
- GABA
43
Name 2 similarities between the nociceptive nerves and thermoreceptive nerves
1. Both have free nerve endings
| 2. Both involve C fibres and A-delta fibres
44
What thermal stimuli are A-delta axons responsible for?
Cold
45
What thermal stimuli are C-fibres responsible for?
Warm & cold
46
Describe the trigeminal thermoreceptive pathway
Primary afferent neurone cell bodies in the trigeminal ganglion in the PNS
1st synapse at the trigeminal nucleus caudalis, takes the trigemino-thalamic tract to the contralateral thalamus
Synapse at the thalamus then at the somatosensory cortex
47
Actions of warm receptors in response to warming and cooling
Warming: Results in an increase in frequency of action potentials
Cooling: Results in transient inhibition
48
Actions of cold receptors in response to warming and cooling
Warming: Results in transient inhibition
Cooling: Results in excitation
49
List the 3 types of proprioceptors in the masticatory system
1. Joint receptors
2. Muscle spindles
3. Golgi tendon organs
50
Function of the secondary nerve endings
Detects length of fibres
51
Function of the primary annulo-spiral nerve ending
Detects length of fibres and speed of change of length
52
What are the two types of fibres that make up the muscle structure?
1. Extrafusal
| 2. Intrafusal
53
Where do the cell bodies of muscle spindles lie in?
Trigeminal mesencephalic nucleus
54
Where do muscle spindle afferents synapse in?
V motor nucleus
55
What happens when the muscle contracts?
Contractile ends contract; non-contractile portion remain taut, hence shortening the muscle
56
Role of muscle spindle (x3)
1. Receive information about muscle length
2. Acts to maintain muscle length
3. Load compensation
57
Name 3 types of joint receptors + where they can be found + function
1. Pacinian - in ligaments - acceleration
2. Golgi - in ligament - position
3. Ruffini - in capsule - movement
58
Where are golgi tendon organs found? What is their positioning in relation to muscle fibres?
Found in tendons; in series with muscle fibres
| Very few are also found in masticatory muscles
59
Function of golgi tendon organs
Play a role in (inhibitory) reflex - prevention of excessive stretch of muscle
60
3 roles of mastication
1. Breakdown of foodstuff in preparation for swallowing by increasing surface area for chemical digestion and release of chemicals for sense of taste
2. Stimulation of salivary flow (Reflex stimulated by chewing)
3. Growth and maintenance of oro-facial tissues
61
How important is mastication
Mastication can be:
- very important - for red meat and vegetables
- quite important - for white meat
- not very important - for fish, egg, bread, cheese, rice (not necessary but helps to speed up absorption)
62
Sequence of ingestion of food
- Stage I transport: From lips to cheek teeth
- Mastication (chewing)
- Stage II transport: From cheek teeth to back of tongue (bolus)
- Swallowing
63
Describe the chewing cycle
1. Opening
2. Fast closing
3. Slow closing
4. Intercuspal
64
Describe the movements of the working side of the condylar head during opening
Rotation around vertical axis, slight lateral movement and very slight posterior movement
65
Describe the movements of the non-working side of the condylar head during opening
Moves downwards, forwards and medially as described by Bennett's angle
66
Describe the movements of the working side of condylar head during closing
Moves medially to normal position in glenoid fossa and rotates back to normal orientation
67
Describe the movements of the non-working side of the condylar head during closing
Moves upwards, backwards and laterally as described by Bennett's angle
68
Describe the condylar movements during the chewing cycle.
During opening, the working end of the condylar head rotates around the vertical axis, making a slight lateral movement and very slight posterior movement. The non-working end moves downwards, forwards and medially.
During closing, the working end of the condylar head moves medially back to its normal position in glenoid fossa and rotates back to normal orientation, while the non-working end moves upwards, backwards and laterally.
69
Define reflex
A reflex is a predictable response to a given stimulus
70
What is reflex latency?
The time from stimulus to effect.
71
What is conduction time dependent on? (x2)
1. Neurone speed --> Fibre Type
| 2. Distance
72
Examples of stretch reflexes (x2)
Knee-jerk
| Jaw-jerk
73
Which receptor is involved in jaw jerk reflex?
Muscle spindle
74
What is the effect of the jaw jerk reflex?
Contraction of the masseter muscle
75
What are the roles of stretch reflexes? (x2)
- tonic: resist gravity; maintain posture
| - phasic: load compensation during chewing and stabilizes jaw during vigorous head movements
76
How is the rest/postural position maintained?
When at rest and active, there is minimal jaw elevator muscle activity. The passive response is that the jaw elevators are relaxed. It is difficult to demonstrate as the passive visco-elastics come from within muscles.
During vigorous movement, visco-elastic forces supplemented by stretch reflexes keep it there.
77
When is a protective reflex stimulated? Give an example of a protective reflex in the jaw.
Stimulated in response to a noxious stimulus.
| e.g. jaw "opening" reflex
78
How many synapses are there in the jaw opening reflex?
2
79
Effect of jaw opening reflex
- contraction of jaw depressors (i.e. jaw opening muscles: ABD, Mylohyoid, Geniohyoid) in animals
- in humans: inactivation of jaw closers (i.e. masseter, temporalis, medial pterugoid) - INHIBITORY JAW RFLEX
80
Role of the inhibitory jaw reflex
Prevents overloading of the masticatory system and facilitates opening to expel noxious material and minimize damage to intra/peri-oral structures
81
Response of inhibitory jaw reflex
Inactivation of jaw closing muscles - masseter, temporalis, medial pterygoid
82
Stimulus of jaw unloading reflex
Sudden closure following hard biting e.g. when a hard/brittle food breaks
83
Response of jaw unloading reflex
Inactivation of jaw closing muscles + Activation of jaw opening muscles
84
Nerves involved in the parasympathetic control of saliva secretion
CN VII (Submandibular and Sublingual glands) + CN IX (Otic ganglion - parotid gland + lingual glands)
85
Neurotransmitter of preganglionic axon involved in parasympathetic control of saliva secretion
Acetycholine
86
Neurotransmitter of postganglionic axon involved in parasympathetic control of saliva secretion
Acetylcholine
87
Type of receptor involved in the parasympathetic control of saliva secretion
Muscarinic
88
Effects of parasympathetic control of saliva secretion (x3)
1. Responsible for most of the increase in volume of saliva flow
2. Small, variable increase in organic components
3. Contraction of myoepithelial cells
89
Effects of sympathetic control of saliva secretion (x3)
1. Production of viscous saliva (which gives the impression of a dry mouth, but in actual fact, salivary secretion has not been inhibited)
2. Increased exocytosis of organic components
3. Contraction of myoepithelial cells
90
Antagonist in the parasympathetic control of saliva secretion
Atropine
91
Short preganglionic axon; Long postganglionic axon
| parasympathetic / sympathetic control of salivary secretion?
Sympathetic
92
Long preganglionic axon; Short postganglionic axon
Parasympathetic
93
How does gustatory sweating result? What syndrome is this called?
Frey's syndrome -
During parotid gland surgery, there is a damage to the auriculotemporal nerve. The nerves regenerate but are however mixed and misdirected. The nerve that was parasympathetic to salivary glands get attached to those sympathetic for facial sweat glands and vice versa. This results in the activation of sweat glands upon salivary stimulant.
94
What are the 3 types of control of oro-facial blood vessels?
1. Neural
2. Hormonal
3. Metabolic
95
What are the autonomic nerves responsible for the control of pulpal blood vessels?
1. a1 receptor - sympathetic vasoconstrictor (main)
| 2. b2 receptors = sympathetic vasodilator
96
What does the speech process involve? (x2)
1. Generation of sound by vocal folds setting the air particles into vibration (phonation)
2. Modify the sound to produce specific complex speech sounds (resonance & articulation)
97
Where is Wernicke's area located?
Left cortex; in the junction between parietal and temporal lobes
98
Where does Wernicke's area receive its input from?
- Visual cortex (Occipital lobe) - reading comprehension and describing what is seen
- Auditory cortex (Temporal lobe) - understanding spoken words
99
Role of Broca's area in the actual production of speech (x2)
- Coordination of breathing and muscles involved in the speech process
- Controls word formation
(i. e. speaking ability)
100
Role of Wernicke's area in the actual production of speech (x3)
- Understanding written + spoken words
- Generation of meaningful language
- Formulates coherent patterns of speech which are transferred to Broca's area to control motor activity
101
Describe the myoelastic aerodynamic theory
Vocal folds are initially closed and air pressure builds up from expiration as the airway is obstructed. The build up of pressure opens the folds and air quickly rushes through. The decrease in pressure and elasticity of vocal folds will result in them closing off subsequently. The build up of air pressure from expiration results in a repeating cycle.
102
Define phonation
Phonation refers to the production of sound in the larynx by the vibration of the vocal folds in the larynx.
It is initiated by the active closing of the vocal folds followed by passive vibration of the folds
103
What is the frequency of fold vibration determined by? (x4)
1. Size of the vocal fold
2. Fold tension
3. Force of expiration
4. Frequency of fold vibration
