What Are the Nerves in the Brain?

Also called "cranium nerve". It is a pair of left and right nerves emitted from the brain and belongs to the peripheral nervous system. There are 12 pairs of human brain nerves: olfactory nerve, optic nerve, oculomotor nerve, pulley nerve, trigeminal nerve, abduction nerve, sacral facial nerve, sacral nerve, genioglossopharyngeal nerve, vagus nerve, sacral nerve Nerve, hypoglossal nerve. They are mainly distributed in the head and face, and the vagus nerve is also distributed to the internal organs of the thorax and abdomen. Among these 12 pairs of brain nerves, the first pair, , and are sensory nerves; the third pair, , , , and are motor nerves; the fifth, , , and X pairs are mixed nerves.

Chinese name: Brain nerve
Foreign name: Cranial nerve
Overview: "Cranial nerve

Olfactory nerve damage: Basic introduction to differential diagnosis
Optic nerve damage: Etiology and clinical manifestations
Motor nerve damage: Etiology and clinical manifestations
Trigeminal nerve damage: Etiology and clinical manifestations

Cerebral nerve anatomy and physiological functions:

Cerebral olfactory nerve:

The human olfactory nerve begins in the olfactory mucosa of the nasal cavity. The central processes of the olfactory cells first merge and interweave into clumps in the mucosa, and then form 15 to 20 olfactory filaments from the clumps. The olfactory filaments leave the olfactory mucosa, pass through the holes in the ethmoidal plate and enter the anterior cranial fossa, ending at the olfactory bulb. Olfactory cells are both the primary afferent neurons of the olfactory sense and the receiving cells of the olfactory receptors. The olfactory neuron myelin sheath is covered with a double-layered "sheath" formed by the dura mater and arachnoid membrane. The intracranial subarachnoid space can extend through the space under this sheath to the olfactory mucosa. Therefore, some patients with increased intracranial pressure may also experience cerebrospinal fluid leakage from the nasal cavity. When the anterior cranial fossa is broken, the olfactory wire can be torn off, causing an olfactory disorder.

Cerebral optic nerve:

The optic nerve originates from the ganglion cell layer of the retina. It is originated from the fiber on the nasal side of the retina. After the optic cross, it is combined with the fiber on the temporal side of the retina on the opposite eyeball to form the optic bundle. After the neuron replacement, fibers are emitted through the posterior limb of the inner capsule to form optic radiation, which terminates in the central cortex of the wedge gyrus and lingual gyrus on both sides of the occipital lobe, that is, the striatum. The fibers of the macula are projected to the rear of the striated area, and the fibers of the retinal region are projected to the front of the striated area. The path of light reflection does not pass through the lateral geniculate body, and the optic beam passes through the superior thalamus into the midbrain and is associated with the oculomotor nucleus. The examination includes vision, color vision, visual field and fundus examination.

Cranial nerve and oculomotor nerve:

The oculomotor nucleus, which originates from the midbrain, contains two fibers of body movement and visceral movement. Somatic motor fibers govern the movement of the lower rectus muscle, medial rectus muscle, lower oblique muscle, superior rectus muscle, and superior levator muscle of the eyeball. Visceral motor fibers (parasympathetic fibers) dominate the pupil sphincter and ciliary muscle, making the pupils smaller and the lens more convex. The oculomotor nerve injury is mainly manifested as drooping of the upper eyelid, squinting of the eyeballs, and dilated pupils.

Cerebral nerves:

The fibers from the nucleus of the trochlear nucleus, which originates from the lower part of the oculomotor nucleus in the superior colliculus plane of the midbrain, move toward the dorsal roof and advance around the outside of the brain's foot, penetrate into the outer wall of the cavernous sinus, and enter the orbit through the supraorbital fissure. The oblique muscles dominate this muscle. Simple palsy nerve paralysis is rare, manifested by weakened downward and outward movement of the affected eye, and diplopia.

Cerebral trigeminal nerve:

There are three branches, the first eye nerve is the sensory nerve, the second maxillary nerve is the sensory nerve, and the third mandibular nerve is the mixed nerve (containing sensory and motor fibers). Sensory fibers are distributed in the face, eyes, nose, and mouth, and the feelings of conduction pain, warmth, and touch, and the proprioception of extraocular muscles and chewing muscles. Motor fibers are distributed in the masticatory muscles, which dominate the movement of the masticatory muscles. Trigeminal nerve injury is manifested by paralysis and atrophy of the masticatory muscles, loss of sensation in the skin of the head and face, mouth, nasal mucosa, teeth and gingival mucosa, and disappearance of corneal reflex.

Brain nerve abduction nerve:

Starting from the abductor nucleus from the lower part of the pontine, the axons form the abductor nerve, which are distributed in the rectus muscles outside the eye, which dominate the lateral movement of the eyeballs. Intraocular strabismus when the abductor is injured.

Cranial nerve facial nerve:

The facial nerve contains motor, sensory, and parasympathetic fibers. Motor fibers originate from the nucleus of the facial nerve located on the ventral side of the caudal caudate, and control the facial muscles other than the chewing muscles and levator levator muscles, as well as the ear muscles, occipital muscles, and platysma. Taste fibers originate from the geniculate ganglion and dominate the 2/3 of the taste of the tongue. A few sensory fibers convey the general sensation of the auricle, external auditory canal, and part of the eardrum to the skin, lacrimal gland, salivary gland, and part of the mucous membrane of the mouth. Parasympathetic fibers originate from the upper salivary nucleus and control the secretion of the sublingual and submandibular glands.

Cerebral nerve and auditory nerve:

Also known as the "vestibular snail nerve" or auditory nerve is composed of two parts, the snail nerve and the vestibular nerve. The sensory neurons of the snail nerve are located in the cochlea's spiral organ (Curtis's organ) and conduct auditory impulses. Sensory neurons of the vestibular nerve are located in the vestibular organs of the inner ear (cystic plaques, ampulla), and conduct positional impulses. The auditory nerve damage manifested as dizziness, nystagmus and hearing impairment.

Cerebral Glossopharyngeal Nerve:

The glossopharyngeal nerve includes three types: sensory, motor, and parasympathetic. The sensation originates from the upper ganglion and the rock (lower) ganglion, which are distributed around: the taste buds behind the 1/3 of the tongue, which conducts the sense of taste; to the pharynx, the soft palate, the 1/3 of the tongue, the tonsils, and the zygomatic arches on both sides , Eustachian tube, and tympanic cavity, receiving mucosal sensation; to the carotid sinus and carotid bulb, that is, the sinus nerve (related to the reflex of respiration, pulse, and blood pressure). Their central branches terminate in the solitary nucleus of the medulla oblongata. Exercise starts from the suspicious nucleus and is distributed in the styloid process of the pharyngeal muscle. Parasympathy originates from the lower salivary nucleus, passes through the tympanic nerve, the superficial petrosal nerve, and terminates in the ear ganglia. Postganglionic fibers dominate the parotid secretion.

Cerebral vagus nerve:

The motor fibers originate from the suspicious nucleus and run parallel to the glossopharyngeal nerve. After passing through the brain stem, they pass through the jugular foramen to the cranial cavity and supply all pharyngeal, laryngeal, and soft palate muscles except for the soft palate muscle and the pharyngeal muscle. The sensory neurons are in the cervical ganglia and nodal ganglia near the jugular foramen. The peripheral branches of the cervical ganglion conduct part of the general sensations of the external auditory canal, tympanic membrane, and auricle; the central branch branches into the spinal nucleus of the brain stem of the trigeminal nerve. The peripheral branches of the nodular ganglion conduct the sensations of the pharynx, larynx, trachea, esophagus, and internal organs, as well as the taste of the pharynx, soft palate, hard palate, and epiglottis; the central branch enters the arcuate nucleus. Parasympathetic nerves originate from the dorsal nucleus of the vagus nerve at the bottom of the fourth ventricle and are distributed to internal organs.

Cerebellar and nerve:

The accessory nerve is composed of special visceral motor fibers and somatic motor fibers. The former originates from the suspicious nucleus and innervates the pharyngeal muscle, the latter originates from the paranuclear nucleus and innervates the sternocleidomastoid and trapezius muscles. When one side nerve is injured, the papillary mastoid muscle of the side is paralyzed, and the head is weak and turned to the opposite side. The trapezius muscle is paralyzed and the shoulder is sagging and the shoulder is weak.

Cerebellar nerve and hypoglossal nerve:

The hypoglossal nerve originates from the hypoglossal nucleus near the midline of the dorsal part of the medullary bulb. Its nerve roots pass through the anterolateral groove of the lateral side of the medullary cone and pass through the hypoglossal neural tube to the extracranial area to control the tongue muscle. The tongue sticking out is mainly the effect of the genioglossus muscle, and the tongue retracting inward is mainly the effect of the hyoid hyoid muscle. The hypoglossal nerve is only innervated by the contralateral cortical bulbus. The central damage of the hypoglossal nerve causes paralysis of the contralateral central hypoglossal nerve, without atrophy of the tongue muscle, often accompanied by hemiplegia, which is more common in cerebrovascular accidents. When the peripheral hypoglossal nerve is paralyzed, the tongue significantly shrinks. Progressive degenerative diseases of the sublingual nucleus can also be accompanied by muscle tremors.