suspensorium

Suspensorium refers to the set of bones and cartilages that suspend the jaws from the skull and transmit the forces of feeding during jaw opening and closing. It forms the jaw suspension apparatus, connecting the cranium with the mandible and shaping how the jaw moves in different vertebrates. The exact components vary across groups, but a typical suspensorial series includes upper jaw elements such as the palatoquadrate in primitive forms and a posterior support element such as the hyomandibula or quadrate, along with lower jaw elements like the articular. Together, these structures anchor the jaw to the skull and allow coordinated motion.

Across vertebrates, jaw suspension has evolved in diverse ways. Historical classifications describe autostylic, amphistylic, hyostylic, and metautostylic modes, indicating different degrees and points of contact between the jaw elements and the skull. In cartilaginous fishes, amphibians, and several extinct lineages, multiple articulations aid jaw support. In many bony fishes, hyostyly is common, with the hyomandibula playing a major suspensorial role. In mammals, the suspensorial arrangement has been substantially modified: the main functional jaw joint becomes between the dentary (lower jaw) and the squamosal, and elements of the suspensorium contribute to the formation of auditory ossicles, notably the malleus and incus, reflecting an evolutionary link between feeding mechanics and hearing.

The term emphasizes the mechanical linkage that allows jaw movement and force transmission, and it highlights the evolutionary continuity between feeding structures and other skull components.