[see-nuh s muh-rid-ee-ah-nee-ee, sahy-nuh s muh-rid-ee-ey-nee-ahy] /ˈsi nəs məˌrɪd iˈɑ niˌi, ˈsaɪ nəs məˌrɪd iˈeɪ niˌaɪ/
an area on the equator of Mars, appearing as a dark region when viewed telescopically from the earth.
noun, Anatomy. 1. sinoatrial node. sinus node n. See sinoatrial node.
- Sinus of dura mater
sinus of dura mater n. Any of the various venous channels located in the dura mater and lined with epithelial cells. Also called cerebral sinus, dural sinus.
[sahy-nuh s uh v val-sal-vuh] /ˈsaɪ nəs əv vælˈsæl və/ noun, Anatomy. 1. any of the pouches of the aorta and the pulmonary artery opposite the flaps of the semilunar valves into which blood returning to the heart flows, closing the valves.
- Sinus of vena cava
sinus of vena cava n. The portion of the cavity of the right atrium of the heart that receives the blood from the venae cavae and is separated from the rest of the atrium by the terminal crest.