The otic ganglion is a small

parasympathetic ganglion Parasympathetic ganglia are the autonomic ganglia of the parasympathetic nervous system. Most are small terminal ganglia or intramural ganglia, so named because they lie near or within (respectively) the organs they innervate. The exceptions are ...

located immediately below the foramen ovale in the infratemporal fossa and on the medial surface of the

mandibular nerve In neuroanatomy, the mandibular nerve (V) is the largest of the three divisions of the trigeminal nerve, the fifth cranial nerve (CN V). Unlike the other divisions of the trigeminal nerve ( ophthalmic nerve, maxillary nerve) which contain only ...

. It is functionally associated with the

glossopharyngeal nerve The glossopharyngeal nerve (), also known as the ninth cranial nerve, cranial nerve IX, or simply CN IX, is a cranial nerve that exits the brainstem from the sides of the upper medulla, just anterior (closer to the nose) to the vagus nerve. ...

and innervates the

parotid gland The parotid gland is a major salivary gland in many animals. In humans, the two parotid glands are present on either side of the mouth and in front of both ears. They are the largest of the salivary glands. Each parotid is wrapped around the ma ...

for salivation. It is one of four parasympathetic ganglia of the head and neck. The others are the

ciliary ganglion The ciliary ganglion is a bundle of nerve parasympathetic ganglion located just behind the eye in the posterior orbit. It is 1–2 mm in diameter and in humans contains approximately 2,500 neurons. The ganglion contains postganglionic parasympath ...

, the

submandibular ganglion The submandibular ganglion (or submaxillary ganglion in older texts) is part of the human autonomic nervous system. It is one of four parasympathetic ganglia of the head and neck. (The others are the otic ganglion, pterygopalatine ganglion, and ci ...

and the

pterygopalatine ganglion The pterygopalatine ganglion (aka Meckel's ganglion, nasal ganglion, or sphenopalatine ganglion) is a parasympathetic ganglion found in the pterygopalatine fossa. It is largely innervated by the greater petrosal nerve (a branch of the facial ner ...

Structure and relations

The otic ganglion is a small (2–3 mm), oval shaped, flattened

of a reddish-grey color, located immediately below the foramen ovale in the infratemporal fossa and on the medial surface of the

. It is in relation, laterally, with the trunk of the mandibular nerve at the point where the motor and sensory roots join; medially, with the cartilaginous part of the

auditory tube Auditory means of or relating to the process of hearing: * Auditory system, the neurological structures and pathways of sound perception ** Auditory bulla, part of auditory system found in mammals other than primates ** Auditory nerve, also known ...

, and the origin of the

tensor veli palatini The tensor veli palatini muscle (tensor palati or tensor muscle of the velum palatinum) is a broad, thin, ribbon-like muscle in the head that tenses the soft palate. Structure The tensor veli palatini is found anterior-lateral to the levator ve ...

; posteriorly, with the middle meningeal artery. It surrounds the origin of the nerve to the medial pterygoid.

Connections

The preganglionic

parasympathetic The parasympathetic nervous system (PSNS) is one of the three divisions of the autonomic nervous system, the others being the sympathetic nervous system and the enteric nervous system. The enteric nervous system is sometimes considered part of ...

fibres originate in the

inferior salivatory nucleus The salivatory nuclei are the superior salivatory nucleus, and the inferior salivatory nucleus that innervate the salivary glands. They are located in the pontine tegmentum in the brainstem. They both are examples of cranial nerve nuclei. The sup ...

of the

. They leave the glossopharyngeal nerve by its tympanic branch and then pass via the

tympanic plexus In the tympanic cavity, the tympanic nerve (a branch of CN IX) divides into branches which, along with sympathetic fibres from the carotid plexus, form the tympanic plexus. This plexus is located on the surface of the promontory. This tympanic p ...

and the

lesser petrosal nerve The lesser petrosal nerve (also known as the small superficial petrosal nerve) is the general visceral efferent (GVE) component of the glossopharyngeal nerve (CN IX), carrying parasympathetic preganglionic fibers from the tympanic plexus to the p ...

to the otic ganglion. Here, the fibers synapse and the postganglionic fibers pass by communicating branches to the auriculotemporal nerve, which conveys them to the

. They produce vasodilator and secretomotor effects. Its sympathetic root is derived from the plexus on the middle meningeal artery. It contains post-ganglionic fibers arising in the superior cervical ganglion. The fibers pass through the ganglion without relay and reach the

via the auriculotemporal nerve. They are vasomotor in function. The sensory root comes from the auriculotemporal nerve and is sensory to the

. The motor fibers supplying the medial pterygoid and the

and the

tensor tympani The tensor tympani is a muscle within the middle ear, located in the bony canal above the bony part of the auditory tube, and connects to the malleus bone. Its role is to dampen loud sounds, such as those produced from chewing, shouting, or th ...

pass through the ganglion without relay. The ganglion is connected to the chorda tympani nerve and also to the nerve of the pterygoid canal. These pathways provide an alternate pathway of taste from the anterior two-thirds of the tongue. These fibers do not pass through the middle ear.

Clinical significance

Frey's syndrome Frey's syndrome (also known as Baillarger's syndrome, Dupuy's syndrome, auriculotemporal syndrome, or Frey-Baillarger syndrome) is a rare neurological disorder resulting from damage to or near the parotid glands responsible for making saliva, and ...

is caused by re-routing of parasympathetic and sympathetic fibres of the auriculotemporal nerve (V3) within the otic ganglion. It is a complication of surgery involving the parotid gland whereby injury to these branches, which innervate the parotid gland and sweat glands of the face respectively, form abnormal connections. Salivation leads to perspiration and flushing of the pre-auricular region and is called 'gustatory sweating'.

Additional images

File:Gray788.png, Plan of the facial and intermediate nerves and their communication with other nerves. File:Gray839.png, Diagram of efferent sympathetic nervous system.

References

External links

* (, ) {{Authority control Autonomic ganglia of the head and neck Parasympathetic ganglia Glossopharyngeal nerve