Trigeminal sensory pathway > trigeminal sensory nucleus & sensory inputs (Advanced)

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Trigeminal sensory pathway > trigeminal sensory nucleus & sensory inputs (Advanced)

 

The trigeminal sensory nucleus and its connections:

• The trigeminal sensory nucleus is a continuation of the dorsal horn of the spinal cord into the brain.
• It receives somatosensory information chiefly from the sensory division of the trigeminal nerve with nerve endings in the face, nasal cavity and oral cavity including the teeth, and some parts of the dura mater.
• It also has a minor input from somatosensory endings of some other cranial nerves (facial, glossopharyngeal and vagus nerves).
• The trigeminal sensory nucleus extends from the midbrain to the spinal cord. Its major part (principal sensory nucleus of the trigeminal nerve) is in the pons and receives touch, pressure and stretch information.
• Inferior to this is the long, thin spinal nucleus of the trigeminal nerve. This is divided into three parts, from above to below: pars oralis, pars interpolaris and pars caudalis. In general, the pars oralis receives sensation from the oral cavity, while the pars caudalis is concerned with pain and temperature. However, the functions of the different regions are more complex than this and are still being researched.
• Axons from the trigeminal nerve pass down the external side of the spinal nucleus at the trigeminal spinal tract to reach their synaptic destinations in the spinal trigeminal nucleus.
• In the midbrain, the mesencephalic trigeminal sensory nucleus receives axons conveying proprioception from the teeth and jaw joints. This pathway is unusual because the ganglion cell bodies are situated in the nucleus itself rather than in the trigeminal ganglion outside the brainstem.
• The mesencephalic nucleus is not connected to the thalamus but has reflex connections to muscles of the head including jaws, and to the cerebellum.
• The trigemino-thalamic tract connects the principal and spinal nuclei to the thalamus, from which information is relayed to the somatosensory cortex.
• The trigeminal sensory nucleus is also connected to various other brain regions.