glossopharyngeal nerve, origin an course and termination of glossopharyngeal nerve, functional component of the nerve, sensory and motor component of glossopharyngeal nerve, gag reflex

1. GLOSSOPHARYNGEAL
NERVE
DR. SANA YASEEN
ANATOMY DEPARTMENT

2. INTRODUCTION
• the ninth cranial nerve (CN IX), is a mixed nerve that
carries afferent sensory and efferent motor information.
• It exits the brainstem out from the sides of the upper
medulla, just rostral (closer to the nose) to the vagus
nerve.

3. TYPES OF FIBERS AND NUCLEI
 Sensory fibers
Motor fibers
Parasympathetic fibers
• Nucleus of tractus solitarius
• Nucleus ambiguus
• Inferior salivatory nucleus

5. Course of glossopharyngeus muscle
• Glossopharyngeal nerve leaves the medulla through anterolateral face
between olives and inferior cerebellar peuncle.
• It passes laterally in the posterior cranial fossa and leaves the skull via jugular
foramen and enters into superior and inferior sensory glossopharyngeal
ganglion.
• The nerve descend through the upper part of the neck along with internal
jugular vein and internal carotid artery and reach posterior border of
stylopharyngeus muscle.
• Then it passes forward between superior and middle constrictor muscle of
the pharynx to give sensory branch to mucous membrane of pharynx and
and posterior thir of the tongue.

6. SENSORY FIBERS
• SVA: TASTE
• GVA
• GSA: TOUCH PAIN TEMPERATURE FIBERS

9. MOTOR FIBERS
• GVE: secretion of parotid gland
• SVE : stylopharyngeus muscle

10. SVA FIBERS:
• Carries taste sensation from posterior one third of the tongue.
• Reaches inferior ganglion of glosopharyngeal nerve and enters into
posterior cranial fossa through jugular foramen and ends by synapsing into
nucleus of tractus solitarius
SVE FIBERS :
• Supplies stylopharyngeus muscle
• Nucleus ambigus located in medulla give riseses to SVE fibers.
• It leaves the fossa via jugular foramen and reaches the palate and supply
stylopharyngeus muscle

11. GSA FIBERS:
• Carries touch pain temperature sensation from psrt of skin of ear, external
acoustic meatus, tympanic membrane, tympanic cavity, pharyngo tympanic
tube.
• The fibers runs to reach superior ganglion of glossopharyngeal nerve
andpasses through the jugular foramen and enters the medulla.
• Ends by synapsing in the spinal nucleus of trigeminal nerve.
• Before entering the brain stem it gives off a recurrent baranch t dura
matter. It carries pain sensation.

12. GVE FIBERS:
• Parasympathetic fibers arises from inferior salivatory nucleus leaves the
cranial cavity by passing through the jugular foramen and enters into
tympanic cavity by passing through its floor.
• There it is known as tympanic nerve / tympanic branch of
glossopharyngeal nerve
• Hence it makes up a plexus called tympanic plexus. Few fibers from
tympanic plexus move upward known as lesser petrosal nerve, runs below
ptyregoid canal and reaches the otic ganglion..
• From here post synaptic fibers arises and reaches parotid gland.

14. GVA FIBERS:
• Touch, pain, temperature fibers arising from oropharynx, laryngopharynx,
epithelial tissue from ligual and palatine tonsils, part of uvula, soft palat,
and posterior 1/3rd of tongue runs backward towards petrous ganglion.
• Also fibers from carotid bodies, carotid sinus goes as GVA fibers and
enters cranial cavity through jugular foramen.
• These fibers ends by synapsing in nucleus of tractus solitarius and dorsal
nucleus of vagus.

17. Clinical Relevance - Gag Reflex
• The glossopharyngeal nerve supplies sensory innervation to posterior
third of the tongue for general sensation and taste. The integrity of this
nerve can be tested by testing patients general sensation and that of taste
on the posterior third of the tongue.
• Isolated damage to the glossopharyngeal nerve is rare and usually also
involve the vagus nerve.
• So we elicite the gag reflex, swallowing test. An absent gag reflex and
impaire swallowing signifies damage to the glossopharyngeal nerve.