Glossopharyngeal (IX) and vagus (X) lesions
Nerve fibres arise from nuclei in the medulla to form these two nerves, which pass out via the jugular foramen.
They have motor, sensory and autonomic functions. Glossopharyngeal receives taste and common sensation from the posterior third of the tongue, the oropharynx via the pharyngeal plexus, and the tonsillar fossa and soft palate.
Vagus carries motor fibres to the muscles of the palate, pharnyx and larynx. It also carries autonomic innervation to the heart, respiratory tract and gut.
Central causes include vascular lesions of the medulla, tumours, syringobulbia and motor neurone disease. Aneurysms and tumours in the posterior fossa and meningitis may affect the nerves. The left recurrent laryngeal nerve (a branch of the vagus) may be damaged in head and neck surgery, or compressed by hilar lymph nodes from lung tumours.
Impaired gag reflex (IX forms the sensory component, X the motor), a hoarse voice and abnormal swallow.