| Name: | primary motor neuron |
|---|---|
| Synonyms: | primary motoneuron |
| Definition: | Motor neurons that arise during the first day of development. Primary motoneurons have larger diameter cell bodies and axons than secondary motoneurons and are positioned more dorsally and medially than secondary motoneurons. Primary motoneurons are present in a single bilateral pair of clusters in each spinal segment and innervate axial muscle fibers in the corresponding pair of myotomes. Axons make a conspicuous loop around the Mauthner axon before entering the ventral root. |
| Ontology: | Anatomy Ontology [ZFA:0009244] |
| Name: | structure |
|---|---|
| Synonyms: | conformation, relational structural quality |
| Definition: | A morphology quality inhering in a bearer by virtue of the bearer's relative position, shape, arrangements and connectivity of an organism's various parts; the pattern underlying its form. |
| Ontology: | Phenotypic Quality Ontology [PATO:0000141] |