The lower cranial nerves include 9,10,11 and 12. The hypoglossal nerve is considered seperately because of its exit via the hypoglossal canal. The glossopharyngeal, vagus, and spinal accessory nerve leave the skull base via the jugular foramen with the carotid artery and the internal jugular vein.
The glossopharyngeal nerve has motor, sensory and parasympathetic fibres.
The glossopharyngeal nucleus lies in the medulla.
The Motor Supply- supplies the stylopharyngeus muscle
The Parasympathetic Supply- post ganglionic fibres innervate the parotid gland
Sensory fibres- innervate the posterior 1/3 of the tongue, pharynx, eustachian tube, ans carotid body/sinus
Like the glossopharyngeal nerve, it has motor, sensory and parasympathetic functions.
Motor fibres- supply the pharynx, larynx, soft palate
Lesions of the soft palate– nasal quality of speech (hot potatoe voice), uvula deviation away from lesions
Lesions of the pharynx– dysphagia if bilateral
Note this is important from an ENT point of view:
The tensors of the vocal cord is via the Superior Laryngeal Nerve that affects the tone of the voice via its innervation to the cricothyroid muscle
The posterior cricoarytenoid and lateral crico-arytenoid are innervated by the recurrent laryngeal nerves and are involved in abdcution (posterior) and adduction (lateral) of the vocal chords.
Hoarseness and Stridor are complications of laryngeal nerve palsy
Parasympathetic fibres- from the thoracic and abdominal viscera
This is a purely motor nerve supplying two key muscles: the sternacleidomastoid muscle and trapezius muscle.
It has both a spinal part and a cranial part.
Cranial part arises from the lower part of the medulla, and the spinal origin from the 1st 5 cervical segments, which ascend alongside the spinal cord and passes through the jugular foramen and joins with the cranial part
The supranuclear lesion will produce head turning away from the lesion whilst a lower motor neurone lesion will produce ipsilateral shoulder weakness and head turning to the opposite side (sternacleidomastoid)
Lesions of the Lower Cranial Nerves
Like with that of the facial nerve it is important to categorise these
Supranuclear- vascular, motor neurone disease (Pseudobulbar Palsy)
Basal Skull tumours e.g meningioma, epidermoid
Glomous Jugulare Tumour
Vascular, Demyelination, Syringobulbar
Musculature- e.g myasthenia gravis
Posterior Neck Dissection (spinal accessory nerve or penetrating tumour)
Recurrent Laryngeal Nerve Palsy’s e.g thyroid mass, laryngeal cancer
Lower Cranial Nerve Syndromes
Jugular Foramen syndrome- 9,10,11