Jaw and Tongue Muscles in the Australian Lungfish, Neoceratodus forsteri (Osteichthyes: Dipnoi)

: The Australian lungfish, Neoceratodus forsteri , has several muscles associated with feeding. The massive adductor mandibularis muscle of N . forsteri , which closes the jaws, originates on the chondrocranium and inserts on the posterior aspect of Meckel’s cartilage in the mandible. The depressor mandibulae muscle, which opens the jaws, inserts on the medial articulation of the prearticular bones of the mandible and originates on the pectoral girdle. Oblique muscles, originating on the prearticular bone and inserted into tissues of the midline of the mandible, carry out the subterminal grinding movements of the mandible to masticate food. Separate muscles control the hyoid apparatus. Interhyoideus muscles originate on the posterior lateral aspect of the ceratohyal and insert on soft tissues medially to control fine movements of the tongue. The levator hyoideus muscle, originating on the posterolateral chondrocranium and inserting on the cartilage of the posterior ceratohyal, acts with the interhyoideus muscles to move the entire hyoid apparatus forwards and pushes the tongue, supported by the basihyal cartilage, into the space between the mandibular bones to facilitate suctorial actions of the jaws and draw food into the mouth. The paired geniocoracoideus muscle, originating on the pectoral girdle and inserting ventrally on the hypohyal cartilages and anterior ceratohyal bones, and the rectus cervicis muscle, also paired, originating on the pectoral girdle and inserting on the dorsal surface of the hypohyal cartilages, moves the hyoid apparatus into a resting position.