Sinus Iridum, Chang'e 3 & Lunokhod 1 landing sites.png

Sinus may refer to:

Anatomy

* Sinus (anatomy), a sac or cavity in any organ or tissue
** Paranasal sinuses, air cavities in the cranial bones, especially those near the nose, including:
*** Maxillary sinus, is the largest of the paranasal sinuses, under the eyes, in the maxillary bones
*** Frontal sinus, superior to the eyes, in the frontal bone, which forms the hard part of the forehead
*** Ethmoid sinus, formed from several discrete air cells within the ethmoid bone between the eyes and under the nose
*** Sphenoidal sinus, in the sphenoid bone at the center of the skull base under the pituitary gland
** Anal sinuses, the furrows which separate the columns in the rectum
** Dural venous sinuses, venous channels found between layers of dura mater in the brain
* Sinus (botany), a space or indentation, usually on a leaf

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 heart
* 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 uses

* Sinus (Chalcidice), a town of ancient Chalcidice, Greece
* ''Sinus'', gulf or bay in Latin, used in numerous toponyms in ancient writing (e.g., Sinus Magnus, Sinus Flanaticus, etc.)
* Sine, a trigonometric math function (Latin ''sinus'')

See also

* Sinus Medii, a small lunar mare
* Sinus Successus, a lunar feature
* Sines, a municipality in Alentejo, Portugal (Latin ''Sinus'')
* Sinusitis, a common ailment resulting in the inflammation of the paranasal sinuses

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