Cranial nerve 5 conduction pathway in the spinal cord

Tractus spinalis nervi trigemini

Conduction pathway, trigeminal spinal, spinal pathway of the triplet nerve

The spinal cord of the triplet nerve (tractus spinalis nervi trigemini) runs on the outside of the spinal cord of the triplet nerve, throughout its length from the pons down into the cervical spinal cord. The nerve fibers in the pathway are led into the pons through the sensory part of the trigeminal nerve , their cell bodies are located in the trigeminal ganglia and are of the type primary afferents. The orbit contains mainly small myelinated (A-delta) and unmyelinated (C-afferent) nerve fibers that mediate pain and temperature, as well as filaments for diffuse touch and pressure sensations from the face with its cavities (eyes, nose and mouth). At spinal cord level, the orbit passes into the border zone of Lissauer.

The spinal trigeminal pathway ends in the spinal nucleus in such a way that:
1/ Pars oralis catchment area is still quite unclear.
2/ Pars interpolaris receives signals from the oral cavity, especially pain and temperature stimuli from the dental pulp and pressure, strain and pain sensations from the periodontal ligaments (= the connective tissue strands that anchor the teeth where they are inserted into the dental alveoli of the jawbones).
3/ Pars caudalis receives pain and temperature stimuli from the entire corresponding half of the face.