GLOSSOPHARYNGEAL NERVE
- The glossopharyngeal nerve, also known as cranial nerve IX, is a mixed nerve.
Functions:
- Motor: to one muscle developed from 3ʳᵈ pharyngeal arch (Stylopharyngeus muscle).
Involves in the process of swallowing.
- Sensory: carries special sensations (taste) from posterior 1/3 of tongue & circumvallate papillae. It receives also general sensations from oropharynx, post. 1/3 of tongue, tonsils, auditory tube and middle ear.
- Parasympathetic: to parotid gland.
* The parasympathetic only from the midbrain & very low regions of spinal cord. While the sympathetic fibers from the spinal cord.
Neuclei:
- Motor nucleus: it is the upper part of nucleus
- ambigus (located in medulla oblongata).
- Sensory nuclei:
- Nucleus Solitaris: its middle part recieves taste sensation.
- Spinal nucleus of trigeminal n: It recieves general sensory fibers from middle ear, auditory pharanyx ....
from the Pons extends
- Parasympathetic nucleus:
- Inferior salivatory nucleus.
Course:
- The glossopharyngeal nerve exits the skull through the jugular (1) foramen, along with vagus n. (X) & the accessory n. (XI).
- Immediately outside the jugular foramen are placed two sensory ganglia that belong to the glossopharyngeal nerve, the superior and the inferior ganglia.
*Only sensory nerves have ganglions
- It passes between the internal jugular vein & internal carotid artery.
- After passing through the jugular foramen, it descends forward & inferiorly, to the root of the tongue.
- Then the nerve passes between the stylopharyngus m. and the styloglossus m. enters the prestyloid space and then divides under the mucosa of the post. 1/3 of the tongue, into many branches.