Trigeminal system Flashcards
what are the three divisions of the trigeminal nerve and name if they are sensory or motor or both?
V1- ophthalmic - sensory
V2- maxilllary - sensory
V3- mandibular -sensory and motor
T/F CN V is the Major Sensory nerve to the head and contains both proprioception and nociception
true
remember proprioception is DCML
nociception is ALS
peripheral sensory afferents of the head converge at what?
trigeminal ganglion
trigeminal ganglion is to the head as?
dorsal root ganglion is to the body
what are the four nuclei of the trigeminal nucleus
mesencephalic nucleus
chief sensory nucleus (DCML)
spinal trigeminal nucleus (ALS)
motor nucleus
what are the boundaries of the trigeminal nucleus?
midbrain to C3
the second order neurons from the chief nucleus go both ipsilateral and contralateral to the VPM to maintain what?
symmetrical facial movements
all the contra lateral neurons travel to the thalamus in what?
trigeminothalamic tract
what two nuclei are involved in the jaw jerk reflex?
the mesencephalic and motor nucleus
** this basically the function of these two nuclei and don’t really participate in much else.
where do second order trigeminal neurons originate?
- principal (chief) trigeminal nuclei(DCML) pons
- spinal trigeminal nucleus (ALS) medulla/spinal cord
chief trigeminal nucleus
mediates fine touch, joint, vibration
located in pons
when do the second order neurons decussate?
immediately and head to the trigeminothalamic tract and head to the thalamus
spinal trigeminal nucleus
mediates pain and temperature
how far does the spinal trigeminal nucleus descend into the spinal cord?
C2-C3 and is continuous with the dorsal horn
why is the spinal trigeminal nucleus said to be messy?
because the decussation can happen anywhere in the whole nucleus
**similar to tract of lissauer
when fibers from the spinal nucleus decussate what tract do they join?
spinothalamic tract
secondary neurons from the trigeminal nerve synapse in what part of the thalamus?
VPM
from the thalamus the fibers travel through what?
internal capsule in the posterior limb
describe local gate control of nociceptive inputs
- 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.
T/F Transmission of nociceptive information can be inhibited by activation of cutaneous afferents?
true
mesencephalic nucleus
sensory
mandibular proprioception
**primary neuron will be in here NOT trigeminal nucleus
motor nucleus
- muscles of mastication
- homologous to ventral horn of spinal cord
- corticobulbar upper motor neurons synapse on lower motor neurons originating in this nucleus
jaw jerk reflex
- 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
what does the presence of an exaggerated jaw jerk reflex imply?
bilateral disease above the level of the pons
eye blink response
touch the cornea, V1 senses this and sends information to the chief nucleus, which the synapses on the facial nucleus to blink
*3 neurons
is the eye blink consensual?
yes
in the eye blink response is the ipsilateral side slower or faster?
faster because there are less neuronal synapses than on the contra lateral side
what purpose does the reticular formation play in the eye blink response?
makes you move and get out of the way
rubrospinal tract
in you cut the neuron in the medulla of the eye blink response what happens?
you lose the consensual response
dental procedures that cause inferior alveolar nerve injury
implant root canal fracture of mandible local anesthetic extraction of third molar
the inferior alveolar nerve block includes what nerves?
lingual inferior alveolar mental incisive long buccal
teeth do not have motor or parasympathetic nerves. They do have sympathetic nerves, what is their job?
involved in anti inflammation
also required for eruption of teeth
if the needle enters the inferior alveolar nerve what can happen?
partial nerve injury with paresthesia/dystesthesia that generally resolves.
However on rare occasions can develop into a sustained neuropathic pain
