A mandible refers to either of two distinct anatomical structures:
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In Vertebrates: The lower jaw bone, which forms the movable part of the mouth. In most mammals, including humans, the mandible is a single bone (the dentary) that articulates with the temporal bone of the skull at the temporomandibular joint (TMJ). Its primary functions include supporting the lower teeth, facilitating mastication (chewing), speech, and the opening and closing of the mouth. In non-mammalian vertebrates (e.g., reptiles, birds, fish), the lower jaw may be composed of multiple fused bones.
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In Arthropods: One of a pair of mouthparts found in various arthropod subphyla, including insects, myriapods, and crustaceans (collectively known as Mandibulata). These are typically hardened, unsegmented, and chitinous appendages located near the mouth opening. Arthropod mandibles are primarily used for biting, crushing, tearing, or grinding food, and their specific morphology varies greatly depending on the feeding habits of the species. They are distinct from the chelicerae found in chelicerate arthropods (e.g., spiders, scorpions).