Flashcards in trigeminal nerve lecture Deck (45):
what stimuli can the trigeminal nerve detect?
chemesthesis (common chemical sense)
___________ is the ability to sense 3-dimensionality, such as size, texture and hardness
The trigeminal nerve has ___ main branches. name them:
1) Opthalmic (sensory only)
2) Maxillary (sensory only)
3) mandibular (Sensory & Motor)
what are the 3 names for the trigeminal ganglion?
name the segments of the spinal trigeminal nucleus
3) caudalis (medullary dorsal horn)
before signals from the principal sensory nucleus reach the primary somatic sensory cortex (in the parietal cortex), where do the nerve fibers synapse?
Ventral Posterior Medial Nucleus of the Thalamus
which types of sensory neurons are found in the Trigeminal nerve?
what are the 4 types of mechanoreceptors?
1) meissners corpuscle (RA1)
2) Merkel disks (SA1)
3) pacinian corpuscle (RA2)
4) Ruffini endings (SA2)
which type of mechanoreceptor senses vibration? Pressure? discriminative touch? Skin stretch?
Vibration- Pacinian corpuscle
Pressure- Merkel disk
Discriminative touch- Meissners corpuscle
Skin stretch- Ruffini endings
how do ENaC channels transmit signals concerning the "stretch" of skin?
Stretch causes membrane channels to open leading to depolarization
Factors Influencing Mechanoreceptor function:
1. Size of fiber and degree of myelination
2. Location or receptor (superficial vs deep)
3. Structure of ending, e.g. degree of encapsulation
- ENacS & TRP channels
what do Von Frey Hairs measure?
T/F: males typically have a higher sensitivity to 2-point discrimination
females are more sensitive
what mechanoreceptors does the infraorbital nerve contain? which is it missing?
1. Both SAI and SAII
3. No RAII ****no pacinian corpuscles
due to its lack of RA2, what sensation can the infraorbital nerve not detect?
the Perioral and Facial area has low __________ sensitivity
Lack of _________ leads to low vibrotactile sensitivity of face
Lack of pacinian corpuscles
___________ mechanoreceptor Endings Predominate in Tongue (and palate)
the coiled endings (Krause end bulbs) in the mouth are similar to what structure
Tongue has both rapidly and slowly adapting mechanoreceptors despite what?
only having one kind of ending! (compare to hand)
the tongue has High density and small receptive fields in what area?
at the tip
the face has a lack of what receptor? what does it have a low sensitivity to?
Lack of pacinian corpuscles (RAII)
Low vibration sensitivity
Unlike the face, the tongue uses _________ receptors, giving it a high degree of _______ sensitivity
Krause end bulbs
High degree of tactile sensitivity
Trigeminal Dysfunction Following Third Molar Extraction:
Lip impacted more often than tongue
Can lead to tongue biting And hot fluid burns & tics:
e.g. fingers to chin
Taste problems not commonly reported
what is the rate of nerve dysfunction following third molar extraction?
(only 0.2% of patients had permanent damage)
what nerves innervate the TMJ?
1) Masseter nerve (anterior)
2) posterior deep temporal nerve (medial)
3) Auriculotemporal nerve (posterior)
TMJ Mechanoreceptors are mostly what type?
mostly free nerve endings (c-fibers)
Ruffini > Golgi tendon organs > Pacinian
T/F: posterior teeth (molars) are more sensitive than anterior teeth (incisors)
False: anterior teeth more sensitive than posterior
which type of nerve endings are responsible for the innervation of the PDL?
1) Complex Ruffini
2) Simple Ruffini
3) Unmyelinated Free nerve endings
Nerves from the Trigeminal ganglia are more abundant at what part of the PDL? what about nerves from the mesencephalic nucleus?
Trigeminal ganglia- gingival to middle portion of PDL
Mesencephalic nucleus- Apex of tooth
the mechanoreceptors of the PDL are ________ sensitive
(faster the force is applied- higher firing rate)
T/F: the mechanoreceptors of the PDL have directional sensitivity
PDL nerve fibers are generally more sensitive to forces in what directions?
labial and distal forces
Denture & Implant Patient have Trouble __________ Force but do not have Trouble _________ Force
Denture & Implant Patient have Trouble Controlling Force but do not have Trouble Generating Force
Denture Patients Show Less _________ Sensitivity
PDL Receptor Function:
detect force to teeth
which type of nerve fibers in the mouth are temperature sensitive?
A-delta and C-fiber
(A-beta fibers are only proprioceptive and touch)
for sensitivity to heat, the ________ is most sensitive of intra-oral tissues
Temperature Transduction is Mediated by ___________________
Transient Receptor Potentials
the trigeminal motor nucleus, and the trigeminal principal sensory nucleus, are both found in which CNS structure?
what are the 2 types of "RA" (rapid adaptation) mechanoreceptors?
which has a small, sharp receptive field?
Meissners and Pacinian corpuscles
Meissners have a small, sharp receptive field
which mechanoreceptors are "SA" (slow adaptation)?
which of these 2 has a small, sharp receptive field?
Merkel disks and Ruffini endings
merkels disks have a smaller, sharper receptive field
where do the "reflex" pathway fibers of the PDL travel to?
-trigeminal mesencephalic nucleus
then to the:
where do the "sensory" pathway fibers of the PDL travel to?
A) trigeminal principal sensory nucleus
B) Spinal trigeminal nucleus (oralis)