From ZooTerms (Dictionary of Invertebrate Zoology)
Arthropoda) In various arthropods, an internal sclerotized ridge, plate or other process of the cephalic exoskeleton that functions for muscle and connective tissue attachment; sometimes called entosternite.endosternite (noun; Greek endon, within; sternon, chest): 1. (
2. (Arthropoda: Crustacea) a. In Notostraca, the mesodermal plate beneath the anterior portion of the alimentary canal. b. In certain Decapoda, a firm calcareous plate of the anterior thorax between the nerve cord and alimentary canal.