| lethal | Deadly, fatal. Origin: L. Lethalis, from lethum = death (18 Nov 1997) |
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| lethal coefficient | <microbiology> That concentration of disinfectant that kills bacteria at 20-25캜 in the shortest period of time. (05 Mar 2000) |
| lethal dwarfism | Dwarfism leading to intrauterine or neonatal death. (05 Mar 2000) |
| lethal equivalent | A combination of selective effects that on average have the same impact on the composition of the gene pool as one death; e.g., two carriers at 50% risk of dying would be the lethal equivalent of one carrier at 100% risk, in the population genetics of recessive traits lethal equivalent is expressed as twice the sum of the expected number of deaths ascribable to the genetic load. Expression used of the genetic load of recessive genes in heterozygous state that if in homozygous state would cause death or carry a risk of death. The expected number of deaths from all such genes is expressed in lethal equivalent. (05 Mar 2000) |
| lethal factor | A disorder that prevents effective reproduction by those affected; e.g., Klinefelter syndrome. (05 Mar 2000) |
| lethal gene | A gene that produces a genotype that leads to death of the organism before reproduction is possible or that precludes reproduction; for a recessive gene the homozygous or hemizygous state is lethal. (05 Mar 2000) |
| lethal midline granuloma | Destruction of the nasal septum, hard palate, lateral nasal walls, paranasal sinuses, skin of the face, orbit and nasopharynx by an inflammatory infiltrate with atypical lymphocytic and histiocytic cells; presumably a form of lymphoma in most cases. An obsolete term for polymorphic reticulosis. Synonym: granuloma gangrenescens, malignant granuloma, midline malignant reticulosis granuloma. (05 Mar 2000) |
| lethal mutation | <genetics, molecular biology> Mutation that eventually results in the death of an organism carrying the mutation. (18 Nov 1997) |
| anterior median fissure of medulla oblongata | The longitudinal groove in the midline of the anterior aspect of the medulla oblongata; it is the medullary equivalent of the anterior median fissure of the spinal cord and ends at the foramen caecum posterius; its caudal part is obliterated by the decussation of the pyramids. Synonym: fissura mediana anterior medullae oblongatae, anteromedian groove. (05 Mar 2000) |
| anterior median fissure of spinal cord | A deep median fissure on the anterior surface of the spinal cord. Synonym: fissura mediana anterior medullae spinalis, anteromedian groove, sulcus ventralis. (05 Mar 2000) |
| anterior median line | The line of intersection of the midsagittal plane with the anterior surface of the body. Synonym: linea mediana anterior. (05 Mar 2000) |
| palmar branch of median nerve | <anatomy, nerve> Branch of median nerve arising proximal to flexor retinaculum and running superficial to it to supply skin of proximal central palm and thenar eminence. Since it does not traverse carpal tunnel, it is not affected by carpal tunnel syndrome, even though it supplies skin distal to carpal tunnel. Synonym: ramus palmaris nervi mediani. (05 Mar 2000) |
| medial root of median nerve | <anatomy, nerve> The part of the median nerve coming from the medial cord of the brachial plexus. Synonym: radix medialis nervi mediani. (05 Mar 2000) |
| median | <statistics> Any value that divides the probability of a random variable in half, i.e. The probability of observing a value above the median and the probability of observing a value below the median are both less than or equal to one half. For a finite population or sample, the median is the middle value of an odd number of values (arranged in ascending order) or any value between the two middle values of an even number of values, in the latter case it is conventional to use the average of the two middle values. Origin: L. Medianus (18 Nov 1997) |
| median antebrachial vein | It begins at the base of the dorsum of the thumb, curves around the radial side, ascends the middle of the forearm, and just below the bend of the elbow divides into the intermediate basilic and intermediate cephalic veins; sometimes it divides lower down, one branch going to the basilic vein, the other to the intermediate vein of the elbow. Synonym: vena intermedia antebrachii, intermediate antebrachial vein, intermediate vein of forearm, median vein of forearm, vena mediana antebrachii. (05 Mar 2000) |