episternum

from The Century Dictionary.

• noun In spatangoid sea-urchins, the third pair of plates on the ventral face of the posterior interradius.
• noun In mammals, the manubrium sterni: the presternum of most authors.
• noun In lower vertebrates, some presternal part. See interclavicle.
• noun In entomology, the anterior one of the three sclerites into which the propleuron, the mesopleuron, and the metapleuron of an insect are severally typically divisible, lying above the sternum, below the tergum, and in front of an epimeron.
• noun In Chelonia, same as epiplastron: so called by most anatomists, who have considered it an element of a sternum. See second cut under Chelonia.
• noun plural In comparative anatomy, the lateral pieces of the inferior or ventral are of the somite of a crustacean.

from the GNU version of the Collaborative International Dictionary of English.

• noun A median bone connected with the sternum, in many vertebrates; the interclavicle.
• noun Same as epiplastron.
• noun (Zoöl.) One of the lateral pieces next to the sternum in the thorax of insects.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun anatomy The upper segment of the sternum