Two types of sensory fibers have cell bodies in the mesencephalic nucleus : proprioceptor fibers from the jaw and mechanoreceptor fibers from the teeth.
2.
Signals from muscle spindles on the tongue travel through the hypoglossal nerve, moving onto the lingual nerve which synapses on the mesencephalic nucleus.
3.
They are automatic activities, requiring little conscious attention and involving a sensory component ( feedback about touch-position ) processed at the unconscious level in the mesencephalic nucleus.
4.
As with most other reflexes, the response to the stimulus is monosynaptic, with sensory neurons of the trigeminal mesencephalic nucleus sending axons to the trigeminal motor nucleus, which in turn innervates the masseter.
5.
Proprioception of the head stems from the muscles innervated by the trigeminal nerve, where the Gasserian ganglion ( first-order sensory neuron ), reaching the mesencephalic tract and the mesencephalic nucleus of trigeminal nerve.
6.
The alar plate specifically later on becomes the dorsal gray of the spinal cord, and develops into the sensory nuclei of cranial nerves mesencephalic nucleus of V, and main sensory nucleus of V are also developed from this plate.
7.
The parts of the trigeminal nucleus receive different types of sensory information; the spinal trigeminal nucleus receives pain-temperature fibers, the principal sensory nucleus receives touch-position fibers and the mesencephalic nucleus receives proprioceptor and mechanoreceptor fibers from the jaws and teeth.
8.
Electrical synapses are present throughout the central nervous system and have been studied specifically in the neocortex, hippocampus, thalamic reticular nucleus, locus coeruleus, inferior olivary nucleus, mesencephalic nucleus of the trigeminal nerve, olfactory bulb, retina, and spinal cord of vertebrates.
9.
However, it should be noted that FoxP2 expression is found in several nearby brain regions ( not including the locus coeruleus, mesencephalic nucleus of the trigeminal, or laterodorsal tegmental nucleus ), so it is not unique to the pre-LC . That is, every pre-LC neuron expresses FoxP2, but not every neuron that expresses FoxP2 is part of the pre-LC.
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