The sternum is a median bone that, with the anterior portion of the ribs, forms the anterior boundary of the bony thorax.

The term [sternum] comes from the Greek, meaning "flat chest or flat surface". In early anatomy, the sternum was known by a Latin term [gladius] referring to the similarity of the sternum to the short sword of the gladiators.

The sternum is composed by three segments, from superior to inferior they are the:

1. Manubrium: This is Latin for "handle" (of the sword)
2. Body: This segment is formed by four separate bones that fuse together later in life. Each separate bony component of the sternal body is known as a "sternabra" (plural: sternabrae)
3. Xiphoid appendix: The term [xiphoid] is Greek and means "similar to a straight sword", but it refers only to the lowest portion of the sternum. Sometimes called the [xiphisternum], the xiphoid appendage or process is cartilaginous and is the last cartilage to ossify in the human.

The boundary between the manubrium and sternal body is known as the "sternal angle" or the "angle of Louis"named after Antoine Louis, a French physician. Click on the image of the thorax to see a detailed image of the sternum.

Images property of: CAA.Inc.Artist: David M. Klein