a. (sb.) [ad. L. tricuspis, -cuspid-em three-pointed, f. tri-, TRI- + cuspis point: cf. F. tricuspide (Littré).] Having three cusps or points. a. Tricuspid valve or valves (Anat.): the valve consisting of three triangular segments (or, as otherwise regarded, the set of three triangular valves) which guards the opening from the right auricle into the right ventricle of the heart. Also absol. or as sb.; hence attrib., as tricuspid murmur, obstruction, opening, regurgitation, etc.

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1670.  Phil. Trans., V. 2097. We did also observe two Ventricles with the tricuspid [and] sigmoid-valves.

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1834.  J. Forbes, Laennec’s Dis. Chest (ed. 4), 547. In hypertrophy of the right ventricle … the thickening is always a little greater in the vicinity of the tricuspid valves.

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1872.  Huxley, Physiol., ii. 36. On the right side there are … three of these broad pointed membranes, whence the whole apparatus is called the tricuspid valve.

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1877.  Roberts, Handbk. Med. (ed. 3), II. 10. Said to accompany tricuspid obstruction. Ibid., 43. Tricuspid Regurgitation.

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1898.  Allbutt’s Syst. Med., V. 786. Valvular incompetence … at the tricuspid opening. Ibid., 869. We may notice occasionally … a tricuspid systolic murmur.

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  b.  Of various structures, as a tooth, leaf, etc.: also absol. or as sb. a tricuspid tooth.

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1849.  Florist, 212. There is something very striking … about their tricuspid petals, and quaint, lively markings.

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1856.  Woodward, Mollusca, III. 449. The central teeth are … tricuspid in Loligo.

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1881.  J. Anderson, Scot. in Early Chr. T., iii. 130. In the West Highland crosses they are … terminated by a peculiar conventional, tricuspid leaf.

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  So Tricuspidal, Tricuspidate, Tricuspidated adjs. in same sense.

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1822–34.  Good’s Study Med. (ed. 4), I. 520. The *tricuspidal valve, with the … sigmoid valve of the pulmonary artery … never exhibit bony deposits.

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1852.  Salmon, Higher Plane Curves, vi. (1879), 253. The quartic is tricuspidal.

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1752.  J. Hill, Hist. Anim., 11. The Brachionus, with … a *tricuspidate tail.

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1881.  Baker, in Jrnl. Linn. Soc., XVIII. 280. Stigma capitate, obscurely tricuspidate.

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1822.  J. Parkinson, Outl. Oryctol., 197. An inequivalved … shell; *tricuspidated at the base. Ibid., 275. Teeth of cartilaginous fishes … triangular, conical, single pointed, tricuspidated, tridentated.

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