| AR | absolute risk; accounts receivable; achievement ratio; actinic reticuloid [syndrome]; active resista... |
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| ARA | Academy of Rehabilitative Audiometry; acetylene reduction activity; American Rheumatism Association;... |
| ARR | aortic root replacement |
| AWAR | anterior wall of aortic root |
| BOR | basal optic root; before time of operation; bowels open regularly; branchio-oto-renal [syndrome] |
| root pressure | <botany> Pressure in the roots which, when the shoot is cut off, will cause liquid to ooze from the root stump, the mechanisms and tissues involved in this process are not clearly understood. (09 Oct 1997) |
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| root resection | Excision of the apical portion of a tooth through an opening made in the overlying labial, buccal, or palatal alveolar bone. (12 Dec 1998) |
| root resorption | Resorption in which cementum or dentin is lost from the root of a tooth owing to cementoclastic or osteoclastic activity in conditions such as trauma of occlusion or neoplasms. (12 Dec 1998) |
| root sheath | One of the epidermic layers of the hair follicle: external root sheath is continuous with the stratum basale and stratum spinosum of the epidermis; internal root sheath comprises the cuticle of the internal roots, Huxley's layer, and Henle's layer. (05 Mar 2000) |
| root sprout | <botany> A living shoot which grows from the root of a plant whose above-ground portion has been cut down. (09 Oct 1997) |
| root tip | The tip of a tooth root, the part farthest from the incisal or occlusal side. Synonym: apex radicis dentis, root apex, root tip. (05 Mar 2000) |
| clinical root | That portion of a tooth embedded in the investing structures; the portion of a tooth not visible in the oral cavity. Synonym: radix clinica. (05 Mar 2000) |
| cochlear root of vestibulocochlear nerve | <anatomy, nerve> One of the components of the vestibulocochlear nerve; it is made up of the central processes of the bipolar neurons which compose the spiral (cochlear) ganglion in the spiral canal of the modiolus of the bony cochlea; the cochlear root enters the cranial cavity by passing in fascicles through the spiral foraminous tract at the bottom of the internal auditory meatus; it enters the brainstem through the pontomedullary groove, closely adhering to the caudoventral aspect of the vestibular root, and distributes its fibres to the ventral and dorsal cochlear nuclei in the floor of the lateral recess of the fourth ventricle. Synonym: radix cochlearis, cochlear root of vestibulocochlear nerve, inferior root of vestibulocochlear nerve, radix inferior nervi vestibulocochlearis. (05 Mar 2000) |
| cochlear root of VIII nerve | <anatomy, nerve> One of the components of the vestibulocochlear nerve; it is made up of the central processes of the bipolar neurons which compose the spiral (cochlear) ganglion in the spiral canal of the modiolus of the bony cochlea; the cochlear root enters the cranial cavity by passing in fascicles through the spiral foraminous tract at the bottom of the internal auditory meatus; it enters the brainstem through the pontomedullary groove, closely adhering to the caudoventral aspect of the vestibular root, and distributes its fibres to the ventral and dorsal cochlear nuclei in the floor of the lateral recess of the fourth ventricle. Synonym: radix cochlearis, cochlear root of vestibulocochlear nerve, inferior root of vestibulocochlear nerve, radix inferior nervi vestibulocochlearis. (05 Mar 2000) |
| motor root | The motor root of a spinal nerve. Synonym: radix anterior, radix motoria, anterior root, motor root, radix ventralis. (05 Mar 2000) |
| motor root of ciliary ganglion | A branch of the oculomotor nerve supplying parasympathetic preganglionic nerve fibres to the ciliary ganglion. Synonym: radix parasympathica ganglii ciliaris, radix oculomotoria ganglii ciliaris, motor root of ciliary ganglion, oculomotor root of ciliary ganglion, radix brevis ganglii ciliaris, short root of ciliary ganglion. (05 Mar 2000) |
| motor root of trigeminal nerve | <anatomy, nerve> The smaller root of the trigeminal nerve, composed of fibres originating from the trigeminal motor nucleus and emerging from the pons medial to the much larger sensory root, to join the mandibular nerve; it carries motor and proprioceptive fibres to the muscles derived from the first bronchial (mandibular) arch, including the four muscles of mastication, plus the mylohyoid, anterior belly of the digastric, and the tensores tympani and veli palati. Synonym: radix motoria nervi trigemini, masticator nerve, portio minor nervi trigemini. (05 Mar 2000) |
| plant root cap | A cone-shaped structure in plants made up of a mass of meristematic cells that covers and protects the tip of a growing root. It is the putative site of gravity sensing in plant roots. (12 Dec 1998) |
| cotton-root bark | Dried root bark of Gossypium herbaceum and other species of Gossypium (family Malvaceae). Has been used as an abortifacient and oxytocic. (05 Mar 2000) |
| cranial root of accessory nerve | <anatomy, nerve> The roots of the accessory nerve which arise from the medulla; the nerve fibres of the cranial root join the intracranial portion of the vagus nerve and are distributed to the pharyngeal plexus, providing the motor innervation of the soft palate (except the tensor veli palati) and the pharynx. Synonym: pars vagalis nervi accessorii, radices craniales, accessory portion of spinal accessory nerve, cranial roots, vagal part of accessory nerve, vagal part. (05 Mar 2000) |