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Peripheral lesions| Cranial Nerve VII - Facial Nerve | Page 17 of 28 |
Course of the Greater Petrosal Nerve
At the geniculate ganglion the greater petrosal nerve turns anteriorly and medially exiting the temporal bone via the petrosal foramen and entering the middle cranial fossa.
Figure 7-15a. Course of the greater petrosal nerve through the temporal bone.
The greater petrosal nerve passes deep to the trigeminal ganglion to enter the foramen lacerum. The nerve traverses the foramen and enters a canal at the base of the medial pterygoid plate in conjunction with sympathetic fibers (deep petrosal nerve) branching from the plexus following the internal carotid artery. The parasympathetic and sympathetic fibers together make up the nerve of the pterygoid canal.
Upon exiting the pterygoid canal, pre-ganglionic parasympathetic fibers of CN VII synapse in the pterygopalatine ganglion which is suspended from the fibers of the maxillary division of the trigeminal nerve (V2) in the pterygopalatine fossa.
Post-ganglionic parasympathetic fibers then follow the fibers of V2 to reach the lacrimal gland (via the lacrimal nerve) and the mucous membranes of the nasal and oral pharynx.
