Pterygopalatine Fossa and Palate - LO 8
8. The pterygopalatine ganglion receives preganglionic parasympathetic fibers from what nerve? Which nerve(s) will carry the postganglionic parasympathetic fibers to their destination? To what gland do the postganglionic fibers travel?
The pterygopalatine ganglion is the largest of the peripheral parasympathetic ganglia, and is located in the pterygopalatine fossa. The ganglion is medial and inferior to the maxillary n. (V2) and lateral to the sphenopalatine foramen. Many nerve branches from the maxillary n. (V2) travel through the ganglion without synapsing.
Preganglionic parasympathetic fibers bound for the pterygopalatine ganglion are conveyed by the greater petrosal n. (CN VII). This greater petrosal n. joins with the deep petrosal n. (postganglionic sympathetic fibers from the perivascular plexus of the ICA) in the pterygoid canal to form the nerve of the pterygoid canal. This nerve enters the pterygopalatine ganglion posteriorly. The preganglionic parasympathetic fibers synapse, whereas the sympathetic fibers pass through.
Anatomists have classically understood (and taught) that the secretomotor postganglionic fibers to the lacrimal gland were conducted by the lacrimal n. from fibers transmitted from the pterygopalatine ganglion via the zygomaticotemporal brs. (i.e. pterygopalatine ganglion → zygomaticotemporal brs. → lacrimal n. → lacrimal gland). Recent studies demonstrate considerable variation in the course of these fibers, with the majority of cases showing secretomotor postganglionic fibers from the pterygopalatine ganglion directly innervating the lacrimal gland via the zygomaticotemporal brs. Variants do exist that reflect the ‘classic condition.’