Anatomy of a Mouth
The mouth (oral cavity) consists of several components, including the teeth, gingiva (gums), tongue, palate, cheeks, lips and floor of the mouth. With the exception of the teeth, the mouth is lined by mucous membranes.
The teeth are held within the jaw bones and serve several important functions beyond allowing you to chew.
Your teeth enable you to speak properly and clearly, and contribute to your facial shape and appearance. Children usually have 20 deciduous (primary) teeth and begin to develop their first permanent teeth by age six. Adults typically develop 32 permanent teeth.
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The area of the tooth closest to the tongue is referred to as the lingual surface. For the front teeth, the area closest to the lips is called the labial surface. For the back teeth (molars and premolars), the area that faces the cheeks is called the buccal surface, and the biting (chewing) area is called the occlusal surface.
There are different types of permanent teeth, each of which performs a specific function.
Central Incisors: The central incisors are the front teeth. Adults have four central incisors; two on the upper and two on the lower arches. These teeth are sharp and shaped like a chisel for cutting food.
Lateral Incisors: The four lateral incisors are located next to the central incisors on both arches, one on either side. These teeth have sharp incisal edges intended for tearing food.
Canines: The canine teeth are the sharp teeth located on either side of the lateral incisors. Canine teeth (also known as cuspids) work together with the incisors to tear and bite food.
Premolars: The premolars (also known as bicuspids) are the eight teeth located next to the cuspids; two on each side of the mouth, four on the upper and four on the lower arches. These teeth are smaller than the molars and have two cusps on the biting area for tearing and crushing food. The premolars closest to the incisors are called the first premolars, while the ones closest to the molars are called the second premolars.
Molars: Molars are the large teeth with four cusps located in the back of the mouth behind the premolars. Adults have twelve molars (four being wisdom teeth), with six in the upper and six in the lower arches; three on each side of the mouth. Molars have wide, flat surfaces for biting, chewing and grinding food.
Wisdom Teeth: Wisdom teeth, which are included among the molars, are the final four molars that most adults develop. These teeth are located in the very back of the mouth, two in the upper and two in the lower arches. Wisdom teeth typically erupt during the teen years but can develop at any time. It also is not unusual for wisdom teeth to be impacted (below the gumline) and not erupt at all. Not all wisdom teeth require extraction. However, due to the risk of overcrowding, infection or misalignment, your dentist may determine that your wisdom teeth should be removed.
The gingiva is the soft tissue in the mouth known as the gums that covers the bone holding the teeth in place. The gingiva surrounds the teeth and covers the jaw bone, creating a protective barrier.
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The tongue is a muscular organ in the mouth with several functions. It is attached to the bottom of the mouth by a membrane on its underside called the lingual frenum. The top surface of the tongue contains papillae, the tiny nodules or bumps that include the taste buds.
One of the functions of the tongue is taste, but it also facilitates chewing, digesting, swallowing and speaking. The tongue is very flexible. With the help of the cheeks, it guides food to be chewed by the teeth so it can be properly swallowed and digested. The tongue also works with the teeth to form certain speech patterns, making speech possible.
The palate, which refers to the roof of the mouth, is divided into two parts: the hard palate and the soft palate.
The hard palate is the solid, immovable area of the roof of the mouth that attaches to the teeth and gums, forming an arch. The soft palate, located behind the hard palate towards the back of the throat, is the flexible area of the mouth where the gag reflex occurs.
The cheeks form the sides of the mouth and continue along the front of the face to the lips. The cheeks are composed of subcutaneous fat, with the outside layer covered by skin and the inside consisting of a mucous membrane. The cheek muscles (the buccinators) are instrumental in smiling, swallowing, compression and keeping food in the mouth for chewing and digestion.
The lips are the soft and pliable fleshy tissue that connects to the front area of the cheeks. The outside of the lips is covered by skin. The gingiva attaches to the part of the lips inside the mouth that is covered by the mucous membrane. Blood vessels close to the surface of the skin give lips their red color.
Of all the organs in the human body, the lips are among the most mobile. In addition to facilitating speech, the lips help keep food between the teeth while also guiding it through the mouth. Lips also enable suckling during infancy. The lips are very sensitive and have numerous receptors on their surface to help determine temperature and texture of food.
The Floor of the Mouth
The floor of the mouth consists largely of the tongue. It is formed by mucous membranes that extend inward from both sides of the lower jawbone and from the tongue to the gumline, forming a crescent shape. Within the floor of the mouth are glands, portions of the muscles of the tongue and nerves.