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ROBERT S. JAMPEL, CHARLES I. BLOOMGARDEN; Individual Extraocular Muscle Function From Faradic Stimulation of the Oculomotor and Trochlear Nerves of the Macaque. Invest. Ophthalmol. Vis. Sci. 1963;2(3):265-271. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
The functions of the individual extraocular muscles of the monkey (Macaca mulatta) were determined hij faradic stimulation of the intracranial segments of the oculomotor and trochlear nerves. The individual muscles innervated by the oculomotor nerve were isolated, by sectioning the tendons and check ligaments of those muscles not under study. The superior oblique muscle produced intorsion of the globe of about 25 degrees around, an axis pole located on the horizontal corneal meridian at the lateral corneal limbus. The intorsion was associated with a depression of the pupillary axis of about 16 degrees and an abduction of about 3.5 degrees. The components of the movement were not significantly influenced, by the position of the globe in the horizontal plane. The inferior rectus muscle produced two different eye movements, depending on the stimulus parameters. With higher voltages it moved, the globe straight down in the midline, adducted, and abducted, positions. With lower voltages itproduced extorsion of the globe of about 22 degrees around, an axis pole located, on the horizontal corneal meridian at the medial corneal limbus. The extorsion of the globe was associated with a depression of the pupillary axis of about 16 degrees and, an adduction of about 3.5 degrees. The components of this movement were not influenced by the position of the globe in the horizontal plane in the midline position and in adduction. In abduction the globe moved, toward the midline position while it underwent extorsion. The inferior oblique and superior rectus muscles elevated, the globe in all positions in the horizontal plane, except that, in adduction, contraction of the inferior oblique caused the eye to move to the midline position while it elevated. The medial rectus muscle adducted. the globe to a constant end position from any site in the horizontal and vertical planes. These findings are at variance with traditional teachings since they indicate that the actions of the individual extraocular muscles do not take place around the postulated axis of Fick. The axes of rotation of the individual extraocular muscles appear to vary with the position of the globe.
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