Pterygopalatine+Fossa

=**Objectives**=


 * 1. Give the location of the pterygopalatine fossa.**

The PT fossa is a small pyramidal-shaped space located posterior and inferior to the apex of the orbit and deep to the infratemporal fossa. It has three walls: the anterior wall is formed by the posterior aspect of the maxilla, the posterior wall is formed by the pterygoid process of the sphenoid bone, and the medial aspect is formed by the vertical portion of the palatine bone. The lateral aspect is open to the infratemporal fossa through the ptergyomaxillary fissure.


 * 2. Give the significance of the pterygopalatine fossa.**

The pterygopalatine fossa is a crossroads or a hub for the third portion of the maxillary artery and its branches, the maxillary nerve and its braches, and the pterygopalatine ganglion and nerve of the pterygoid canal.

The maxillary artery enters the PT fossa from the infratemporal fossa using the pterygomaxillary fissure. It passes through the fossa and exits as the sphenopalatine artery through the sphenopalatine foramen. On its way through, it gives off an infraorbital artery through the infraorbital canal, pharyngeal artery through the pharyngeal canal, artery of the pterygoid canal through the pterygoid canal, a posterior alveolar artery back out the pterygomaxillary fossa, and a descending palatine artery through the palatine canal.

Meanwhile, the maxillary nerve enters via the foramen rotundum where it gives off an infraorbital nerve to the infraorbital canal, sphenopalatine nerve to the sphenopalatine foramen, pharyngeal nerve to the pharyngeal canal, and greater and lesser palatine nerves) through the palatine canal.

Some of the preganglionic parasympathetic fibers following the facial nerve and the greater petrosal nerve head towards the pterygopalatine ganglion which is housed within the PT fossa. On its way, postganglionic sympathetic fibers from the superior cervical ganglion travel along the deep petrosal nerve which unites with the greater petrosal nerve and enter the pterygoid canal, forming the nerve of the pterygoid canal. When this nerve exits into the PT fossa, the parasympathetic fibers synapse on the pterygopalatine ganglion. Parasympathetic fibers then follow the branches of the maxillary to supply innervation to glands and mucus membranes. Sympathetic fibers may also follow the maxillary nerve to supply vasculature but can also take alternate routes following other named nerves and arteries.


 * 3. List the branches of CN V2. Be able to give the distribution of each of these branches and the functional components of each.**

There are five major branches of the maxillary nerve in the PT fossa. This division of the trigeminal nerve transmits only sensory information. The maxillary nerve enters the PT fossa via the foramen rotundum. It gives off the nasopalatine nerve, infraorbital nerve, pharyngeal nerve, and greater and lesser palatine nerves which supply sensory information to the nasopharynx, nasal and oral cavities, floor of the orbit, and the skin on the face inferior to the orbit. Some of these nerves will pass through the pterygopalatine ganglion but do no synapse since they are sensory fibers.

However, preganglionic parasympathetic fibers from the facial nerve travel on the nerve of the pterygoid canal to enter the PT fossa and synapse on the pterygopalatine ganglion. Postganglionic parasympathetic fibers then distribute along the branches of the maxillary nerve to supply parasympathetic innervation to glands and mucus membranes.


 * 4. Explain the formation of the nerve of the pterygoid canal. Where did it come from? Where is it going? What neuroanl cells are located in the pterygopalatine ganglion?**

Parasympathetic fibers in greater petrosal join sympathetic fibers from deep petrosal nerve to form the nerve of pterygoid canal. The nerve of the pterygoid canal enters the posterior aspect of the PT fossa and ends in the pterygopalatine ganglion. Preganglionic parasympathetic fibers traveling in the nerve of the pterygoid canal and synapse in the pterygopalatine ganglion.


 * 5. Give the distribution of the branches of CN V2 that contain postganglionic parasympathetic fibers as well as those that contain postganglionic sympathetic fibers. Are these the same?**

Preganglionic parasympathetic fibers traveling in the nerve of the pterygoid canal enter the posterior aspect of the PT fossa and course toward the pterygopalatine ganglion. These preganglionic fibers synapse in the pterygopalatine ganglion and postganglionic parasympathetic fibers are distributed from the ganglion along the branches of the maxillary nerve. Postganglionic sympathetic path is the same, only the sympathetic fibers do not synapse when passing through the ganglion.


 * 6. List the branches of the terminal portion of the maxillary artery. Give teh distribution of each of the branches.**


 * The posterior superior alveolar artery is the first branch of this portion of the artery. It exits the fossa via the pterygomaxillary fissure and pierces the maxilla to supply the upper teeth.
 * Descending palatine artery exits through the palatine canal divides into greater and lesser palatine arteries which supply the hard and soft palate respectivly.
 * The artery of the pterygoid canal enters the pterygoid canal and supplies the upper part of the pharynx, auditory tube and tympanic cavity.
 * The small pharyngeal artery exits via the pharyngeal canal and supplies the roof of the nose and pharynx, sphenoid sinus and suditory tube.
 * The infraorbital artery traverses the inferior orbital fissure and then enters the infraorbital canal dividing into alveolar arteries (teeth) and supplying the lower eyelids.
 * The terminal branch, sphenopalatine artery, enters the nasal cavity via the sphenopalatine foramen and supplies the nasal cavity.


 * 7. Explain how (via what foramen, groove, or space) the pterygopalatine fossa comunicates with the surrounding areas such as the nasal cavity, oral cavity, orbit, infratemporal fossa, and the middle cranial fossa.**

__Laterally__ the PT fossa is directly communicates with the infratemporal fossa through the pterygomaxillary fissure. __Medially__ the sphenopalatine foramen opens into the nasal cavity. __Posteriorly__ there are three openings: __superior aspect of the anterior wall__ the inferior orbital fissure leads to the infraorbital canal on the floor of the orbit. __Inferiorly__ the PT fossa opens to the oral cavity via the greater palatine canal
 * Pharyngeal canal leads to the nasopharynx. (most medial)
 * Pterygoid canal near the center of the posterior wall
 * Foramen rotundum opens into the middle cranial fossa


 * Chart**


 * **Pathway** || **Destination** || **Artery** || **Nerve** ||
 * Infraorbital Canal || Face; Floor of the Orbit || Infraorbital Artery || Infraorbital Nerve ||
 * Sphenopalatine Foramen || Nasal Cavity || Sphenopalatine Artery || Sphenopalatine Nerve ||
 * Pharyngeal Canal || Nasopharynx || Pharyngeal Artery || Pharyngeal Nerve ||
 * Foramen Rotundum || Middle Cranial Fossa || || Maxillary Nerve (CN V2) ||
 * Pterygoid Canal || Pterygoid Process || Artery of the Pterygoid Canal || Nerve of the Pterygoid Canal ||
 * Pterygomaxillary Fissure || Infratemporal Fossa || Maxillary Artery (entering); Posterior Alveolar Artery (exiting) || ||
 * Palatine Canal || Oral Cavity || Descending Palatine Artery (splits to greater and lesser palatine arteries) || Greater and Lesser Palatine Nerves ||

Note: the nerve of the pterygoid canal is not a branch of the maxillary nerve. Rather, it contains a parasympathetic component and a sympathetic component. The parasympathetic component is preganglionic and originates from the brainstem > facial nerve > geniculate nucleus > greater petrosal nerve. The sympathetic component is postganglionic and originates from cervical lateral horn > ventral root > white ramus > superior cervical ganglion (synapse) > deep petrosal nerve. The deep petrosal nerve joins the greater petrosal nerve to form the nerve of the pterygoid canal which transverses the canal to reach the PT fossa. Preganglionic parasympathetic fibers synapse in the pterygopalatine ganglion and postganglionic parasympathetic fibers distribute along branches of the maxillary nerve (CN V2). Sympathetic fibers pass through the pterygopalatine ganglion and distribute either along the maxillary nerve or along other named nerves or arteries.