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Human teeth function to mechanically break down items of food by cutting and crushing them in preparation for swallowing and digesting. As such, they are considered part of the human digestive system. [1] Humans have four types of teeth: incisors, canines, premolars, and molars, which each have a specific function. The incisors cut the food ...
Diagram of tooth anatomy. Dental anatomy is a field of anatomy dedicated to the study of human tooth structures. The development, appearance, and classification of teeth fall within its purview. (The function of teeth as they contact one another falls elsewhere, under dental occlusion.)
facial region includes the lower half of the head beginning below the ears. The forehead is referred to as the frontal region. The eyes are referred to as the orbital or ocular region. The cheeks are referred to as the buccal region. The ears are referred to as the auricle or otic region. The nose is referred to as the nasal region.
Two rows of teeth are supported by facial bones of the skull, the maxilla above and the mandible below. Adults have 32 permanent teeth, and children have 20 deciduous teeth. There are various tooth shapes for different jobs. For example, when chewing, the upper teeth work together with the lower teeth of the same shape to bite, chew, and tear food.
The dashes (-) in the formula are likewise not mathematical operators, but spacers, meaning "to": for instance the human formula is 2.1.2.2-3 2.1.2.2-3 meaning that people may have 2 or 3 molars on each side of each jaw. 'd' denotes deciduous teeth (i.e. milk or baby teeth); lower case also indicates temporary teeth.
In humans, the ear is described as having three parts: the outer ear, the middle ear and the inner ear. The outer ear consists of the auricle and the ear canal . Since the outer ear is the only visible portion of the ear, the word "ear" often refers to the external part (auricle) alone. [ 1 ]
In humans, the molar teeth have either four or five cusps. Adult humans have 12 molars, in four groups of three at the back of the mouth. The third, rearmost molar in each group is called a wisdom tooth. It is the last tooth to appear, breaking through the front of the gum at about the age of 20, although this varies among individuals and ...
Opossums have 18, whereas armadillos have none. Cats, dogs, foxes, pigs, and horses have twelve. Rodents have four. Rabbits and hares were once considered rodents, but are distinguished by having six—one small pair, called "peg teeth", is located directly behind the most anterior pair. Incisors are used to bite off tough foods, such as red meat.