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[1] [2] Early human ancestors have varied symphysial morphology, but none of them have a well-developed chin. The origin of the chin is traditionally associated with the anterior–posterior breadth shortening of the dental arch or tooth row; however, its general mechanical or functional advantage during feeding, developmental origin, and link ...
The general characterizing feature of the dental morphology of humans are the lack of facial prognathism, a parabola-shaped mandible and maxilla, and molars that are the same size as the front teeth. Humans also have small crowns in relation to body mass and tend to show a reduction in cusp and root number. [ 8 ]
The angle of the mandible (a.k.a. gonial angle, Masseteric Tuberosity, and Masseteric Insertion) is located at the posterior border at the junction of the lower border of the ramus of the mandible.
The necessity of translation to produce further opening past that which can be accomplished with a sole rotation of the condyle can be demonstrated by placing a resistant fist against the chin and trying to open the mouth more than 20 or so mm. The resting position of the temporomandibular joint is not with the teeth biting together.
In human anatomy, the facial skeleton of the skull the external surface of the mandible is marked in the median line by a faint ridge, indicating the mandibular symphysis (Latin: symphysis menti) or line of junction where the two lateral halves of the mandible typically fuse in the first year of life (6–9 months after birth). [1]
The size and shape of the bones making up this structure are responsible for the size and shape of a person's chin. Synonyms of mental protuberance include mental process and protuberantia mentalis. Mental in this sense derives from Latin mentum (chin), not mens (mind), source of the more common meaning of mental.
The mentalis muscle causes a weak upward-inward movement of the soft tissue complex of the chin. [2] This raises the central portion of the lower lip. [2] In the setting of lip incompetence (the upper and lower lips not touching each other at rest), the contraction of the mentalis muscle can bring temporary but strained oral competence.
The face is the front of an animal's head that features the eyes, nose and mouth, and through which animals express many of their emotions. [1] [2] The face is crucial for human identity, and damage such as scarring or developmental deformities may affect the psyche adversely.