Sinus

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The term sinus (Latin for "bay", "pocket", "curve" or "bosom") is used in various contexts.

[edit] Anatomy

A sinus is a sack or cavity in any organ or tissue, or an abnormal cavity or passage caused by the destruction of tissue. In common usage, "sinus" usually refers to the paranasal sinuses, which are air cavities in the cranial bones, especially those near the nose and connecting to it.

The term "sinus" is also used for the following structures:

• The dural venous sinuses, venous channels found between layers of dura mater in the brain.
• A chronically infected tract such as a passage between an abscess and the skin. It is however distinct from a fistula which is a tract connecting two epithelialised surfaces.
• Another name for the nostril.
• Various structures of the heart:
  • The sinus node is a structure in the superior part of the right atrium of the heart, producing the electrical impulse for the heart's contraction.
  • "Sinus" is also sometimes used short for sinus rhythm.
  • The coronary sinus is a vein collecting blood from the heart and draining into the right atrium.
  • The sinus venosus is a cavity in the heart of embryos.
  • The sinus venarum is a part of the wall of the right atrium in adults; it develops from the sinus venosus.
• The hemocoel, a space filled with hemolymph in organisms with open circulatory systems.

[edit] Astronomy

• The "bays" on the Moon; see Sinus and Paludes.

[edit] Mathematics

• Sine or sinus is a trigonometric function.
• Sine or sinus hyperbolicus is a hyperbolic function

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