The cranial nerves
The olfactory nerve (n. olfactorius) (I pair) refers to the nerves of special sensitivity. It starts from the olfactory receptors of nasal mucosa in the upper turbinate. Is a thin nerve fibers 15-20 formed by non-fleshy fibers. The filaments do not form a common trunk and enter the cranial cavity through the cribriform lamina of the ethmoid bone, which are attached to the cells of the olfactory bulb (bullus olfactorius), which is a set of mitral cells. Intertwined with the dendrites of matrix, fibers, filaments form the olfactory tract (tractus olfactorius). Olfactory fibers conduct impulses to the path of the subcortical, or primary, olfactory centers, where part of the fiber is sent to the cerebral cortex (arched gyrus).
The optic nerve (n. opticus) (II pair) also refers to the nerves of special sensitivity. Its fibers start from the ganglion cells of the retina. They form the nerve enters the orbit, and then - in the cranial cavity through the optic canal of sphenoid bone. In the area of the sphenoid bone nerve fibers partially overlap, ie, crisscross fibers extending from the medial half of the retina. Turning to the opposite side, the medial fibers are connected with the fibers of the lateral part, as a result of the place of crossing begins optic tract (tractus opticus), which ends in the subcortical centers of vision, consisting of the lateral geniculate nucleus, thalamus, and upper Hills roof plate of the midbrain. From subcortical centers of the pulses received in the visual analyzer, located in the cortex of the occipital lobe on both sides of the calcarine sulcus.
Oculomotor nerve (n. oculomotorius) (III pair) is mixed. Nucleus of the oculomotor nerve lies at the upper hills of the midbrain, cerebral peduncles in the lid, the medial side where the nerve exits. From the skull through the upper slit orbital oculomotor nerve passes into the orbit and divides into two branches - the top and bottom. The branches of the oculomotor nerve to the muscle suit, elevating the upper eyelid, upper, inner and lower rectus and inferior oblique muscle to the eyeball.
Trochlear nerve (n. trochlearis) (IV pair) belongs to the motor nerves. The core of the nerve block is located in the midbrain. Rounding the brain stem to the lateral side, the nerve enters the base of the brain, passing between the stem and temporal lobes. Then, together with the oculomotor nerve passes from the skull into the orbit and supplies the upper oblique muscle of the eyeball.
Trigeminal nerve (n. trigeminus) (V pair) is mixed. It is isolated motor nucleus, which is on the lid of the bridge and giving rise to fibers that form the motor root (radix motoria), and sensitive core. Sensory fibers from just a trigeminal unit cells (ganglion trigeminale) and form a sensitive root (radix sensoria). Both the spine out of the brain at the border bridge and middle legs of the cerebellum and are divided into orbital, maxillary and mandibular branches. Orbital nerve (n. ophthalmicus) sensitive, out of the skull into the orbit through the slit and verhneglaznichnuyu divided into three branches:
- Frontal nerve (n. frontalis), which allows multiple branches, going to the forehead and bridge of the nose;
- Lacrimal nerve (n. lacrimalis), extending along the outer wall of the orbit and ending in the lacrimal gland and upper eyelid;
- Nosoresnichny nerve (n. nasociliaris), bound to the eyeball, eyelids, lacrimal sac, the mucosa of lattice cells sphenoid sinus, nasal cavity, and skin of the nasal bridge.
Maxillary nerve (n. maxillaris) is also sensitive. He comes out of the skull in palatal winglike-hole through a round hole and goes into the orbit through the infraorbital gap. Then passes through the infraorbital groove and infraorbital canal. On this part of the maxillary nerve is called the infraorbital nerve (n. infraorbitalis). He goes through the suborbital foramen and penetrates the skin. All the way from the maxillary nerve depart the following branches:
- Zygomatic nerve (n. zygomaticus) is sent to the skin of the neck and anterior regions of the temporal region;
- The upper alveolar nerve (nn. alveolaris superiores) pierce the thickness of the upper jaw, forming the upper dental plexus, whose branches innervate the teeth and gums of the upper jaw;
- Palatine nerves (nn. palatini) are by and large and small palatine canals and enter the mouth through large and small palatal holes, going to the mucosa of the hard and soft palate;
- The rear nasal branches (rr. nasales posterior) go to the mucosa of the nasal cavity through the wedge-palatal opening.
Mandibular nerve (n. mandibularis) is mixed, leaves the skull through the foramen ovale in a large wing of the sphenoid bone and divides into sensory, motor, and mixed branches.
Sensitive branch include:
- Ushno-temporal nerve (n. auriculotemporalis), headed for the front of the pinna, external auditory canal and the skin of the temple;
- Buccal nerve (n. buccalis), which innervates the buccal mucosa;
- Lingual nerve (n. lingualis), giving the branches occurring in the first two-thirds of the dorsum of the tongue.
The motor branch include:
- Chewing nerve (n. massetericus), which innervates the masticatory muscles;
- Deep temporal nerves (nn. temporales profundi), bound to the temporal muscle;
- Medial and lateral pterygoid nerves (nn. pterygoidei medialis et lateralis), suitable to the muscles of the same name;
- Nerve muscles that bend the soft palate (n. tensoris veli palatini), which innervate the muscle of the same name and the soft palate;
- Nerve muscles that bend the ear drum (n. tensoris timpani), innervating the same name of the muscle.
Mixed is a branch of the inferior alveolar nerve (n. alveolaris inferior). His motor branch goes to the jaw-hyoid muscle and anterior belly of the digastric muscle. Then, going through the hole of the lower jaw of the same name in the channel, it gives branches, forming the lower dental plexus, thus innerviruya gums and teeth of the mandible. The final branch of the inferior alveolar nerve is called the mental nerve (n. mentalis), passes through the hole of the lower jaw chin and goes to the lower lip and chin skin.
Abducens (n. abducens) (VI pair) belongs to the motor nerves. Its core lies in the area of the bridge, where the nerve enters the base of the brain, passing between the pyramid and the bridge. From the skull of abducens goes through the slit in the eye socket verhneglaznichnuyu where innervates the lateral rectus muscle of the eyeball.
The facial nerve (n. facialis) (VII pair) is also a motor nerve, whose nucleus is located in the area of the bridge. Passing between the bridge and the olive tree, the nerve is on the base of the brain, and then through the internal auditory opening enters the temporal bone. Going to the internal acoustic meatus and the facial nerve canal, the facial nerve exits through the stylomastoid opening to the outside of the skull base. Passing through the thickness of the parotid gland and branching on terminal branches, the nerve forms on the face of the so-called large crows feet. Terminal branches of the facial nerve are divided into temporal, zygomatic, buccal. Also secrete cervical branch of the facial nerve and marginal mandibular branch. Terminal branches innervate the inferior belly of the digastric muscle, muscles of facial expression and partly platysma.
Preddverno-cochlear nerve (n. vestibulocochlearis) (VIII pair) belongs to the special sensitivity of the nerves and is composed of two parts: preddverno root (radix vestibularis) and the cochlear nerve root (radix cochlearis), starting inside the pyramid of the temporal bone in the inner the ear. Preddverno nerve conducts impulses from a static device, which is located on the eve and the semicircular canals of the inner ear. The cochlear nerve is the conductor of the pulse organ of Corti, located in the cochlea of the inner ear and responds to auditory stimuli. Both the nerve out of the pyramid of the temporal bone into the brain through the internal auditory opening, passing through the internal auditory canal. Place them out is located lateral to the facial nerve. Nerve fibers end in the nuclei of these nerves, which lie in the lateral corners of the rhomboid fossa.
Glossopharyngeal nerve (n. glossopharyngeus) (IX pair) is mixed, with a predominance of sensitive parts. Sensory fibers start from sensitive sites located in the jugular openings through which the glossopharyngeal nerve exits the skull, and the motor, as well as the vagus nerve - from the dual-core cell, occurring in the diamond-shaped hole.
The sensory nerves include:
- Jacobson nerve (n. tympanicus), next to the tympanum, where it forms a plexus, whose branches are directed to the mucous membrane of the tympanum and auditory tube;
- Lingual branch (rr. linguales), which innervate the posterior third of tongue;
- Pharyngeal branches (rr. pharyngei), bound to the mucosa of the pharynx;
- Branch of the amygdala (rr. tonsillares), which are suitable to the mucous membrane of the tonsils and arches.
Motor nerves include:
- Branch shiloglotochnoy muscle (r. musculi stylopharyngei), innervate the muscle shiloglotochnuyu;
- Pharyngeal branches (rr. pharyngei), which combine with the vagus nerve, are sent to the muscles of the pharynx.
The vagus nerve (n. vagus) (X pair) is mixed. Its motor fibers from the cells start motor nucleus, and sensitive - sensitive ganglion cells from occurring in the jugular orifice. From the brain of the vagus nerve goes behind the olive tree, and the skull - through the jugular hole and is divided into many branches, bound to the organs of the head, neck, chest and abdominal cavities.
The head office includes:
- A branch of the brain (r. meningeus), a guide to the dura mater posterior cranial fossa;
- Ear branch (r. auricularis), which innervates the skin of the ear and ear canal.
- Pharyngeal branches (rr. pharyngei), which participate in the formation of the pharyngeal plexus, joined by branches of the glossopharyngeal nerve and innervate the muscles of the pharynx and palatine arches, and sensory nerves innervate the mucosa of the pharynx;
- The upper laryngeal nerve (n. laryngeus superior), innervating the area of the mucous membrane of larynx, vocal cords lie above, and some muscles of the larynx;
- Upper and lower branches of the heart (rr. cardiaci cervicales superiores et inferiores), which participate in the formation of the cardiac plexus that innervate the heart.
- Recurrent laryngeal nerve (n. laryngeus recurrens), which, branching, innervates the trachea and esophagus, and its ultimate branch, called the lower laryngeal nerve (n. laryngeus inferior), is sent to the mucosa and muscles of the larynx;
- Thoracic cardiac branch (rr. cardiaci thoracici), taking part in the formation of cardiac plexus;
- Bronchial and tracheal branches (rr. bronchiales et tracheales), going to the mucosa, smooth muscle and glands of the bronchi and trachea;
- Esophageal branches (rr. esophagei), innervate the wall of the esophagus.
- Front and rear gastric branches (rr. gastrici anteriores et posteriores), which descend from the esophagus to the stomach, forming the anterior and posterior gastric plexus and innerviruya mucosa and gastric glands;
- Celiac branches (rr. celiaci) are an extension of the gastric nerves and blood vessels together with the sympathetic plexuses are sent to the pancreas, liver, spleen, kidney, small intestine and colon, up to the sigmoid colon.
|In Fig. 265.
Diagram of the nerves of the head
1 - branch of the facial nerve;
2 - orbital nerve;
3 - maxillary nerve;
4 - mandibular nerve;
5 - deep temporal nerve;
6 - Lateral pterygoid nerve;
7 - medial pterygoid nerve;
8 - chewing nerve;
9 - anterior auricular nerve;
10 - posterior auricular nerve;
11 - inferior alveolar nerve;
12 - the facial nerve;
13 - hypoglossal nerve
|In Fig. 266.
Nerves of Neck
1 - hypoglossal nerve;
2 - additional nerve;
3 - phrenic nerve;
4 - the vagus nerve;
5 - recurrent laryngeal nerve;
6 - the pericardium;
7 - the right lung;
8 - pleura;
9 - intramuscular plexus aperture
|In Fig. 267.
Nerves of the neck and shoulder girdle
1 - hypoglossal nerve;
2 - additional nerve;
3 - small occipital nerve;
4 - cervical plexus;
5 - the vagus nerve;
6 - supraclavicular nerves;
7 - the medial and lateral pectoral nerves;
8 - long thoracic nerve;
9 - branches of intercostal nerves
Accessory nerve (n. accessorius) (XI pair) refers to the motor nerves and consists of two parts. Wandering of the accessory nerve is represented by cranial roots (radices craniales), starting from the motor nucleus, occurring in the medulla, and going from the brain of an olive, below the vagus nerve. Go to the spinal part include spinal roots (radices spinales), heading from the spinal cord up and out into the cranial cavity through the foramen magnum. After the release of both parts are combined and a common trunk out of the skull through the jugular hole, where he again divided into inner and outer branches. The inner branch is sent to the vagus nerve, while the outer trapezoid approaches and sternocleidomastoid muscles.
Hypoglossal nerve (n. hypoglossus) (XII pair) also refers to the motor nerves. It starts from the nucleus, the rhomboid fossa in the overlying and passing between the pyramid and the olive tree, leaves the brain in the skull, and from there via the hypoglossal nerve is sent to the muscles of the language. One of its branches, falling, connected to a branch of the cervical plexus and participates in the formation of cervical loops innervates muscles of the neck, located below the hyoid bone.
a., aa. — arteria, arteriae (artery, the artery)
lig., ligg. — ligamentum, ligamenta (ligament, the ligaments)
m., mm. — musculus, musculi (muscle, the muscle)
n., nn. — nervus, nervi (nerve, the nerve)
r., rr. — ramus, rami (branch)
s. — seu (or)
v., vv. — vena, venae (vienna)