Annulus
A ringlike structure, or any body part that is shaped like a ring. Applied to many small ring-shaped structures. The base of a heart valve that supports the valve's leaflets is called the annulus. A ring-shaped pancreas that encircles the duodenum is an annular pancreas. "Annulus" is a misspelling of the Latin "anulus" (a little ring), the diminutive of the Latin "anus" (a ring of more substantial size).
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SYN: ring.

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an·nu·lus 'an-yə-ləs n, pl -li -.lī also -lus·es a ringlike part, structure, or marking esp any of various ringlike anatomical parts (as the inguinal ring)

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n.
(in anatomy) a circular opening or ring-shaped structure.
annular adj.

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an·nu·lus (anґu-ləs) gen. and pl. anґnuli [L., from anus ring] a ring or ringlike structure; in official anatomical terminology, spelled anulus [TA], q.v. for terms not found here.

Medical dictionary. 2011.

Look at other dictionaries:

  • Annulus — (or anulus), being the Latin and French for ring , is a term used to describe various ring or circle shaped objects (or openings):cite book | last = Martim de Albuquerque | first = | title = Notes and Queries | publisher = Oxford University Press …   Wikipedia

  • Annulus — (lat. anulus = der Ring) bezeichnet: Annulus (Mikroskopie), eine oktagonale elektronendichte Region der Kernhülle einer Zelle in der Elektronenmikroskopie Annulus (Muskel), ein ringförmiges Muskelfeld etwa beim Nautilus oder den Bartwürmern eine… …   Deutsch Wikipedia

  • annulus — [an′yo͞o ləs, an′yələs] n. pl. annuli [an′yo͞olī΄, an′yəlī΄] or annuluses [L annulus, for anulus: see ANNULAR] any ring or ringlike part, mark, etc …   English World dictionary

  • Annulus — An nu*lus, n.; pl. {Annuli}. [L.] 1. A ring; a ringlike part or space. [1913 Webster] 2. (Geom.) (a) A space contained between the circumferences of two circles, one within the other. (b) The solid formed by a circle revolving around a line which …   The Collaborative International Dictionary of English

  • Annŭlus — (lat.), 1) überhaupt Ring; so A. piscatorĭus (Fischerring), Siegelring des Papstes, s. Fischerring; A. pronubus, Verlobungs od. Trauring; 2) (Anat.), A. abdominālis (A. inguinālis, A. orālis), der Bauchring, s.d.; A. irĭdis, Irisring, s. Auge; A …   Pierer's Universal-Lexikon

  • Annŭlus — (lat.), Ring; A. piscatorius, der Fischerring des Papstes …   Meyers Großes Konversations-Lexikon

  • annulus — (n.) 1560s, medical, from misspelling of L. anulus little ring, finger ring, a dim. of anus (see ANUS (Cf. anus)) …   Etymology dictionary

  • annulus — A growth zone that forms once a year; for most fish an annulus is identified as the zone that forms during a period of slow or no growth, often during the winter season (see opaque) …   Fisheries — dictionary

  • annulus — (plural annuli) a ring or rings on a fish scale or in a bony or cartilaginous structure corresponding to a year of growth. In a scale usually consists of closely arranged ridges (circuli). An accessory annulus is a ring caused by retarded or… …   Dictionary of ichthyology

  • annulus — n.; pl. li luses [L. annulus, ring] 1. Any ring like circling of a joint, segment, spot or mark. 2. (BRYOZOA: Phylactolaemata) The outer epidermal layer of a statoblast that encircles the protective capsule. 3. (NEMATA) The interstice area… …   Dictionary of invertebrate zoology

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