trigeminal nerve lecture

Question 1

what stimuli can the trigeminal nerve detect?

Answer 1

pain
touch
temperature
proprioception
chemesthesis (common chemical sense)
Stereognosis
Flavour

Question 2

___________ is the ability to sense 3-dimensionality, such as size, texture and hardness

Answer 2

Stereognosis

Question 3

The trigeminal nerve has ___ main branches. name them:

Answer 3

3 branches:

1) Opthalmic (sensory only)
2) Maxillary (sensory only)
3) mandibular (Sensory & Motor)

Question 4

what are the 3 names for the trigeminal ganglion?

Answer 4

Trigeminal ganglion
Gasserian ganglion
Semilunar ganglion

Question 5

name the segments of the spinal trigeminal nucleus

Answer 5

1) oralis
2) interpolaris
3) caudalis (medullary dorsal horn)

Question 6

before signals from the principal sensory nucleus reach the primary somatic sensory cortex (in the parietal cortex), where do the nerve fibers synapse?

Answer 6

Ventral Posterior Medial Nucleus of the Thalamus

Question 7

which types of sensory neurons are found in the Trigeminal nerve?

Answer 7

A-beta

A-delta

C fibers

Question 8

what are the 4 types of mechanoreceptors?

Answer 8

1) meissners corpuscle (RA1)
2) Merkel disks (SA1)
3) pacinian corpuscle (RA2)
4) Ruffini endings (SA2)

Question 9

which type of mechanoreceptor senses vibration? Pressure? discriminative touch? Skin stretch?

Answer 9

Vibration- Pacinian corpuscle

Pressure- Merkel disk

Discriminative touch- Meissners corpuscle

Skin stretch- Ruffini endings

Question 10

how do ENaC channels transmit signals concerning the “stretch” of skin?

Answer 10

Stretch causes membrane channels to open leading to depolarization

Question 11

Factors Influencing Mechanoreceptor function:

Answer 11

1. Size of fiber and degree of myelination
2. Location or receptor (superficial vs deep)
3. Structure of ending, e.g. degree of encapsulation
4. Transduction
   
   • ENacS & TRP channels

Question 12

what do Von Frey Hairs measure?

Answer 12

Touch discrimination

Question 13

T/F: males typically have a higher sensitivity to 2-point discrimination

Answer 13

False

females are more sensitive

Question 14

what mechanoreceptors does the infraorbital nerve contain? which is it missing?

Answer 14

1. Both SAI and SAII
2. RAI
3. No RAII **no pacinian corpuscles

Question 15

due to its lack of RA2, what sensation can the infraorbital nerve not detect?

Answer 15

vibration

Question 16

the Perioral and Facial area has low __________ sensitivity

Answer 16

vibrotactile

Question 17

Lack of _________ leads to low vibrotactile sensitivity of face

Answer 17

Lack of pacinian corpuscles

Question 18

___________ mechanoreceptor Endings Predominate in Tongue (and palate)

Answer 18

Unencapsulated

Question 19

the coiled endings (Krause end bulbs) in the mouth are similar to what structure

Answer 19

Meissner corpuscles

Question 20

Tongue has both rapidly and slowly adapting mechanoreceptors despite what?

Answer 20

only having one kind of ending! (compare to hand)

Question 21

the tongue has High density and small receptive fields in what area?

Answer 21

at the tip

Question 22

the face has a lack of what receptor? what does it have a low sensitivity to?

Answer 22

Lack of pacinian corpuscles (RAII)

Low vibration sensitivity

Question 23

Unlike the face, the tongue uses _________ receptors, giving it a high degree of _______ sensitivity

Answer 23

Krause end bulbs

High degree of tactile sensitivity

Question 24

Trigeminal Dysfunction Following Third Molar Extraction:

Answer 24

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

Question 25

what is the rate of nerve dysfunction following third molar extraction?

Answer 25

1.2% | only 0.2% of patients had permanent damage

Question 26

what nerves innervate the TMJ?

Answer 26

1) Masseter nerve (anterior) 2) posterior deep temporal nerve (medial) 3) Auriculotemporal nerve (posterior)

Question 27

TMJ Mechanoreceptors are mostly what type?

Answer 27

mostly free nerve endings (c-fibers) Ruffini > Golgi tendon organs > Pacinian

Question 28

T/F: posterior teeth (molars) are more sensitive than anterior teeth (incisors)

Answer 28

False: anterior teeth more sensitive than posterior

Question 29

which type of nerve endings are responsible for the innervation of the PDL?

Answer 29

1) Complex Ruffini 2) Simple Ruffini 3) Unmyelinated Free nerve endings

Question 30

Nerves from the Trigeminal ganglia are more abundant at what part of the PDL? what about nerves from the mesencephalic nucleus?

Answer 30

Trigeminal ganglia- gingival to middle portion of PDL Mesencephalic nucleus- Apex of tooth

Question 31

the mechanoreceptors of the PDL are ________ sensitive

Answer 31

rate | faster the force is applied- higher firing rate

Question 32

T/F: the mechanoreceptors of the PDL have directional sensitivity

Answer 32

true

Question 33

PDL nerve fibers are generally more sensitive to forces in what directions?

Answer 33

labial and distal forces

Question 34

Denture & Implant Patient have Trouble __________ Force but do not have Trouble _________ Force

Answer 34

Denture & Implant Patient have Trouble Controlling Force but do not have Trouble Generating Force

Question 35

Denture Patients Show Less _________ Sensitivity

Answer 35

Stereognosis Sensitivity

Question 36

PDL Receptor Function:

Answer 36

``` detect force to teeth interdental discrimination stereognosis jaw reflexes salivation ```

Question 37

which type of nerve fibers in the mouth are temperature sensitive?

Answer 37

A-delta and C-fiber | A-beta fibers are only proprioceptive and touch

Question 38

for sensitivity to heat, the ________ is most sensitive of intra-oral tissues

Answer 38

tongue tip

Question 39

Temperature Transduction is Mediated by ___________________

Answer 39

Transient Receptor Potentials | TRP channels

Question 40

the trigeminal motor nucleus, and the trigeminal principal sensory nucleus, are both found in which CNS structure?

Answer 40

the pons

Question 41

what are the 2 types of "RA" (rapid adaptation) mechanoreceptors? which has a small, sharp receptive field?

Answer 41

Meissners and Pacinian corpuscles Meissners have a small, sharp receptive field

Question 42

which mechanoreceptors are "SA" (slow adaptation)? which of these 2 has a small, sharp receptive field?

Answer 42

Merkel disks and Ruffini endings merkels disks have a smaller, sharper receptive field

Question 43

where do the "reflex" pathway fibers of the PDL travel to?

Answer 43

-trigeminal mesencephalic nucleus then to the: - salivary nucleus - motor nucleus

Question 44

where do the "sensory" pathway fibers of the PDL travel to?

Answer 44

A) trigeminal principal sensory nucleus | B) Spinal trigeminal nucleus (oralis)

Question 45

which section of the Spinal trigeminal nucleus receives temperature stimuli?

Answer 45

interpolaris