Pterygopalatine fossa

Question 1

Describe the pathway for lacrimation?

btw: greater petrosal also carries special sensory taste fibers to the palate

Answer 1

Preganglionic parasymapthetics are traveling in the greater petrosal nerve (from facial)

They join with the deep petrosal nerve off of hte internal carotid (which carries sympathetics) and become the nerve of the pterygoid canal.

This nerve continues and parasympathetics synapse at the pterygopalatine ganglion.

Then the postparasympathetics continue on the maxillary nerve which branches into the zygomatic nerve

Then via a communicating branch connects the parasympathetics to the lacrimal nerve which continues to the lacrimal gland

-the sympathetics don’t synapse on the ganglion, they innervate blood vessels and muscous glands of the head/neck

Question 2

Describe what nerves enters and leaves the pterygopalatine fossa in every relevant direciton.

Answer 2

Posterior (middle cranial fossa)
-foramen rotundum (maxillary nerve)
-pterygoid canal
(nerve of the pterygoid canal = greater and deep petrosal nerves)

Medial (nasal cavity)

• sphenopalatine foramen
• nasopalatine nerve (carries general sensory, parasympathetics and sympathetics for the nasal cavity mucosa)

Lateral (infratemporal fossa)

• pterygomaxillary fissure
• no nerves

Anterior (orbit)

• inferior orbital fissure
• maxillary nerve exits the fossa
• general sensory of the face

Inferior (oral cavity)

• greater palatine foramen
• palatine nerves (carry sympathetics, parasympathetics and special taste from the greater petrosal nerve) TO PALATE

Question 3

What is the pathway for palatine taste?

What about the parasympathetic innervation of palatine mucosa?

Answer 3

1. Lesser palatine nerves
2. Go through but do not synpase in the pterygopalatine ganglion
3. Continue through the greater petrosal nerve
4. Their cell bodies are in the genu.

Parasympathetics:

1. Greater petrosal nerve > PG (SYNAPSE) > lesser palatine nerve.

–almost the same as the palatine taste—-

Question 4

Describe sympathetic innervation of the pterygopalatine fossa

Answer 4

All postganglionic sympathetics come off the carotids and travel through the deep petrosal nerve.

Then at the pterygopalatine ganglion, it branches in every way, into the maxillary nerve, onto the walls of the nasal cavity, down the palatine nerves

They vasoconstrict and decrease muscous secretion.

Question 5

What is the course of the maxillary nerve

Answer 5

Originating from the trigeminal ganglion in the middle cranial fossa, the maxillary nerve enters the foramen rotundum in to pterygopalatine fossa.

Then it splits into the zygomatic nerve superiorly and continues anteriorly.

Then it exits anteriorly through the inferior orbital fissure to become the infraorbital nerve.

Then it travels along the floor of the orbit and travels through the infraorbital canal, out the infraorbital foramen onto the face.

Question 6

Describe the pathway of the somatic sensory innervation of the palate and nasal cavity.

Answer 6

The branches come from the palatine nerves and nasopalatine nerves up through the pterygopalatine ganglion, up the pterygopalatine nerves into the maxillary nerve. Then the maxillary nerve continues posteriorly into the middle cranial fossa and the cell bodies for general sensation are in the trigeminal ganglion.

Question 7

what is the pathway of the greater petrosal nerve

Answer 7

Comes off of the facial nerve while it is running in the inner ear, it exits via the hiatus for the greater petrosal nerve

then it enters the middle cranial fossa.

Then it enters foramen lacerum.

Then it travels in the pterygoid canal

To reach the pterygopalatine fossa.

Question 8

Describe the blood supply of the pterygopalatine fossa.

Answer 8

The maxillary artery enters the pterygopalatine fossa via the pterygomaxillary fissure

Then it gives off three branches

Anterior: infraorbital artery

Medial: sphenopalatine artery (posterior nose)

Inferior: descending palatine artery

Question 9

How does brain freeze occur?

Answer 9

The cell bodies of general sensation from the palate, nasal mucosa, skin of face above and below the eye are all brought by branches of the maxillary nerve + opthalmic nerve to the trigeminal ganglion.

When you eat something cold, the sensation is brough up in palatine nerves through the PG, through the pterygopalatine nerves into the maxillary nerve and into the ganglion.

The brain perceives incorrectly that this noxious stimulus is coming from the maxillary region so you feel pain there.