extraocular movements would be a test for cranial nerve vi involving a pen light.
extraocular movements would be a test for cranial nerve vi involving a pen light.
a test for cranial nerve vi involving a pen light would be?
extraocular movements
referring to the neural pathway schematic diagram, the entire pupillary light reflex system can be visualized as having eight neural segments, numbered 1 through 8. odd-numbered segments 1, 3, 5, and 7 are on the left. even-numbered segments 2, 4, 6, and 8 are on the right. segments 1 and 2 each includes both the retina and the optic nerve (cranial nerve #2). segments 3 and 4 are nerve fibers that cross from the pretectal nucleus on one side to the edinger-westphal nucleus on the contralateral side. segments 5 and 6 are fibers that connect the pretectal nucleus on one side to the edinger-westphal nucleus on the same side. segments 3, 4, 5, and 6 are all located within a compact region within the midbrain. segments 7 and 8 each contains parasympathetic fibers that courses from the edinger-westphal nucleus, through the ciliary ganglion, along the oculomotor nerve (cranial nerve #3), to the ciliary sphincter, the muscular structure within the iris.
pupillary light reflex
nonselective horizontal gaze palsies are caused by lesions in the abducens nucleus. this is where the cranial nerve vi leaves on its way to the lateral rectus muscle, which controls eye movement horizontally away from the midline of the body. the cranial nerve vi also has interneurons connecting to the medial rectus, which controls horizontal eye movement towards from the midline of the body. since the lateral rectus controls movement away from the center of the body, a lesion in the abducens nucleus disrupts the pathways controlling outward movements, not allowing the right eye to move right and the left eye to move left. nerve vi has the longest subarachnoid distance to its target tissue, making it susceptible to lesions. lesions anywhere in the abducens nucleus, cranial nerve vi neurons, or interneurons can affect eye movement towards the side of the lesion. lesions on both sides of the abducens nucleus can cause a total loss of horizontal eye movement.
conjugate gaze palsy