Eighth cranial nerve and tinnitus,ringing in the ears morning jacket,fluctuating hearing loss without vertigo causas,hoop earrings hip hop xalapa - Reviews

Author: admin, 27.11.2013. Category: Treatment For Tinnitus

The vestibulocochlear nerve (auditory vestibular nerve), known as the eighth cranial nerve, transmits sound and equilibrium (balance) information from the inner ear to the brain. The vestibulocochlear nerve consists mostly of bipolar neurons and splits into two large divisions: the cochlear nerve and the vestibular nerve. The cochlear nerve travels away from the cochlea of the inner ear where it starts as the spiral ganglia.
This is the nerve along which the sensory cells (the hair cells) of the inner ear transmit information to the brain. The vestibulocochlear nerve carries axons of type SSA, special somatic afferent, which carry the modalities of hearing and equilibrium. Some older texts call the nerve the acoustic or auditory nerve,[2] but these terms have fallen out of widespread use because they fail to recognize the nerve's role in the vestibular system.
Upper part of medulla spinalis and hind- and mid-brains; posterior aspect, exposed in situ. OBJECTIVE: This paper reviews the current literature on involvement of the vestibular division of the eighth cranial nerve in peripheral neuropathies. OBJECTIVE: Children with auditory neuropathy spectrum disorder (ANSD) account for about 10% of paediatric patients referred for cochlear implantation. Send Home Our method Usage examples Index Contact StatisticsWe do not evaluate or guarantee the accuracy of any content in this site.
Glioma.jpg The mass lesion here is arising in the acoustic (eighth cranial) nerve at the cerebellopontine angle. The vestibular ganglion houses the cell bodies of the bipolar neurons and extends processes to five sensory organs. It consists of the cochlear nerve, carrying information about hearing, and the vestibular nerve, carrying information about balance.
Vestibulopathy may be associated with ANSD, and may have implications when formulating management plans in this patient group.
Vestibulocochlear Nerve The vestibulocochlear nerve is a sensory nerve that conducts two special senses: hearing (audition) and balance (vestibular). The vestibulocochlear nerve is the eighth of twelve cranial nerves which carry information about hearing and balance. The vestibulocochlear nerve has a cochlear part (COCHLEAR NERVE) which is concerned with hearing and a vestibular part (vestibular nerve) which mediates the sense of balance and head position. Metastases most often appear at the border of the grey and white matter in the distribution of the middle cerebral artery, as in this case, because that is where the blood flow (vascular distribution) is most likely to take metastases. It is the inner hair cells of the organ of Corti that are responsible for activation of afferent receptors in response to pressure waves reaching the basilar membrane through the transduction of sound. It emerges from the pontomedullary junction and exits the inner skull via the internal acoustic meatus (or internal auditory meatus) in the temporal bone.
The fibers of the cochlear nerve originate from neurons of the spiral ganglion and project to the cochlear nuclei (cochlear nucleus). The exact mechanism by which sound is transmitted by the neurons of the cochlear nerve is uncertain; the two competing theories are place theory and temporal theory. Hair cells of the cristae activate afferent receptors in response to rotational acceleration.
The other two sensory organs supplied by the vestibular neurons are the maculae of the saccule and utricle. Hair cells of the maculae in the utricle activate afferent receptors in response to linear acceleration while hair cells of the maculae in the saccule respond to vertically directed linear force. The separate motor nuclei of 5th and 7th cranial and the nucleus ambiguus of 9th, 10th and 11th cranial nerves represent branchio-motor nuclei.3. General visceral efferent column (viscero­motor):They convey pre-ganglionic para­sympathetic fibres and supply smooth muscles, cardiac muscle (by the vagus) and secreto-motor fibres to glands.
The geniculate ganglion contains neurons of taste sensation and possibly of cutaneous sensation.Proprioceptic senses from the muscles of mastication and extraocular muscles are located in the brain stem as the mesencephalic nucleus of the 5th nerve.
General visceral afferent column and this is represented by the dorsal nucleus of vagus nerve which is considered to be a mixed nuclear mass having viscero-motor and viscero-sensory components.2.
General somatic afferent columns receives tactile, pain and thermal sensations and is represen­ted by the principal sensory nucleus and the spinal nucleus of the 5th cranial nerve.The principal nucleus receives primarily tactile sensation, and the spinal nucleus pain and temperature sensation from the trigeminal area of face and scalp. In addition, the spianl nucleus serves as a common termination for the pain and thermal sensations conveyed by the facial (?), glossopharyngeal and vagus nerves.4.


It is in series with the third, fourth and sixth cranial and ventral roots of the spinal nerves.
It represents the fusion of ventral roots of four pre-cervical nerves, the dorsal roots of which disappear entirely.
Therefore, the hypo­glossal nerve is spinal in behaviour, but cranial in outlook.Deep origin (Fig.
Each bundle pierces the Dura mater separately and in the lower part of the canal the bundles unite to form a single nerve trunk.
Sometimes the hypoglossal canal is divided by a spicule of bone which indicates the composite origin of the nerve (Fig. In order to reach the interval between the vein and artery, the nerve passes laterally with a downward inclination and makes a half-spiral turn around the inferior ganglion of the vagus nerve with which it is united by connective tissue.The nerve passes vertically downward between the internal jugular vein and internal carotid artery, and lies in front of the vagus. It passes deep to the posterior belly of digastric and stylohyoid muscles, and appears in the carotid triangle at the level of the angle of the mandible.In the carotid triangle the nerve winds forward around the lower sternomastoid branch of the occipital artery and crosses superficial to the internal carotid, external carotid and the loop of the first part of lingual arteries. Here the nerve is covered by skin, superficial fascia, platysma and investing layer of deep cervical fascia, and is crossed superficially by the common facial vein.The nerve passes forward and upward above the greater cornu of the hyoid bone and appears in the digastric triangle after passing deep to the posterior belly of digastric and stylohyoid muscles. Here the nerve rests on the hyoglossus, is accompanied by a pair of veins (vena comitans hypoglossi) and is related to the second part of lingual artery deep to the hyoglossus.On the hyoglossus muscle, the nerve is related successively above with the deep part of sub-mandibular gland and its duct, submandibular ganglion and lingual nerve. Finally the nerve passes deep to the mylohyoid muscle, pierces genioglossus and reaches the substance of the tongue.Branches (Figs. Meningeal branch:It recurs through the hypoglossal canal and supplies the meninges of posterior cranial fossa and the diploic tissue of occipital bone.
This branch conveys the fibres from C1 and sympathetic fibres from the superior cervical ganglion.2.
Descending branch:It arises from the hypoglossal nerve when the latter winds round the occipital artery and carries the fibres of C1. It passes downward in front of the carotid sheath, forms superior ramus of ansa cervicalis and supplies the superior belly of the omohyoid muscle.Thereafter it joins with the descendens cervicalis which is derived from the fibres of C2 and C3 to form a loop known as ansa cervicalis (ansa hypoglossi).
Branches from the ansa supply the sternohyoid, sternothyroid and inferior belly of omohyoid muscles. Muscular branches:These supply all intrinsic and extrinsic muscles of tongue except the palatoglossus.
The latter is supplied by the cranial part of accessory nerve through the pharyngeal plexus.The geniohyoid (not a tongue muscle) is, however, supplied by fibres from C1.
As the myotome migrates from behind forward to invade the tongue along the epi-pericardial ridge, it carries the nerve of the myotome. The vagus nerve is, however, separated from the accessory nerve by an arachnoid partition (Fig. It enters the posterior triangle of neck at the middle of the posterior border of the sternomastoid, where the nerve is hooked superficially upward by the lesser occipital nerve and is surrounded by a group of superficial cervical lymph nodes.In the posterior triangle the accessory nerve passes downward and backward, and is covered by the skin, superficial fascia, platysma and investing layer of deep cervical fascia. Here it rests on the levator scapulae separated by the prevertebral fascia, and communicates with C2 and C3 nerves. The accessory nerve is a genuine content and highest structure of the posterior triangle.The nerve passes deep to the anterior border of trapezius about 5 cm above the clavicle, joins with the 3rd and 4th cervical nerves and forms a sub-trapezoid plexus. Hence each nerve is called vagus or wandering nerve.It acts as the chief pathway of the cranial part of parasympathetic system and supplies the derivatives of fore gut and mid gut, as well as the heart. Each nerve consists of three parts— cervical, thoracic and abdominal, and contains myelinated and unmyelinated fibres.Number of myelinated fibres in the mid-cervical region of the human vagus nerve is about 16,500 on the right side and 20,000 on the left side. Cervical part presents two ganglia—superior and inferior.Superior or jugular ganglion is small, about 4 mm in diameter, and situated close to the jugular foramen. It contains pseudo- unipolar sensory neurons for general visceral and special visceral (taste) sensations.It communicates with the superior cervical ganglion of the sympathetic trunk, and with the hypoglossal nerve which makes a half-spiral turn around the inferior ganglion. Cranial part of accessory nerve joins with the trunk of vagus below the inferior ganglion.Nuclear origins and their functional components (Fig.
Some of the post-ganglionic vagal fibres in the gut wall liberate, instead of acetylcholine, ATP-like substances (purniergic).Viscero-sensory fibres from the aforesaid organs have their cells of origin in the nodose ganglion of the vagus, and the fibres terminate mostly in the dorsal nucleus of vagus and partly in the nucleus of tractus solitarius. Here the vagus runs in a common sheath of dura mater with the accessory nerve, although an arachnoid septum intervenes between them (Fig. The hepatic branches pass to the right through the lesser omentum to reach the porta hepatis and divide into ascending and descending branches.The ascending branches supply the liver and biliary apparatus.
The descending branches also known as pyloric branches subdivide in the form of inverted ‘Y’ to supply the pre-pyloric stomach, pyloric sphincter and the duodenum.The gastric branches supply the antero-superior surface of stomach, except the pre-pyloric region, by dividing into six to ten branches.


From the superior ganglion(a) Meningeal branch:It supplies the dura mater of posterior cranial fossa. From the inferior ganglion—(c) Pharyngeal branches:Most of the fibres are derived from the cranial part of accessory nerve and supply muscles of pharynx and soft palate. The internal laryngeal nerve is essentially sensory, pierces the thyrohyoid membrane and supplies the vallecula, piriform fossa and laryngeal mucous membrane as far below as the vocal folds.It also provides a twig to supply the arytenoideus transversus muscle and probably conveys proprioceptive fibres. Cardiac branches join with the deep cardiac plexus, except the inferior cervical cardiac branch of left vagus which forms superficial cardiac plexus. These are concerned with the reflex inhibition of cardiac activity.(g) Right recurrent laryngeal nerve (Fig.
As it ascends, it lodges in the left tracheo- oesophageal groove or a little in front of the groove, similar to the recurrent nerve of the right side and appears in the neck.In the neck both right and left recurrent nerves undergo, more or less, identical course and relations. At the lower end of the lateral lobe of thyroid gland, the nerve presents variable relations with the loop of inferior thyroid artery.On the right side the nerve passes in equal proportions in front of the arterial loop, or behind it, or between the terminal divisions of the artery. On the left side the nerve lies most often behind than in front of the loop of the artery.On its further upward course, each nerve occupies the medial surface of the lobe of the thyroid gland. On the left side, the dorsal part of the sixth aortic arch persists as the ductus arteriosus in foetal life and ligamentum arteriosum after birth, the fifth arch disappears entirely, and the left fourth aortic arch forms part of the arch of aorta.Hence, the left recurrent nerve hooks below the arch of aorta on the left side of ligamentum arteriosum.
On the right side, the dorsal part of sixth aortic arch disappears, the fifth arch entirely atrophies and the right fourth aortic arch forms the proximal part of right subclavian artery.This explains why the right recurrent nerve hooks below the first part of right subclavian artery. On rare occasions the right subclavian artery takes anomalous origin from the junction of the arch of aorta and descending aorta.This is due to disappearance of the right fourth aortic arch and persistence of the right dorsal aorta below the origin of the right seventh interseg- mental artery.
In such condition the right recurrent nerve does not recur upon any structure and reaches the larynx directly.1. The sensory fibres from the lungs are concerned with Hering-Breuer and cough reflexes, from the pulmonary arteries acting as baro-receptors, and from the pulmonary veins acting as chemo- receptors.2. Gastric branches:These are secretomotor to the glands, motor to the gastric musculature and inhibitory to the pyloric sphincter. Coeliac branches:These supply small and large guts, act as secreto-motor to the glands and augment peristalsis.
Both ganglia contain pseudo-unipolar sensory neurons for somatic and visceral sensations.The inferior ganglion is the larger one and lodges in a triangular depression on the under surface of petrous temporal. From the inferior ganglion the trunk of glossopharyngeal nerve bends sharply downward and leaves the skull through the intermediate compartment of jugular foramen, accompanied by the vagus and accessory nerves.Here the glossopharyngeal rests on a groove of jugular tubercle of ocipital bone, and passes in a separate sheath of Dura mater in front of the vagus and accessory nerves.
The inferior petrosal sinus separates the glossopharyngeal from the vagus and accessory nerves (Fig.
Tympanic branch:It arises from the inferior ganglion and conveys primarily preganglionic secreto-motor fibres.
It enters the tympanic cavity through a tympanic canaliculus in front of the jugular fossa, and ramifies beneath the mucous membrane of the promontory, where it intermingles with the carotido-tympanic nerves from the sympathetic plexus around the internal carotid artery, and forms a tympanic plexus.Branches from the tympanic plexus provide sensory fibres to the mucous membrane of tympanic cavity, tympanic membrane, mastoid antrum and mastoid air cells, and most of the auditory tube. It furnishes a communicating branch to the greater petrosal nerve of facial.But the main contribution of the tympanic plexus is the formation of the lesser petrosal nerve which conveys secreto-motor fibres. The lesser petrosal nerve passes successively through a hiatus of the tegment tympani of petrous temporal, leaves the middle cranial fossa through the foramen ovale or canaliculus innominatus and makes synaptic contacts with the neurons of the otic ganglion in the infra-temporal fossa.The post-ganglionic secretomotor fibres from the otic ganglion accompany the auriculo-temporal nerve, and through the latter supply the parotid gland.
Carotid branch:It ramifies in the wall of the carotid sinus and in the carotid body, and joins with the similar branches of the vagus and sympathetic nerves.
The carotid nerves act as baro-receptors and chemo-receptors to regulate the blood pressure and heart rate.3. Pharyngeal branches:These are three or four in number and ramify on the buccopharyngeal fascia overlying the middle constrictor muscle, where they join with the pharyngeal branches of the vagus and the superior cervical sympathetic ganglion to form the pharyngeal plexus of nerves. The glossopharyngeal component of the plexus provides sensory branches to the mucous membrane of the pharynx.4. Tonsillar branches:These supply the palatine tonsil and form a plexus around it, after joining with the middle and posterior palatine (lesser) nerves.




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