Mandible

The mandiblelower jaw, or jawbone (from Latin mandibula, "jawbone") in the human, is the largest, strongest and lowest bone in the face. It forms the lower jaw and holds the lower teeth in place. In the midline on the anterior surface of the mandible is a faint ridge, an indication of the mandibular symphysis, where the bone is formed by the fusion of right and left processes during mandibular development. Like other symphyses in the body, this is a midline articulation where the bones are joined by fibrocartilage, but this articulation fuses together in early childhood.

Structure

The mandible consists of:

  • a curved, horizontal portion, the body or base. (See body of mandible).
  • two perpendicular parts, the rami, or ramus for each one, unite with the ends of the body nearly at right angles. (See ramus mandibulae). The angle formed at this junction is called gonial angle.
  • Alveolar process, the tooth bearing area of the mandible (upper part of the body of the mandible)
  • Condyle, superior (upper) and posterior projection from the ramus, which makes the temporomandibular joint with the temporal bone
  • Mandible (insect mouthpart)

    Insect mandibles are a pair of appendages near the insect’s mouth, and the most anterior of the three pairs of oral appendages (the labrum is more anterior, but is a single fused structure). Their function is typically to grasp, crush, or cut the insect’s food, or to defend against predators or rivals. Insect mandibles, which appear to be evolutionarily derived from legs, move in the horizontal plane unlike those of vertebrates, which appear to be derived from gill arches and move vertically.

    Grasshoppers, crickets, and other simple insects

    The mouthparts of orthopteran insects are often used as a basic example of mandibulate (chewing) mouthparts, and the mandibles themselves are likewise generalized in structure. They are large and hardened, shaped like pinchers, with cutting surfaces on the distal portion and chewing or grinding surfaces basally. They are usually lined with teeth and move sideways. Large pieces of leaves can therefore be cut and then pulverized near the actual mouth opening. This same simple structure is seen in all of the remaining Polyneopteran insect orders, with the exception of the Paraneoptera (Hemiptera, Thysanoptera, and Phthiraptera). Likewise, the mandibles of adult and larval Odonata are simple and generalized, while Ephemeroptera rarely feed as adults, though the larvae ("nymphs") have simple mandibles.

    Mandible (arthropod mouthpart)

    The mandible (from Latin: mandibula or mandĭbŭ-lum, a jaw) of an arthropod is a pair of mouthparts used either for biting or cutting and holding food. Mandibles are often simply referred to as jaws. Mandibles are present in the extant subphyla Myriapoda (millipedes and others), Crustacea and Hexapoda (insects etc.). These groups make up the clade Mandibulata, which is currently believed to be the sister group to the rest of arthropods, the clade Arachnomorpha (Chelicerata and Trilobita).

    Unlike the chelicerae of arachnids, mandibles can often be used to chew food. Mandibulates also differ by having antennae, and also by having three distinct body regions: head, thorax and abdomen. (The cephalothorax (or prosoma) of chelicerates is a fusion of head and thorax.)

    Insects

    Insect mandibles are as diverse in form as their food. For instance, grasshoppers and many other plant-eating insects have sharp-edged mandibles that move side to side. Most butterflies and moths lack mandibles as they mainly feed on nectar from flowers.

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    The Oldest Known Ant Specimen Held Its Prey With Weird Mandibles, Researchers Claim

    Gizmodo 26 Apr 2025
    The paleontological treasure sat in a fossil collection in Brazil, unnoticed ....
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