Expansion
Gag reflex afferent, posterior tongue taste and palatal sensation
Expansion
Functions of IX
- Sensory: posterior third of the tongue including taste, oropharynx, middle ear, and the carotid sinus and body baroreceptors and chemoreceptors
- Motor: stylopharyngeus only
- Parasympathetic: parotid gland, via the otic ganglion
The test
- Gag reflex: touch the posterior pharyngeal wall with a spatula. The afferent limb is IX and the efferent is X. It is uncomfortable, poorly reproducible and absent in up to a fifth of normal people, so it should be used sparingly and never as a test of swallow safety
- Palatal sensation, compared side to side
- Taste on the posterior third of the tongue, rarely tested in practice
- Speak and swallow: IX and X are assessed together in practice, through voice quality, a cough, and the ability to swallow water safely
Because IX is almost never affected alone, an abnormality points to a lesion affecting the lower cranial nerves together:
- Jugular foramen syndrome (IX, X, XI), from a glomus tumour, schwannoma or skull base fracture
- Lateral medullary (Wallenberg) syndrome
- Bulbar palsy, a lower motor neurone lesion with a nasal voice, wasted fasciculating tongue and absent gag
- Pseudobulbar palsy, an upper motor neurone lesion with spastic speech, a small stiff tongue, brisk jaw jerk and emotional lability
Glossopharyngeal neuralgia gives lancinating throat and ear pain triggered by swallowing, and can provoke syncope through the carotid sinus.