The nerves extending from and entering the brain are called cranial nerves. The distribution and brief description of them separately is discussed in the next article.
Types of nerves and pathology
There are several types of nerves:
- motor;
- mixed
- sensitive.
Neurology of motor cranial nerves,as sensitive and mixed, has pronounced manifestations that experts can easily diagnose. In addition to isolated lesions of individual nerves, those that belong to different groups at the same time may be affected. Thanks to the knowledge of their location and functions, it is possible not only to understand which nerve is broken, but also to localize the affected area. This becomes achievable through special techniques using high-tech equipment. For example, in ophthalmic practice, using modern technology, it is possible to find out the state of the fundus, optic nerve, determine the field of view and the lesions.
Good value reveals carotid andvertebral angiography. But more detailed information can be obtained using computed tomography. With it you can see the individual trunks of the nerves and identify tumors and other changes in the auditory, visual and other nerves.
To investigate the trigeminal and auditory nerves was made possible by the method of cortical somatosensory potentials. Also in this case, audiography and nystagmography are used.
The development of electromyography has expanded the possibilitiesfor more detailed information about the cranial nerves. Now you can explore, for example, reflex blinking response, spontaneous muscle activity during facial expressions and chewing, muscles of the tongue, palate, and so on.
Let us dwell on each of the data pairs.nerves. There are a total of 12 pairs of cranial nerves. The table where all of them are listed is listed at the end of the article. In the meantime, consider each of the pairs separately.
1 pair. Description
Сюда входит обонятельный нерв из группы sensitive. At the same time, receptor cells are disseminated in the epithelium of the nasal cavity in the olfactory part. Thin nerve cell processes are concentrated in the olfactory filaments, representing the olfactory nerves. From the nasal nerve into the cavity of the skull through the holes of the ethmoid plate, and ends in the bulb, where the central olfactory pathways originate.
2 pair. Optic nerve
This pair includes the optic nervegroup of sensitive. The axons of the neurons here go out through the trellised plate from the eyeball with one barrel, which falls into the cranial cavity. At the base of the brain, the fibers of these nerves on both sides converge and create an optic chiasm and tracts. The paths go to the cranial body and the thalamus cushion, after which the central visual path is directed to the occipital lobe of the brain.
3 pair. Motor nerve
Oculomotor (motor) createdthe fibers of the nerve pass from those nerves that are in the gray matter under the aqueduct of the brain. It passes to the base between the legs, after which it enters the orbit and innervates the eye muscles (except for the upper oblique and external straight, other cranial nerves are responsible for their innervation, 12 pairs, the table indicating which clearly illustrates them all together). This is due to the parasympathetic fibers contained in the nerve.
4 pair. Block nerve
This pair includes a block nerve (motor),originating from the nucleus under the water line of the brain and emerging to the surface in the region of the brain sail. In this part, the cross is obtained, the leg bends around and penetration into the eye socket. This pair is innervated by the superior oblique muscle.
5 pair of 12 pairs of cranial nerves
Таблица продолжается тройничным нервом, already related to mixed. In its trunk there are sensory and motor nuclei, and on the base - their roots and branches. Sensitive fibers originate from the cells of the trigeminal ganglion, whose dendrites create peripheral branches innervating the skin of the hair part of the head in front, as well as the face, gums with teeth, eye conjunctiva, mucous membranes of the nose, mouth, tongue.
Motor fibers (from the root of the trigeminal nerve) are connected to the mandibular nerve branch, pass and innervate the masticatory muscles.
6 pair. Nerve
The next one is included in 12 pairs of cranialnerves (the table refers it to the group of motor nerves) pair includes the abducent nerve. It starts from the cell nuclei in the pons, penetrates the base and moves forward to the orbital fissure from above and further to the orbit. It innervates the direct eye muscle (external).
7 pair. Facial nerve
This pair consists of the facial nerve.(motor), created from the cell processes of the motor nucleus. Fibers begin their way in the trunk at the bottom of the fourth ventricle, pass around the nucleus of the fourth nerve, descend to the base and exit to the cerebellar cortex. Then it moves to the auditory orifice, into the canal of the facial nerve. After the parotid gland, it is divided into branches innervating facial and facial muscles, as well as a number of others. In addition, a branch extending from its trunk innervates the muscle located in the middle ear.
8 pair. Auditory nerve
Восьмая пара из 12 пар черепно-мозговых нервов (the table identifies it as a sensory nerve) consists of the auditory, or pre-door-cochlear nerve, comprising two parts: the pre-door and cochlear. The cochlear part consists of dendrites and axons of a spiral knot located in the bone cochlea. And the other part departs from the vestibular node at the bottom of the ear canal. The nerve on both sides connects to the auditory canal in the auditory nerve.
The fibers of the predoor end in the nuclei that are in the diamond-shaped fossa, and the cochlear - in the cochlear nuclei of the pons.
9 pair. Glossopharyngeal nerve
Таблица черепно-мозговых нервов продолжается ninth pair, which is represented by the glossopharyngeal nerve. It includes sensitive, motor, secretory and taste fibers. There are close links with the wandering and intermediate nerves. Many nuclei of the nerve in question are located in the medulla oblongata. They are common with the tenth and twelfth pairs.
The nerve fibers of the pair unite in the trunk,leaving the cranial cavity. For the posterior third of the palate and tongue it is the gustatory and sensory nerve, for the inner ear and the pharynx it is sensitive, for the pharynx it is the motor nerve, for the parotid gland it is the secretory.
10 pair. Nervus vagus
Далее таблица черепно-мозговых нервов continues with a pair consisting of the vagus nerve, which is endowed with different functions. The trunk starts from the roots in the medulla oblongata. Coming out of the cranial cavity, the nerve innervates the striated muscles in the throat, as well as in the larynx, sky, trachea, bronchi and digestive organs.
Чувствительные волокна иннервируют затылочную brain area, ear canal outside, other organs. Secretory fibers are sent to the stomach and pancreas, vasomotor - to the vessels, parasympathetic - to the heart.
11 pair. Description of the extension nerve
The extra nerve presented in this pairconsists of upper and lower sections. The first comes out of the motor nucleus of the medulla, and the second from the nucleus in the horns of the spinal cord. The roots are connected to each other and out of the skull, along with a tenth pair. Some of them go to this vagus nerve.
It innervates the muscles - sternocleidomastoid and trapezoidal.
12 pair
The summary table of the cranial nerves ends with a pair with the hypoglossal nerve. Its core is located at the bottom of the medulla. Coming out of the skull, he innervates the lingual muscles.
These are the approximate schemes of 12 pairs of cranial nerves. Summarize the above.
Look at the list for cranial nerves, 12 pairs. The table is as follows.
Conclusion
This is the structure and function of these nerves.Each pair plays its most important role. Each nerve is a part of a huge system and depends on it just as the whole system depends on the functioning of individual nerves.
