Anatomy of the trigeminal nerve, its branches

Nerves are the basis of the nervous system. Most of them are cranial, that is, they leave the brain. One of these nerves is the trigeminal. What is the anatomy of the trigeminal nerve?

What is it?

The triple nerve is in its structure a nerve of a mixed type. Refers to 5 pairs of cranial nerves.

It includes sensitive (afferent, centripetal) and motor (centrifugal) fibers, due to which pulses from both surface (pain and temperature) and deep (proprioceptive) receptors are transmitted along this nerve. Motor innervation is carried out by the motor nucleus, which innervates mainly the chewing muscles. What is the anatomy of the trigeminal nerve and the localization of its branches?

The nerve leaves the brain in the bridge area. Leaving the brain, most of it passes through the pyramid of the temporal bone. At its apex, the nerve divides into three branches: the orbital (r.ophthalmicus), the maxillary (r.maxillaris) and the mandibular (r.mandibularis).

This nerve is of interest to neurologists because it provides the innervation of the whole area of the face. Quite often, his lesions are observed in hypothermia, trauma in the facial area, and certain diseases of the musculoskeletal system.

What is the anatomy of the trigeminal nerve, its branches?

The optic nerve

The first branch of the trigeminal nerve is the ophthalmic nerve or the nervus ophthalmicus.

This is the thinnest branch that extends from the trigeminal nerve. It performs primarily the function of reception. It innervates the forehead skin, some parts of the temporal and parietal region, the upper eyelid, the back of the nose, some sinuses of the facial bones and partially the mucous membrane of the nasal cavity.

The nerve consists of about thirty relatively small bundles of nerve fibers. The nerve enters the orbit at the outer wall of the eye sine, where it gives branches to the block and drain nerves. In the area of the upper orbital nerve cutting, the nerve divides into three smaller and finer bundles - tear, frontal and ciliary nerves.

Close their localization to the eyeball often leads to their defeat as a result of injury to the orbit or supraorbital area.

The ciliary nerve, in turn, forms the ciliary ganglion located on the border of the inner and middle third of the optic nerve. It includes parasympathetic nerve endings involved in the innervation of the glands of the eye and the peri-ocular area.

The maxillary nerve

Another branch of the trigeminal nerve is the maxillary or nervus maxillaris.

It leaves the cranial cavity through an oval window. From it, it enters the pterygoid palatine fossa. Passing through it, the nerve continues into the lower one, passing through the lower orbital hole. Passing through it, the nerve passes in the same channel on the bottom wall of the orbit. On his face, he emerges through the lower orbital opening, where he splits into smaller branches. They form connections with the branches of the facial nerve and innervate the skin of the lower eyelid, upper lip and lateral surface of the face. In addition, such branches as the zygomatic nerve, the upper alveolar branches forming the plexus near the teeth, and the ganglionar branches connecting the maxillary nerve with the pterygo-palatine ganglion depart from the maxillary nerve.

The defeat of this nerve is observed with massive facial trauma, neuritis, operations on the teeth and sinuses.

The mandibular nerve

The third and most complex branch of the trigeminal nerve is the mandibular or nervus mandibularis. In its composition, it has, in addition to the sensitive branches, practically the entire part of the trigeminal nerve root, emerging from the motor nucleus, the nucleus motorius, to the muscles of the lower jaw. As a result of this arrangement, innervates these muscles, as well as the skin that covers them. The nerve leaves the skull through the foramen ovale (an oval window or hole), after which it is divided into 2 groups of branches:

• Muscle branches go to the masticatory muscles - pterygoid muscle, temporal; The musculus digastricus is also innervated.
• Sensitive branches go to the mucous membrane of the cheek, and also to the bottom of the oral cavity. Partially these branches innervate and language. The largest and longest branch of the mandibular nerve is the lower alveolus (in other sources - the alveolar) nerve, passes through the chin aperture with the same artery and leaves into the canal of the lower jaw, where the lower alveolar plexus is formed.

We can assume that it is this branch that continues the trigeminal nerve. Anatomy, the scheme of this nerve (structure) and its properties (mixed nerve fiber) allow us to consider this branch terminal. Despite the fact that it forms the lower alveolar nerve plexus, the place of its termination can be considered an entry into the mandibular canal.

The course of nerve fibers

What is the anatomy of the trigeminal nerve (structure and course of its branches)?

The structure of the trigeminal nerve is similar to that of any of the spinal nerves. The triple nerve has a special large node - the trigeminal ganglion. This formation is located in the middle cranial fossa. On all sides it is surrounded by sheets of dura mater. The node has dendrites, which form three major major branches of the trigeminal nerve. The sensitive nerve root penetrates through the middle legs of the cerebellum, where it closes on three nuclei of the brain - the upper and the middle, each of which contains specific sensitive neurons. The motor part of the nerve starts from the motor nucleus - the nucleus motorius.

Due to this arrangement, the nerve can be exposed to both the brain and surrounding tissues, which is why it is of particular interest to neurologists.

What are the main types of lesions that are characteristic of the nerve?

Diseases of the trigeminal nerve

What processes influence the functional capacity of this formation, and how can the trigeminal nerve be affected?

The anatomy of its course predisposes to the development of canalopathies - infringement of the branches of the nerve passing through the canal or opening, surrounding formations. In this case, knowledge of the topography of the nerve and certain topical features allows us to establish the level of its damage and take appropriate measures.

Another, no less important factor is the influence of surrounding tissues. Most often the nerves are affected by brain tumors. Growing up, they contribute to squeezing it and the appearance of a corresponding clinical picture.

The anatomy of the trigeminal nerve (the knowledge of its branches and the sites of its projection on the face) makes it possible to determine the exit points of the branches of the nerve and, by electrophysiological methods of stimulation, stimulate them, or, taking into account the location of the branches, to conduct appropriate treatment of the underlying disease that led to the appearance of pathological symptoms.

Examination of the trigeminal nerve

Examination of the function of the trigeminal nerve is carried out in determining the sensitivity of the skin areas that it innervates, as well as in the ability of the patient to strain and relax the chewing musculature. The examination of the nerve is carried out by palpation of the points of its exit on the face. How to determine how sensitive the trigeminal nerve is? Its anatomy makes it possible to determine the activity of sensitive neurons located under the skin.

Determination of sensitivity is carried out wetted in cold or hot solution with cotton wool or a tampon. Pain sensitivity is checked by touching the needle.

To check the motor function, the patient is asked to perform several chewing movements.

In the presence of pathology, there is a change in sensitivity in one or more zones of innervation or the patient's inability to perform properly chewing movements. There is a deviation of the jaw in the sore side or excessive muscle spasm. The tension in the chewing muscles is determined by pressing them during the act of chewing.

Why you need to know the topography

Topographic anatomy of the trigeminal nerve is necessary for the precise determination of the lesion site. Knowing where the branch passes, what clinical signs are characteristic for its defeat and how they can become complicated, it is possible to determine the scope and treatment plan.

Knowledge of the location and course of the branches of this nerve is placed on the shoulders of neurologists and neurosurgeons. It is these specialists who for the most part are faced with diseases in which the trigeminal nerve is affected. Anatomy (a photo obtained with the help of MRI) allows you to determine the tactics of treatment and take appropriate measures.

When the first signs of a lesion of one or another branch of the nerve appear, you should immediately seek help from a doctor of the appropriate specialization to determine the diagnosis and design an algorithm for treatment.