Structure and Origin
- The greater petrosal nerve is a nerve of the head.
- It contains pre-ganglionic parasympathetic fibers.
- It branches from the facial nerve (CN VII).
- It is derived from the parasympathetic part of the nervus intermedius component of CN VII.
- Its cell bodies are located in the superior salivary nucleus.
- Preganglionic parasympathetic fibers arise in the superior salivary nucleus.
- They join with general somatic sensory and special sensory fibers to form the nervus intermedius.
- The nervus intermedius exits the cranial cavity at the internal auditory meatus.
- It joins with the motor root of the facial nerve at the geniculate ganglion.
- Preganglionic parasympathetic fibers exit the geniculate ganglion as the greater petrosal nerve.

Gustatory Sensory Component
- The greater petrosal nerve conveys gustatory (taste) sensory information from the palate.
- This information is relayed to the pterygopalatine ganglion by the lesser palatine nerves.
- The gustatory sensory fibers synapse in the geniculate ganglion.
- The greater petrosal nerve carries these fibers to the ganglion.
- The ganglion is involved in taste sensation.

Course
- The greater petrosal nerve enters the petrous part of the temporal bone.
- It travels anteromedially through the bone at a 45° angle.
- It emerges into the middle cranial fossa through the hiatus for greater petrosal nerve.
- The nerve is situated between the two layers of the dura mater in the middle cranial fossa.
- It passes obliquely anterior-ward along a groove upon the floor of the fossa.

Clinical Significance
- During surgery of the middle cranial fossa, manipulation of the dura mater may affect the greater petrosal nerve.
- This can cause hemorrhaging or edema at the geniculate ganglion.
- Compression of the facial nerve may result in transient facial paralysis.
- The greater petrosal nerve is involved in autonomic innervation of the lacrimal gland.
- The terminal parts of the pathway can vary between individuals.

Notable Points
- The greater petrosal nerve is derived from the nervus intermedius component of CN VII.
- Its cell bodies are located in the superior salivary nucleus.
- The nervus intermedius exits the cranial cavity at the internal auditory meatus.
- Preganglionic parasympathetic fibers exit the geniculate ganglion as the greater petrosal nerve.

Greater petrosal nerve (Wikipedia)

The greater petrosal nerve (or greater superficial petrosal nerve) is a nerve of the head mainly containing pre-ganglionic parasympathetic fibres which ultimately synapse in the pterygopalatine ganglion. It branches from the facial nerve (CN VII) and is derived from the parasympathetic part of the nervus intermedius component of CN VII, with its cell bodies located in the superior salivary nucleus. In the connective tissue substance of the foramen lacerum,^{[citation needed]} the greater petrosal nerve unites with the (sympathetic) deep petrosal nerve to form the nerve of the pterygoid canal (vidian nerve) which proceeds to the pterygopalatine ganglion.

Greater petrosal nerve
Alveolar branches of superior maxillary nerve and sphenopalatine ganglion.
Plan of the facial and intermediate nerves and their communication with other nerves.
Details
From	facial nerve
To	nerve of pterygoid canal
Innervates	parasympathetics to lacrimal glands
Identifiers
Latin	nervus petrosus major
TA98	A14.2.01.117
TA2	6289
FMA	53417
Anatomical terms of neuroanatomy [edit on Wikidata]

It forms part of a chain of nerves that provide secretomotor innervation to the lacrimal gland and mucosal glands of nasal cavity and palate.^{[citation needed]}