| ORS | olfactory reference syndrome; oral rehydration solution; oral surgery, oral surgeon; Orthopaedic Res... |
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| OT | objective test; oblique talus; occlusion time; occupational therapist, occupational therapy; ocular ... |
| OTU | olfactory tubercle; operational taxonomic unit |
| GnRH | Gonadotropin Releasing Hormone [HP 1898, 2034] = LHRH = Go... |
| MALT | Mucosa Associated Lymphoid Tissue |
| olfactory nerve | <anatomy, nerve> The olfactory nerve carries impulses for the sense of smell. Synonym: cranial nerve I. (27 Sep 1997) |
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| olfactory nerves | Collective term denoting the numerous olfactory filaments: slender fascicles each composed of the thin, unmyelinated axons of 8 to 12 of the bipolar olfactory receptor cells in the olfactory portion of the nasal mucosa; the olfactory filaments pass through the cribriform plate of the ethmoid bone and enter the olfactory bulb, where they terminate in synaptic contact with mitral cells, tufted cells, and granule cells. See: olfactory tract. Synonym: nervi olfactorii, fila olfactoria, first cranial nerve, nerve of smell, olfactory fila. (05 Mar 2000) |
| olfactory neuroblastoma | <tumour> A rare, often slowly growing malignant tumour of primitive nerve cells, usually arising in the olfactory area of the nasal cavity. Synonym: olfactory esthesioneuroblastoma. (05 Mar 2000) |
| olfactory neurons | Sensory neurons from the lining of the nose. They are the only neurons that continue to divide and differentiate throughout an organisms life. (18 Nov 1997) |
| olfactory organ | The olfactory region in the superior portion of the nasal cavity. Synonym: organum olfactus, organ of smell. (05 Mar 2000) |
| olfactory pathways | Set of nerve fibres conducting impulses from olfactory receptors to the cerebral cortex. It includes the olfactory nerve, olfactory bulb, olfactory tract, olfactory tubercle, anterior perforated substance, and olfactory cortex. (12 Dec 1998) |
| olfactory peduncle | A nervelike, white band composed primarily of nerve fibres originating from the mitral cells and tufted cells of the olfactory bulb but also containing the scattered cells of the anterior olfactory nucleus. The tract is closely applied to the ventral surface of the frontal lobe, and attaches itself to the base of the cerebral hemisphere at the olfactory trigone, beyond which it extends in the form of the olfactory striae which distribute their fibres to the olfactory tubercle and, in largest number, to the olfactory cortex on and around the uncus of the parahippocampal gyrus. See: olfactory nerves. Synonym: tractus olfactorius, olfactory peduncle. (05 Mar 2000) |
| olfactory pits | The paired depressions formed when the nasal placodes come to lie below the general external contour of the developing face as a result of the rapid growth of the adjacent nasal elevations; the pit's are the primordia of the rostral portions of the nasal chambers. Synonym: olfactory pits. (05 Mar 2000) |
| olfactory placodes | Paired ectodermal placode's which come to lie in the bottom of the olfactory pits as the pits are deepened by the growth of the surrounding medial and lateral nasal processes. Synonym: nasal placodes. (05 Mar 2000) |
| olfactory pyramid | A small area of gray matter situated between the roots of the olfactory tracts; it is continuous caudally with the anterior perforated substance. (05 Mar 2000) |
| olfactory receptor cells | Very slender nerve cell's, with large nuclei and surmounted by six to eight long, sensitive cilia in the olfactory epithelium at the roof of the nose; they are the receptors for smell. Synonym: olfactory cells, Schultze's cells. (05 Mar 2000) |
| olfactory receptor neurons | Neurons in the olfactory epithelium with proteins (receptors, odourant) that bind, and thus detect, odourants. Olfactory receptor neurons are bipolar. They send to the surface of the epithelium apical dendrites with non-motile cilia from which project odourant receptor molecules. Their unmyelinated axons synapse in the olfactory bulb of the brain. Unlike other neurons, they can be generated from precursor cells in adults. (12 Dec 1998) |
| olfactory roots | Three distinct fibre bands (stria medialis, stria intermedia, stria lateralis) that caudally extend the olfactory tract beyond its attachment to the olfactory trigone. The medial stria curves dorsally into the tenia tecta; the intermediate, often barely visible, extends straight back and terminates in the olfactory tubercle; the lateral olfactory stria, the largest of the three, passes along the lateral side of the olfactory tubercle, curving laterally as far as the limen insulae, then sharply medially to reach the uncus of the parahippocampal gyrus where it terminates in the plexiform layer of the olfactory cortex. See: medial longitudinal stria. Synonym: striae olfactoriae, olfactory roots. (05 Mar 2000) |
| olfactory striae | Three distinct fibre bands (stria medialis, stria intermedia, stria lateralis) that caudally extend the olfactory tract beyond its attachment to the olfactory trigone. The medial stria curves dorsally into the tenia tecta; the intermediate, often barely visible, extends straight back and terminates in the olfactory tubercle; the lateral olfactory stria, the largest of the three, passes along the lateral side of the olfactory tubercle, curving laterally as far as the limen insulae, then sharply medially to reach the uncus of the parahippocampal gyrus where it terminates in the plexiform layer of the olfactory cortex. See: medial longitudinal stria. Synonym: striae olfactoriae, olfactory roots. (05 Mar 2000) |
| olfactory sulcus | The sagittal sulcus on the inferior or orbital surface of each frontal lobe of the cerebrum, demarcating the straight gyrus from the orbital gyri, and covered on the orbital surface by the olfactory bulb and tract. Synonym: sulcus olfactorius, olfactory groove. (05 Mar 2000) |