tritocerebrum

tritocerebrum (noun; Greek tritos, third; Latin cerebrum, brain): (Arthropoda) The posterior (third) small part of an arthropod brain that gives rise to nerves that innervate the labium, the digestive tract (stomatogastric nerves), the chelicerae of chelicerates, and the second antennae of crustaceans

See also: metacerebrum.