Innervation and structure of extraocular muscles in the monkey in comparison to those of the cat

摘要: Motoneurones that innervate the medial rectus, lateral and accessory rectus muscles in monkey have been identified localized by retrograde transport of horseradish peroxidase. Medial motoneurones were located within both dorsal ventral regions oculomotor nucleus, with a differential distribution along rostral-caudal axis nucleus. Lateral predominantly abducens distributed throughout extent muscle comprised group large cells approximately 0.5 mm to rostral protion corresponding nucleus Tsuchida ('06). The subgroup motoneurones, which muscles, thus do not occupy brain stem location similar cat whose retractor bulbi muscle, presumably is homologous. A few also overlapping motoneurones. Electron microscope examination revealed presence three morphological types singly innervated fibers two multiply exhibited orbital, intermediate, global muscle. resembled portion containing one type fiber. These findings indicate central differences brainstem locations are correlated peripheral only morphology, but possibly mechanical roles, they innervate. appears evolved structurally functionally towards more role patterned eye movement. Furthermore, phylogenetic regression various movement this associated lower vertebrates may be assumed other extraocular higher mammals, including humans.