Anatomy of the pterygopalatine (sphenopalatine) fossa

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The pterygopalatine fossa, sometimes called the sphenopalatine fossa, is a cavity in our skull that sits behind the maxilla.
We are going to think of the pterygopalatine fossa as a house for sale, and talk about its design, location, neighbours, and even the furnishings it comes with.First, let’s talk about the shape of the house.
The pterygopalatine fossa is shaped like an upside down trapezoidal prism and it is situated in a prime location, just posterior to the maxilla.
So right off the bat, it makes sense that it’s bounded anteriorly by the posterior aspect of the maxilla! Posteriorly, it’s bounded by the pterygoid process of the sphenoid.
Medially, the fossa is bounded by the perpendicular plate of the palatine bone whereas laterally it opens into the pterygomaxillary fissure.
Its roof is formed by the infratemporal surface of the greater wing of the sphenoid bone and it is incomplete as there is an opening into the inferior orbital fissure.
Finally, the floor is formed by the pyramidal process of the palatine bone with an opening into the palatine canal.This means the pterygopalatine fossa’s neighbours include the middle cranial fossa, infratemporal fossa, orbit, nasal cavity, the roof of the oral cavity, and maxillary sinus and the pharyngeal vault .
Now, the pterygopalatine fossa communicates with its neighbors, aka surrounding structures, through many openings. First, it communicates with the middle cranial fossa through the foramen rotundum, located anteromedially on the sphenoid bone.
The foramen rotundum provides passage for the maxillary nerve, which is the second main division of cranial nerve V. Another connection to the middle cranial fossa is through the pterygoid canal within the sphenoid bone.
The canal provides passage for the nerve and artery of the pterygoid canal. The pterygopalatine fossa communicates with the infratemporal fossa through the pterygomaxillary fissure, which transmits the posterior superior alveolar nerve and artery and the maxillary artery.
It communicates with the nasal cavity through the sphenopalatine foramen, which transmits the sphenopalatine artery and vein, and the nasopalatine nerve.
Fifth, it communicates with the orbit through the inferior orbital fissure, which provides passage for the zygomatic branch of the maxillary nerve and the infraorbital nerve, artery and vein.
Next, it communicates with the pharynx via the palatovaginal canal, which transmits the pharyngeal nerve and artery. Lastly, the pterygopalatine fossa communicates with the mucosa of the hard and soft palate via the palatine canal.
Before we move on, can you recall the boundaries of the pterygopalatine fossa? Now, this house also comes fully furnished.
Some of the most important structures you can find within the fossa include the terminal part of the maxillary artery and the proximal parts of its branches; their accompanying veins; the maxillary nerve; and the pterygopalatine ganglion.First, the maxillary artery is one of the terminal branches of the external carotid artery.
From its origin posterior to the lateral pterygoid muscle, it passes anteriorly through the infratemporal fossa, and eventually makes its way to the pterygomaxillary fissure.
Then, it enters the pterygopalatine fossa and eventually terminates as the sphenopalatine artery. The maxillary artery gives off branches along its trajectory which usually accompany the nerves entering and exiting the fossa.
First is the descending palatine artery, which passes through the palatine canal and divides into the greater palatine artery and lesser palatine artery to supply most of the soft palate and hard palate.
Next is the posterior superior alveolar artery which exits the fossa through the pterygomaxillary fissure and then enters the alveolar foramen of the maxilla to supply the maxillary sinus and the upper premolar and molar teeth and their gingivae.
There’s also the pharyngeal artery, which supplies the roof of the nasal cavity and the sphenoidal sinus, and the artery of the pterygoid canal, which supplies the tympanic cavity.
Both branches also supply the pharynx and pharyngotympanic tube.Next is the infraorbital artery which enters the inferior orbital fissure, travels through the infraorbital canal and exits the skull through the infraorbital foramen.
It supplies the inferior oblique and inferior rectus muscles, lacrimal sac, maxillary canines and incisors, the mucosa of the maxillary sinus, and the overlying skin.
Finally, the sphenopalatine artery exits the pterygopalatine fossa through the sphenopalatine foramen. From here, it enters the nasal cavity, where it gives rise to lateral nasal and septal branches that supply its lateral and medial walls.
Next up, there’s the maxillary nerve. It originates in the middle cranial fossa, and runs anteriorly through the foramen rotundum to enter the posterior wall of the pterygopalatine fossa.
The maxillary nerve gives off 8 branches. The first one is the zygomatic nerve, which enters the orbit through the inferior orbital fissure and gives off the zygomaticofacial nerve and zygomaticotemporal nerve.
The zygomaticofacial nerve leaves the orbit and emerges on the anterolateral aspect of the zygomatic bone, supplying the overlying skin.
The zygomaticotemporal nerve leaves the orbit and enters the temporal fossa to supply the skin over the temple. Next is the posterior superior alveolar nerve, which travels with its arterial counterpart to supply the maxillary sinus, the molar teeth, and their adjacent gingivae.
Next up, the infraorbital nerve, which follows the infraorbital artery to supply the mucosa of the maxillary sinus; premolar, canine, and incisors maxillary teeth; skin and conjunctiva of the inferior eyelid, lateral nose and antero-inferior septum; and the skin and mucosa of the upper lip.The next branch is the nasopalatine nerve, which travels through the sphenopalatine foramen to enter the nasal cavity.
It runs across the nasal septum to the incisive canal where it then enters the roof of the oral cavity. It supplies the nasal septum and the anterior part of the oral mucosa of the hard palate.
Next is the pharyngeal nerve, which passes posteriorly to supply the mucosa of the nasopharynx. Finally, the greater palatine nerve and lesser palatine nerve follow their associated arteries.
The greater palatine nerve supplies most of the gingivae and mucous membrane of the hard palate whereas the lesser palatine nerve supplies the soft palate.Okay, finally, let’s talk about the nerve of the pterygoid canal and the pterygopalatine ganglion.
The nerve of the pterygoid canal forms in the middle cranial fossa by the joining of the greater petrosal nerve, a branch from the facial nerve, and the deep petrosal nerve, a branch from the internal carotid plexus.
The greater petrosal nerve branches from the facial nerve at the geniculate ganglion, and carries preganglionic parasympathetic fibres.
Postganglionic sympathetic fibres from the superior cervical sympathetic ganglion in the neck form the internal carotid plexus.
In the middle cranial fossa, some fibres leave the plexus as the deep petrosal nerve and join with the greater petrosal nerve to form the nerve of the pterygoid canal, which exits through the foramen lacerum to enter the pterygopalatine fossa.
Once it enters the fossa, it passes through the pterygopalatine ganglion where ONLY the parasympathetic fibers from the greater petrosal nerve synapse.
The sympathetic fibers from the deep petrosal nerve fibers DO NOT synapse in the ganglion but instead pass directly through.
Both the parasympathetic and sympathetic fibres leave the ganglion with branches of the maxillary nerve, on which they hitchhike to their targets!Before the recap, can you recall the main branches of the maxillary nerve in the pterygopalatine fossa?
All right, as a quick recap… the pterygopalatine fossa is bounded anteriorly by the maxilla and posteriorly by the pterygoid process of the sphenoid; medially by the perpendicular plate of the palatine bone, and laterally by the pterygomaxillary fissure.
The roof is formed by the infratemporal surface of the greater wing of the sphenoid and the floor by the pyramidal process of the palatine bone.
The fossa communicates with the: middle cranial fossa through the foramen rotundum and the pterygoid canal; the infratemporal fossa through the pterygomaxillary fissure; the nasal cavity through the sphenopalatine foramen; the pharynx through the palatovaginal canal; the orbit through the inferior orbital fissure; and the palate through the palatine canal.
The fossa contains the terminal portion of the maxillary artery, the maxillary nerve, and the pterygopalatine ganglion, which receives preganglionic parasympathetic fibers via the greater petrosal nerve and postganglionic sympathetic fibers via the deep petrosal nerve.
Only the parasympathetic fibres synapse in the ganglion and both the parasympathetic and sympathetic fibres leave the ganglion with branches