ANATOMY AND APPLIED ASPECTS OF GLOSSOPHARYNGEAL NERVE

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ANATOMY AND APPLIED ASPECTS OF
GLOSSOPHARYNGEAL NERVE

• presented by Dr navas

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• The glossopharyngeal nerve supplies the tongue,
  throat, and one of the salivary glands (the
  parotid gland). Problems with the
  glossopharyngeal nerve result in trouble with
  taste and swallowing.
• "Glosso-" comes from the Greek "glossa", the
  tongue and "pharynx" is the Greek for throat. So
  the glossopharyngeal nerve is the nerve that
  serves the tongue and throat.

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• The glossopharyngeal nerve contains both motor
  and sensory fibers, and is distributed, as its
  name implies, to the tongue and pharynx. It is
  the nerve of ordinary sensation to the mucous
  membrane of the pharynx, fauces, and palatine
  tonsil, and the nerve of taste to the posterior
  part of the tongue. It is attached by three or
  four filaments to the upper part of the medulla
  oblongata.

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• In the jugular foramen ,there are two sensory
  ganglion connected to the ninth cranial nerve
  the superior and inferior glossopharyngeal
  ganglia. General sensory components from the skin
  of the external ear, inner surface of the
  tympanic membrane, posterior one-third of the
  tongue and the upper pharynx join either the
  superior or inferior glossopharyngeal ganglia.
  The ganglia send central processes into the brain
  stem which terminate in the caudal part of the
  spinal trigeminal nucleus. Visceral sensory nerve
  fibers originate from the carotid body (oxygen
  tension measurement) and carotid sinus (blood
  pressure changes).

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• The visceral sensory nerve components connect to
  the inferior glossopharngeal ganglion. The
  central process extend from the ganglion and
  enter the brain stem to terminate in the nucleus
  solitarius. Taste from the posterior one-third of
  the tongue travels via nerve fibers that enter
  the inferior glossopharnygeal ganglion. The
  central process that carry this special sense
  travel through the jugular foramen and enter the
  brain stem. They terminate in the rostral part of
  the nucleus solitarius (gustatory nucleus).

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•  The somatic motor fibers spring from the cells
  of the nucleus ambiguous.
• The nucleus ambiguous also gives origin to the
  motor branches of the glossopharyngeal and vagus
  nerves, and to the cranial part of the accessory
  nerve.
• The sympathetic efferent fibers from the dorsal
  nucleus.
• The visceromotor or parasympathetic part of the
  ninth nerve originate in the inferior salivatory
  nucleus. Nerve fibers from this nucleus join the
  other components of the ninth nerve during their
  exit from the brain stem.

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• From the medulla oblongata, the glossopharyngeal
  nerve leaves the skull through the central part
  of the jugular foramen, in a separate sheath of
  the dura mater, lateral to and in front of the
  vagus and accessory nerves and passes forward
  between the internal jugular vein and internal
  carotid artery it innervates the palatine
  tonsil, the mucous membrane of the fauces and
  base of the tongue(-anterior two third by lingual
  nerve-), and the mucous glands of the
  mouth(touch,pain sensitivity ,temperature,taste
  etc).

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• In passing through the jugular foramen, the nerve
  presents two ganglia, the superior and the
  petrous
• The Superior Ganglion (ganglion superius jugular
  ganglion) is situated in the upper part of the
  groove in which the nerve is lodged during its
  passage through the jugular foramen.
•   The Petrous Ganglion (ganglion petrosum
  inferior ganglion) is larger than the superior
  and is situated in the lower border of the
  petrous portion of the temporal bone.

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Plan of upper portions of glossopharyngeal,
vagus, and accessory nerves.
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• Branches of Communication.The glossopharyngeal
  nerve communicates with the vagus, sympathetic,
  and facial.
• Branches of Distribution.The branches of
  distribution of the glossopharyngeal are the
  tympanic, carotid, pharyngeal, muscular,
  tonsillar, and lingual.

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• The Tympanic Nerve (n. tympanicus nerve of
  Jacobson) arises from the petrous ganglion . In
  the tympanic cavity it divides into branches
  which form the tympanic plexus .This plexus gives
  off (1) the lesser superficial petrosal nerve
  (2) a branch to join the greater superficial
  petrosal nerve and (3) branches to the tympanic
  cavity.
•   The Carotid Branches (n. caroticotympanicus
  superior and n. caroticotympanicus inferior)
  descend along the trunk of the internal carotid
  artery as far as its origin, communicating with
  the pharyngeal branch of the vagus, and with
  branches of the sympathetic

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• The Pharyngeal Branches (rami pharyngei) are
  three or four filaments which unite, opposite the
  Constrictor pharyngis medius, with the pharyngeal
  branches of the vagus and sympathetic, to form
  the pharyngeal plexus branches from this plexus
  perforate the muscular coat of the pharynx and
  supply its muscles and mucous membrane.
•   The Muscular Branch (ramus stylopharyngeus) is
  distributed to the Stylopharyngeus(to elevate the
  pharynx,as in gagging or swallowing).

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• The Tonsillar Branches (rami tonsillares) supply
  the palatine tonsil.
•  The Lingual Branches (rami linguales) are two in
  number one supplies the papillæ vallatæ and the
  mucous membrane covering the base of the tongue
  the other supplies the mucous membrane and
  follicular glands of the posterior part of the
  tongue, and communicates with the lingual nerve

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APPLIED ANATOMY

• GAG REFLEX It is possible to touch the anterior
  part of the tongue with out feeling discomfort.
  When the posterior part is touched, the
  individual gags. CN IX, CN X, are responsible for
  the muscular contractions of each side of the
  pharynx .

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• Isolated lesions of CN 9 or its nuclei are
  uncommon and not associated with perceptible
  disability. Taste is absent on the posterior
  third of the tongue and the gag reflex is absent
  on the side of the lesion. Injuries of the CN 9
  resulting from infection or tumors are usually
  accompanied by signs of involvement of adjacent
  nerves.

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• Because CN 9, CNX and CN11 pass through the
  jugular foramen, tumors in this region produce
  multiple cranial nerve palsies- jugular foramen
  syndrome.
• A pain in the distribution of CN9 may be
  associated with injury to the nerve in the neck
  from a tumor

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• Glossopharyngeal neuralgia of CN9 is
  uncommon,usually begins after the age of 40,occur
  more often in men and its cause is unknown. The
  sudden intensification of pain in the back of the
  throat, the area near the tonsils, the back of
  the tongue, and part of the ear,. is of a
  burning or stabbing character. These paroxysms of
  pain are often initiated by swallowing,
  protruding the tongue, talking, or touching the
  palatine tonsil. Pain paroxysms occur during
  eating when trigger areas are stimulated.

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• The glossopharyngeal nerve is tested
  clinically in the following ways
• On tickling the posterior wall of the pharynx,
  there is reflex contraction of the throat
  muscles. No such contraction occurs when the
  ninth nerve is paralysed.
• Taste sensibility on the posterior one third of
  the tongue can also be tested. It is lost in
  ninth nerve lesions.

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