TBL26 - Pterygopalatine Fossa

Question 1

What forms the medial wall of the infratemporal fossa? What is the pterygopalatine fossa and what does it communicate with?

Answer 1

1) The lateral pterygoid plate forms the medial wall of the infratemporal fossa
2) The pterygopalatine fossa is a small intracranial space that communicates with the infratemporal fossa via the pterygomaxillary fissure

Question 2

Where does the sphenopalatine foramen reside, what does the palatine bone contribute to, and what does the palatine bone form? What function does the spheno-palatine foramen serve?

Answer 2

1) The sphenopalatine foramen resides in the vertical plate of the palatine bone, which contributes to the lateral wall of the nasal cavity and forms the medial wall of the pterygopalatine fossa
2) The spheno-palatine foramen serves as a conduit between the pterygopalatine fossa and nasal cavity

Question 3

What does the inferior orbital fissure demarcate? What is the fissure a conduit between?

Answer 3

1) The inferior orbital fissure demarcates the inferior and lateral walls of the orbit
2) The fissure is a conduit between the pterygopalatine fossa and orbit

Question 4

Where is the foramen rotundum located and what does it open into? What does CN V2 enter once it traverses the foramen rotundum? What ganglion does the fossa contain?

Answer 4

1) The foramen rotundum is in the cranial base and opens into the pterygopalatine fossa
2) CN V2 traverses the foramen rotundum into the pterygopalatine fossa
3) The fossa contains the pterygopalatine ganglion

Question 5

How is the deeply placed fossa surgically accessed?

Answer 5

1) Surgical access to the deeply placed pterygopalatine
fossa is gained through the maxillary sinus
2) After elevating the upper lip, the maxillary gingiva and anterior wall of the sinus are transversed to enter the
sinus

Question 6

What does the maxillary artery traverse to enter the pterygopalatine fossa and what artery arises from this fossa? This artery then passes through the sphenopalatine foramen to enter what?

Answer 6

1) The maxillary artery traverses the pterygomaxillary fissure into the pterygopalatine fossa where the sphenopalatine artery arises
2) This artery passes through the sphenopalatine foramen into the mucosa of the nasal cavity

Question 7

Where does the infraorbital nerve arise from and what does it enter? Where does the nerve course? What is the infraorbital artery a branch of? What are branches of the maxillary artery that accompany the respective branches of CN V2 to the palate?

Answer 7

1) The infraorbital nerve arises from CN V2 and enters the infraorbital fissure
2) The nerve courses along the floor of the orbit to the infraorbital foramen
3) The infraorbital artery is a branch of the maxillary artery
4) The greater palatine, lesser palatine, and nasopalatine arteries are branches of the maxillary artery that accompany the respective branches of CN V2 to the palate

Question 8

What nerves arise from CN V2 in the pterygopalatine fossa?

Answer 8

The infraorbital nerve, greater and lesser palatine nerves, and nasopalatine nerve arise from CN V2 in the pterygopalatine fossa

Question 9

What nerves exit the pterygopalatine fossa via the palatine canal and where does this canal course? Where do branches of the greater palatine nerve exit and what do they innervate?

Answer 9

1) The greater and lesser palatine nerves exit the pterygopalatine fossa via the palatine canal (not labeled) that courses within the vertical plate of the palatine bone to the greater and lesser palatine foramina
2) Branches of the greater palatine nerve exit the palatine canal to innervate the region of nasal mucosa labeled CN V2

Question 10

What do branches of the nasopalatine nerve innervate? After branching from CN V2 in the pterygopalatine fossa, where does the nasopalatine nerve traverse to enter the septal mucosa and where does it course?

Answer 10

1) Branches of the nasopalatine nerve innervate the region of the nasal septal mucosa labeled CN V2
2) After branching from CN V2 in the pterygopalatine fossa, the nasopalatine nerve traverses the sphenopalatine foramen into the septal mucosa and courses to the incisive foramen for access to the anterior hard palate

Question 11

Where is the internal acoustic meatus located? When CN VII traverses the meatus, what does it enter?

Answer 11

1) The internal acoustic meatus is in the cranial base

2) CN VII traverses the meatus into the petrous part of the temporal bone

Question 12

What is the geniculate ganglion and where does it reside?

Answer 12

The geniculate ganglion, the sensory ganglion of CN VII for taste, resides at the end of the internal acoustic meatus

Question 13

En route to the stylomastoid foramen, where do somatic motor fibers of CN VII pass through? What type of branch off of CN VII is the greater petrosal nerve and where does it arise?

Answer 13

1) Somatic motor fibers of CN VII pass directly through the ganglion en route to the stylomastoid foramen
2) The greater petrosal nerve, a presynaptic parasympathetic branch, arises at the abrupt 90° turn of the facial nerve as it traverses through the geniculate ganglion

Question 14

What does the greater petrosal nerve pass through to enter the cranial cavity and where does it course once inside the cranial cavity?

Answer 14

The greater petrosal nerve passes through a small fissure in the petrous temporal bone to enter the cranial cavity where it courses anteriorly along the cranial base

Question 15

What do postsynaptic sympathetic fibers form around the internal carotid artery? Where do these postsynaptic fibers arise from? What is the source of postsynaptic sympathetic fibers in the cranial cavity?

Answer 15

1) Postsynaptic sympathetic fibers form a plexus around the internal carotid artery
2) The postsynaptic fibers arise from the superior cervical ganglia
3) The carotid plexus is the source of post-synaptic sympathetic fibers in the cranial cavity (entrance of the internal carotid into the cranial cavity will be studied later)

Question 16

Where does the deep petrosal nerve branch from and what does it join to form the nerve of the pterygoid canal? When this nerve traverses the canal, what does it enter?

Answer 16

1) The deep petrosal nerve branches from the carotid plexus and joins the greater petrosal nerve to form the nerve of the pterygoid canal
2) The nerve traverses the canal (to be studied later) into the pterygopalatine fossa

Question 17

After the nerve of the pterygoid canal enters the pterygopalatine fossa, where do fibers of the greater petrosal nerve synapse? What do postsynaptic parasympathetic fibers join and for what purpose?

Answer 17

1) After the nerve of the pterygoid canal enters the pterygopalatine fossa, fibers of the greater petrosal nerve synapse in the pterygopalatine ganglion
2) The postsynaptic para-sympathetic fibers then join the zygomatic nerve, another branch of CN V2, for transport through the infraorbital fissure into the orbit

Question 18

In the orbit, a branch of the zygomatic nerve carries the parasympathetic fibers onto which nerve and where? What does this nerve provide to the structure it is transported to?

Answer 18

1) In the orbit, a branch of the zygomatic nerve carries the parasympathetic fibers onto the lacrimal nerve, a branch of CN V1, for transport to the lacrimal gland (to be studied later)
2) The lacrimal nerve provides somatic sensory fibers to the gland