Trigeminal system

Question 1

what are the three divisions of the trigeminal nerve and name if they are sensory or motor or both?

Answer 1

V1- ophthalmic - sensory
V2- maxilllary - sensory
V3- mandibular -sensory and motor

Question 2

T/F CN V is the Major Sensory nerve to the head and contains both proprioception and nociception

Answer 2

true
remember proprioception is DCML
nociception is ALS

Question 3

peripheral sensory afferents of the head converge at what?

Answer 3

trigeminal ganglion

Question 4

trigeminal ganglion is to the head as?

Answer 4

dorsal root ganglion is to the body

Question 5

what are the four nuclei of the trigeminal nucleus

Answer 5

mesencephalic nucleus
chief sensory nucleus (DCML)
spinal trigeminal nucleus (ALS)
motor nucleus

Question 6

what are the boundaries of the trigeminal nucleus?

Answer 6

midbrain to C3

Question 7

the second order neurons from the chief nucleus go both ipsilateral and contralateral to the VPM to maintain what?

Answer 7

symmetrical facial movements

Question 8

all the contra lateral neurons travel to the thalamus in what?

Answer 8

trigeminothalamic tract

Question 9

what two nuclei are involved in the jaw jerk reflex?

Answer 9

the mesencephalic and motor nucleus

** this basically the function of these two nuclei and don’t really participate in much else.

Question 10

where do second order trigeminal neurons originate?

Answer 10

• principal (chief) trigeminal nuclei(DCML) pons

- spinal trigeminal nucleus (ALS) medulla/spinal cord

Question 11

chief trigeminal nucleus

Answer 11

mediates fine touch, joint, vibration

located in pons

Question 12

when do the second order neurons decussate?

Answer 12

immediately and head to the trigeminothalamic tract and head to the thalamus

Question 13

spinal trigeminal nucleus

Answer 13

mediates pain and temperature

Question 14

how far does the spinal trigeminal nucleus descend into the spinal cord?

Answer 14

C2-C3 and is continuous with the dorsal horn

Question 15

why is the spinal trigeminal nucleus said to be messy?

Answer 15

because the decussation can happen anywhere in the whole nucleus
**similar to tract of lissauer

Question 16

when fibers from the spinal nucleus decussate what tract do they join?

Answer 16

spinothalamic tract

Question 17

secondary neurons from the trigeminal nerve synapse in what part of the thalamus?

Answer 17

VPM

Question 18

from the thalamus the fibers travel through what?

Answer 18

internal capsule in the posterior limb

Question 19

describe local gate control of nociceptive inputs

Answer 19

• C fibers will inhibit the interneuron and activate the secondary neuron
• alpha and beta fibers will activate the interneuron to inhibit the secondary neuron
• *since the alpha and beta fibers are fast than the C fibers you can over ride the pain by rubbing an area of pain.

Question 20

T/F Transmission of nociceptive information can be inhibited by activation of cutaneous afferents?

Answer 20

true

Question 21

mesencephalic nucleus

Answer 21

sensory
mandibular proprioception
**primary neuron will be in here NOT trigeminal nucleus

Question 22

motor nucleus

Answer 22

• muscles of mastication
• homologous to ventral horn of spinal cord
• corticobulbar upper motor neurons synapse on lower motor neurons originating in this nucleus

Question 23

jaw jerk reflex

Answer 23

• muscle spindle from masseter senses it being pulled and sends signal to mesencephalic nucleus, which then synapses on the motor nucleus to masseter muscle to constrict.
• 2 neurons

Question 24

what does the presence of an exaggerated jaw jerk reflex imply?

Answer 24

bilateral disease above the level of the pons

Question 25

eye blink response

Answer 25

touch the cornea, V1 senses this and sends information to the chief nucleus, which the synapses on the facial nucleus to blink
*3 neurons

Question 26

is the eye blink consensual?

Answer 26

yes

Question 27

in the eye blink response is the ipsilateral side slower or faster?

Answer 27

faster because there are less neuronal synapses than on the contra lateral side

Question 28

what purpose does the reticular formation play in the eye blink response?

Answer 28

makes you move and get out of the way

rubrospinal tract

Question 29

in you cut the neuron in the medulla of the eye blink response what happens?

Answer 29

you lose the consensual response

Question 30

dental procedures that cause inferior alveolar nerve injury

Answer 30

implant
root canal
fracture of mandible 
local anesthetic
extraction of third molar

Question 31

the inferior alveolar nerve block includes what nerves?

Answer 31

lingual
inferior alveolar
mental 
incisive
long buccal

Question 32

teeth do not have motor or parasympathetic nerves. They do have sympathetic nerves, what is their job?

Answer 32

involved in anti inflammation

also required for eruption of teeth

Question 33

if the needle enters the inferior alveolar nerve what can happen?

Answer 33

partial nerve injury with paresthesia/dystesthesia that generally resolves.
However on rare occasions can develop into a sustained neuropathic pain