Family Friendly & Specialty Dentists in London, UK
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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.
