part of overlaps develops from mesothoracic episternum leg joint mesothoracic leg mesothoracic coxa proximal joint of mesothoracic coxa fly_anatomy.ontology J Th2 The joint between the proximal end of the mesothoracic coxa and the mesothoracic episternum or katepisternum. The fossa (socket) of this joint is part of the katepisternum. The condyle (ball) is part of the coxa. This joint is located ventrally. FBbt:00007662 body-coxa joint presumptive proximal joint of mesothoracic coxa