1. Also known as deglutition is divided into 3 phases
Swallowing
Also known as deglutition is divided into 3 phases

2. Three stages of swallowing

3. The buccal phase This phase occurs voluntarily in the mouth
It involves breaking down of food in the mouth and food is chewed and mixed with saliva.
This turns the food into a bolus ,which makes it easier to swallow.
Occlusal action of lips help in creating an effective seal preventing the bolus from dribbling out of the oral cavity .
Finally tongue forces the bolus (food and fluid ) towards the pharynx ( throat ) .
Therefore tongue plays an important role in this process .

5. The pharyngeal phase Occurs involuntary .
Pharynx (throat ) is involved in this stage .
When food enters the pharynx ( upper throat area ,above the voice box) ,the soft palate and uvula fold upward and cover the nasopharynx.
This cap prevents the bolus from going into the nasal cavity.
The epiglottis is a flexible cartilaginous flaps at the top of the larynx( voice box,where we breathe) fold down as the larynx rises.
As the opening of the larynx is closed ,food or bolus can pass only in the oesophagus tuibe .

6. The oesophageal phase Occurs involuntary
Oesophagus ( food pipe ) is the tube that transports food directly to the stomach. Oesophageal ,normally closed ,opens to allow bolus to pass when the larynx rises during swallowing .
Peristalsis of oesophagus ,which helps to push food into the stomach.

7. Nerves of the mouth The facial nerve, also known as cranial nerve VII
origin – fibres originate the pons ,travel through the internal acoustic meatus ,and emerge through the stlomastoid foramen the lateral aspects of the face.
Motor functions include ;
facial expression eg smile.
It also innervates two salivary glands and the lacrimal gland ( tear gland )
Sensory function ;
Responsible for the sensation of taste in the anterior two-thirds of your mouth. .

9. Facial nerve or CN VII
Bell’s palsy :paralysis of facial muscles and loss of taste .
Caused by herplex simplex 1 virus.
Corner of mouth sags and lower eyelid droops.
Tears drip continuously and eye cannot be completely closed.
Condition may disappear spontaneously without treatment.

10. Nerves The trigeminal nerve, also known as cranial nerve V,
Fibers originates from the face to pons via the superior orbital fissure ,the foramen rotundum and foramen ovale .
Sensory function -is the most important nerve involved in facial sensation.
Motor function - Innervates the muscles of mastication,helps jaw move up and down .
Disorder
Trigeminal neuralgia –inflammation of nerve ,when nerve is cut ,results in sensation on that side of face.

12. The glassopharyngeal nerve :Cranial nerve IX
The glossopharyngeal nerve
Origin
Emerges from the medulla oblongata ,leave the skull via the jugular foramen ,and run to throat.
Is a mixed nerve with motor and sensory functions .
Sensory function
Fibers conduct taste in the posterior one-third of the tongue and general sensory impulse from the tongue and pharyx..
Motor function
Innervates part of the tongue and pharynx and provide motor fibers to the
parotid salivary glands .

14. The Vegas nerve or cranial nerve 10
The Vagus Nerve Or Cranial Nerve 10
Our body has a nerve called cranial nerve X, also known as the vagus nerve, which is a very important player in our body. This is because it's a nerve that innervates the heart, lungs and the digestive tract( oseophagus ). There is one vagal nerve on either side of your body.
The only cranial nerve that extends beyond the head and neck.
The vegus nerve is mixed nerve .
its sensory function is taste .
Motor function-The vagus nerve is involved in controlling muscles that help us swallow our food and move it along our digestive tract in a process we call 'peristalsis.' Peristalsis is basically a series of muscular contractions and expansions in your gastrointestinal tract that serve to move food down the GI tract.the

16. Cranial XI:Accessory
Formed from the cranial root emerging from the medulla oblongata and spinal root arising from the superior region of the spinal cord.
The spinal root passes upward ino thecranium via foramen magnum.
The accesory nerve leave the cranium nerve via the jugular nerve foramen.
Primarily a motor nerve
Supplies nerve to the pharynx, larynx,and soft palate .

18. Tongue disorders
Tongue disorders commonly occur in people who smoke or consume excessive alcohol.
The tongue is a powerful muscle involved in the critical functions of speaking, chewing and swallowing.
A variety of diseases and disorders can affect the tongue including infections, injuries, chronic irritation, abnormal tissue growth and congenital conditions.
Many tongue disorders are short-lived; others may cause long- term difficulties, requiring ongoing medical management.

19. Leukoplakia
Leukoplakia is a painless grey or white patch on the tongue that develops in response to chronic irritation.
These patches can also develop on the inner cheek regions of the mouth.
Cigarette or pipe smoking and use of chewing tobacco increase the risk for development of leukoplakia.
Irritation caused by poorly fitting dentures or rough spots on the teeth can also lead to leukoplakia.
. A variant of this disorder known as hairy leukoplakia commonly occurs in people with a weakened immune system.

21. Macroglossia
Macroglossia describes abnormal tongue enlargement. This condition can cause misalignment of the teeth and speech difficulties. Macroglossia often occurs with certain congenital or inherited conditions, including Down syndrome, congenital hypothyroidism and primary amyloidosis.
Macroglossia can also occur due to tongue swelling or abnormal tissue growth caused by a variety of disorders including multiple myeloma, sarcoidosis, tongue tumors and certain infections.

22. Glossitis is inflammation of the tongue, which may be transient or chronic
The tongue may swell, and the surface characteristically appears smooth and red or abnormally pale.
Tenderness and burning commonly occur, which may interfere with speaking, chewing and swallowing. Taste disturbances often accompany glossitis.
Transient episodes of glossitis may occur due to burning the tongue with hot foods or liquids, oral herpes, thrush and allergic reactions to mouthwash, toothpaste or the plastics in dental appliances such as retainers or dentures.
Persistent glossitis can occur with vitamin B12 and folic acid deficiencies, iron deficiency anemia, syphilis, oral lichen planus and aphthous ulcers.
Glossitis

23. Tongue cancer Tongue cancer is a form of head and neck cancer.
Cancers of the forward two-thirds of the tongue are oral tongue cancers.
Those at the back of the tongue are tongue base cancers. Tongue cancers usually present as a lump or a non healing ulcer.
squamous cell carcinoma as the most common form of the disease.
Smoking, use of chewing tobacco and excessive alcohol consumption increase the risk for the development of tongue cancer.