Parasympathetic supply to the head and neck stems from four parasympathetic ganglia, which receives fibres from CN III, VII and IX. CN X also has parasympathetic function but is mainly concerned with below the neck. Sympathetic (from the superior cervical ganglion) and sensory fibres also pass through the ganglia (without synapsing). They are therefore involved in autonomic control of the eye, salivary glands and lacrimal glands and include the ciliary, otic, pterygopalatine and submandibular ganglions.

Ciliary ganglion

Located posterolaterally in the intraconal space of the orbit (towards orbital apex) between the optic nerve and the lateral rectus muscle, the ciliary ganglion receives preganglionic parasympathetic fibres from the Edinger-Westphal nucleus via the oculomotor nerve. It sends postganglionic short ciliary nerves to supply the ciliary body (includes ciliary muscle for accommodation) and the sphincter pupillae (for pupillary constriction).

Sympathetic fibres originate from the superior cervical ganglion, traveling via the internal carotid plexus then the nasociliary nerve (branch of CN Va). Reaching the the ciliary ganglion, they pass through without synapsing and supply dilator pupillae, tarsal muscles, sweating and arteries. Sensory fibres from the eyeball also pass through the ganglion to the nasocilliary nerve (branch of Va) via the small communicating branch of the ciliary ganglion.

CLINICAL CORNER

Ciliary ganglion pathology can produce a tonic pupil, where the pupil does not react to light and slowly accommodates. It can also cause Adie syndrome, when a non-reactive, slowly accommodating pupil is associated with absent deep tendon reflexes and diaphoresis (excessive sweating)

Otic ganglion

Located in the infratemporal fossa, the otic ganglion lies immediately below the foramen ovale, medial to the mandibular division of the trigeminal nerve, and supplies the parotid gland.

The parasympathetic fibres originate from the inferior salivary nucleus via the glossopharyngeal nerve which joins with a branch of the tympanic nerve (Jacobson’s nerve) to form the tympanic plexus in the middle ear and which exits as the lesser petrosal nerve. The lesser petrosal nerve passes into the middle cranial fossa, out through foramen ovale and finally into the ganglion.

Sympathetic vasomotor fibres from the superior cervical ganglion pass through the ganglion and join the auriculotemporal nerve to innervate the parotid gland. Sensory fibres from the parotid gland also travel in the auriculotemporal nerve.

CLINICAL CORNER

Otic gland pathologies include Frey syndrome – salivation will also induce perspiration and erythema (redness) of the cheek.

Pterygopalatine ganglion

The pterygopalatine ganglion is located in the pterygopalatine fossa anterior to the opening of the pterygoid canal and foramen rotundum, adjacent to the sphenopalatine foramen. It supplies the lacrimal gland and mucosal glands in the nose, nasopharynx, sinuses and soft palate and branches include the nasopalatine nerve, posterior superior nasal nerves, greater palatine nerve, lesser palatine nerves and the pharyngeal nerve.

It receives parasympathetic fibres from the superior salivary nucleus via the greater petrosal nerve and nerve of pterygoid canal from the nervus intermedius (all components of the facial nerve).

Sympathetic fibres originate from the superior cervical ganglion, travelling via the carotid plexus to the deep petrosal nerve, which joins the greater petrosal nerve to become nerve of the pterygoid canal. Lastly, there is a sensory root from the trigeminal ganglion via the maxillary nerve.

Submandibular ganglion

The submandibular ganglion is small and suspended under the lingual nerve, inferior to the submandibular duct on the hyoglossus muscle. Parasymathetic secretomotor fibres come from the superior salivary nucleus via the nervus intermedius and then the chorda tympani of the facial nerve to supply the sublingual and submandibular salivary glands. Sympathetic innervation arises from the superior cervical ganglion via the facial artery. There is also a sensory root via the lingual nerve