Superior salivatory nucleus

At a glance

English

Superior salivatory nucleus

Latin (TA2)

Nucleus salivatorius superior

System

Brain and spinal cord

Region

Head

Side

Paired, left and right

About the superior salivatory nucleus

The superior salivatory nucleus is a visceral motor cranial nerve nucleus in the lower pons. It is a loose group of small neurons scattered in the reticular formation of the pontine tegmentum, just dorsomedial to the motor nucleus of the facial nerve. Immediately below it lies the inferior salivatory nucleus, which serves the glossopharyngeal nerve, and below that the dorsal motor nucleus of the vagus. Some authors call the part that serves the lacrimal gland the lacrimal nucleus.

Its neurons are preganglionic parasympathetic cells. Their axons leave the brainstem in the nervus intermedius, the smaller root of the facial nerve, and run with it into the internal acoustic meatus and the facial canal. At the geniculate ganglion one group leaves in the greater petrosal nerve. This joins the deep petrosal nerve to form the pterygoid canal nerve and ends in the pterygopalatine ganglion, where the fibres synapse. Postganglionic fibres from the ganglion supply the lacrimal gland and the mucous glands lining the nose, palate and pharynx.

A second group continues in the facial canal and leaves in the chorda tympani, which crosses the middle ear and joins the lingual nerve. These fibres synapse in the submandibular ganglion, and its postganglionic fibres stimulate secretion and widen the vessels of the sublingual and submandibular salivary glands. The parotid gland is not served by this nucleus; it receives its parasympathetic supply from the inferior salivatory nucleus through the glossopharyngeal nerve and otic ganglion.

The nucleus is driven by taste and smell, by the hypothalamus and by emotional input, which explains watering of the mouth and eyes. A facial nerve lesion close to the brainstem or near the geniculate ganglion reduces tear and saliva flow on that side, a useful clue to the level of injury. Misdirected regrowth of these fibres after Bell palsy can cause crocodile tears, weeping while eating.

Function and supply

Function

Sends preganglionic parasympathetic fibres in the facial nerve that drive secretion from the lacrimal gland, nasal and palatal glands, and the sublingual and submandibular salivary glands.

Blood supply

Pontine branches of the basilar artery.