![]() Phoria: mild weakness present only with one eye covered (as in, exophoria).Hypertropia: abnormal vertical deviation of one eye.Esotropia: abnormal medial deviation of one eye.Exotropia: abnormal lateral deviation of one eye.Dysconjugate gaze: results from improperly working extraocular muscle and causes diplopia.Of Interest : Monocular diplopia or polyopia (3 or more images) can be caused by ophthalmological disease, d/o of visual cortex, or psychiatric conditions, but not by eye movement abnormality. Disorders of CN III, IV, VI, and their central pathways.Disorders of the neuromuscular junction (e.g., myasthenia gravis).Disorders of the extraocular muscles (e.g., thyroid disease, orbital myositis).Mechanical problems (e.g., orbital fracture with muscle entrapment).Abducens nerve is highly susceptible to downward traction injury produced by elevated intracranial pressure.Trochlear nerves are only cranial nerves to exit brainstem dorsally and in a completely crossed fashion they are susceptible to compression from cerebellar tumors and to shear injury from head trauma.Oculomotor nucleus lesions affect the contralateral superior rectus (further explanation in text, p.Unilateral weakness of the levator palpebrae superior, or unilateral papillary dilation, cannot arise from unilateral lesions of the oculomotor nucleus.The parasympathetic fibers controlling pupil constriction are susceptible to compression from aneurysms, particularly arising from the nearby posterior communicating artery.Ciliary Muscle: adjusts thickness of lens in response to viewing distance.Pupillary Dilator Muscle: makes pupil larger.Pupillary Constrictor Muscle: makes pupil smaller.Levator Palpebrae Superior: elevates eyelid innervated by superior division of CN III.Muscles 1 – 4 are responsible for horizontal and vertical eye movements muscles 5 & 6 are responsible for torsional movements Inferior oblique (elevation and extorsion) Superior oblique (depression and intorsion) Inferior rectus (depression and extorsion) Superior rectus (elevation and intorsion) Supranuclear Pathways: involve brainstem and forebrain circuits that control eye movements through connections with the nuclei of CN III, IV, and VIĮxtraocular Muscles, Nerves, and Nuclei Six Extraocular MusclesĬN III (oculomotor – inferior division) moves eye towards nose.Nuclear and Infranuclear Pathways: involve brainstem nuclei of CN III, IV, and VI the peripheral nerves arising from these nuclei and the eye movements muscles.Internal Ocular Muscles – control pupillary size and accommodation.Extraocular Muscles – cause the eyes to move within the orbits.It is sometimes called conventional angiography to distinguish it from computed tomography (CT) angiography and magnetic. read more, or cerebral angiography Angiography In angiography, x-rays are used to produce detailed images of blood vessels. ![]() In modern scanners, the x-ray detector usually. read more, CT angiography CT angiography In computed tomography (CT), which used to be called computed axial tomography (CAT), an x-ray source and x-ray detector rotate around a person. MRI does not use x-rays and is usually very safe. read more (lumbar puncture), magnetic resonance angiography Magnetic resonance angiography (MRA) In magnetic resonance imaging (MRI), a strong magnetic field and very high frequency radio waves are used to produce highly detailed images. Electroencephalography (EEG) is a simple, painless procedure in which. If CT (or MRI) does not detect blood, a spinal tap Spinal Tap Diagnostic procedures may be needed to confirm a diagnosis suggested by the medical history and neurologic examination. If a ruptured aneurysm is suspected, CT (or MRI) is done immediately. ![]()
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