| AMR | acoustic muscle reflex; activity metabolic rate; acute mitral stenosis; alopecia-mental retardation ... |
|---|---|
| AN | acanthosis nigricans; acne neonatorum; acoustic neuroma; adult, normal; ala nasi; amyl nitrate; aneu... |
| ANT | acoustic noise test; adenine nucleotide translocator; aminonitrothiazole; anterior |
| Ap4CH | apical four-chamber plane |
| ART | absolute retention time; Accredited Record Technician; acoustic reflex test; algebraic reconstructio... |
| acoustic aphasia | An impairment in comprehension of the auditory forms of language and communication, including the ability to write from dictation in the presence of normal hearing. Spontaneous speech, reading, and writing are not affected. Synonym: acoustic aphasia, word deafness. (05 Mar 2000) |
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| acoustic area | The floor of the lateral recess of the fourth ventricle, extending medially to the limiting sulcus and overlying the cochlear and vestibular nuclei of the rhombencephalon. Synonym: area acustica. (05 Mar 2000) |
| acoustic cell | A hair cell of the organ of Corti. (05 Mar 2000) |
| acoustic crest | An elevation on the inner surface of the ampulla of each saemicircular duct; filaments of the vestibular nerve pass through the crista to reach hair cells on its surface; the hair cells are capped by the cupula, a gelatinous protein-polysaccharide mass. Synonym: crista ampullaris, acoustic crest, transverse septum. (05 Mar 2000) |
| acoustic enhancement | A manifestation of increased acoustic signal amplitude returning from regions beyond an object which causes little or no attenuation of the sound beam. Compare: acoustic shadow. (05 Mar 2000) |
| acoustic impedance | The resistance that a material offers to the passage of a sound wave (colloquial); a property of a medium computed as the product of density and sound propagation speed (characteristic acoustic impedance). Discontinuities in acoustic impedance are responsible for the echoes on which ultrasound imaging is based. Unit: the rayl. (05 Mar 2000) |
| acoustic impedance tests | Objective tests of middle ear function based on the difficulty (impedance) or ease (admittance) of sound flow through the middle ear. These include static impedance and dynamic impedance (i.e., tympanometry and impedance tests in conjunction with intra-aural muscle reflex elicitation). This term is used also for various components of impedance and admittance (e.g., compliance, conductance, reactance, resistance, susceptance). (12 Dec 1998) |
| acoustic lemniscus | A bundle of ascending fibres that originate from the cochlear and auditory relay nuclei of the rhombencephalon, enter the trapezoid body, a transverse fibre stratum in which about half their number decussate, and from here turn rostrally along the lateral side of the spinothalamic tract; in the midbrain, it arches dorsally and enters the inferior colliculus in which all of its fibres terminate; the auditory pathway is transsynaptically extended from here by the brachium of the inferior colliculus to the medial geniculate body of the thalamus, from which in turn the auditory radiation leads to the auditory cortex; intercalated in the trapezoid body and along the ascending trajectory of the lemniscus are several cell groups in which part of the fibres synapse. Synonym: lemniscus lateralis, acoustic lemniscus, auditory lemniscus, auditory tract, lateral fillet. (05 Mar 2000) |
| acoustic lens | In ultrasonography, a lens used to focus or diverge a sound beam; may be simulated by electronic manipulation of signals. (05 Mar 2000) |
| acoustic maculae | Thickened areas of the saccule and utricle where the termination of the vestibular nerve occurs. (12 Dec 1998) |
| acoustic meatus | The passage leading inward through the tympanic portion of the temporal bone, from the auricle to the tympanic membrane; it consists of a bony (inner) portion and a fibrocartilaginous (outer) portion, the cartilaginous external acoustic meatus. Synonym: meatus acusticus externus, acoustic meatus, antrum auris, auditory canal, external auditory meatus. (05 Mar 2000) |
| acoustic nerve | <anatomy, nerve> The 8th cranial nerve. The acoustic (or vestibulocochlear) nerve has a cochlear part which is concerned with hearing and a vestibular part which mediates the sense of balance and head position. The fibres of the cochlear nerve originate from neurons of the spiral ganglion and project to the cochlear nuclei. The fibres of the vestibular nerve arise from neurons of scarpa's ganglion and project to the vestibular nuclei. (12 Dec 1998) |
| acoustic nerve diseases | Diseases of the eighth cranial nerve. These include vestibular neuronitis, cochlear neuritis and acoustic neuroma. (12 Dec 1998) |
| acoustic neurilemoma | <tumour> Schwannoma arising from cranial nerve eight. (05 Mar 2000) |
| acoustic neuroma | <oncology, tumour> This is a benign tumour of the 8th cranial nerve. 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. Incidence: 1 in 100,000. (13 Nov 1997) |