Abstract
Abstract: :
Purpose: Human and non-human Primate extraocular muscles have a limited and patchy distribution of neurotendonous endings in the "myotendinous" area and they probably develop after infancy. It is likely that these nerve fibers serve a sensory function, possibly "proprioceptive-effectors." The enthesial area of the extraocular muscle tendon (the distal portion of the extraocular muscle tendon that joins with the scleral fibers) has not been the object of the same search for the presence of neural tissue as in the myotendinous area. To develop a surgical technique for acquisition of the tendino-scleral (enthesial) area of the extraocular muscle tendon and to search for, and characterize, the microscopic anatomy of these nerve terminals. Methods: Sixteen extraocular rectus muscle tendon-scleral (enthesial) specimens from normal human (2), cadavers (4), macaque primates (4), and patients with congenital nystagmus (6) were obtained and investigated using transmission electron microscopy. Results: Enthesial neurovascular structures were identified in both species. The enthesial area showed structures consisting of various developmental stages of meylinated and unmeylinated nerve fibers with associated supporting vascular capillaries. Anomalous neurovascular structures were found in the enthesis of patients with congenital nystagmus. Conclusion: This study confirms the presence of normal and abnormal neural activity in the enthesial area of the extraocular muscle tendon. Neurovascular abnormalities in the enthesial part of the extraocular muscle tendon may be part of disease pathogenesis. Disruption of these probable afferent central nervous system inputs occurs during surgery for eye movement disorders and strabismus, thus, possibly influencing treatment outcomes.
Keywords: 405 extraocular muscles: structure • 493 nystagmus • 590 strabismus: etiology