Head And Neck Autonomic Nervous Supply

The autonomic nervous system is regulated by the hypothalamus

The sympathetic chain

• First order neurone cell body: hypothalamus
• Second order neurone cell body (preganglionic): ciliospinal centre of Budge

• The first and second order neurones synapse in the centre of Budge, which is located in cell columns of the spinal cord, between C8 and T2.

• Third order neurone cell body (postganglionic): superior cervical ganglion
• Most preganglionic fibres exit the spinal cord in the T1 nerve root
• Cell bodies originate in the lateral gray horns of the spinal cord
• Myelinated axons leave the cord with the anterior nerve roots

• These form the white rami communicantes to the paravertebral ganglia of the sympathetic trunk/chain

• Cervical portion of the sympathetic chain extends from the base of the skull to the neck of the first rib near the lung apex

• There are two sympathetic trunks which extend the length of the vertebral column from the skull base to the coccyx

• There are three ganglia in the neck and all sit anterior to the transverse processes of the cervical vertebrae but behind the carotid sheath and covered by prevertebral fascia

• The extension into the thorax is through the neck of the first rib and is covered by pleura within the thorax

• The preganglionic fibres synapse with an excitor neuron in the superior cervical ganglion
• The non-myelinated postganglionic fibres leave via the gray rami communicantes

• They ‘hitch-hike’ along the internal and external carotid to their destinations in the head and neck.

• Superior cervical ganglion branches
• Internal carotid nerve forms the internal carotid plexus around the artery
• Gray rami communicantes
• Arterial branches to the common and external carotid arteries
• Cranial nerve branches to the 9th, 10th, and 12th CNs
• Pharyngeal branches
• Superior cardiac branch

Summary of parasympathetic supply

• Midline nuclei in the brainstem give rise to myelinated preganglionic fibres

• Edinger-westphal nucleus supplies fibres that ‘hitch-hike’ with the oculomotor nerve to the ciliary ganglion and onward to the sphincter pupillae and ciliary muscles

• Super salivatory nucleus produces fibres which derive the nervus intermedius of the seventh cranial nerve, and which supply the lacrimal, submandibular, sublingual, nasal and palatal glands

• Inferior salivatory nucleus is associated with the glossopharyngeal nerve supplying the parotid gland

• Dorsal motor nucleus is the secretomotor nucleus of the vagus nerve
• The cranial parasympathetic ganglia are:
• Ciliary ganglion
• Pterygopalatine ganglion
• Submandibular ganglion
• Otic ganglion
• NB: all receive a sensory root from the trigeminal nerve

Ciliary ganglion

This is the primary autonomic ganglion of the orbit

• Sits near the orbital apex and lateral to the optic nerve
• Sympathetic input comes from the internal carotid plexus (vasomotor)

• Parasympathetic fibres come from the inferior division of the oculomotor nerve heading for the inferior oblique (and originating in the Edinger-westphal nucleus)

• These fibres actually synapse in the ganglion giving rise to post-gangionic fibres which pass to the eyeball via the short ciliary nerves to innervate the ciliary muscle and sphincter pupillae

• Short ciliary nerves contain parasympathetic, sympathetic and sensory fibres 

Pterygopalatine ganglion

• Found in the pterygopalatine fossa and suspended from the lower edge of the maxillary nerve

• Receives parasympathetic, sympathetic and sensory fibres

• Parasympathetic supply originates from the nervus intermedius (itself from the superior salivatory aka lacrimatory nucleus of the facial nerve) 

• Travels in the greater petrosal nerve to the pterygoid canal to form the vidian nerve which reaches the pterygopalatine ganglion

• Post-ganglionic fibres hitch-hike on the zygomaticotemporal branch of the maxillary nerve and on to the lacrimal nerve before entering the lacrimal gland

• Sympathetic supply derives from the deep petrosal nerve (originally from the internal carotid plexus) and also joins the vidian nerve

• Vidian nerve (aka nerve of the pterygoid canal): this is a confluence of the greater and deep petrosal nerves

• Sensory fibres from the maxillary division of the trigeminal nerve pass through to innervate the palate, nasopharynx, lateral nose and parts of nasal septum