Mouth is also known as Oral Cavity , it is bounded by muscles and bones.
Anteriorly - by the lips.
Posteriorly - it is continuous by the oropharynx .
Laterally - by the muscles of the cheeks .
Superiorly - by the bony hard palate and muscular soft palate.
Inferiorly - by the muscular tongue and the soft tissue of the floor of the mouth.
The oral cavity is lined throughout with mucous membrane, consisting of stratified squamous epithelium containing small mucous-secreting gland.
The part of the mouth between the gums and cheeks is the vestibule and the reminder of its interior is the oral cavity.the mucous membrane lining of the cheeks and lips is reflected onto the gums and it is continuous with the skin of the face.
The palate forms the roof of the mouth and is divided into the anterior hard palate and the posterior soft palate.The hard palate is formed by the maxilla and the palatine bones.the soft palate, which is muscular ,curves downward from the posterior end of the hard palate and blends with the wall of the pharynx at the side.
The Uvula is a curved fold of muscle covered with mucous membrane, hanging down from the middle of the free border of the soft palate. It is originating from the upper end of the uvula are four folds of mucous membrane, two passing downwards at each side to form membranous arches. The posterior folds, one on each side, are the Palatopharyngeal arches and the two anterior folds are the palatoglossal arches. On each side, between the arches , is a collection of lymphoid tissue called the palatine tonsils.
The tongue is composed of voluntary muscle. It is attached by it base to the hyoid bone and by a fold of its mucous membrane covering, called the frenulum, to the floor of the mouth . The superior surface consists of stratified squamous epithelium, with numerous papillae . Many of these contain sensory receptors for the sense of taste in the taste buds.
The tongue plays an important part in:
1- Chewing
2- Swallowing
3- Speech
4- Taste
Nerve endings of the sense of taste are presents in the papillae and widely distributed in the epithelium of the tongue.
Blood Supply of Tongue
The main arterial blood supply to the tongue is by the lingual branch of the external carotid artery. Venous drainage is by the lingual vein, which joins the internal jugular vein.
The nerves involved are-
1- the hypoglossal nerve , which supply the voluntary muscle
2- the lingual branch of the mandibular nerves, which arise from the 5th cranial nerves, are the nerves of somatic sensations.i.e. pain, temperature and touch.
3- the facial and glossopharyngeal nerves , the nerves of the taste.
The teeth are embedded in the alveoli or sockets of the alveolar ridges of the mandible and maxilla. Babies are born with two sets, or dentition are present, in immature form, in the mandible and maxilla.
There are 20 temporary teeth, 10 in each jaw. They begin to erupt at about 6 month of age, and should all be presents by 24 months. The permanent teeth begin to replace the deciduous teeth in the 6th year of age and this dentition, consisting of 32 teeth, is usually complete by the 21st year.
Teeth have different shapes depending on their functions. Incisor and canine teeth are cutting teeth and are used for biting off pieces of food, whereas the premolar and molar teeth, with broad, flat surfaces, are used for grinding or chewing food.
Structure of a teeth
Although the shapes of the different teeth vary, the structure is the same and consist of :
The crown- the part that protrudes from the gum
The gum - the part embedded in the bone.
The neck - the slightly narrowed region where the crown merges with the root.
In the centre of the tooth is the pulp cavity containing blood vessels, lymph vessels and nerves, and surrounding this is a hard ivory-like substance called dentine. The dentine of the crown is covered by a thin layer of very hard substance resembling bone, called cementum, which secures the tooth in its socket . Blood vessels and nerves pass to the tooth through a small foramen at the apex of each root.
Most of the arterial blood supply to the teeth is by branches of the maxillary arteries. The venous drainage is by a number of veins which empty into the internal jugular veins
The nerve supply to the upper teeth is by branches of the maxillary nerves and to the lower teeth by branches of the mandibular nerves. These are both branches of the trigeminal nerves.
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