What are the mastoid processes of the temporal bones. In what cases is trepanation of the mastoid process

Mastoiditis is a disease that many people face. But not everyone knows about what the mastoid processes are, and where they are. What is the structure of this part of the temporal bone? How dangerous is the inflammation of these structures, and what can the disease be caused by? Many people are interested in these questions.

Where are the mastoid processes?

The ovoid process is the lower part of the temporal bone. If we talk about its location, it is located below and behind the main part of the skull.

The process itself has the shape of a cone, the base of which is bordered by the region around the middle cranial fossa. The apex of the appendage is directed downwards - in it some muscles are attached, in particular the sternocleidomastoid muscle. The base of the cone borders on the hard shell of the brain (which is why the infectious inflammation of this site is so dangerous, because pathogenic microorganisms can penetrate directly into nerve tissues).

In the subcutaneous tissue that covers this part of the temporal bone, there are lymph nodes and vessels, behind the vein and artery. There are also branches of small and large ear nerves.

It should be noted that the mastoid processes can have different shapes. In some people they are long with a narrow foot, others - short, but with a wide base. This anatomical feature largely depends on genetic inheritance.

The structure of the mastoid process

As already mentioned, this part of the temporal bone resembles a cone in shape. In modern anatomy, it is customary to single out the so-called Shipo triangle, which is located in the anterosurface of the appendage. Behind the triangle is bounded by the mastoid scallop, and in front of it the border passes at the back of the external auditory canal.

The internal structure of the appendage resembles a porous sponge, since there are many hollow cells, which are nothing but airy appendages of the tympanic cavity. The number and size of such cells can be different and depends on the characteristics of growth and development of the organism (for example, ear inflammation in childhood leaves its mark on the structure of the mastoid process).

In the area of the Shipo triangle is the largest cell, called an antrum or cave. This structure is formed due to close interaction with the tympanic cavity and is present in every person (unlike smaller cells, the number of which can vary).

Types of mastoid processes

As already mentioned, the mastoid process of the temporal bone can have a different internal structure. In the first year of the baby's life, an antrum is formed. Up to three years there is an active pneumatization of the internal tissues of the appendage, which is accompanied by the appearance of hollow cells. By the way, this process lasts throughout the life of a person. Depending on the number and size of the cavities, it is customary to distinguish several types of structure:

• Pneumatic mastoid processes are characterized by the formation of large cells that fill the entire inner part of this bone structure.
• With a sclerotic type within the shoot there are practically no cells.
• In the diploid mastoid process there are small cells that contain a small amount of bone marrow.

It should be noted that most often doctors detect traces of mixed cavity formation in this part of the temporal bone. Again, everything depends on the genetic characteristics of the organism, the rate of development, as well as the presence of injuries and inflammatory diseases in childhood and adolescence.

Inflammation of the mastoid process and its causes

A disease in which inflammation of the tissues of the mastoid processes is observed is called mastoiditis. Most often the cause is infection, and pathogens can enter this area of the skull in different ways.

Most often, this disease develops against the background of otitis. The infection enters the mastoid process of the temporal bone from the tympanic cavity or auditory canal. In some cases, inflammation develops when the skull is directly injured in the area of the temple or ear. The source of infection may be inflamed lymph nodes located in this zone. Much less often the cause of the disease is a systemic infection of the blood.

The main symptoms of inflammation

The main signs of mastoiditis largely depend on the severity and stage of the disease. For example, at the initial stages it is very difficult to distinguish the inflammation of the mastoid process from ordinary otitis.

Patients complain of a sharp, shooting pain in the ear. There is a fever, weakness and aches in the body, headaches. Appears discharge from the auditory canal.

In the absence of therapy or inadequate treatment (for example, too rapid discontinuation of antibiotics), the clinical picture changes. The ostium-shaped process of the ear gradually becomes filled with pus, and under pressure the bony septa between the cells are destroyed. Skin and subcutaneous tissues behind the auricle swell and blush, become hard, hot to the touch. Ear pain becomes stronger, and thick purulent masses emerge from the ear canal.

Inflammation from the cavities of the mastoid process can spread under the periosteum - pus accumulates already in the layer of subcutaneous tissue. Quite often, the abscess ruptures itself, as a result of which a fistula is formed on the skin.

How dangerous is the disease? The most common complications

As already mentioned, the mastoid process behind the ear is located and borders with important organs. Therefore, the lack of timely therapy is fraught with dangerous consequences. If the focus breaks into the middle and inner ear cavity, a labyrinth is developed. Inflammation of the inner ear is accompanied by noise in the ears, hearing loss, as well as defeat of the body of balance, which leads to disruption of coordination of movements.

The ostoidal processes border on the hard shells of the brain. Infection can spread to nerve tissue, which leads to the development of meningitis, encephalitis, and sometimes abscesses.

Dangerous is the penetration of infections into the blood vessels responsible for the blood circulation of the brain - this is fraught with not only inflammation of the vascular walls, but also the formation of thrombi, clogged arteries and even death.

To the complications of mastoiditis can be attributed and lesion of the facial nerve. After all, the mastoid process behind the ears is very close to the nerve fibers.

How is mastoiditis treated?

As you can see, mastoiditis is an extremely dangerous disease, therefore adequate therapy is simply necessary. Any delay and attempts at self-treatment can lead to a number of dangerous complications.

As a rule, the treatment is carried out in a hospital, where the doctor has the opportunity to constantly monitor the patient's condition. Patients are prescribed intravenous antibiotics, which help to fight with bacterial infection. In addition, it is necessary to create conditions for the free release of purulent masses from the auditory canal.

When you need trepanation of the mastoid process?

Unfortunately, conservative therapy is effective only at the initial stages of mastoiditis. If pus began to accumulate in the cavities of the lower part of the temporal bone, then surgical intervention is necessary. Trepanation of the mastoid process begins with the opening of the bone wall of the appendage. After this, the surgeon, using tools, cleans tissues from pus, treats them with antiseptics and antibacterial solutions. A special drainage system is then installed, which provides for easy and rapid removal of secretions, as well as local administration of antibiotics.