Medial rectus subgroups of the oculomotor nucleus and their abducens internuclear input in the monkey

摘要: Physiological experiments show that the abducens internuclear pathway is involved in activation of only medial rectus (MR) eye muscle. Previous anatomical have shown this terminates multiple foci within oculomotor nucleus (OMN) monkey, and not over classical motoneuron subgroup. In study location MR motoneurons monkey OMN reinvestigated, compared with detailed pattern terminations pathway. The were labelled by injections retrograde tracer substances, HRP [125I] wheat germ agglutinin (WGA), into extraocular muscles. Labelled found three main divisions, called subgroup A, B, C. Subgroup A corresponds mainly to ventral B lies dorsal caudal OMN, occupying an area classically reserved for inferior (IR). However, representation IR be further rostral OMN. C on dorsomedial border Its cells are significantly smaller than those group B. addition could independently other subgroups small outer (orbital) layer This indicates a functional difference between subgroups. It suggested may important tonic component activity, possibly convergence. terminals, injection tritiated amino acids abudens nucleus, exactly position motoneurons. These provide new picture internal organization, support physiological findings activates