| raphespinal fibres | Nerve fibres originating from cells of the nuclei raphe magnus, pallidus, and obscurus of the pons and medulla and terminating in the spinal cord gray matter; fibres involved in the descending inhibition of nociceptive input in the dorsal (posterior) horn; they contain serotonin. (05 Mar 2000) |
|---|
| nuclei raphes | Collections of small neurons centrally scattered among many fibres from the level of the trochlear nucleus in the midbrain to the hypoglossal area in the medulla oblongata. (12 Dec 1998) |
|---|