The pharynx is located behind the nasal and oral cavities. It is a tube that is in open communication with both the nasal cavity or cavum nasi and with the oral cavity or cavum oris. In the pharynx, the respiratory and food path intersect. The pharynx is therefore part of both the respiratory tract and the digestive tract (see image below).
The open connection to the nose can be closed during the swallowing process. The palatum molle and the uvula are pulled up and close off the nasopharynx, the nasal pharynx. The pharynx at the bottom of the pharynx closes the windpipe, so that the food does not end up in it, but in the esophagus.
At the transition from the mouth to the throat, between the two palate arches lie the throat tonsils, tonsilla palatina. In the nasopharynx lie the nasal tonsils, tonsilla pharyngea. The Eustachian tube runs between the pharynx and the middle ear. The Eustachian tube is pulled open when we swallow. The air pressure in the middle ear and that on the outside of the eardrum then becomes the same. The lymphatic tissue of the tonsilla pharyngea around the entrance of the Eustachian tube serves to prevent infection of the middle ear.
The salivary glands
Saliva is mainly produced by three pairs of large salivary glands. These salivary glands are located around the oral cavity. The Latin name for gland is glandula (abbreviated gl.).
The large salivary glands are the glandula parotis, the glandula sublingualis and the glandula submandibularis. These glands together produce around 90% of the total amount of saliva. The remaining 10% is produced by the many small salivary glands that can be found on the palatum (palate), the tongue, the lips and in the cheek. This can be as many as 450 to 750. These small salivary glands are also called accessory salivary glands. Each gland has its own drainage channel that flows into the oral cavity (see images below).
The glandula parotis is also called the salivary gland, because it is located just in front of the ear. It rises from the outside of the jaw corner (angulus mandibulae) along the ascending branch of the lower jaw (ramus mandibulae) and lies on top of the musculus (abbreviated m.) Masseter.
The gl. parotis has one drain, the ductus parotideus. This runs forward over the meter mass meter, then bends and runs straight through the meter buccinator to the mouth. In the mouth the drain runs out at the level of the first molar in the upper jaw. There is a small bulge in the cheek mucosa.
The gl. parotis makes serous saliva, meaning that the saliva is thin or watery. The gland is especially active when eating and then produces a lot of saliva in a short time.
The glandula sublingualis or lower-tongue salivary gland lies, as the name implies, under the tongue on top of the floor of the mouth. The gland has many drainage channels. Because it lies directly under the tongue, the drainage channels come out under the tongue.
The saliva of the gl. sublingualis is mainly mukeus, that is, thick and slimy. The production of the gland is fairly constant throughout the day.
The glandula submandibularis or lower jaw salivary gland lies, as the name implies, under the lower jaw, or, more precisely, at the rear edge of the mouth floor muscles. Sometimes a part of the gland is still on the back edge of the mylohyoid.
The gl. submandibularis has one drain, the Whartoni duct. This drain runs over the mouth floor muscles and also comes out under the tongue.
The saliva of the gl. submandibularis is mainly serous, but also to a small extent mukeus.
Saliva has an important role in our daily functioning and in food processing.
The third function of saliva is protection. Saliva can protect the tissues of the oral cavity in various ways, namely:
- Mechanical cleaning. Saliva has a flushing effect. Bacteria are swallowed and thus the growth of dental plaque is limited.
- Lubrication of the teeth. Mucines (a protein-carbohydrate compound) in saliva produce sticky saliva (colloidal solution) and reduce wear of the teeth due to chewing forces.
- Humidification and lubrication of the oral mucosa. In this way speaking, chewing and swallowing become possible.
- Buffer effect. The acid attacks after eating food and drink are neutralized by bicarbonate in saliva.
- Aggregation of bacteria. Saliva inhibits the adhesion of bacteria to the tissues of the oral cavity.
- Antimicrobial activity. Enzymes in saliva inhibit bacterial and fungal formation and virus infection.
Saliva contributes to digestion. The purpose of digestion is to process the food so that the valuable components can be absorbed into the blood. The mouth forms the start of the digestive tract. In the oral cavity the saliva is added to the food and the food parts are chewed smaller. A food slurry is created that is easy to swallow.
Saliva contains the enzyme amylase. This enzyme can break down carbohydrates and thus forms the first step in digestion.
The amount and composition of the saliva depend on the time of day and the nature of the stimuli. At night (at rest) you produce less saliva than during the day. Saliva secretion is also influenced by:
- Taste and smell stimuli. For example, when you are at the bakery, the smell runs into the mouth.
- Mechanical incentives. For example during speaking or when chewing hard food or chewing gum.
- Pain or pressure stimuli. A painful mouth or pressure from a prosthesis gives rise to the production of serous saliva.
- Hormonal conditions. Women in transition often produce less saliva.
- Psychological factors. When speaking in public you can get a dry mouth from tension.
- Medicines. Some medicines affect saliva production.
The total amount of saliva produced by the salivary glands can vary from 500 to 1,500 ml / day. Constant mukeus saliva is formed throughout the day. Serous saliva secretion greatly increases with eating. The composition also changes; in particular the acid-neutralizing capacity (buffer effect) increases.
Blood supply to the head and neck area
The brain is the body's control center. The brain has a good blood supply. Both the supply of blood (with oxygen and nutrients) and the discharge (carbonic acid and waste / degradation products) is important. Brain tissue is a body tissue that cannot live without oxygen for long.
The carotid arteries and arteries provide blood flow to the head and neck. The carotid arteries are direct branches of the aorta, the body artery that comes from the heart. The carotid arteries (one on each side) branch into two main branches:
- The carotid artery interna, an internal branch that runs through a hole in the skull base to the brain;
- The external carotid artery, an external branch that takes care of all tissues and organs on the outside of the skull. The external branch in turn also branches off, even many times.
The veins ensure the drainage of the blood. The veins run in much the same way as the arteries. The two major veins of the head are the vena jugularis interna and the vena jugularis externa. They come together in the vena jugularis, the main vein of the neck. The jugular vena flows into the upper hollow vein. This vein comes out in the right atrium (see image below).
The body will always try to maintain the blood supply to the head for as long as possible. Blood vessels can narrow and widen because there is (smooth) muscle tissue in the walls of the blood vessels. If a blood shortage threatens, the blood vessels to the head will widen, while the blood supply to the other organs decreases, because those blood vessels narrow.
Lymph system of the head and neck area
The system of lymph vessels and lymph nodes is needed to transport tissue fluid back to the bloodstream. Due to the high pressure of the blood, fluid is pressed out of the blood vessels in the capillaries. If this fluid is not returned to the bloodstream, no fluid remains in the bloodstream. As soon as the tissue fluid has been sucked into the lymph vessels, we speak of lymph.
The lymphatic system consists of lymph vessels and lymph nodes, because they are not real glands. The lymph nodes are the purification stations for the lymph. Purification consists of removing microorganisms and other particles that occur in the lymph from the fluid. After all, it is not intended that foreign bodies enter the bloodstream.
White blood cells, the lymphocytes, are formed in the lymph nodes. The lymphocytes are important for the body's defense against microorganisms (see image below).
A lymph node purifies the lymph from a certain part of the body, in this case from the head. A lymph node that takes care of a certain region is called a regional lymph node. The large regional lymph nodes of the head and neck are located near the ear and at the lower edge of the mandible. From there, the lymphatic vessels and the lymph nodes run along with the neck (arterial) veins.
If you have inflammation, the regional lymph nodes will try to fight it. They swell.