| IRE | internal rotation in extension; iron-responsive element; isolated rabbit eye |
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| IRF | idiopathic retroperitoneal fibrosis; impulse response function; interferon regulatory factor; intern... |
| IRS | immunoreactive secretion; infrared spectrophotometry; insulin receptor species; insulin receptor sub... |
| ISH | icteric serum hepatitis; in situ hybridization; internal self helper; International Society of Hemat... |
| ITA | inferior temporal artery; internal thoracic artery; International Tuberculosis Association |
| internal urethral sphincter | The complete collar of smooth muscle cells of the neck of the urinary bladder which extend distally to surround the preprostatic sportion of the male urethra. There is not a comparable structure in the neck of the femoral bladder; the internal urethral sphincter may exist to prevent reflux of semen into bladder. Synonym: annulus urethralis, internal urethral sphincter, musculus sphincter vesicae, preprostate urethral sphincter, proximal urethral sphincter, sphincter muscle of urinary bladder. (05 Mar 2000) |
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| opening of internal acoustic meatus | The inner opening of the internal acoustic meatus on the posterior surface of the petrous part of the temporal bone. Synonym: porus acusticus internus, internal acoustic foramen, internal acoustic pore, auditory pore, internal auditory foramen, orifice of internal acoustic meatus. (05 Mar 2000) |
| orifice of internal acoustic meatus | The inner opening of the internal acoustic meatus on the posterior surface of the petrous part of the temporal bone. Synonym: porus acusticus internus, internal acoustic foramen, internal acoustic pore, auditory pore, internal auditory foramen, orifice of internal acoustic meatus. (05 Mar 2000) |
| thymic branches of internal thoracic artery | <anatomy, artery> See: mediastinal branches of internal thoracic artery. (05 Mar 2000) |
| transverse crest of internal acoustic meatus | A horizontal ridge that divides the fundus of the internal acoustic meatus into a superior and an inferior area. In the former are the introitus of the facial canal and openings for the branches of the vestibular nerve to the utricle and to the ampullae of the anterior and lateral saemicircular canals. In the latter are openings for the cochlear nerve, and for branches of the vestibular nerve to the saccule and to the ampulla of the posterior saemicircular canal. Synonym: crista transversa, falciform crest, transverse crest. (05 Mar 2000) |
| lamina internal ossium cranii | The inner table of one of the cranial bones; it is more compact and harder than the outer table. Synonym: lamina internal ossium cranii. (05 Mar 2000) |
| lateral costal branch of internal thoracic artery | <anatomy, artery> A variable branch of internal thoracic artery that runs lateral and parallel to the internal thoracic artery on the deep surface of the rib cage; anastomosis: posterior intercostal arteries. Synonym: ramus costalis lateralis arteriae thoracicae internae. (05 Mar 2000) |
| fracture fixation, internal | The use of internal devices (metal plates, nails, rods, etc.) to hold the position of a fracture in proper alignment. (12 Dec 1998) |
| fundus of internal acoustic meatus | The thin cribriform plate of bone separating the cochlea and vestibule from the internal acoustic meatus; a transverse crest divides it into two regions; in the superior region are located the area nervi facialis and the area vestibularis superior; in the inferior region are located the area cochleae, area vestibularis inferior, and foramen singulare. Synonym: fundus meatus acustici interni, fundus of internal auditory meatus. (05 Mar 2000) |
| fundus of internal auditory meatus | The thin cribriform plate of bone separating the cochlea and vestibule from the internal acoustic meatus; a transverse crest divides it into two regions; in the superior region are located the area nervi facialis and the area vestibularis superior; in the inferior region are located the area cochleae, area vestibularis inferior, and foramen singulare. Synonym: fundus meatus acustici interni, fundus of internal auditory meatus. (05 Mar 2000) |
| abducens nerve | <anatomy, nerve> The 6th cranial nerve. The abducens nerve originates in the abducens nucleus of the pons and sends motor fibres to the lateral rectus muscles of the eye. Damage to the nerve or its nucleus disrupts horizontal eye movement control. (12 Dec 1998) |
| abducent nerve | <anatomy> The abducent nerve enervates a muscle which moves the eyeball. Lesions of the sixth cranial nerve result in deviation of the eyeball outward and double vision. Synonym: cranial nerve VI. (27 Sep 1997) |
| accessory nerve | <anatomy, nerve> The accessory nerve enervates the sternocleidomastoid muscles and the trapezius muscles. Lesions of the eleventh result in drooping of the shoulder and inability to rotate the head away from the affected side. Synonym: cranial nerve XI. (27 Sep 1997) |
| accessory nerve lymph nodes | The nodes of the lateral deep cervical group that are located along the accessory nerve; their efferent vessels pass to the supraclavicular lymph nodes. Synonym: companion lymph nodes of accessory nerve, nodi lymphatici comitantes nervi accessorii. (05 Mar 2000) |
| accessory nerve trunk | Part of the accessory nerve formed within the cranial cavity by the union of the cranial and spinal roots, which then divides within the jugular foramen into internal and external branches, the former uniting with the vagus, the latter exiting the foramen as in independent branch which is commonly considered to be the accessory nerve. (05 Mar 2000) |