käkben

Käkben is the Swedish term for the bones that form the jaw in humans and many vertebrates. The jaw consists of two bones: the maxilla (upper jaw) and the mandible (lower jaw). The maxilla forms most of the upper jaw, houses the upper teeth, and contributes to the floor of the orbit, the sides of the nasal cavity, and the palate. The mandible is the strongest bone of the skull and holds the lower teeth; it articulates with the temporal bones at the temporomandibular joints, and it is moved by the muscles of mastication and ligaments to enable biting, chewing, and speech.

Development and clinical notes: The jaw bones ossify mainly by intramembranous ossification, with the condylar region of the mandible undergoing endochondral ossification to allow postnatal growth. The alveolar processes support tooth sockets and participate in occlusion. Clinically, the jaw bones can be involved in fractures (most commonly the mandible), temporomandibular joint disorders, and dental implant planning. Variation exists among species in size, shape, and degree of mobility, but the basic arrangement—an upper jaw and a movable lower jaw—is widespread in gnathostomes.