Cranial nerves comprise twelve pairs of nerves that begin in the brain and serve many muscles, glands, internal organs, as well as the sensory apparatus of the neck and head. These pairs are directly related to the activities of such functions as motor, sensory, secretory and reflex. Cranial nerves are located in various parts of the brain. Thanks to these nerves, there are many processes associated with the work of all organs of the human body. They in a certain sequence depart from the brain. Traditionally, in anatomy, cranial nerves are indicated by Roman numerals.
The olfactory nerve belongs to the first pair . Its receptors are located in the upper region of the nasal cavity, in the mucous membrane. The nerve consists of about twenty thin in structure threads. These filaments do not have a common trunk, and penetrate into the region of the skull through the ethmoid plate of the bone, attaching to the cells of the olfactory bulb, which is represented by a set of mitral cells. An impulse passes to the primary centers of smell, and from there to the cerebral cortex.
II pair forms the optic nerve. Its function is to deliver information from the retina, which is the light-reflecting shell of the eye.
The fibers of this nerve originate from the ganglion cells that make up the retina of the eye. The nerve formed by these fibers passes through the eye sockets, and from there into the cranial cavity.
III pair is the oculomotor nerve. Its core is located on one straight line with the upper bulges of the midbrain. It is divided into lower and upper branches, which are connected to the muscle that raises the upper eyelid, and to the lower oblique muscle of the eyeball.
IV pair is called a block nerve. It belongs to the motor nerves. Its core is located in the midbrain. Bypassing the leg of this brain from the lateral side, the block nerve goes to its base, located between the temporal lobe and the leg. Further, this nerve together with the oculomotor nerve passes from the cranial region directly to the orbit.
V pair forms the trigeminal nerve, which also enters the cranial nerves. Even in the cranial region, it is divided into three large branches. This nerve makes the eyes and skin of the forehead sensitive. The skin of the face between the mouth and the eye, as well as the mucous membranes of the nasal and upper parts of the oral cavity, are innervated by the maxillary nerve. Facial skin located below the mouth, oral mucosa, lower teeth, tongue innervate the mandibular nerve. Also under his control are the chewing muscles.
VI pair is the abducent nerve. Its core is located in the area of the bridge. The nerve controls the eye muscles, which are responsible for the position of the eyeball and its movement. If it is damaged, strabismus may occur.
The facial nerve, which forms the VII pair, also enters the cranial nerves. Its branches are divided into temporal, buccal and zygomatic. The nerve innervates the facial muscles, and its intermediate part, called autonomic, controls the salivary glands and the taste sensitivity of the tongue.
VIII pair is represented by the vestibulo-cochlear nerve. This is the nerve of the auditory organ. It consists of a vestibular root and cochlear. The roots begin inside the pyramid in the thickness of the temporal bone in the inner ear.
IX pair has the name of the glossopharyngeal nerve. This is the nerve of taste sensitivity of the posterior region of the tongue, also involved in the work of the parotid salivary gland and the process of swallowing.
X pair represents the vagus nerve. It is directly related to speech and swallowing. Innervates the muscles of the pharynx, palate, and larynx. The nerve is divided into many branches directed to the organs of the head and neck, as well as the abdominal and thoracic cavities.
XI pair is called the accessory nerve. It originates from the medulla oblongata and controls the trapezius muscle, as well as the sternocleidomastoid.
XII pair forms the hyoid nerve. He innervates all muscles of the tongue without exception.
Human nerves are responsible for the operation of all systems and organs. They are susceptible to various environmental changes, causing unpleasant painful sensations, and can lead to malfunctions of the whole body systems.