Mouth
The mouth is divided into :
1- the vestibule : the part of mouth between the gums and cheek .
2- Oral cavity .
The oral cavity is lined throughout with mucous membrane , consisting of stratified squamous epithelium containing small mucus-secreting glands.
The part of the mouth between the gums and the cheeks is the vestibule and the remainder of the cavity is the oral cavity . The mucous membrane lining of the cheeks and the lips is reflected onto the gums or alveolar ridges and is continuous with the skin of the face.
The mouth is bounded by muscle and bones :
Anteriorly >>>> by the lips.
Posteiorly >>>> it is continuous with the oropharynx.
Laterally >>>> by the muscle of the cheeks.
Superiorly >>>> by the bone hard palate and muscular soft palate.
Inferiorly >>>> by the muscular tongue and the soft tissues of the floor of the mouth .
The palate
It form the root of the mouth and is divided into :
1- the interior hard palate .
It is formed by the maxilla and the palatine bones.
2- the posterior soft palate .
It is muscular , curves downwards from the posterior end of the hard palate and blends with the walls of the pharynx at the sides
Tongue
It is a voluntary muscular structure that 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 , called the frenulum , to the floor of the mouth . The superior surface consists of stratified squamous epithelium, with numerous papillae.
Function of the tongue :
*chewing. *swallowing.
*speech. *taste.
Blood supply :
*Arterial supply by lingual branch of external carotid artery.
*Venous drainage is by lingual vein, and internal jugular vein.
Nerve supply :
*the hypoglossal nerves, and the mandibular nerve.
* the facial and glossopharyngeal nerve.
Teeth
The teeth are embedded in the alveoli of the alveolar ridges of the mandible and the 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 month.
Structure of a tooth :
*the crown >>>> the part that protrudes from the gum.
*the root >>>> the part embedded in the bone.
*the neck >>>> the slightly narrowed region where the crown merges with the root.
Function of the teeth:
1- used for biting off pieces of food .
2- whereas the premolar and molar teeth. With broad, flat surfaces
3- used for grinding or chewing food.
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.
Blood supply :
Arterial supply by maxillary artery.
Venous drainag by internal jugular veins.
Nerve supply :
*maxillary nerves.
*mandibular nerves. *trigemial nerves
Pharynx
It is a tube 12 to 14cm long that extends from the base of the skull to the level of the 6 th cervical vertebra. It lies behind the nose, mouth and larynx and is wider at its upper end.
Structure of the pharynx :-
Superiorly ____ the inferior surface of the base of the skull.
Inferiorly ____ it is continuous with the oesophagus .
Anteriorly ____ the wall is incomplete .
Posteriorly____ areolar tissue ,involuntary muscle and the bodies of the first six cervical vertebrae
Blood and nerve supply :-
*The facial artery, the facial and internal jugular vain.
*Parasympathetic supply by vagus and gloss pharyngeal nerves.
*sympathetic nerve supply by nerves from the superior cervical ganglia.
Oesophagus
It is about 25cm long and about 2cm in diameter and lies in the median plane in the thorax in front of the vertebral column behind the trachea and the heart .
Structure of the oesophagus :-
There are four layers of tissue as shown .as the oesophagus is almost entirely in the thorax the outer covering , the adventitia ,consists of elastic fibrous tissue that attaches the oesophagus to the surrounding structures.
Functions of oesophagus :-
- formation of a bolus.
- swallowing.
Blood supply :
Arterial: the paired esophageal arteries , the thoracic aorta. phrenic arteries and the left gastic branch of the celiac artery.
Venous drainage: the azygos and homozygous veins, left gastric vein, upward and downward venous drainage
The mouth is divided into :
1- the vestibule : the part of mouth between the gums and cheek .
2- Oral cavity .
The oral cavity is lined throughout with mucous membrane , consisting of stratified squamous epithelium containing small mucus-secreting glands.
The part of the mouth between the gums and the cheeks is the vestibule and the remainder of the cavity is the oral cavity . The mucous membrane lining of the cheeks and the lips is reflected onto the gums or alveolar ridges and is continuous with the skin of the face.
The mouth is bounded by muscle and bones :
Anteriorly >>>> by the lips.
Posteiorly >>>> it is continuous with the oropharynx.
Laterally >>>> by the muscle of the cheeks.
Superiorly >>>> by the bone hard palate and muscular soft palate.
Inferiorly >>>> by the muscular tongue and the soft tissues of the floor of the mouth .
The palate
It form the root of the mouth and is divided into :
1- the interior hard palate .
It is formed by the maxilla and the palatine bones.
2- the posterior soft palate .
It is muscular , curves downwards from the posterior end of the hard palate and blends with the walls of the pharynx at the sides
Tongue
It is a voluntary muscular structure that 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 , called the frenulum , to the floor of the mouth . The superior surface consists of stratified squamous epithelium, with numerous papillae.
Function of the tongue :
*chewing. *swallowing.
*speech. *taste.
Blood supply :
*Arterial supply by lingual branch of external carotid artery.
*Venous drainage is by lingual vein, and internal jugular vein.
Nerve supply :
*the hypoglossal nerves, and the mandibular nerve.
* the facial and glossopharyngeal nerve.
Teeth
The teeth are embedded in the alveoli of the alveolar ridges of the mandible and the 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 month.
Structure of a tooth :
*the crown >>>> the part that protrudes from the gum.
*the root >>>> the part embedded in the bone.
*the neck >>>> the slightly narrowed region where the crown merges with the root.
Function of the teeth:
1- used for biting off pieces of food .
2- whereas the premolar and molar teeth. With broad, flat surfaces
3- used for grinding or chewing food.
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.
Blood supply :
Arterial supply by maxillary artery.
Venous drainag by internal jugular veins.
Nerve supply :
*maxillary nerves.
*mandibular nerves. *trigemial nerves
Pharynx
It is a tube 12 to 14cm long that extends from the base of the skull to the level of the 6 th cervical vertebra. It lies behind the nose, mouth and larynx and is wider at its upper end.
Structure of the pharynx :-
Superiorly ____ the inferior surface of the base of the skull.
Inferiorly ____ it is continuous with the oesophagus .
Anteriorly ____ the wall is incomplete .
Posteriorly____ areolar tissue ,involuntary muscle and the bodies of the first six cervical vertebrae
Blood and nerve supply :-
*The facial artery, the facial and internal jugular vain.
*Parasympathetic supply by vagus and gloss pharyngeal nerves.
*sympathetic nerve supply by nerves from the superior cervical ganglia.
Oesophagus
It is about 25cm long and about 2cm in diameter and lies in the median plane in the thorax in front of the vertebral column behind the trachea and the heart .
Structure of the oesophagus :-
There are four layers of tissue as shown .as the oesophagus is almost entirely in the thorax the outer covering , the adventitia ,consists of elastic fibrous tissue that attaches the oesophagus to the surrounding structures.
Functions of oesophagus :-
- formation of a bolus.
- swallowing.
Blood supply :
Arterial: the paired esophageal arteries , the thoracic aorta. phrenic arteries and the left gastic branch of the celiac artery.
Venous drainage: the azygos and homozygous veins, left gastric vein, upward and downward venous drainage
.