THE MOUTH
Mouth is bounded by muscles and bones
Anterioly -by lips
Posteriorly-continuous with the oropharynx
Laterally -by the muscles of the cheeks
Superiorly-by the bony hard palate and muscular soft palate
Inferiorly-by muscular tongue and soft tissues of the floor of the mouth
• The oral cavity is lined throughout with mucous membrane consisting 0f stratified
squamous epithelium containing small mucus -secreting glands
• The part of the mouth between the cheeks and gums is called vistibule
-The palate forms the roof of the mouth and is divided into the anterior hard palate and
posterior soft palate .
-The bones forming the hard palate are the maxilla and palatine bones .
-The soft palate is muscular ,curvesdownwards from the posterior end of the hard palate and
blends with the walls of the pharynx at the sides
-The uvula is a curved fold of muscles covered with mucous membrane ,hanging down from the
middle of the free border of the soft palate
-There are four folds of the mucous membrane ,two passing downwards at each side to form
membranous arches.
-The posterior folds one on each side are 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 tonsil.
THE TONGUE
-The tongue is a voluntary muscular structure which occupies the floor of the mouth .It is
attached by its base to the hyoid bone and by a fold of its mucous membrane covering
-The superior surface consists of stratified squamous epithelium ,with numerous papillae which
are little projections containing nerve endings of the sense of taste
Types of papillae.
1.Vallate papillae -usually between 8 and 12 and are arranged in v invertedshape towards the
base of the tongue
2.Fungiform papillae -mainly at the tip and edges of the tongue and more numerous than
vallate papillae
3.Filiform papillae -they are the smallest and most numerous on the surface of the anterior two
thirds of the tongue
BLOOD SUPPLY
-The main arterial blood supply to the tongue is by the lingual branch of the external caratoid
artery
-venous drainage is by the lingual vein which joins the internal jugular vein
-Nerves involved are;
• Hypoglossal nerve -its the 12th cranial nerve which supply the voluntary muscles tissue
• Lingual branch of the manibular nerves -somatic[ordinary] sensation example
pain ,temperature and touch
• Facial and glossopharyngeal nerves -7th and 9th cranial nerve ,which are the nerves of
the special sensation of taste .
FUNCTIONS OF THE TONGUE
-Chewing
-swallowing
-speech
-taste
TEETH
-The teeth are embeded in the alveoli or sockets of the alveolar ridges of the mandible
-There are two sets temporary and deciduous
-There are 20 temporary teeth,10 in each jaw
-There are 32 teeth in total that should be complete at 24 th year
FUNCTIONS OF TEETH
-The incisorsand canine teeth are the cutting teeth and are used for bitting
STRUCTURE OF A TOOTH
-The crown - the part that potrudes fromthe gum
-The root -the part embeded 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.
-Outside the dentine of the crown is a thin layer of very hard substance ,the enamel
- The cement fixes the tooth in its socket
BLOOD SUPPPLY
• 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 jegular veins
NERVE SUPPLY
-The nerve supply to the upper teeth is by branches of the maxillary nerves and lower teeth by
the branches of mandibular nerves
-This are booth branches of the trigeminal nerve
SALIVA
Composition of saliva
-Saliva is the combined secretions from the salivary glands the small mucus-secreting
-About 1.5 litres of saliva is produced daily and consist of ;
• water
• mineral salts
• Enzymes;saliva amylase
• mucus
• Lysozyme
• Immunoglobulins
• Blood clotting factors
FUNCTIONS OF Saliva
1. Lubrication of food -Dry food entering the mouth is moistened and lubricated by saliva
before it can be made into bolus ready for swallowing
2. cleansing and lubricating -An adequate flow of saliva is necessary to cleanse the mouth
and keep its tissues soft ,moist and pliable . Helps to prevent damage to the mucous
membrane by rough or abrasive fooodstuffs
3. Non -specific defence -lysozyme,immunoglobulins and clotting factors combat invading
microbes
4. Taste -The taste buds are stimulated only by chemical substances in solution .Dry foods
stimulate the sense of taste only after thorough mixing with saliva
5. Chemical digestion of polysaccharides -saliva contains the enzyme amylase that begins
the breakdown of complex sugars ,reducing them to the dissaccharide maltose
