Otic Ganglion – Anatomy, Location, Roots & function
Otic ganglion is a small parasympathetic ganglion connected to the mandibular branch of trigeminal nerve and provides a relay station to the secretomotor fibres to the parotid gland.
Topographically, it is intimately related to the mandibular nerve but functionally it is related to glossopharyngeal nerve.
The otic ganglion is likely one of the 4 parasympathetic ganglia of the pinnacle. A set of sensory neurons of the mandibular nerve, it really works with the glossopharyngeal nerve and mandibular nerves to offer operate to a number of salivary glands.
It additionally has a motor operate in chewing.
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Ganglia are teams of nerves, sometimes with associated capabilities, that meet up inside a capsule of connective tissue. They serve basically as nerve relay stations, shuttling data backwards and forwards between totally different components of the nervous system.
The mind comprises 12 ganglia on either side, in symmetrical pairs, however they’re typically referred to within the singular.
Eight of the cranial nerve ganglia are sensory, whereas 4 are parasympathetic, together with the –
• Otic ganglion
• Ciliary ganglion
• Submandibular ganglion
• Pterygopalatine ganglion
Size of otic ganglion
• Pinhead (2–3 mm in size).
• The otic ganglion is the smallest of the parasympathetic cranial ganglia. It’s flat—just 0.4 millimeters (mm) thick—and oval shaped. It typically measures just 2 mm long and 1.5 mm wide.
Location of otic ganglion
• it is located in Infratemporal fossa, just below the foramen ovale.
• The otic ganglion is housed in a small structure called the infratemporal fossa. A fossa is a hollow area in the skull. The infratemporal fossa is on the side of the head between your temple and your jaw.
Lateral : Mandibular nerve.
Medial : Tensor palati muscle.
Posterior : Middle meningeal artery.
Anterior : Medial pterygoid muscle.
Roots or connection of otic ganglion
- Parasympathetic motor (secretomotor): From lesser petrosal nerve.
Preganglionic parasympathetic fibres arise from inferior salivatory nucleus; pass successively through glossopharyngeal nerve, tympanic branch of glossopharyngeal nerve (Jacobson’s nerve), tympanic plexus and lesser petrosal nerve to relay in the ganglion.
Postganglionic parasympathetic fibres from ganglion cells pass through auriculo-temporal nerve to supply parotid gland.
- Sympathetic : From sympathetic plexus around the middle meningeal artery.
Preganglionic sympathetic fibres arise from T1 and T2 spinal segments, enter the cervical sympathetic chain at the level of its inferior ganglion and then ascend to relay in the superior cervical sympathetic ganglion.
The postganglionic fibres arise from this ganglion and form plexus around the middle meningeal artery. They then pass through the ganglion without relay to reach the parotid gland via auriculo temporal nerve. They are vasomotor in nature and responsible for thick salivary secretion.
- Sensory: From auriculotemporal nerve
- Somatic motor: Nerve to medial pterygoid. It passes through ganglion to supply medial pterygoid, tensor palati, and tensor tympani muscle.
• In humans, the chorda tympani nerve is connected to the otic ganglion and nerve to pterygoid canal.
• connections provide an alternative pathway of taste sensations from anterior two-third of the tongue.
• Clinical evidence suggests that in humans the parotid
gland also receives secretomotor fibres through chorda tympani nerve.
•Otic ganglion, like different parasympathetic ganglia, is derived from Schwann cell precursors. These precursors migrate by way of preganglionic axons and differentiate into peripheral neurons after they attain the location of the grownup ganglionic construction into which they develop.
•By thirty two to 34 days of embryonic life, otic ganglia are observable in people, and by the 20th week of intra-uterine life, will probably be a well-developed construction.
• It has not too long ago come to mild that the otic ganglion and pterygopalatine ganglia are a single and undifferentiated cell mass until the sixteenth week of gestation and later get separated by rising ala temporalis.
• They then reconnect by secondarily-formed speaking department, the nervus sphenopidalis.
Blood supply and lymphatics
• Research has proven that the postganglionic fibers rising from the otic ganglion innervate the blood vessels of the circle of Willis versus the vertebrobasilar artery.
• The postganglionic otic fibers additionally terminate within the cavernous sinus by way of the exterior sphenoid nerve and type the cavernous sinus plexus with the sympathetic fibers from the interior carotid artery.
Clinical anatomy of otic ganglion
• The otic ganglion might become a new target in headache disorders.
• Frey’s syndrome (auriculotemporal nerve syndrome) – Sometimes penetrating wounds of the parotid gland might harm auriculotemporal and nice auricular nerves.
The auriculotemporal nerve incorporates parasympathetic (secretomotor), sensory, and sympathetic fibres. The nice auricular nerve incorporates sensory and sudomotor fibres.
When these nerves are reduce, throughout regeneration the secretomotor fibres develop into endoneurial sheaths of fibres supplying cutaneous receptors for ache, contact and temperature, and sympathetic fibres supplying sweat glands and blood vessels. Thus a stimulus supposed for salivation evokes cutaneous hyperesthesia, sweating, and flushing.
The presenting features of Frey’s syndrome are:
(a) When an individual eats, the ipsilateral cheek (parotid area) turns into purple, scorching, and painful. It is related with beads of perspiration (gustatory sweating).
(b) When an individual shaves, there’s cutaneous hyperesthesia in entrance of the ear.
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