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In vertebrates, the lower jaw or mandible is the mobile component that articulates at its posterior processes, or rami (singular ramus), with the temporal bones of the skull on either side; the word jaw used in the singular typically refers to the lower jaw. The upper jaw or maxilla is more or less fixed with the skull and is composed of two bones, the maxillae, fused intimately at the median line by a suture; incomplete closure of this suture and surrounding structures may be involved in the malformation known as cleft palate. The maxillary bones form parts of the roof of the mouth, the floor and sides of the nasal cavity, and the floor of the orbit or eye socket. The jaws typically accommodate the teeth or form the bases for the attachment of a beak.

In reptiles, the mandible is made up of five bones. In the evolution of mammalSubclass Monotremata Monotremata Subclass Marsupialia Didelphimorphia Paucituberculata Microbiotheria Dasyuromorphia Peramelemorphia Notoryctemorphia Diprotodontia Subclass Placentalia Xenarthra Dermoptera Desmostylia Scandentia Primates Rodentia Lagomorps, four of these bones were reduced in size and incorporated into the ear. In their reduced form, they are known as the malleusThe malleus is hammer-shaped small bone or ossicle of the middle ear which connects with the incus and is attached to the inner surface of the eardrum. It transmits the sound vibrations from the eardrum to the incus''. The malleus is unique to mammals, an and incusThe incus is the anvil-shaped small bone or ossicle in the middle ear. It connects the malleus to the stapes. The incus only exists in mammals, and is derived from a reptilian upper jaw bone, the quadrate. See also Bone terminology Terms for anatomical lo; along with the more ancient stapesThe stapes or stirrup is the stirrup-shaped small bone or ossicle in the middle ear which attaches the incus to the fenestra ovalis, the " oval window" which is adjacent to the vestibule of the inner ear. It is the smallest bone in the human body. The sta, they are the ossiclesThe ossicles (also called auditory ossicles are the three smallest bones in the human body. They are contained within the middle ear space and serve to transmit sounds from the air to the fluid filled labyrinth ( cochlea). The absence of the auditory ossi. This adaptation is advantageous, not only because a one-bone jaw is stronger, but also because the malleus and incus improve hearing.

The term jaws is also used for articles resembling jaws in appearance or function, for example:

• the pincer-like grasping or crushing parts of a hand toolThis page discusses common devices known as "tools". For the band, see Tool (band). For other meanings, see Tool (disambiguation). A tool is, among other things, a device that provides a mechanical or mental advantage in accomplishing a task. Most tools e, as of pliersPliers are hand tools primarily for gripping and cutting that use leverage and numerous different jaw configurations to grip, turn, pull, cut or crimp a variety of things. They are a tool common to many dexterous trades and occupations. History Pliers wer, a clampA clamp is a device to hold or secure an object, to prevent it from moving. Types of clamps include Bench clamp G clamp Mitre clamp Screw clamp Speed clamp Toggle clamp Web clamp Wheel clamp Other meanings Clamp meter CLAMP is a team of four women who cre, or a wrench
• the sides of a topographical pass or channel
• the space bounded by a croquet hoop, or the angled pair of cushions marking the entrance to the pocket of a billiards table
• metaphorically, the threshold of a usually perilous situation

See also:

• Jaws of Life (device)
• Jaws (movie)
• Jaws (James Bond character)