Annulus

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Annulus (or anulus), being the Latin and French for "ring", is a term used to describe various ring or circle shaped objects (or openings):^[1][2]

• Annulus (botany), the ring-like row of cells surrounding the sorus of ferns and responsible for opening it when ripe
• Annulus (entomology), an antennal unit in simple antennae, or a ring-like marking or structure surrounding a joint or segment.
• Annulus (Herpetology), reference to too small an opening that can be a potential death trap for a reptile that can't pass through. The size difference of the two cylindrical forms (The body of the animal vs. the circumference of the opening).
• Annulus (anatomy) refers to several structures in human anatomy. The spelling "anulus" is preferred under Terminologia Anatomica, but both spellings are commonly found. Examples include:
  • Annulus fibrosus cordis, the ring-like structure on a heart valve where the valve leaflets are anchored
  • Annulus fibrosus disci intervertebralis, the outer wall of the invertebral disc
  • Annulus femoralis
  • Annulus inguinalis superficialis
  • Annulus inguinalis profundus
  • Annulus tendineus communis
  • The fourth finger of the hand, usu. the left hand, known commonly as the ring finger.
• Annulus (ichthyology), the annual rings that form in fish scales or bone sections
• Annulus (malacology), the annual rings that form in bivalve shells
• Annulus (mycology), the "ring" on a mushroom stem
• Annulus (astronomy), the ring of light from the visible part of the photosphere seen at the greatest extent of an annular eclipse
• Annulus (cosmology), the ring around the lens on which strong gravitationally lensed images of one source appear
• Annulus (mathematics), a ring-shaped geometric figure
• Annulus (firestop), the space in a penetration seal surrounding a penetrant, i.e. between a pipe or electrical conduit, or cable and a sleeve, with or without a firestop
• Annulus (oil well), the tube shaped void between a pipe string and a surrounding pipe string or formation.
• Annulus (microscopy), a circular opening "disk" below a specimen slide, required for Phase Contrast microscopy

• Annular hurricane, a hurricane that is nearly symmetrical and takes longer to weaken than normal hurricanes.
• Annular ring, a small metal torus that is used to create a via in a printed circuit board.
• Annulet (ring), a heraldic charge in the shape of an annulus.

[edit] References

• Sharp, J. M., Jr., 1999, A Glossary of Hydrogeological Terms: The University of Texas, Austin, Texas
• Principles of Contaminant Hydrogeology - Google Books Resultby Christopher M. Palmer - 1996 - Science - 256 pages
• Schnirel, Brian - Leeway Corucia Research Center (LCRC), 2008 Watching for potential death traps

The Official Discussion Board of the American Association of Zoo Keepers ... General discussion forum.

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