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.

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