Somatosensation of the Face Flashcards
what sensations does the tregeminal nerve carry, what for which areas?
pain, temperature, light touch, discriminative touch, conscious and unconscious proprioception
for anterior 2/3 of the face and head
trigeminal nerve divisions
-location of divisons
V1 - ophthalmic division -above orbit V2 - maxillary division -below orbit and above mouth V3 - mandibular division -below mouth
V1, V2, V3 sensory vs. motor
V1 and V2
-all sensory
V3
-mixed
trigeminal system parallel pathways
trigeminoreticulothalamic
trigeminomesencephalic
CN V nociception and thermal sensation 1st order neuron
- cell body location
- types of fibers
- where do the fibers go?
- where do they synapse
cell body in trigeminal ganglia
-located on floor of middle cranial fossa
myelinated and unmyelinated fibers (A-delta and C)
enter Spinal tract of V at the level of the middle pons
fibers descend ipsilaterally in this tract to synapse in the Spinal trigeminal nucleus located in the medulla
CN V nociception and thermal sensation 2nd order neuron
- cell body location
- where do the fibers go?
- where does it synapse
cell body in the Spinal Nucleus of V
fibers cross the midline and line up adjacent to the cervical component of the medial lemniscus
tract then ascends contra as the ventral trigenimal thalamic tract to synapse in the ventral posteromedial (VPM) thalamic nucleus
spinal trigeminal nucleus
- divisions
- how is it organized
three divisions
each organized in a topographical pattern with respect to the distribution of incoming sensory information
CN V nociception and thermal sensation 3rd order neuron
-location
located in the ventral posteriomedial (VPM) thalamic nucleus
-this is the medial division of the same nucleus that is the site of the third order neurons of the somatosensory systems of the body
CN V nociception and thermal sensation 3rd order neuron
- where do these fibers go?
- where do they synapse
leave thalamus and ascend to the cortex in the posterior limb of the internal capsule
synapse in face area of primary somatosensory cortex; postcentral gyrus; Brodmann’s areas 3, 1, 2
pathological condition associated with the transmission of pain via the trigeminal nerve
trigeminal neuralgia or Tic douloureux
trigeminal neuralgia
- characteristic
- cause is sometimes attributed to…
marked by excruciating pain
-set off by mild stimulation
sometimes attributed to a compression of the nerve by swelling of the nerve sheath
trigeminal neuralgia
- how is it sometimes cured
- why is this technique possible?
surgically cut the decending fibers in the spinal tract of V
possible due to the topographical distribution of the fibers carrying the pain sensation and the anatomical location on the lateral surface of the caudal medulla
CN V touch 1st order neuron
- cell body location
- topographic organization
cell bodies in trigeminal ganglion
tophgraphic organization similar to that for pain and temerature over the three peripheral branches of this nerve
CN V touch 2nd order neuron
- cell body location
- -this areas is concerned with…
main sensory nucleus (discriminative touch)
-concerned with two-point discrimination over the entire distribution of the trigeminal nerve
CN V touch 2nd order neuron
- where do the majority of axons travel?
- where do the minority of axons travel?
- where do all these axons end?
majority of axons leaving this nucleus cross the midline and ascent in the ventral trigeminothalamic tract (VTT)
there is an extra pathway that ascends ipsilaterally in a dorsal trigeminothalamic tarct (DTT)
all axons ascend to end in the ventral posteromedial thalamic nucleus
