Sinus may refer to:

In anatomy, where a sinus is a sac or cavity in any organ or tissue:

• Sinus (anatomy), description of the general term
• Anal sinuses, the furrows which separate the columns in the rectum
• Paranasal sinuses, air cavities in the cranial bones, especially those near the nose
• Dural venous sinuses, venous channels found between layers of dura mater in the brain

In the heart:

• Sinus node, a structure in the superior part of the right atrium
• Sinus rhythm, normal beating on an ECG
• Coronary sinus, a vein collecting blood from the myocardium
• Sinus venosus, a cavity in the heart of embryos
• Sinus venarum, a part of the wall of the right atrium in adults, developed from the sinus venosus

Other:

• Sinus (botany), a space or indentation, usually on a leaf
• Sinus Asperitatis, an area on the Moon

See also

• Hemocoel, a space filled with hemolymph in organisms with open circulatory systems
• Sine a trigonometric math function (Latin sinus)
• Sines, Portugal, a municipality in Alentejo (Latin Sinus)
• Sinusitis, a common ailment resulting in the inflammation of the paranasal sinuses

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