| external aperture of cochlear canaliculus | The external opening of the cochlear aqueduct on the temporal bone medial to the jugular fossa. Synonym: apertura externa canaliculi cochleae. (05 Mar 2000) |
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| external aperture of vestibular aqueduct | The external opening of the vestibular aqueduct on the posterior surface of the petrous part of the temporal bone near the groove for the sigmoid sinus. Synonym: apertura externa aqueductus vestibuli. (05 Mar 2000) |
| bony part of external acoustic meatus | The medial two-thirds of the external acoustic meatus which is formed as the tympanic plate of the temporal bone develops; it extends approximately 16 mm. From its junction with the cartilaginous part to the tympanic membrane. (05 Mar 2000) |
| cartilaginous part of external acoustic meatus | The lateral third of the external acoustic meatus which is continuous with the auricular cartilage and attached to the circumference of the bony part. (05 Mar 2000) |
| nerve of external acoustic meatus | A branch of the auriculotemporal nerve supplying the lining of the external acoustic meatus. Synonym: nervus meatus acustici externi. (05 Mar 2000) |
| notches in cartilage of external acoustic meatus | (usually) two vertical fissures in the anterior portion of the cartilage of the external auditory meatus, filled by fibrous tissue. Synonym: incisurae cartilaginis meatus acustici externi, Duverney's fissures, incisurae santorini, Santorini's fissures, Santorini's incisures. (05 Mar 2000) |
| isthmus of external acoustic meatus | The narrowest portion of this canal in the bony part near its deep termination. Synonym: isthmus meatus acustici externi. (05 Mar 2000) |
| opening of external acoustic meatus | The orifice of the external acoustic meatus in the tympanic portion of the temporal bone. Synonym: porus acusticus externus, external acoustic foramen, external acoustic pore, external auditory pore, external auditory foramen, orifice of external acoustic meatus. (05 Mar 2000) |
| orifice of external acoustic meatus | The orifice of the external acoustic meatus in the tympanic portion of the temporal bone. Synonym: porus acusticus externus, external acoustic foramen, external acoustic pore, external auditory pore, external auditory foramen, orifice of external acoustic meatus. (05 Mar 2000) |
| external acoustic foramen | The orifice of the external acoustic meatus in the tympanic portion of the temporal bone. Synonym: porus acusticus externus, external acoustic foramen, external acoustic pore, external auditory pore, external auditory foramen, orifice of external acoustic meatus. (05 Mar 2000) |
| external 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) |
| external acoustic pore | The orifice of the external acoustic meatus in the tympanic portion of the temporal bone. Synonym: porus acusticus externus, external acoustic foramen, external acoustic pore, external auditory pore, external auditory foramen, orifice of external acoustic meatus. (05 Mar 2000) |
| angle of aperture | <ophthalmology, optics> The angle formed by lines drawn from the ends of the diameter of a lens to its point of focus. See: angular aperture. (05 Mar 2000) |
| angular aperture | The angle, in air, of light that passes from the object to the ends of the diameter of the front lens of the microscope objective. (05 Mar 2000) |
| anterior nasal aperture | The anterior nasal opening in the skull. Synonym: apertura piriformis, piriform opening. (05 Mar 2000) |