sinus node


: a small mass of tissue that is embedded in the musculature of the right atrium of higher vertebrates and that originates the impulses stimulating the heartbeat

Example Sentences

Recent Examples on the Web Hearts beat when the sinus node, a small mass of tissue in the right upper chamber, transmits an impulse to the heart cells. Michael Ciaglo, National Geographic, 5 June 2020 Over the course of a day, a person’s heart beats about 100,000 times, and each beat begins with an electrical signal generated in the sinus node in the heart’s upper right chamber. Emily Sohn, Washington Post, 7 Mar. 2018

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'sinus node.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

Word History

First Known Use

1937, in the meaning defined above

Time Traveler
The first known use of sinus node was in 1937

Dictionary Entries Near sinus node

Cite this Entry

“Sinus node.” Dictionary, Merriam-Webster, Accessed 5 Jun. 2023.

Medical Definition

sinus node

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