Quick Facts
Origin: Geniculate ganglion.
Course: Passes through the greater petrosal hiatus and along the cranial surface of the middle cranial fossa to the foramen lacerum. It joins with the deep petrosal nerve to form the nerve of the pterygoid canal.
Branches: Nerve of the pterygoid canal.
Supply: Parasympathetic fibers to the lacrimal, oral, nasal, and palatine glands.
Related parts of the anatomy
Origin
The greater petrosal nerve is a branch of the facial nerve that emerges from the geniculate ganglion. Its preganglionic parasympathetic fibers originate in the superior salivatory nucleus of the pons (Myckatyn and Mackinnon, 2004).
Course
The greater petrosal nerve has a complex course. It emerges from the geniculate ganglion and passes through the petrous part of the temporal bone back into the middle cranial fossa via the greater petrosal hiatus. It runs along the surface of the middle cranial fossa anteriorly in a small groove until it reaches the foramen lacerum. Here it joins with the sympathetic fibers of the deep petrosal nerve to form the nerve of the pterygoid canal.
While this marks the end of the greater petrosal nerve, it is typically discussed in relation to the entire pathway, from greater petrosal nerve to target. With this in mind, the greater petrosal nerve, as the nerve of the pterygoid canal passes through the pterygoid canal and synapses on the pterygopalatine ganglion. Post-ganglionic parasympathetic fibers travel along nerves associated with the pterygopalatine ganglion and the maxillary nerve to the oral cavity, nasal cavity, and palate to supply small glands in these regions. The parasympathetic fibers to the lacrimal gland travel with the zygomatic nerve to the orbit where they join with the lacrimal nerve of the ophthalmic branch of trigeminal to reach the lacrimal gland.
Branches
The greater petrosal nerve does not give rise to branches. It does join with the deep petrosal nerve (sympathetic) to form the nerve of the pterygoid canal.
The fibers of the deep petrosal nerve terminate by synapsing with postganglionic parasympathetic fibers in the pterygopalatine ganglion.
Supplied Structures
The greater petrosal nerve supplies most of the glands of the face with parasympathetic innervation.
After synapsing with postganglionic parasympathetic fibers in the pterygopalatine ganglion, the impulses carried by the greater petrosal nerve are sent to the following glands:
—lacrimal gland, via branches of the maxillary and ophthalmic nerves;
—small glands in the oral cavity, nasal cavity, and palate by way of the nasopalatine, pharyngeal, greater palatine, and lesser palatine nerves.
List of Clinical Correlates
—Dry eye
References
Myckatyn, T. M. & Mackinnon, S. E. (2004) A review of facial nerve anatomy. Semin Plast Surg, 18(1), 5-12.
