| OP | occipitoparietal; occipitoposterior; occiput posterior; octapeptide; olfactory peduncle; opening pre... |
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| opg | opening |
| OS | left eye [Lat. oculus sinister]; occipitosacral; occupational safety; office surgery; Omenn syndrome... |
| PAo | airway opening pressure; ascending aortic pressure; pulmonary artery occlusion pressure |
| Po | opening pressure |
| vestibular ligament | <anatomy> The thin fibrous layer that lies in the ventricular fold of the larynx. Synonym: ligamentum vestibulare, ligamentum ventriculare, ventricular ligament. (05 Mar 2000) |
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| vestibular lip of limbus of spiral lamina | vestibular labium of limbus of spiral lamina |
| vestibular membrane | The membrane separating the cochlear duct from the vestibular canal; it consists of squamous epithelial cells with microvilli toward the ductus, a basement membrane, and a thin layer of connective tissue toward the scala. Synonym: membrana vestibularis, paries vestibularis ductus cochlearis, Reissner's membrane, vestibular wall of cochlear duct. (05 Mar 2000) |
| vestibular nerve | <anatomy, nerve> The vestibular part of the acoustic (8th cranial) nerve. The vestibular nerve fibres arise from neurons of scarpa's ganglion and project peripherally to vestibular hair cells and centrally to the vestibular nuclei of the brainstem. These fibres mediate the sense of balance and head position. (12 Dec 1998) |
| vestibular neuronitis | A paroxysmal attack of severe vertigo, not accompanied by deafness or tinnitus, which affects young to middle-aged adults, often following a non-specific upper respiratory infection; due to unilateral vestibular dysfunction. Synonym: endemic paralytic vertigo, epidemic vertigo, Gerlier's disease, kubisagari, kubisagaru, paralyzing vertigo. (05 Mar 2000) |
| vestibular nuclei | The four cellular masses in the floor of the fourth ventricle giving rise to a widely dispersed special sensory system. (12 Dec 1998) |
| vestibular nucleus | One of a group of four main nuclei that includes: the lateral vestibular nucleus (Deiters' nucleus), medial vestibular nucleus (Schwalbe's nucleus), superior vestibular nucleus (Bechterew's nucleus), and inferior vestibular nucleus, located in the lateral region of the hindbrain beneath the floor of the rhomboid fossa. They receive primary fibres of the vestibular nerve, are reciprocally connected with the flocculonodular lobe of the cerebellum, and project by way of the medial longitudinal fasciculus to the abducens, trochlear, and oculomotor nuclei and to the ventral horn of the spinal cord. The lateral vestibular nucleus projects to the ipsilateral ventral horn of the spinal cord by the vestibulospinal tract. Synonym: nucleus vestibularis. (05 Mar 2000) |
| vestibular nystagmus | Nystagmus resulting from physiological stimuli to the labyrinth that may be rotatory, caloric, compressive, or galvanic, or due to labyrinthal lesions. See: Barany's sign. Synonym: labyrinthine nystagmus. (05 Mar 2000) |
| vestibular ocular reflex | <clinical sign> Reflex movement of the eyes in the opposite direction to that which the head is moved, e.g., the eyes being lowered as the head is raised, and the reverse (Cantelli's sign); an indication of functional integrity of the brainstem tegmental pathways and cranial nerves involved in eye movement. Synonym: vestibular ocular reflex. (05 Mar 2000) |
| vestibular organ | Collective term for the utricle, saccule, and saemicircular ducts of the membranous labyrinth, each having a single patch of ciliated receptor epithelium innervated by the vestibular nerve: macula of sacculus, macula of utriculus, and cristae of the saemicircular ducts. (05 Mar 2000) |
| vestibular part of vestibulocochlear nerve | <anatomy, nerve> The vestibular part of the acoustic (8th cranial) nerve. The vestibular nerve fibres arise from neurons of scarpa's ganglion and project peripherally to vestibular hair cells and centrally to the vestibular nuclei of the brainstem. These fibres mediate the sense of balance and head position. (12 Dec 1998) |
| vestibular root | Radix vestibularis, radix superior nervi vestibulocochlearis, superior root of vestibulocochlear nerve, vestibular root of vestibulocochlear nerve. (05 Mar 2000) |
| vestibular root of vestibulocochlear nerve | Radix vestibularis, radix superior nervi vestibulocochlearis, superior root of vestibulocochlear nerve, vestibular root of vestibulocochlear nerve. (05 Mar 2000) |
| vestibular schwannoma | <oncology, tumour> This is a benign tumour of the 8th cranial nerve that affects approximately 1 out of 100,000 people. This tumour arises from the myelin forming Schwann cells that coat the 8th cranial nerve (acoustic nerve). Clinical presentation usually includes hearing deficit. Diagnosis can be made with auditory evoked potentials and/or MRI scanning of the brain. Vertigo and tinnitus may be associated symptoms. Surgical removal of this tumour involves dissection, cautery and obliteration with laser. (27 Sep 1997) |
| vestibular screen | A screen made of acrylic resin that covers the labial or buccal surfaces of one or both dental arches; used to treat oral habits and to stimulate tooth movement by using perioral muscle force. (05 Mar 2000) |