Скачать или смотреть DIGESTIVE SYSTEM SALIVARY GLANDS (Major and Minor)DENTAL MLT RADILOGY part 2

MAJOR SALIVARY GLANDS
▶ Parotid --- paired and the largest
▶ Submandibular --- one on each side of the face under the angle of jaw
▶ Sublingual---single and the smallest
COMPOSITION AND FUNCTIONS OF SALIVA

▶ Chemically, saliva is 99 % water and 1 % solutes.
▶ About 1.5 litres of saliva is produced daily and it consists of:
▶ Water
▶ Ions, including sodium, potassium, chloride, bicarbonate, and phosphate
▶ A digestive enzyme: salivary amylase
▶ Mucus
▶ Lysozyme
▶ Antimicrobial substances immunoglobulins

FUNCTIONS OF SALIVA


▶ Chemical digestion of polysaccharides
▶ Lubrication of food
▶ Helps in speech
▶ Cleaning and lubricating the mouth
▶ Appreciation of taste—only saliva soluble food can stimulate the taste buds

Tongue

▶ The tongue is an accessory digestive system organ composed of skeletal muscle covered with mucous membrane.
▶ Together with its associated muscles, it forms the floor of the oral cavity.
▶ It is attached by its base to the hyoid bone and by a fold of its mucous membrane covering, called the frenulum, to the floor of the mouth.
▶ The tongue is divided into symmetrical lateral halves by a median septum
that extends its entire length.
▶ The superior surface consists of stratified squamous epithelium, with numerous papillae (little projections). Many of these contain sensory receptors (specialised nerve endings) for the sense of taste in the taste buds.
▶ There are several types of papilla; however no clear relationship between these and discrimination of different tastes has been found.

FUNCTIONS OF TONGUE


The tongue plays an important part in:
▶ Chewing (mastication)
▶ Swallowing (deglutition)
▶ Speech
▶ Taste
TEETH

▶ The teeth, or dentes are accessory digestive system organs located in sockets of the alveolar ridges of the mandible and maxillae.
▶ The alveolar ridges are covered by the gingivae or gums,
which extend slightly into each socket.
▶ A typical tooth has three major external regions:
• Crown: The crown is the visible portion above the level of the gums.
• Root: Embedded in the socket are one to three roots.
• Neck: The neck is the constricted junction of the crown and root near the gum line.

TEETH

▶ Babies are born with two sets, or dentitions, the temporary or
deciduous teeth and the permanent teeth.
▶ At birth the teeth of both dentitions are present, in immature form, in the mandible and maxilla.
▶ There are 20 temporary teeth, 10 in each jaw. They begin to erupt when the child is about 6 months old, and should all be present 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.
FUNCTIONS OF TEETH


Teeth have different shapes depending on their functions.
▶ Incisors and canine teeth are the cutting teeth and are used for biting off pieces of food.
▶ The premolar and molar teeth, with broad, flat surfaces, are used for grinding or chewing food.