Topography and Neighboring Structures
The ganglion is located in the pterygopalatine fossa (fossa pterygopalatina). This fossa features several openings through which nerves and vessels functionally and topographically related to the ganglion pass:
- Foramen rotundum (foramen rotundum) — transmits the maxillary nerve (n. maxillaris) into the fossa.
- Pterygoid canal (canalis pterygoideus) — transmits the nerve and artery of the pterygoid canal to the ganglion.
- Greater palatine canal (canalis palatinus major) — transmits the greater palatine nerve (n. palatinus major).
- Sphenopalatine foramen (foramen sphenopalatinum) — transmits the posterior nasal branches.
Roots of the Ganglion (Sources of Innervation)
The pterygopalatine ganglion is formed by three types of nerve fibers:
- Parasympathetic root — greater petrosal nerve (n. petrosus major). It originates from the nervus intermedius (n. intermedius, part of the facial nerve — CN VII). These fibers synapse in the pterygopalatine ganglion.
- Sympathetic root — deep petrosal nerve (n. petrosus profundus).
- Sensory root — ganglionic branches (nn. pterygopalatini) arising from the maxillary nerve.
Formation of the Vidian Nerve: The greater and deep petrosal nerves unite to form the nerve of the pterygoid canal (n. canalis pterygoidei). It traverses the canal of the same name at the base of the pterygoid process and enters the ganglion.
Branches and Zones of Innervation
Postganglionic and passing fibers of the ganglion are distributed to several head structures:
- Lacrimal gland: receives efferent parasympathetic secretomotor fibers originating from the superior salivatory nucleus (nucleus salivatorius superior).
- Nasal cavity mucosa: the posterior regions are innervated by posterior nasal branches (nn. nasales posteriores).
- Palate and nasopharynx.
The ganglion gives rise to the following nerves: greater, middle, and lesser palatine nerves (n. palatinus major, medius et anterior), as well as the nasopalatine nerve (n. nasopalatīnus).
Note: Taste pathway diagrams occasionally note a potential alternative route for afferent fibers from the anterior tongue running via the greater petrosal nerve and pterygopalatine ganglion.
Regulation of Lacrimation
Because the ganglion is involved in lacrimal gland innervation, it mediates various reflex pathways:
- Emotional lacrimation: hypothalamic central influence (emotions) on the lacrimal glands is mediated via the brainstem reticular formation.
- Reflex lacrimation in response to conjunctival irritation: mediated by fibers running from the spinal trigeminal nucleus (nucleus spinalis nervi trigemini) to the lacrimal glands.
Blood Supply
Blood supply to the pterygopalatine ganglion and adjacent tissues is provided by the artery of the pterygoid canal (a. canalis pterygoidei). It travels through the pterygoid canal into the pterygopalatine fossa.