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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.
The facial skeleton comprises the facial bones that may attach to build a portion of the skull. [1] The remainder of the skull is the neurocranium.. In human anatomy and development, the facial skeleton is sometimes called the membranous viscerocranium, which comprises the mandible and dermatocranial elements that are not part of the braincase.
Fractures of the mandible are common. However, coronoid process fractures are very rare. [1] Isolated fractures of the coronoid process caused by direct trauma are rare, as it is anatomically protected by the complex zygomatic arch/ temporo-zygomatic bone and their associated muscles.
When the lower jaw is pushed anteriorly as far as possible with some teeth in contact, it is said to be maximum protrusion. In Posselt's border movement diagram, maximum protrusion is the most anterior based on the sagittal view. Condyles are in the most anterior position and determined partly by stylomandibular ligaments. [8]
The condyloid process or condylar process is the process on the human and other mammalian species' mandibles that ends in a condyle, the mandibular condyle.It is thicker than the coronoid process of the mandible and consists of two portions: the condyle and the constricted portion which supports it, the neck.
The condyle of the mandible articulates with the temporal bone in the mandibular fossa. The mandibular fossa is a concave depression in the squamous portion of the temporal bone. These two bones are actually separated by an articular disc, which divides the joint into two distinct compartments.
It is composed of 270 bones at the time of birth, [2] but later decreases to 206: 80 bones in the axial skeleton and 126 bones in the appendicular skeleton. 172 of 206 bones are part of a pair and the remaining 34 are unpaired. [3] Many small accessory bones, such as sesamoid bones, are not included in this.
In mammals, the jaws are made up of the mandible (lower jaw) and the maxilla (upper jaw). 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 ...