Sternum (arthropod anatomy)
（重定向自Sternite）
![Throacic and abdominal sterna of a beetle. A Mesosternum, B Metasternum, 1 first abdominal sternite, 2-6 rest of sternites](/Images/godic/202502/13/Certtallum_ebulinum_under4648.jpg")
- This article is about the insect body parts. For the vertebrate breastbone, see sternum and human sternum.
The sternum (pl. "sterna") is the ventral portion of a segment of an arthropod thorax or abdomen.
In insects, the sterna are usually single, large sclerites, and external. However, they can sometimes be divided in two or more, in which case the subunits are called sternites, and may also be modified on the terminal abdominal segments so as to form part of the functional genitalia, in which case they are frequently reduced in size and development, and may become internalized and/or membranous.