the trigeminal system Flashcards
are flavor and taste the same thing?
No! taste is the chemesthesis – chemoreception of a molcule by specifci receptors. Flavor is POLYMODAL– the product of a combination of modalities – taste +olfaction+ temrperature + chemesthesis + texture
The trigeminal nerve has 3 divisions. Are the divisions sensory, motor, or both?
The 3 division of the trigeminal nerve are:
CNV1 , Opthalmic brnach = SENSORY only
V2 = Maxillary brnach = SENSORY only
V3 = mandibular brnach = SEnsory AND MOTOR, both
what are the part of the spinal trigeminal nuckleus and what do they detect?
The spinal trigeminal nuclues receives afferent signals in the 3 subnuclei (listed from superior to inferior// top to bottom )
oralis : fine touch
interpolaris : temperature and pain
caudalis (aka medullary dorsal horn) = PAIN, nociceptor
what is the ascending pathway of the trigeminal nerve?
The sensory compoenet (afferent) of the trigeminal nerve goes to botht he principal sensory nucleus (brainstem) and the spinal trigeminal nucleus (in spinal cord) »_space; then both go to the ventral posterior medial nucleus of the thalamus, and then go to the primary somatosensory cortex of the parietal lobe (homunculus)
Sensory information from a tooth goes to two differnet nuclei – what signals go where?
The sensory signals from a tooth are spatially divided (though overap in the middle exists) .. so the middle of hte toooth and incisal have sensory that goes to the trigeminal ganglia (aka Waserian ganglia aka semilunar ganglia) … the sensory afferents from the middle and apilca portion of hte tooth ascend to the mesencephalic nuckeus, some overap is present in the middle areas of hre toth
Are anterior or posterior teeth more sensitive?
Anterior teeth are more sensitive than posterior teeth… mandibular teeth have a similar sensitivity amt (via von frey) as maxillary teeth
What does it mean for action potentials to be rate sensitive?
For action potentials to be rate sensitive, the faster the rate of stimulus, the More AP that are fired.
for example clinically,, faster injection of anesthesia is more painful (more pain AP signals sent) than a slower injection of anesthesia where felt as less painful bc fewer pain AP signals are dent).
the periodontal ligament mechanoreceptor is rate senstive
T/F the location of hte Ruffini ending neuron in thePDL determines senstivity ((bc diff cells have diff directional senstivites)
True. Ruffini endings detect skin stretch (SA2). Based on the location of hte unencapsularws Ruffini endings in the periodontal ligament PDL, different directional senstivies are felt bc diff cells have diff sensitivities.
Generally, the PDL is more sensitive to forces pushing FROM the labial and distal
The PDL is most sensitive to forces pushing in which two directions?
The PDL is most senstive (more AP fired off) to forces pushing towards the labial and distal directions
T/F The PDL is important for stereognosis sensitivity
True. THe PDL is importnat for stereognosis senstivitity (knowledge of 3D relationships..). Evidence of this exists in the control of denture or implant patients vs normal dentition.. normal dentition always exhibited finer motor control than any appliances wothout hte PDL
Which muscle fibers are temperature senstive?
The A0delta and C0fibers of the muscle (both also detect pain and chemesthesis) are also both temeprature senstive
- A-delta has faster conduction and sharp pain modality
- c-fibers have slower conduction and dull pain modality
Is the oral cavity more sensitive to hot or cold temperatures
the oral cavity is more senstive to warm temepratures than to cold temeratures (more variation in AP firing patterns.. ). however, senses respont more harshly to cold temperatures
Of the intra-oral tissues, what location is the most senstive to warm/ hot temperature?
Of the intra-oral tissues, the TIP of the Tongue is the most sensitive location to warm/hot temperatures (think, burning tongue on pizza)
T/F TRP channels, transient receptor potential channels, are sensitive and involved in temerpature tranduction
True! TRP channels (part of the molecular interaciton, 2 cell system) of trnaduction are inovled and senstive to temperatures. Different TRP channels respond to a differnt range of tmeperature for activation,. Some of these channels are also sensitive to chemesthesis where they respond to chemical snese such as capsaisin- spicy ((but NOT a special sense of taste)
the RESULT of TRP actvation = CA++ influx and therefore AP
which TRP channel is responsive to capsaicin? what else is this same channel senstive to?
TRP V1, (transient receptor potnetial V1) channel is responsive to capsaisin (chemesthesis chemical sense NOT special sense of taste NOT flavor) AS WELL AS Temperature! responds to very hot temerpatures of over 42 ^ C
