IX - Glossopharyngeal Nerve Flashcards
How many fibers does CN IX have?
It is one of the few nerves that has 3 types of fibres. These are motor, sensory and parasympathetic
Motor fibres enable movement
Sensory fibres enable taste, touch and temperature sensation
Parasympathetic helps tissue and organs rest when not in use
Correlate the FIBERS to the FUNCTIONS of the glossopharyngeal nerve
Special viceral afferent (SVA) these are fibers pick up taste from the posterior one third of the tongue via the forngiform and valet papillae, pass through the jugular foramen to the solitary nucleus in the medulla.
Special visceral efferent fibers (SVE) are the main motor fibers of the glossopharyngeal nerve and supply motor innervation to the stylopharyngeus muscle, This muscle is responsible for elevating the larynx and pharynx especially during speaking and swallowing
General visceral efferent fibers (GVE) provide parasympathetic innervation to the parotid glands.
General visceral afferent fibers (GVA) carries touch, pain and temperature sensation from the oropharynx, laryngopharynx, posterior one third of the tongue and tonsils to the Doral nucleus of vagus
General somatic afferent fibers (GSA) pain, touch and temperature sensation from the pinna, external acoustic meatus and tympanic cavity are taken into the medulla to the spinal nucleus of the trigeminal nerve.
Describe the gag reflex
What are the symptoms of glossopharyngeal nerve palsy?
Dysphagia
Loss of carotid sinus reflex
Absent gag reflex
Parotid gland secretory dysfunction
Reduced sensation over the posterior third of the tongue
Which conditions re associated with a dysfunctional CN IX?
Styloid fracture
Eagle syndrome
Glossopharyngeal neuralgia
How do you test for the gag reflex?
GAG REFLEX; to test this reflex, the examiner touches the back of the patient’s throat with a tongue depressor to elicit the gag response. This is a protective mechanism that helps prevent choking by triggering a reflective contraction of the throat muscles upon stimulation
Describe the swallowing test that looks at CN IX functionality
SWALLOWING TEST; the patient is asked to swallow a liquid or solid foodstuff while observing for any difficulty or abnormality in the swallowing process.
How do you test for taste sensation?
TASTE SENSATION TEST; this is done by applying taste stimuli which can be sweet, bitter, or sour to the back of the tongue and asking the patient to identify the taste
What is the palatal elevation test?
PALATAL ELEVATION TEST; this is done by observing the movement of the soft palate when the patient says ‘ah.’ The soft palate should elevate symmetrically and the uvula should remain midline. Deviation of the uvula to one side may indicate dysfunction of the cranial nerves.
