Nervous System Part II

Cranial nerves

Neurological exam is one of a series of neurological examinations consisting of: mental status, level of consciousness, cranial nerve function, motor function, reflexes, coordination and gait, and sensory function.

Cranial nerve examination in order to provide the necessary information, cultivated good cooperation between the examiner and the patient during the examination. Patients are often asked her willingness to perform any act by the patient may be considered unreasonable or ridiculous.

Before beginning to be examined, anxiety sufferers must be removed and the patient should be given an explanation of the importance of examination in order to establish the diagnosis. Provide an explanation regarding the duration of the examination, how its done and the pain that may arise can help foster patient trust in the examiner.

A complete history and thorough physical examination coupled with will be able to diagnose about 80% of cases. Although there are a variety of modern diagnostic procedures, but nothing can replace the anamnesis and physical examination.

Cranial nerves come directly from the brain and leaves the skull through the holes in the bone called foramina, there are 12 pairs of cranial nerves are represented by name or by Roman numerals. Nerves are olfactory (I), optic (II), Okulomotorius (III), trochlear (IV), trigeminal (V), abdusens (VI), facial (VII), the vestibule cochlear (VIII), glossofaringeus (IX) , vagus (X), accessory (XI), hipoglosus (XII).

1) NERVE olfactory (N.I)

Olfactory system begins with the side that receives olfactory stimuli. The system consists of the following: olfactory mucosa in the upper nasal cavity, fila olfaktoria, bulbus subkalosal orbital lobe on the medial side. This nerve is a pure sensory nerve fibers-fibers from the nasal mucous membrane and penetrate the area of ​​bone kribriformis etmoidal to bersinaps in olfactory bulbus, from here, olfactory tract runs under the frontal lobe and ending in the medial temporal lobe on the same side.

Olfactory system is the only system of sensory impulses reach the cortex without dirilei in the thalamus. Smells that can provoke the onset of appetite and induction of salivation and foul odor that can cause nausea and vomiting showed that this system has to do with emotion.

The main fibers connecting the olfactory system with autonomous area is the medial forebrain bundle and stria medularis thalamus. Emotions that accompany olfactory stimuli may be related to fiber related to the thalamus, hypothalamus and limbic system.

2) NERVE optic (N. II)

Optic nerve is a pure sensory nerve that starts in the retina. The fibers of this nerve, it passes near the foramen optikum optalmika artery and nerve to join the other side of the base of the brain to form a chiasma optikum. Spatial orientation of the fibers from various parts of the fundus is still intact so that the fibers of the retina was found at the bottom of the inferior part of chiasma optikum and vice versa.

The fibers from the temporal visual field (half of the nasal retina) cross the chiasma, whereas that of a nasal visual field do not intersect. Index fibers for light coming from the chiasma optikum kolikulus superior end, where there is a relationship with both okulomotorius nerve nuclei. Chiasma fibers that leave the rest related to vision and walk in the optic tract toward the lateral genikulatum corpus.

From here the fibers that originate from radiasio optics through the posterior internal capsule and end in the visual cortex of the occipital lobe. In the course of the fibers are separated so that the fibers to lower quadrant through the parietal lobe while for kuadaran up through the temporal lobe. As a result of these fibers dekusasio on optikum chiasma fibers originating from the left visual field ends up in the right occipital lobe and vice versa.

3) NERVE OKULOMOTORIUS (N. III)

Okulomotorius nerve nucleus lies partly in front of the substantia grisea periakuaduktal (motor nucleus) and partly in the substantia grisea (autonomic nuclei). Nucleus is responsible for motor innervation of the medial rectus muscle, superior, and inferior, inferior oblique muscle and the levator muscle palpebrasuperior. Autonomic nucleus or nucleus Edinger-westhpal bermielin very little that the muscles of the eye pupil and inferior is spingter siliaris muscle.

4) NERVE trochlear (N IV)

Trochlear nerve nuclei located in the front as high as inferior kolikuli periakuaduktal and substantia grisea under okulomotorius nucleus. This nerve is the only cranial nerve to exit the dorsal side of the brain stem. Trochlear nerve supplies the superior oblique muscle to move the eye down, into and abduction in a small degree.

5) NERVE trigeminal (N. V)

Trigeminal nerve is composed of a mixture of fibers of motor and sensory fibers.Motor fibers supply the muscles masseter and temporalis muscles. Sensory fibers of the trigeminal nerve is divided into three main branches of the nerve yatu ophthalmicus, maxillary, and mandibular. Sensory area includes the area of ​​skin, forehead, face, oral mucosa, nose, sinuses. Maxillary and mandibular teeth, anterior cranial fossa dura in the middle and anterior parts of the outer ear and auditory canal and the tympanic membrane.

6) NERVE ABDUSENS (N. VI)

Abdusens nerve nucleus is located on each side near the bottom of the pons and the medulla oblongata is located below the fourth ventricle abdusens nerve supplies the lateral rectus muscle.

7) NERVE facial (N. VII)

Facial nerve has motor function and sensory function of motor function derived from the motor nuclei located in the ventrolateral tegmentum of the medulla oblongata near Pontin below. Sensory function derived from the nuclei of sensory and motor nuclei appeared with vestibulocochlear nerve that runs to the lateral to the internal acoustic canal.

Facial nerve motor fibers to the muscles of facial expression consists of orbikularis ocular muscles, muscle buksinator, muscle occipital, frontal muscle, stapedius muscle, muscle stilohioideus, digastriktus posterior muscles and muscle platisma. Sensory fibers leads the anterior tongue taste perception.

8) NERVOUS vestibulocochlear (N. VIII)

Vestibulocochlear nerve consists of two components of the afferent fibers of the auditory and vestibular care that contain afferent fibers that take care of the balance.

The fibers for the hearing came from the organ of Corti and walked to the cochlear nucleus in the pons, from here there is a bilateral transmission genikulatum medial to the corpus and then to the superior temporal lobe gyrus.

The fibers for the balance from the utricle and the semicircular canals and joined the auditory fibers in the facial canal. The fibers are then enters the pons, the fibers spread vestibutor runs through the stem and the cerebellum.

9) NERVE GLOSOFARINGEUS (N. IX)

Glosofaringeus receive a combination of nerve vagus nerve and accessory at a time leaves the cranium through the foramen, the nerve ganglion glosofaringeus has two, namely ganglion intrakranialis superior and inferior ekstrakranialis. After passing through the foramen, the nerve continues between the internal carotid artery and internal jugular vein into the muscle stilofaringeus. Between this muscle and stiloglosal muscles, nerves continue to supply the base of the tongue and pharyngeal mucosa, tonsils and posterior third of the tongue.

10) of the vagus nerve (N. X)

Vagus nerve ganglion which also has two superior or jugular ganglion and the nodosum ganglion or inferior, both located in the area ugularis foramen, the vagus nerve supply the all the viscera of chest and abdomen and conduct impulses from the intestinal wall, heart and lungs.

11) NERVE accessory (N. XI)

Spinal accessory nerve roots and cranial have. Cranial root axons of neurons in the nucleus ambigus of neurons located near the vagus nerve. Accessory nerve is the motor nerves which supply the muscles sternokleidomastoideus and upper trapezius muscles, muscle function sternokleidomastoideus turning the head to the side and trapezius muscles rotate the scapula when the arm lifted up.

12) NERVE HIPOGLOSUS (N. XII)

Hipoglosus nerve nucleus located in the medulla oblongata on each side of the center line to the fourth ventricle and the front where all the produce hipoglosus trigonum. Hipoglosus nerves are motor nerves to supply the muscles of the tongue and muscles of the tongue is stiloglosus, hipoglosus and genioglosus.

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