EX1; Trigeminal System Flashcards
What is the functional significance of the trigeminal system
speech production; positioning tongue for articulation
positioning food for chewing efficacy
salvation
What is stereognosis regarding the trigeminal system
3-dimensionality of objects in the mouth
size, texture, hardness
what is flavor regarding the trigeminal system
taste and olfaction (special senses)
texture, temperature, chemesthesis
What sensations are evoked in the mouth and perioral region regarding trigeminal
touch
temperature
pain
proprioception info regarding the position of the tongue and jaws
Trigeminal fibers can be activated by some chemical stimuli including spices, high concentrations of acid/salt, and some compounds common in dentistry; this is termed what
chemesthesis
What are the three main branches of trigeminal
opthalmic
maxillary
mandibular
Which main branch contains both motor and sensory, as opposed to just sensory
mandibular
Where are the cell bodies for the trigeminal nerve located
in the trigeminal (semi-lunar/Gasserian) ganglia in the temporal bone
At which level of the brain do fibers (axons) of the trigeminal nerve enter and bifurcate into ascending and descending branches ultimately terminating in different brainstem structures with different functions
pons
The ascending branch of trigeminal ends where
in the principal nucleus
What is the function of the ascending branch of trigeminal
light touch perception
The descending branch of trigeminal ends where
in the spinal trigeminal nucleus
What are the three divisions of the spinal trigeminal nucleus
nucleus oralis
nucleus interpolaris
nucleus caudalis
What is the function of nucleus oralis
light touch perception
What is the function of nucleus interpolaris
temperature perception
What is the function of nucleus caudalis
pain perception
The representation of the head and neck is somatotopically organized within each sensory nucleus and sub nucleus in the brainstem, what are these
thalamus
ventral posterior medial nucleus
somatosensory cortex in the parietal lobe
What five things can peripheral nerve fibers be classified as
fiber size conduction velocity threshold modality (what they respond to) type of receptors at the end of the sensory axon
What are the two types of rapidly adapting mechanoreceptors
small receptive fields
large receptive fields
What are the two types of slowly adapting mecahnoreceptors
small receptive fields
large receptive fields
This is the deformation or stretch of the axon membrane that opens Na channels, they by polarizing the axon and causing impulses (action potentials)
transduction
Recent studies suggest that these sodium channels influencing transduction belong to which super family
epithelial NaCl channels; ENac
Mechanical transduction may occur through which specific channels
transient receptor potential channels
In the hand, there is a correlation between receptor what
structure and function
The Ruffini corpuscle (type II SA) is involved with what sensation
skin stretch
The pacinian corpuscle is involved with what sensation
vibration
The response properties of mechanoreceptors are influenced by three sources
degree of myelination
location of receptor (superficial/deep)
structure of the ending (meissner, ruffini, etc)
The Meissner corpuscle is involved with what sensation
light touch/spatial discrimination
The merkel receptor is involved with what sensation
pressure
This receptor ending is surrounded by layers of Schwann cells and collagen
pacinian
When a stimulus is applied to pacinian corpuscles the lamellae resist the force such that only what occurs
the initial impact of the stimulus makes it to the transduction site
When the force is removed from the pacinian corpuscle compressed lamellae imparts what
an off-response to the receptor
These are monofilaments calibrated to bend at specific forces, usually measured in grams; used to establish touch tresholds
von frey hairs
Which portion of the face has a lower threshold for two-point discrimination
facial midline
Oral and facial tissues show specialized patterns of what
innervation and in some instances different anatomical receptor types than are found in the hand
This is the recording from human nerves; map of receptive fields; determines neuron properties
microneurography
True or False
Females are typically more two point discrimination sensitive than males
True
The infraorbital nerve does not contain these fibers, and what does this mean
no RAII or Pacinian corpuscles
we can still feel vibration on our face, the receptor in the hand is thought to mediate this (low vibrotactile sensitivity)
The tongue is innervated by this mandibular nerve, although sensitive, there is not a large varies of receptor endings
lingual nerve
What is the most common type of receptor endings in the lingual nerve
non-encapsulated “coiled nerve endings” referred to as Krause end bulbs
What type of responses are recorded in the tongue
rapidly adapting (RA)
slowly adapting (SA)
which is one of a kind, especially regarding to its ending
*high degree of sensitivity
What two things do Krause end bulbs and Meissner corpuscles have in common
high density and small receipting field at tip
both have rapidly and slowly adapting responses
What are four things affecting the origin of trigeminal dysfunction
oral and facial trauma
complete dentures with loss of underlying tissue
infectious disease (periodontitis)
dental and surgical procedures
True or False
There is much documentation about the mechanoreceptors in the TMJ and evidence indicated these receptors help mediate interdental sensation
False; there is little evidence, but they do mediate interdental sensation
What branches of mandibualr; trigeminal innervate TMJ
auriculotemporal
masseter
posterior deep temporal
Where is the most dense innervation of TMJ
posterior and lateral portion of capsule
What types of nerve endings are found in TMJ
free nerve endings (C-fibers) predominate with only a few specialized endings such as refine endings or golgi tendon organs
Which teeth are more sensitive based upon pressure applied using von frey hairs
midline teeth
What is impacted most with trigeminal disfunction following third molar extraction
the lip is impacted the most; can lead to tongue biting and hot burns
What nerve innervate the PDL
branches of superior and inferior alveolar nerves
What type of nerve ending is found in the PDL
unencapsulated Ruffini type endings
What nuclei and ganglia send fibers to innervate the PDL; they may play a role in different functions
trigeminal ganglion
mesencephalic nucleus
Directional sensitivity of the PDL shows that when forces are directed to the tooth from this direction, the response is the largest
distal direction
These specific fibers also show directional sensitivity
rapidly adapting
These connections are part of the ascending sensory pathway that leads to conscious perception via the principal trigeminal nucleus that projects to the VPM in the thalamus and then o the somatosensory cortex
trigeminal ganglion
Trigeminal ganglion fibers also project to sub nucleus orals, which then projects to motor trigeminal nucleus to produce what
jaw opening reflex via the anterior digastric muscle
These projections can cause salivary secretion via connections to the brainstem salivary nuclei
mesencephalic trigeminal nucleus
An example of rapidly adapting response is as the stimulus is applied more rapidly, what happens to the response latency
it becomes shorter
clincial conditions such as periodontitis can increase what of PDL
increase thresholds (lower sensitivity)
The location of what in the PDL determines sensitivity
Ruffini endings
Denture and implant patients have trouble with force regarding what
they have trouble controlling force but do not have trouble generating force
There is a wide/narrow variation in the perception of warmth in and around the oral and facial regions
wide
There is more/less variation for cold sensation of which is generally perceived more intensely than warmth
less
Temperature sensitive fibers typical respond to a range of stimuli classified as what depending on the peak response
cold or warm
Many of the different these receptors respond to temperature and some receptors also respond to specific chemical stimuli
TRP (transient receptor potential)
