Trigeminal nerve

The trigeminal nerve (Latin, " trigeminal ": in short, trigeminal ) is the fifth cranial nerve (short: V). He leads sensitive (→ Trigeminal perception) and motor fibers, with whom he reached large parts of the head. It owes its name to the division into three main branches:

• V1: Augenast ( ophthalmic nerve )
• V2: Oberkieferast ( maxillary nerve )
• V3: mandibular ( mandibular nerve ).

Development History of the mandibular nerve is the nerve of the first branchial arch.

• 2.1 lesion
• 2.2 trigeminal neuralgia
• 2.3 Trigeminusneurinom

Anatomy

Originate in the brain

The trigeminal nerve are four cranial nerve nuclei ( nuclei ), three sensitive and motor, associated with:

• Mesencephalic nucleus of trigeminal nucleus,
• Pontine trigeminal nucleus ( nucleus principalis = trigeminal ) and
• Spinal trigeminal nucleus are columnar with each other in the brain stem.
• The motor nucleus of trigeminal nucleus is located in the upper hindbrain.

The mesencephalic nucleus of trigeminal proprioceptive information are (unconscious proprioception: position and tension of the muscles, stretching of the ligaments and capsule of the temporomandibular joint, expansion of the gums ) forwarded. However, in contrast to the other trigeminal nuclei it is not Terminationskern, but merely a collection pseudounipolarer primärafferenter neurons that lie in the trigeminal ganglion ( trigeminal ganglion ) relative to the other fibers of the trigeminal nerve. The mesencephalic nucleus is thus a part of the trigeminal ganglion. Furthermore, he also takes afferents from oculomotor, trochlear, abducens nerve (for the proprioception of eye movements ), facial nerve (for the proprioception of the facial muscles ) and hypoglossal nerve (for the proprioception of the tongue muscles) on. From it the proprioceptive information is now routed without switches to the spinal trigeminal nucleus and the nucleus supratrigeminale.

The nucleus principalis trigeminal (also: Nucleus pontine trigeminal nucleus ) receives epikritische information ( pressure, touch, vibration, two-point discrimination, conscious ( made ​​) e depth sensitivity: position and tension of the muscles, stretching of the ligaments and capsule of the temporomandibular joint, elongation of the gums ). The nucleus principalis trigeminal projected via the trigeminal lemniscus to the ventral posteromedial nucleus in the thalamus.

The spinal trigeminal nucleus are fed protopathische information ( gross pressure, pain, temperature, itch, ' Trigeminusriechen ').

The three sensory cranial nerve nuclei can be achieved not only by fibers of the trigeminal nerve, but also get inflows of other cranial nerves, especially the facial nerve, glossopharyngeal and vagus nerves.

The motor nucleus of trigeminal nucleus sends motor fibers to muscles ( muscles of mastication, anterior belly of the digastric muscle and mylohyoid muscle from the floor of the mouth, tensor veli palatini, tensor tympani ).

Nerve roots

The nerve enters the brain surface at Pons. Already there you can differentiate two roots, the radix Sensoria and the motor root. The sensory fibers of the radix Sensoria be after the trigeminal ganglion as portio major trigeminal referred. The motor fibers of the motor root pass through the trigeminal ganglion and nestle the mandibular nerve to. They form the portio minor trigeminal nucleus.

The portio major ( Radix Sensoria ) contains epikritische, protopathische and some proprioceptive fibers, making it so purely sensory. It is associated with a pseudounipolar ganglion, the trigeminal ganglion. This largely corresponds to the ganglia of the spinal nerves, apart from the fact that it no nerve cell bodies of proprioceptive neurons are located. These are evolutionarily related in the brain stem and form the nucleus of the mesencephalic trigeminal nucleus.

The portio minor ( motor root ) contains motor and proprioceptive fibers. It is mixed with it. Of the proprioceptive fibers it contains probably only those that conduct information from the supplied her muscles or tendons. However, these fibers also come from the radix Sensoria and can thus also the portio major and be numbered among.

The proprioceptive fibers have a special feature: Regardless of whether they run in the portio major, or portio minor, they have their cell bodies in the trigeminal ganglion not, but directly in the mesencephalic nucleus of trigeminal nucleus. This is similar in morphology then the pseudounipolar ganglion. It thus represents an exception, since all other cranial nerve nuclei or nuclei in the brain have a multipolar structure.

The portio major is divided into the three major nerves: ophthalmic nerve ( Augenast ), maxillary nerve ( Oberkieferast ) and mandibular nerve ( ramus ). In addition the entire portio minor sets of the mandibular nerve. All the nerves are now leaving the skull. The mandibular nerve pulls through the foramen ovale. The ophthalmic nerve and the maxillary nerve initially run with the oculomotor nerve, the trochlear nerve, the abducens nerve and the internal carotid artery through the cavernous sinus. Then the nerve leaves the ophthalmic middle cranial fossa ( fossa media) through the superior orbital fissure in the direction of eye socket (orbit ). The maxillary nerve through the foramen rotundum pulls.

Diseases

For medical status survey include the testing of Trigeminusdruckpunkte. The three Trigeminusdruckpunkte (left and right three ) are above approximately on a vertical line on the face and under the eye socket and on the chin. At these points occur peripheral branches of the big three main branches from the bone ( above the eye: nerve supraorbital from the supraorbital notch or supraorbital foramen; under the eye: infraorbital nerve infraorbital from the foramen; chin: the mental nerve from the mental foramen ). Usually these pressure points should not be painful, it is the doctor in the investigation.

The cause of a Trigeminusdruckschmerz come intracranial pressure (ICP ), meningitis ( meningitis), inflammation of the sinuses (sinusitis) and trigeminal neuralgia (see below) in question. Other disorders of the trigeminal nerve:

Lesion

The lesion of the trigeminal nerve, a distinction is a central and peripheral sensory loss.

If the nerve is damaged to its original cores ( ie central) so it is depending on the location in the main for the sensory fibers nucleus, the spinal trigeminal nucleus to circular sensitivity losses by the perioral area basis (so-called Sölder lines).

A peripheral lesion usually harms a branch of the trigeminal nerve after its exit from the trigeminal ganglion and results in sensory deficits in the areas of the face, but differ from the sensitivity areas of the cores. Is the mandibular nerve affected, so also is the portio minor - the motor fibers - interrupted and chewing no longer possible. Swallowing may occur due to damage to the branches for mylohyoid muscle and digastric muscle ( Venter anterior). By a lesion of the nerve is also the corneal reflex is not triggered. Also varicella can penetrate into the branches of the nerve and cause a opthalmicus ophthalmic zoster ( erysipelas ).

Trigeminal neuralgia

In the most violent pain in trigeminal neuralgia may occur. These are sometimes described as the strongest known pain. However, treatment is possible.

Trigeminusneurinom

The Trigeminusneurinom is a nerve sheath tumor of the trigeminal nerve. There are three subtypes according to their localization in relation to the porus trigeminus ( anatomically fully infratentorial course of nerves of the posterior fossa in the middle by the Porus; nomenclaturally but the transition from intra- after supratentorial ).