| excavation of optic disc | The normally occurring depression or pit in the centre of the optic disc. Synonym: excavatio disci, depression of optic disk, excavatio papillae, physiologic cup, physiologic excavation. (05 Mar 2000) |
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| lateral root of optic tract | The larger division of the posterior end of the optic tract that terminates in the lateral geniculate body. Synonym: radix lateralis tractus optici. (05 Mar 2000) |
| Leber's hereditary optic atrophy | Hereditary degeneration of the optic nerve and papillomacular bundle with resulting rapid loss of central vision, progressive for several weeks, then usually stationary with permanent central scotoma; age of onset is variable, most often in the third decade; more males than females are affected and transmission is cytoplasmic and strictly on the female side. Mutation on the mitochondrial chromosome involved, which presumably interacts with an X-linked mutant. This mechanism may explain the bizarre sex ratio, which differs significantly from one country to another. (05 Mar 2000) |
| lenticulo-optic | Relating to the lentiform nucleus and the optic tract; specifically refers to branches of the middle cerebral artery considered to supply these structures. (05 Mar 2000) |
| abdominal part of aorta | <anatomy> The largest arterial conduit below the diaphragm. This term refers to the portion of the aorta below the diaphragm to the bifurcation into the right and left common iliac arteries. It supplies blood to the abdominal viscera, pelvic organs and lower extremities. (20 Jun 2000) |
| abdominal part of oesophagus | The part of the oesophagus inferior to the diaphragm. See: oesophagus. Synonym: pars abdominalis oesophagi. (05 Mar 2000) |
| abdominal part of thoracic duct | The part of the thoracic duct between the cisterna chyli and the aortic hiatus of the diaphragm. Synonym: pars abdominalis ductus thoracici. (05 Mar 2000) |
| abdominal part of ureter | The part of the ureter between the renal pelvis and the brim of the pelvis. Synonym: pars abdominalis ureteris. (05 Mar 2000) |
| accessory flower part | <plant biology> Sepal and petal organs found on flowers. The sepals and petals are not essential for pollination but may aid in attracting insects or other organisms. (15 Jan 1998) |
| alar part of nasalis muscle | <anatomy> See: nasalis muscle. Synonym: pars alaris musculi nasalis. (05 Mar 2000) |
| alveolar part of mandible | The portion of the body of the mandible that surrounds and supports the lower teeth. Synonym: pars alveolaris mandibulae. (05 Mar 2000) |
| alveolar soft part sarcoma | <tumour> A malignant tumour formed of a reticular stroma of connective tissue enclosing aggregates of large round or polygonal cells; occurs in subcutaneous and fibromuscular tissues. (05 Mar 2000) |
| annular part of fibrous digital sheath | One of the two circular fibrous bands of the fibrous sheaths of the fingers and toes attached to the shaft of the proximal and middle phalanges. Synonym: pars annularis vaginae fibrosae, annular pulley, annulus of fibrous sheath, ligamentum annulare digitorum. (05 Mar 2000) |
| anterior part | The portion of a structure that tlies most forward, or closest to the front surface relative to other parts; in human anatomy, the ventral portion of a structure. See: anterior part of anterior commissure of brain, anterior part of diaphragmatic surface of liver, anterior part of fornix of vagina. Synonym: pars anterior. (05 Mar 2000) |
| anterior part of anterior commissure of brain | The anterior part of the anterior or rostral commissure of the brain. Synonym: pars anterior commissurae rostralis, pars anterior commissurae anterioris cerebri. (05 Mar 2000) |