Mesencephalic nucleus of trigeminal nerve

Target: Mechanoreceptors of facial muscles

“Mesencephalic nucleus of trigeminal nerve extends from upper end of chief sensory nucleus in the pons to the midbrain where it lies in the central grey matter lateral to the cerebral aqueduct. Because it extends rostrally into the midbrain, it is called mesencephalic nucleus. Like dorsal root ganglia of spinal cord it is made up of pseudounipolar cells (1st order sensory neurons) and appears to have similar functions (the mesencephalic nucleus is unique in the sense that it is the only site in CNS which contains the cell bodies of first order sensory neurons). Peripheral processes of these cells carry proprioceptive impulses from the muscles of mastication, temporomandibular joint, teeth and possibly also from the extrinsic muscles of tongue. Central processes terminate in the motor nuclei of trigeminal nerve of the both sides. These connections establishes the stretch reflex originating in the neuromuscular spindles in masticatory muscles, together with a reflex for control of the force and accuracy of bite “(Barr, N.L., 1972). These reflexes prevent the tongue from being bitten during chewing. Other central processes relay in the cells of reticular formation. From which fibres arise and run through dorsal trigeminal lemniscus to relay in the ventral posteromedial nucleus (VPM) of the thalamus (Fig. 9.4).”