The spinal nucleus and tract of the trigeminal nerve
• Extends from the midpons at the level of entry of the trigeminal root to the upper cervical spinal segments
• Blends into and is continuous with the substantia gelatinosa of the cervical cord
• Subserves the functions of pain and temperature sensation, touch being a function of the main sensory nucleus, which is at the rostral end of the spinal nucleus
Fibers from the ophthalmic division of the nerve are most ventral in the tract and those from the mandibular division are most dorsal, with the maxillary fibers in the middle.
The spinal trigeminal nucleus is medial to the tract and divided into three areas corresponding to the areas shown in Figure 8-4 at A, B, and C. These areas do not have the same cutaneous relationships as the three peripheral branches. Area A cuts through all three peripheral divisions and has its cellular components in the most rostral part of the nucleus, area B is intermediate, and area C is related to the most caudal end of the nucleus. (For an excellent account of the anatomy of the nucleus, see A. Brodal, Neurological Anatomy in Relation to Clinical Medicine, 3rd ed. Oxford University Press, New York, 1981, p. 528.)
When pain loss involves parts of all three peripheral divisions of the trigeminal nerve, consider the possibility of a nuclear location of the lesion.
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