PETROSAL NERVES

N S Mohammed Sheriff

PETROSAL

NERVE

GREATER PETROSAL NERVE The greater petrosal nerve is a branch of the facial

nerve that arises from the geniculate ganglion, a part of the facial nerve inside the facial canal. It enters the middle cranial fossa through the hiatus for the greater petrosal nerve (on the anterior surface of the petrous temporal bone). It proceeds towards the foramen lacerum, where it joins the deep petrosal nerve (sympathetic) to form the nerve of the pterygoid canal. The nerve of the pterygoid canal passes through the pterygoid canal to reach the pterygopalatine ganglion.

SUPPLY: The greater petrosal nerve carries gustatory (taste) and parasympathetic fibres. Postganglionic parasympathetic fibres from pterygopalatine ganglion supply lacrimal gland and the mucosal glands of the nose, palate, and pharynx. The gustatory fibres do not relay in the ganglion and are distributed to the palate.

GREATER PETROSAL NERVE

ORIGIN : Geniculate ganglion of facial nerve

TERMINATION: Pterygopalatine ganglion SUPPLY: Lacrimal gland, mucous glands

of nose, palate and pharynx

PETROSAL NERVE

LESSER PETROSAL NERVE The tympanic plexus has parasympathetic

(preganglionic) roots which contribute to the lesser petrosal nerve. Parasympathetic contribution is from the tympanic nerve which branches from the glossopharyngeal nerve (CN IX) in the jugular foramen

The lesser petrosal nerve exits the temporal bone and enters the middle cranial fossa through the hiatus of lesser petrosal nerve. In some individuals it instead passes through the foramen ovale. It then exits the middle cranial fossa through foramen ovale to the otic ganglion where its parasympathetic fibers synapse. From the otic ganglion, its fibers hitchhike with the auriculotemporal nerve (from V3) to eventually innervate the parotid gland.

LESSER PETROSAL NERVE

ORIGIN :Tympanic Plexus – Preganglionic parasympathetic fibres from IX-CN

TERMINATION: Otic ganglion SUPPLY: Parotid gland

PETROSAL NERVE

DEEP PETROSAL NERVE

The deep petrosal nerve (large deep petrosal nerve) is given off from the carotid plexus, and runs through the carotid canal lateral to the internal carotid artery.

It then enters the cartilaginous substance which fills the foramen lacerum, and joins with the greater superficial petrosal nerve to form the nerve of the pterygoid canal, also known as the Vidian nerve.

It carries postsynaptic sympathetic nerve fibers to the pterygopalatine ganglion, also known as the sphenopalatine ganglion.

These fibers innervate blood vessels and mucous glands of the head and neck

DEEP PETROSAL NERVE

ORIGIN : Sympathetic Plexus around Internal Carotid

TERMINATION: Pterygopalatine Ganglion SUPPLY: Sympathetics fibres distribiuted

through branches of Pterygopalatine Ganglion

PETROSAL NERVE

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