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In jawed vertebrates, the mandible (from the Latin mandibula, 'for chewing'), lower jaw, or jawbone is a bone that makes up the lower – and typically more mobile – component of the mouth (the upper jaw being known as the maxilla). The jawbone is the skull's only movable, posable bone, sharing joints with the cranium's temporal bones.
It is a vestige of the embryonic lower jaw, Meckel cartilage. The ligament becomes accentuated and taut when the mandible is protruded. [4] Other ligaments, called "oto-mandibular ligaments", [5] [6] [7] connect the middle ear with the temporomandibular joint: discomallear (or disco-malleolar) ligament,
In the ape, there is a reinforcement to the lower jaw bone called the simian shelf. In the evolution of the mammalian jaw, two of the bones of the jaw structure (the articular bone of the lower jaw, and quadrate ) were reduced in size and incorporated into the ear , while many others have been fused together. [ 3 ]
Posselt's envelope of motion or Posselt's envelope of movement refers to the range of motion of the lower jaw bone, or mandible. This envelope was first described by Ulf Posselt in 1952. It is a diagrammatic representation of a sagittal view of maximum mandibular movement.
A jaw abnormality is a disorder in the formation, shape and/or size of the jaw. In general abnormalities arise within the jaw when there is a disturbance or fault in the fusion of the mandibular processes. The mandible in particular has the most differential typical growth anomalies than any other bone in the human skeleton.
Sometimes (e.g. in bony fish), the maxilla is called "upper maxilla", with the mandible being the "lower maxilla". Conversely, in birds the upper jaw is often called "upper mandible". In most vertebrates, the foremost part of the upper jaw, to which the incisors are attached in mammals consists of a separate pair of bones, the premaxillae ...
In the mammal configuration, the quadrate and articular bones are much smaller and form part of the middle ear. Note that in mammals the lower jaw consists of only the dentary bone. The articular bone is part of the lower jaw of most vertebrates, including most jawed fish, amphibians, birds and various kinds of reptiles, as well as ancestral ...
In vertebrates, the lower jaw (mandible or jawbone) [10] is a bone forming the skull with the cranium. In lobe-finned fishes and the early fossil tetrapods, the bone homologous to the mandible of mammals is merely the largest of several bones in the lower jaw. It is referred to as the dentary bone, and