retroarticular
The retroarticular is a cartilage bone that forms at the posteroventral tip of Meckel's cartilage where the interoperculomandibular ligament attaches (5.1 mm NL). In the adult it is basically triangular in shape. The retroarticular is ligamentously connected to the interopercle and preopercle posteriorly and abuts the ventral shelf of the dentary anteriorly.