Everyone from school knows about 12 pairs of cranial nerves. They occupy key positions in the functioning of the nervous system. Any violation in their work entails a violation of the work of the whole organism. So the trochlear nerve belongs to the fourth pair.
Location in the brain
It is difficult to understand what and where is located without anatomical preparations. Therefore, it is required to read a detailed description of the location of the nerves. So, the fourth pair is the only one that goes to the back of the brain stem. At the level of the lower mounds of the roof of the midbrain, the nuclei of the trochlear nerve are located. When viewed in the forward direction, they are located forward of the central gray matter. In relation to the nuclei of the oculomotor nerve, the nuclei of the trochlear nerve are located below.
The trochlear nerve forms a decussation on a gray plate called the medullary velum, which forms the operculum of the ventricle. After the nerve exits through the midbrain to the bottom of the lower hillocks. Each pair bends around the leg of the brain from the side. There, the trochlear nerve penetrates into the gap between the temporallobe of the cerebral hemisphere and the brain stem. After, moving forward, it penetrates through the meninges into the outer wall of the cavernous sinus. There, through the superior orbital fissure, it reaches the orbit and exits to the superior oblique muscle of the eye.
Throch nerve: functions, interaction with other pairs of nerves
The main task of the fourth pair of cranial nerves is to provide forward and downward movement of the eye. Normally, the eyeball has several axes of rotation. In total, six muscles are involved in this process. So they distinguish between turning the eye to the temples, to the nose, lifting up and lowering down. An important feature of human eyes is joint movement, since normally a person cannot look with his eyes in different directions. Thus, the oculomotor, trochlear and abducens nerves are included in the general group of oculomotor nerves. Failure of any participant causes impairment of visual function. Thus, the following conclusions can be drawn:
- isolated eye movements not possible;
- both eyes move at the same time;
- a pair of oculomotor muscles always contract.
Research methodology
To determine whether a particular pair of cranial nerves is functioning correctly, doctors use special research methods. To do this, check if a person has double vision. The width of the palpebral fissures, the size of the pupil, and the position of the eyeball are carefully examined. An important diagnostic study is the reaction of the pupil to light. For thisthe patient is asked to close his eyes with his palms and sharply remove them, looking at the light. To study the convergence of the eyes, a conventional hammer is used. It is brought closer to the bridge of the nose, checking the convergence of apples. Accommodation is tested even more simply: the patient closes his eye, the second one looks first at a distant object, then at a close one.
trochlear nerve injury: symptoms and treatment
Since the main function of the fourth pair of cranial nerves is motor, the first and main symptom is paralysis. There is a deviation of the eyeball up and inward. This is clearly seen when the patient is walking up the stairs. Another symptom is double vision, as desynchronization forces the image to be projected onto different parts of the retina.
When all the oculomotor nerves are affected, the following picture is observed: the eye does not move, the pupil is wide, does not react to light. If this is observed in both eyes, then we can talk about damage to the nuclei of the nerves.
Most often this is a consequence of the development of diseases such as neurosyphilis, meningitis, a sign of aneurysm, thrombosis and others. Therefore, it is important for treatment to address the root cause of the condition.
To date, there are no effective methods for the treatment of oculomotor nerves. According to the data, physiotherapy is successfully used, its only drawback is a slow effect or its complete absence. In order for the trochlear nerve to function again, electrical stimulation is often used.
In any case, treatment should only be carried out by a doctor. With the defeat of the cranial pairs of nerves, it is better to usean integrated approach that includes several methods. It is important not to start the process of the disease, since the development will begin to damage the nuclei of the nerves, which significantly reduces the chances of recovery.
