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Home , Lesser palatine arteries, Pharyngeal nerve, Pterygoid canal

Development of a 3D Learning Resource of the Using Cone

Beam Computed Tomography For Dental Students

By

Ryan James Casper

A THESIS

Submitted to the Faculty of the Graduate School in partial fulfillment of the requirements

for the Degree of Master of Science in the Department of Oral Biology

Omaha, Nebraska

April 25th 2012

Abstract

The pterygopalatine fossa is a pyramidal shaped fossa located between the and the . The major contents include the maxillary division of the trigeminal , the , and branches of the 3rd part of the maxillary . The fossa is very difficult for students to visualize in textbooks and the gross laboratory. The increasing use of cone beam computed tomography (CBCT) in dentistry has increased the ability of dental clinicians to visualize anatomical structures in multiple dimensions. The purpose of this study was to develop a 3D learning resource of the pterygopalatine fossa using CBCT for dental students. Anonymized CBCT files were selected from a series of patients with normal anatomy. All of the scans had been performed at 0.3 mm resolution and were reconstructed using Osirix version 3.9.2 in axial, coronal, and sagittal planes. Digital images of a dry specimen and cadaveric dissection of the pterygopalatine fossa were collected using a Canon Powershot ELPH

100 HS. Final Cut version 10.0 was used to create a multimedia learning resource. A multimedia learning resource for the pterygopalatine fossa was created using CBCT videos, CBCT images, cadaver photographs, and skull photographs. The CBCT videos and images incorporated axial, sagittal, and coronal planes of the pterygopalatine fossa.

Labeled and unlabeled cadaver and dry skull specimen photographs were utilized. Audio was integrated to explain the clinical relevance of the anatomy of the pterygopalatine fossa. This learning resource provides dental students a tool to augment their understanding of the anatomy of the pterygopalatine fossa.

iii Acknowledgements

I would like to thank my mentor, Dr. Neil Norton. He has offered support and guidance throughout this project, and has also demonstrated what it takes to be an incredible educator. I would also like to thank Dr. Margaret Jergenson. She offered her knowledge to me when needed and spares no effort in educating her students. These two professors have developed in me a deeper respect for academics.

I would like to thank the Department of Oral Biology and the School of Dentistry for providing the resources and material needed for me to complete my studies and this project.

Lastly, I must thank my wife Natalie. She has an amazing amount of belief in me and that inspires me to want to succeed. Natalie has instilled in me the attitude of never giving up and never giving less than your best. She has incredible amount of passion for life, she is an unbelievable mother to our children, and she is an astonishing wife. I cannot thank her enough.

iv Table of Contents

I. Introduction 1 A. Overview & Purpose 1 B. Cone Beam Computed Tomography 2 C. Osseous Anatomy 7 D. Pterygopalatine Fossa Borders 8 E. Foramina/Fissures and Communications 10 F. Nervous Supply 16 G. Vasculature 22 H. Computer-Assisted Learning 25 II. Materials and Methods 27 A. CBCT 27 B. Dry Skull Specimens 27 C. Dissection 27 D. Software 28 III. Results and Discussion 29 IV. Conclusions 30 V. Citations 31

List of Figures

Figure 1: Pterygopalatine Fossa shown between the infratemporal fossa and the nasal

cavity. 1

Figure 2: 3rd generation CT. 2

Figure 3: 4th generation CT for dental use. 2

Figure 4: Shows the z-axis. 3

Figure 5: Cross-sectional CT slice. 3

Figure 6: 3rd generation CT that has detectors and an x-ray tube rotating within the

gantry. 4

Figure 7: 4th generation CT that has stationary detectors and an x-ray tube that rotates. 4

v Figure 8: X-ray tube and power supply from which it is receiving voltage to send out the

x-ray beam. 5

Figure 9: Compares the shape of the x-ray beam for 3rd and 4th generation CT scanners. 5

Figure 10: Orbital and sphenoidal processes of the perpendicular plate of the palatine

. 8

Figure 11: Anterior, posterior, and medial borders, of the PPF. 9

Figure 12: Superior aspect of superior border of the PPF 9

Figure 13: Pyramidal process fusing with the pterygoid plates. 9

Figure 14: A cube representing the PPF. 10

Figure 15: CBCT axial image of . 11

Figure 16: Dry skull specimen of the lateral opening of the PPF. 11

Figure 17: CBCT sagittal image of the . 12

Figure 18: CBCT axial image of the foramen rotundum. 12

Figure 19: Disarticulated labeling the three posterior openings of the PPF.

12

Figure 20: Superior view of a skull identifying the foramen rotundum. 12

Figure 21: CBCT axial image of the pterygoid and pharyngeal canal. 13

Figure 22: Inferior view of the skull demonstrating the pterygoid canal. 13

Figure 23: CBCT sagittal image of the palatine canal dividing into the greater and lesser

palatine canal. 14

Figure 24: Dissection photo of the palatine canal traveling from the PPF to the palate. 14

Figure 25: CBCT sagittal image of the superior communication of the PPF. 15

Figure 26: Dry skull specimen of the . 15

vi Figure 27: Medial aspect of a skull, illustrating the . 16

Figure 28: Represents a lateral view of the sphenopalatine foramen on a skull. 16

Figure 29: CBCT axial image of the sphenopalatine foramen. 16

Figure 30: CBCT image of the PPF communicating with the nasal cavity. 16

Figure 31: Maxillary division of the and 3rd part of the maxillry artery.

17

Figure 32: Trigeminal ganglion in the . 18

Figure 33: Medial view demonstrating the pterygopalatine ganglion. 19

Figure 34: Nasopalatine nerve traveling anteroinferiorly over the . 21

Figure 35: traveling through the infratemporal foss. 23

Figure 36: Illustration of the . 25

vii I. Introduction A. Overview & Purpose

The pterygopalatine fossa (PPF) is a pyramidal shaped fossa located between the infratemporal fossa and the nasal cavity (Figure 1). The major contents include the maxillary division of the trigeminal nerve, the pterygopalatine ganglion, and branches of the 3rd part of the maxillary artery. Within this space there are also seven different foramina/fissures that allow passage for these and to communicate with surrounding areas. Studying this space can be difficult, especially when using a skull to attempt to visualize where this space is located and the passage of the nerves and vessels.

The purpose of this study was to create a multimedia resource using a combination of cone beam computed tomography (CBCT), cadaver pictures, and dry skull specimen pictures to aid in the study of the pterygopalatine fossa for dental students.

Figure 1: Pterygopalatine Fossa shown between the infratemporal fossa and the nasal cavity.

1 B. Cone Beam Computed Tomography

Computed Tomography (CT) scanning was first developed in 1967 and has continued to advance with the continued development of newer sensors and computers

(Sukovic, 2003). There are two main types of CT that are used, fan beam CT (Figure 2), and CBCT (Figure 3) (MacDonald, 1995).

Figure 2: Fan beam CT for medical use. Figure 3: CBCT for dental use.

CT scanning provides 3-D imaging that is generated by gathering slices of images that are collected from rows of detectors. These images are stacked on each other to construct a 3-D outcome (Dawood, 2009). A single CT slice will show the portion of the anatomy at the level of the slice, which represents a plane within the body. The thickness of the plane is the z-axis (Figure 4). The thickness of a slice can be varied and once it is set, it limits the x-ray beam to scan the selected volume only. CT slices are further sectioned into an x-axis and a y-axis, making a two dimensional square, known as a pixel.

When the z-axis is taken into consideration, a cube is made, and this is known as a voxel

(Figure 5). Each individual pixel will be used to generate a 3-D image (Romans, 1995).

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Figure 4: Illustration of the z-axis, which is Figure 5: Represents a cross-sectional CT the thickness of a CT slice (Romans, L. E. slice that may be stacked to create a 3-D (1995). Introduction to computed image (Romans, L. E. (1995). Introduction tomography. Baltimore: Williams & to computed tomography. Baltimore: Wilkins. Used with the permission of Williams & Wilkins. Used with the publisher.) permission of publisher.)

To produce an image, a generator and gantry are required. A generator simply produces voltage that is transmitted to the x-ray tube (Figure 8). The gantry is the part of the CT system that holds the x-ray tube, which will move in a circular path within the gantry. The x-ray tube will emit x-ray energy, which will pass through the body and will be recorded by detectors. An x-ray beam releases protons that are absorbed by the detector. When the protons are absorbed, the detector generates light, which is converted into electric current that presents data to produce an image (Romans, 1995). Figure 6 illustrates a fan beam CT that has detectors and an x-ray tube rotating within the gantry.

Whereas figure 7 shows a CBCT that has stationary detectors placed around the entire gantry and an x-ray tube that rotates.

The problem with fan beam CT is that there is a high x-ray dose required, the machines are large, generally expensive, and they are typically found only in a hospital setting (Dawood, 2009). An advantage of fan beam CT is that, not only does it generate

3 images with bone, but it is also able to generate images with soft tissue (MacDonald,

1995).

Figure 6: Representation of a 3rd generation Figure 7: Representation of a 4th generation CT that has detectors and an x-ray tube CT that has stationary detectors and an x- rotating within the gantry (MacDonald, D., ray tube that rotates (MacDonald, D., 1955. 1955. (2011). Oral and maxillofacial (2011). Oral and maxillofacial radiology: radiology: A diagnostic approach. Ames, A diagnostic approach. Ames, Iowa: Iowa: Wiley-Blackwell. Used with the Wiley-Blackwell. Used with the permission permission of publisher.) of publisher.)

CBCT was created in 1982 for the purpose of an angiography (Smita Govila,

2007). CBCT is much more suited for dentomaxillofacial settings than the conventional

CT scanners, which are primarily meant for full body scans (Sukovic, 2003). CBCT uses a cone-shaped beam of x-ray photons rather than a fan-shaped beam of helical CT (Figure

9). The cone beam shape of the x-ray beam covers more area than the fan shaped beam of x-ray, thus being able to convert more volume of data in less scan time. CBCT scan the region of interest in a single 360-degree rotation in contrast to the multiple rotations required by a fan-shaped beam. The multiple rotations are required to scan each plane so that individual plane’s can be stacked to make a 3-D image (MacDonald, 1995).

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Figure 8: Illustration of a visual of the x- Figure 9: Compares the shape of the x-ray ray tube and the power supply from which beam for 3rd and 4th generation CT scanners it is receiving voltage to send out the x-ray (MacDonald, D., 1955. (2011). Oral and beam. (White, S. C., & Pharoah, M. J. maxillofacial radiology: A diagnostic (2009). Oral radiology: Principles and approach. Ames, Iowa: Wiley-Blackwell. interpretation. St. Louis, Mo: Used with the permission of publisher.) Mosby/Elsevier. Used with permission of publisher.)

Advantages and Disadvantages

There are many advantages as well as disadvantages using CBCT. A major advantage of CBCT is that the size of a CBCT machine is much smaller than that of a fan beam machine (See Figure 2 & 3) and is approximately ¼ of the cost of a fan beam machine (White, 2009).

A second advantage of CBCT is the access to its viewing. Fan beam CT, primarily used in hospitals, does not typically have software readily available, other than for a radiologist. CBCT typically allow for viewing on a personal computer, which allows for results to be read quickly (Scarfe, 2006). In preparing “Development of a 3D

Learning Resource of the Pterygopalatine Fossa Using Cone Beam Computed

Tomography For Dental Students”, the software Osirix was used to view CBCT images

5 and create video. This software is downloadable for free and has an upgradable version for purchase, although the free version has many capabilities for viewing and labeling.

Another advantage of CBCT is that it generates isotropic voxels. This means that the x, y, and z-axis are all equal. On the other hand fan beam CT generates anisotropic voxels, which means that the x, y, and z-axis are not all equal (MacDonald, 1995).

Because CBCT uses isotropic voxels, a submillimeter resolution is obtained, producing an accurate image (Scarfe, 2006). The isotropic voxels of CBCT allow for good resolution in all planes, whereas an anisotropic voxel only shows good resolution in the axial plane (MacDonald, 1995).

A very important advantage of CBCT is that the effective radiation dose is significantly reduced. In the literature it has been reported to be approximately five times less radiation than the amount needed for fan beam CT and possibly up to 96% less radiation (White, 2009). Additionally, it has been reported the effective dose is equivalent to taking 4 -15 panoramic radiographs (Scarfe, 2006).

A fifth advantage of CBCT is that they require only one rotation around a patient whereas fan beam CT requires multiple rotations. Because only one rotation is required, the scan time for CBCT is generally less than 30 seconds (White, 2009). Thus, because of the quick scan time, there may be less movement from a patient, causing less motion artifact (Scarfe, 2006).

CBCT scans do not have the ability to produce well-defined images of soft tissue, and therefore examining lesions via CBCT does not work well. On the other hand, fan beam CT is capable of producing images with hard and soft tissue (Dawood, 2009).

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C. Osseous Anatomy

Bones surrounding the PPF include the maxilla, sphenoid and palatine bone. The maxilla consists of a body, frontal process, , alveolar process, and palatine process (Norton, 2012). The sphenoid bone consists of a body, greater and lesser wings, and pterygoid process. The pterygoid process is made of a base and the medial and lateral pterygoid plates. The process is located inferior to the body and greater wing of the sphenoid (Daniels, 1998). The palatine bone shown in Figure 10 consists of a horizontal plate, perpendicular plate, and pyramidal process (Norton, 2012). The perpendicular plate, also known as the vertical plate, has an anterior and posterior process that is separated by the sphenoidal notch. When the palatine and sphenoid bone are articulating, this notch makes the sphenopalatine foramen. The anterior process of the perpendicular plate is the orbital process and the posterior process is known as the sphenoidal process (Liebgott, 2011).

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Figure 10: Orbital and sphenoidal processes of the perpendicular plate of the palatine bone (D.L., Daniels, L.P., Mark, J.L., Ulmer, M.F., Mafee, J. McDaniel, N.C., Shah, S. Erickson, L.A., Sether, and S.S., Jaradeh, Osseous anatomy of the pterygopalatine fossa. American Journal of Neuroadiology, 19(8), 1423-32, 1998, © by American Society of Neuroradiology. Used with permission of publisher.)

D. Pterygopalatine Fossa Borders

There is no border on the lateral side of the PPF, only an opening into the infratemporal fossa. Figure 11 shows the anterior, posterior, and medial borders, as well as the infratemporal fossa. The anterior border is the posterior maxilla, the posterior border is the pterygoid process of the sphenoid bone, and the medial border is the perpendicular plate of the palatine bone. The superior border is comprised of the orbital plate of the palatine bone and the inferior surface of the sphenoid bone (Figure 12). The inferior border is the pyramidal process of the palatine bone (Figure 13). The pyramidal process is located inferiorly and posterior to the junction of the horizontal and perpendicular plates of the palatine (Norton, 2012).

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Figure 11: Anterior, posterior, and medial borders, of the PPF, as well as the space lateral to the PPF.

Figure 12: Superior aspect of the Figure 13: Pyramidal process of the comprising the superior border of the PPF palatine bone fusing with the pterygoid (D.L., Daniels, L.P., Mark, J.L., Ulmer, plates of the sphenoid bone (D.L., Daniels, M.F., Mafee, J. McDaniel, N.C., Shah, S. L.P., Mark, J.L., Ulmer, M.F., Mafee, J. Erickson, L.A., Sether, and S.S., Jaradeh, McDaniel, N.C., Shah, S. Erickson, L.A., Osseous anatomy of the pterygopalatine Sether, and S.S., Jaradeh, Osseous fossa. American Journal of Neuroadiology, anatomy of the pterygopalatine fossa. 19(8), 1423-32, 1998, © by American American Journal of Neuroadiology, Society of Neuroradiology. Used with 19(8), 1423-32, 1998, © by American permission of publisher.) Society of Neuroradiology. Used with permission of publisher.)

9 E. Foramina/Fissures and Communications

The seven openings of the PPF are shown in Figure 14. They include the pterygomaxillary fissure, foramen rotundum, pterygoid canal, pharyngeal canal, palatine canal, inferior orbital fissure, and sphenopalatine foramen (Baker, 2010).

Figure 14: Representation of the PPF shown with each of its seven openings allowing for communication to surrounding spaces (Norton, N. S. (2012). Netter's for dentistry. Philadelphia, PA: Elsevier/Saunders; Used with permission of the publisher Netter illustration from www.netterimages.com. © Elsevier Inc. All rights reserved.)

The lateral opening of the PPF is the pterygomaxillary fissure. Figure 15 illustrates a CBCT image of the opening and Figure 16 shows a dry skull specimen representing the pterygomaxillary fissure. Traveling through this fissure are the posterior superior alveolar (p.s.a.) nerve and the 3rd part of the maxillary artery. The source of the p.s.a nerve is the maxillary division of the trigeminal nerve (V2) and it is traveling from

10 the PPF to the infratemporal fossa. The maxillary artery is one of the terminal branches of the and travels from the infratemporal fossa into the PPF

(Norton, 2012).

Figure 15: CBCT axial image of Figure 16: Dry skull specimen of the pterygomaxillary fissure, allowing for lateral opening of the PPF. communication with the infratemporal fossa.

There are three posterior openings in the PPF. The most lateral of these is the foramen rotundum. In the skull the anterior opening of the foramen rotundum is located at the base of the sphenoid bone (Figure 17 & 19). V2 travels through the foramen rotundum from the middle cranial fossa to the PPF (Norton, 2012). This communication is illustrated in Figure 17 and 18. Figure 20 is a dry skull specimen demonstrating where the foramen rotundum begins in the middle cranial fossa.

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Figure 17: CBCT sagittal image of the Figure 18: CBCT axial image of the foramen rotundum communicating with foramen rotundum communicating with the middle cranial fossa. the middle cranial fossa.

Figure 19: Disarticulated sphenoid bone Figure 20: Superior view of a skull seeing labeling the three posterior openings of the the posterior opening of the foramen PPF. rotundum communicating with the middle cranial fossa.

Medial and inferior from the foramen rotundum is the pterygoid canal (Figure

19). In the skull the anterior opening is between the foramen lacerum and the PPF

(Figure 22). The nerve of the pterygoid canal (vidian nerve) is the formation of the

12 and the deep petrosal nerve. The vidian nerve passes through the pterygoid canal to join the pterygopalatine ganglion (Norton, 2012).

Figure 21: CBCT axial image of the Figure 22: Inferior view of the skull pterygoid canal and pharyngeal canal, both demonstrating the pterygoid canal between posterior openings of the PPF. the foramen lacerum and the PPF. The pharyngeal canal is also labeled, entering the nasopharynx.

The most medial opening on the posterior aspect of the PPF is the pharyngeal canal. In the skull this canal is located at the medial edge of the pterygoid process of the sphenoid bone (Figure 19). Figure 21 illustrates that the pharyngeal canal is located between the PPF and the nasopharynx, while Figure 22 shows a dry skull specimen of the opening into the nasopharynx. Traveling through this canal is the pharyngeal nerve and vessels (Norton, 2012).

The inferior opening of the PPF is the palatine canal, which will divide into the greater and lesser palatine canals (Figure 23). The palatine canal and its divisions will travel down to the hard and (Figure 24). The descending palatine artery travels in the palatine canal with the greater and lesser palatine nerves. The descending

13 palatine artery will divide into greater and lesser palatine arteries, traveling in their respective canals. The greater palatine nerve and artery will enter the hard palate through the . The will travel anteriorly towards the where it will anastomose with the sphenopalatine artery. The lesser palatine nerve and artery will travel through the lesser palatine foramen to supply the soft palate and (Norton, 2012).

Figure 23: CBCT sagittal image of the Figure 24: Dissection photo of the palatine palatine canal dividing into the greater and canal traveling from the PPF to the palate. lesser palatine canal.

The superior opening of the PPF is the inferior orbital fissure (Figure 25). This opening is between the PPF and the . Traveling through this fissure are the , , infraorbital vessels, and the inferior ophthalmic vein

(Baker, 2010). The infraorbital nerves and vessels will exit onto the via the (Figure 26).

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Figure 25: CBCT sagittal image of the Figure 26: Dry skull specimen of the superior communication of the PPF. inferior orbital fissure communicating the PPF to the orbit.

The most medial opening of the PPF is the sphenopalatine foramen, seen from a lateral view in Figure 28. From the medial aspect of a skull this foramen is located posterior to the and inferior to the (Figure 27). The sphenopalatine foramen allows for communication between the nasal cavity and PPF

(Figure 29 & 30). Passing through the foramen to enter the nasal cavity are the nasopalatine nerve, posterior superior nasal nerve, and the sphenopalatine vessels

(Norton, 2012).

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Figure 27: Medial aspect of a dry skull Figure 28: Dry skull specimen specimen, illustrating the sphenopalatine representing a lateral view of the foramen posterior to the middle nasal sphenopalatine foramen. concha and inferior to the sphenoid sinus.

Figure 29: CBCT axial image of the Figure 30: CBCT coronal image of the sphenopalatine foramen, illustrating the PPF communicating with the nasal cavity. communication with the nasal cavity.

F. Nervous Supply

Nervous supply traveling through the PPF includes sensory, and autonomic

(parasympathetic and sympathetic) fibers. The sensory fibers travel with the branching

16 of V2, which include the posterior superior alveolar, zygomatic, infraorbital, nasopalatine, greater and lesser palatine, pharyngeal, and ganglionic connections. The autonomic fibers are brought to the PPF from the nerve of the pterygoid canal and distributed to different areas using the nasopalatine, posterior superior nasal, greater and lesser palatine, and pharyngeal nerves (Norton, 2012). Figure 31 shows the infraorbital, posterior superior alveolar, zygomatic, and ganglionic branches coming directly off of

V2, while the nasopalatine, posterior superior nasal, pharyngeal, and greater and lesser palatine nerves arise from the pterygopalatine ganglion.

Figure 31: Illustration of the branching of the maxillary division of the trigeminal nerve and the branching of the arteries of the 3rd part of the maxillary artery in the PPF (Norton, N. S. (2012). Netter's head and neck anatomy for dentistry. Philadelphia, PA: Elsevier/Saunders; Used with permission of the publisher Netter illustration from www.netterimages.com. © Elsevier Inc. All rights reserved.)

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Figure 32: Illustration showing the trigeminal ganglion in the middle cranial fossa with its three branches and V2 traveling through foramen rotundum to give off it’s branches in the PPF (Norton, N. S. (2012). Netter's head and neck anatomy for dentistry. Philadelphia, PA: Elsevier/Saunders; Used with permission of the publisher Netter illustration from www.netterimages.com. © Elsevier Inc. All rights reserved.)

Traveling from the trigeminal ganglion in the middle cranial fossa to the PPF through the foramen rotundum is V2 (Figure 32). Ganglionic branches, the zygomatic nerve, and the posterior superior alveolar nerve are branches of V2 that arise in the PPF.

As V2 enters the it changes names and becomes the infraorbital nerve

(Liebgott, 2011).

The ganglionic branches connect V2 to the pterygopalatine ganglion. These branches carry sensory fibers that pass through the pterygopalatine ganglion to supply nerve branches that are connected to the pterygopalatine ganglion. Nerve branches arising from the pterygopalatine ganglion include the nasopalatine, posterior superior nasal, greater and lesser palatine, and pharyngeal. Also traveling with the ganglionic

18 branches are the sympathetic postganglionic fibers to the lacrimal gland that pass through the pterygopalatine ganglion without synapsing (Norton, 2012).

The posterior superior alveolar nerve is the last branch to come off V2 before it enters the infraorbital canal. This nerve travels through the pterygomaxillary fissure and descends on the infratemporal surface of the maxilla. Dental and maxillary sinus branches from this nerve enter the maxillary sinus through the posterior superior alveolar foramen while gingival branches continue to travel on the outer surface of the maxilla

(Liebgott, 2011). Dental branches supply sensory function to maxillary molars with the possible exception of the mesiobuccal root of the 1st maxillary molars (Norton, 2012).

Maxillary sinus branches innervate the mucosa of the sinus and gingival branches innervate the buccal gingival along the maxillary molars (Liebgott, 2011).

Figure 33: Medial view demonstrating the branches to the pterygopalatine ganglion and branches coming off of the ganglion (Norton, N. S. (2012). Netter's head and neck anatomy for dentistry. Philadelphia, PA: Elsevier/Saunders; Used with permission of the publisher Netter illustration from www.netterimages.com. © Elsevier Inc. All rights reserved.)

19 Traveling through the sphenopalatine foramen are the nasopalatine and posterior superior nasal nerves. The nasopalatine nerve is a branch of V2 carrying sensory fibers.

Traveling with the nasopalatine nerve are parasympathetic and sympathetic fibers. It branches off the pterygopalatine ganglion (Figure 33) and enters the nasal cavity and supplies the posterior roof of the cavity. After entering the nasal cavity, it then travels anteroinferiorly over the nasal septum. While in the nasal cavity it has branches given off that supply the mucosa of the area. The nerve exits the incisive foramen of the maxilla, on the floor of the nasal cavity (Liebgott, 2011). Upon exiting the canal, the nerve lies in the mucoperiosteum, supplying the palatal gingival and mucosa in the area from central incisors to right and left canines (Norton, 2012). At the end point of the nasopalatine nerve, it communicates with the greater palatine nerve (Hollinshead, 1982).

The posterior superior nasal nerve also travels through the sphenopalatine foramen.

Once it enters the nasal cavity it branches into the lateral and medial posterior superior nerves. The lateral nerve supplies the lateral nasal septum while the medial nerve supplies the posterolateral part of the nasal septum (Norton, 2012).

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Figure 34: Illustration of the nasopalatine nerve traveling anteroinferiorly over the nasal septum and exiting through the incisive foramen to enter the oral cavity (Norton, N. S. (2012). Netter's head and neck anatomy for dentistry. Philadelphia, PA: Elsevier/Saunders; Used with permission of the publisher Netter illustration from www.netterimages.com. © Elsevier Inc. All rights reserved.)

The greater and lesser palatine nerves are branches off of the pterygopalatine ganglion that travel through the palatine canal to get to the hard and soft palates, respectively (Figure 33). The greater palatine nerve enters the hard palate through the greater palatine foramen and innervates the mucous membrane, palatal gingival, and palatal glands from the premolars back to the posterior border of the hard palate. The lesser palatine nerve enters the oral cavity through the lesser palatine foramen and innervates the soft palate (Norton, 2012).

The pharyngeal nerve arises from the pterygopalatine ganglion and travels through the pharyngeal canal to go into and innervate the nasopharynx (Norton, 2012).

21 The most superior fissure of the PPF is the inferior orbital fissure. Traveling through this fissure are the infraorbital and zygomatic nerves both of which are entering the orbit. The infraorbital nerve is the continuation of V2 and travels in the infraorbital canal and exits onto the face through the infraorbital foramen. In the canal, this nerve gives off two branches, an anterior superior alveolar, and a middle superior alveolar nerve, if present (Norton, 2012). Both the anterior and middle branches have dental, maxillary sinus, and gingival branches, while the anterior also has nasal branches. Dental branches of the anterior superior alveolar supply sensory function to maxillary central and lateral incisors, as well as maxillary canines. Dental branches of the middle superior alveolar nerve supply sensory function to maxillary premolars and the mesiobuccal root of the 1st maxillary molar. In cases that the middle superior alveolar nerve is absent, the maxillary premolars are innervated by the dental branches of the anterior superior alveolar nerve and the mesiobuccal root of the 1st maxillary molar is innervated by the posterior superior alveolar nerve. Maxillary sinus branches of both the anterior and middle superior alveolar nerves innervate the mucosa of the sinus. Gingival branches of the anterior superior alveolar innervate the vestibular gingiva along the maxillary premolars, while the gingival branches of the middle superior alveolar innervate the vestibular gingival along the canines and incisors. The anterior superior alveolar nerve also has nasal branches that help innervate the nasal septum, lateral wall, and floor of the oral cavity (Liebgott, 2011).

G. Vasculature

Vasculature traveling through the PPF include; maxillary artery (3rd part), infraorbital vessels, descending palatine vessels, vessels of the pterygoid canal,

22 pharyngeal vessels, sphenopalatine vessels, inferior ophthalmic vein, and the pterygoid plexus of veins.

The maxillary artery is a terminal branch of the external carotid and travels through the infratemporal fossa. The 3rd part of the maxillary artery leaves the infratemporal fossa through the pterygomaxillary fissure to enter the pterygopalatine fossa (Figure 35). The branches of the 3rd part of the maxillary artery are: superior alveolar, infraorbital, descending palatine, pharyngeal, sphenopalatine, and artery of the pterygoid canal. All of the branches except the superior alveolar, branch off the maxillary artery within the PPF. Each of these arteries has a vein accompanying them that receive blood from the region in which they are traveling and merge into the pterygoid plexus of veins (Norton, 2012).

Figure 35: Demonstration of the maxillary artery emerging off of the external carotid artery, traveling through the infratemporal fossa to enter the PPF (Norton, N. S. (2012). Netter's head and neck anatomy for dentistry. Philadelphia, PA: Elsevier/Saunders; Used with permission of the publisher Netter illustration from www.netterimages.com. © Elsevier Inc. All rights reserved.)

23 The artery of the pterygoid canal travels posteriorly through the pterygoid canal to supply sphenoid sinus and the auditory tube. The other artery traveling posteriorly is the pharyngeal artery. This artery passes through the pharyngeal canal to supply the auditory tube and nasopharynx (Norton, 2012).

The sphenopalatine artery branches of the 3rd part of the maxillary artery medially, traveling through the sphenopalatine foramen to enter the nasal cavity. In the nasal cavity it gives off posterior lateral nasal branches and posterior septal branches to supply nasal concha, nasal septum, and mucous membranes. Figure 36 shows the sphenopalatine artery traveling through the nasal cavity and exiting through the incisive canal to enter and supply the hard palate (Norton, 2012).

The descending palatine artery travels through the palatine canal and splits to become the greater and lesser palatine arteries. The greater palatine artery exits the greater palatine foramen and supplies mucosa, gingiva, and glands of the hard palate.

The artery travels anteriorly and anastomoses with the sphenopalatine artery. The lesser palatine artery exits at the lesser palatine foramen and supplies the soft palate (Norton,

2012).

24

Figure 36: Illustration of the sphenopalatine artery and its branches supply the nasal concha, nasal septum, and exiting at the incisive foramen (Norton, N. S. (2012). Netter's head and neck anatomy for dentistry. Philadelphia, PA: Elsevier/Saunders. Netter illustration from www.netterimages.com. © Elsevier Inc. All rights reserved.)

The travels anterior through the infraorbital canal and exits through the infraorbital foramen. The infraorbital artery gives off the anterior and middles superior arteries within the infraorbital canal that supply the same regions as the respective nerves. Within the canal the infraorbital artery gives off branches that supply the lacrimal gland and extraoccular muscles (Norton, 2012).

H. Computer-Assisted Learning

Computer-assisted learning has been developed over the years as technology has improved. With the advancement of technology, there is a general increase in interest by students to use all the latest gadgets and software. With this spiked interest, students have the ability to aid their traditional lecture/textbook learning by using computer- assisted learning. There have been studies done to determine if the use of computer- assisted learning is beneficial or even worthwhile (Vichivejpaisal, 2001).

25 One study performed to determine the impact on the ability to interpret cardiotochography used a before and after study to determine if it was beneficial. Their study showed no improvement in the amount that could determine cardiotochography before and after the completion of the computer assisted learning (Milde-Luthander et.al,

2012). The University of Queensland of Dentistry and the University of Queensland

Centre of Clinical Research in Australia completed a study to determine if computer- assisted or digital technologies were more beneficial than a textbook for dental students studying radiography. Their study showed that 95% of students indicated that the digital tool positively enhanced their learning experience by enabling them to better interact and engage themselves with the course material (Vuchkova, 2012).

A study titled “ Does computer-assisted instruction really help to improve the learning process?” showed that there was an insignificant difference between groups that simply used textbooks and a group that used computer-assisted instruction. They further determined that text-based learning is a convenient way to learn when time is limited but when more time is available, computer-assisted instruction certainly can enhance the learning development (Vichivejpaisal, 2001).

A comparison of studies can be endless and go back and forth amongst those who believe it is worthwhile, or those who believe it is more of a hassle and traditional learning is the best option. An article titled “Computer assisted learning in undergraduate medical education” discusses benefits of computer assisted learning and also factors that should be included when considering this option. The author makes points that it is inevitable, flexible, it has unique presentational benefits, it allows for personalize learning, promotes competitive advantage, and may reduce cost of presenting material

26 once the initial program is established. The author also addresses issues to be concerned about, including that a computer can at times be unpredictable and difficult to use without proper training. The author continues to mention that technical support and training could possibly be expensive as well as the initial cost of software, hardware, and additional supplies to set up a computer-assisted learning program (Greenhalgh, 2001).

II. Materials and Methods

A. CBCT

Anonymized CBCT files were selected from a series of patients with normal anatomy from Creighton University School of Dentistry. All of the scans had been performed at 0.3 mm resolution using an i-cat CBCT machine at Creighton University

School of Dentistry.

B. Dry Skull Specimens

Dry Skull specimens were provided by Creighton University School of

Dentistry. Digital images of the specimens were collected using a Canon Powershot

ELPH 100 HS. These images were inserted into Final Cut 10.0 and added to the multimedia resource video.

C. Dissection

Dissection of a lightly embalmed cadaver was done in a cadaver lab at

Creighton University School of Dentistry. Digital photos of nerves and arteries

27 going to and coming from the PPF were collected using a Canon Powershot ELPH

100 HS. These images were inserted into Final Cut 10.0 and added to the multimedia resource video.

D. Software

The CBCT scans were reconstructed using Osirix version 3.9.2 in axial, coronal, and sagittal planes. Using Osirix, the PPF was colored yellow in all sections that it is visible, in the axial, sagittal, and coronal planes. The three planes were then exported as individual videos to Final Cut 10.0 to be inserted into the multimedia learning resource video. Again using Osirix, the PPF and its seven foramina/fissures were all labeled using the color yellow. Additionally, osseous anatomy and anatomical spaces were labeled in additional colors to help in the orientation of where the PPF is located. Pictures of the

PPF and its openings were exported from Osirix in all three planes into Final Cut 10.0 and added into the multimedia learning resource video, after the videos of the colored in

PPF. From Osirix, these same labeled sections were exported as video in all three planes and inserted into the multimedia learning resource video in Final Cut 10.0. The axial view video plays in a superior to inferior aspect, the sagittal view plays in a lateral to medial aspect, and the coronal view plays in an anterior to posterior aspect.

Final Cut version 10.0 is a video-editing program produced by Apple Inc. It was used to create and edit this multimedia learning resource. Additionally, it was used to create voice recordings that were aligned with the proper clips within the video.

28 III. Results and Discussion

A multimedia learning resource for the pterygopalatine fossa was created using

CBCT videos, CBCT images, cadaver photographs, and dry skull specimen photographs.

The CBCT videos and images incorporated axial, sagittal, and coronal planes of the pterygopalatine fossa. Labeled and unlabeled cadaver and skull photographs were utilized. Audio was integrated to explain the clinical relevance of the anatomy of the pterygopalatine fossa.

There have been a number of different studies done comparing traditional learning versus computer-assisted learning. Some reports show that although results do not show a significant difference between the two, computer-assisted learning certainly seems to have its benefits and does enhance the learning process. The goal with this multimedia learning resource was not to replace the traditional learning experience of lecture/textbook learning, but to enhance that learning process. The fundamental basis of what the PPF is, and what is included within the fossa is presented in full detail in the traditional learning experience. From a lecture on the PPF, a student can learn the osseous anatomy that creates boundaries around the PPF, the anatomical spaces that the fossa is communicating with, and the nerves and vessels that are traveling through the fossa. Additionally, students may have the opportunity to dissect a cadaver. Even with this opportunity, the PPF is seen from the medial side and students are generally able to see only the nerve of the pterygoid canal, the greater and lesser palatine nerves with the descending palatine artery, and the infraorbital nerves and vessels. If the dissection is done carefully, the pharyngeal nerve may also be seen. The remaining nerves and vessels traveling through the PPF are often cut and visualizing the foramina/fissures while

29 dissecting may also be difficult. However, the visual aspects of what the PPF is may benefit from this multimedia learning resource that incorporates many different CBCT images and videos, as well as additional dissection and skull photos. In addition, this resource provides students the flexibility to visualize the PPF using their computer, tablets, or other visual technologies. Again, with the advancement of technology, students can not only use these resources to further their understanding, but in some cases, may prefer to use the technological tools.

As far as factors to consider with computer assisted learning, such as cost, support, training, and temperamental computers. The cost of this project was minimal because computers were available, so therefore software was the only purchase required.

The only training required was that needed to use Final Cut Pro and Osirix, both of which were learned on a go as you learn basis. There is minimal training for faculty or for students that will utilize this resource.

Moreover, this resource was created to aid in the visual enhancement of the PPF and is not meant to replace the traditional learning of what the PPF is and that it all entails.

IV. Conclusions

This learning resource provides dental students a tool to augment their understanding of the anatomy of the pterygopalatine fossa.

30 V. Citations

Baker, E. W. 1. (. W., Schünke, M., Schulte, E., & Schumacher, U. (2010). Head and

neck anatomy for dental medicine. New York: Thieme.

Cone-beam computed tomography.(2009). Dental Abstracts, 54(6), 292-295.

Daniels, D. L., Mark, L. P., Ulmer, J. L., Mafee, M. F., McDaniel, J., Shah, N. C., et al.

(1998). Osseous anatomy of the pterygopalatine fossa. AJNR.American Journal of

Neuroradiology, 19(8), 1423.

Govila, S., & Gundappa, M. (2007). Cone beam computed tomography - an overview.

Journal of Conservative Dentistry, 10(2), 53.

Greenhalgh, T. (2001). Computer assisted learning in undergraduate medical education.

BMJ: British Medical Journal, 322(7277), 40-44.

Hollinshead, W. H. 1. (1982). Anatomy for surgeons. United States:

Liebgott, B. (2011). The anatomical basis of dentistry. Maryland Heights, Mo: Elsevier

Mosby.

MacDonald, D., 1955. (2011). Oral and maxillofacial radiology: A diagnostic approach.

Ames, Iowa: Wiley-Blackwell.

31 Millde-Luthander, C., Högberg, U., Nyström, M. E., Pettersson, H., Wiklund, I., &

Grunewald, C. (2012). The impact of a computer assisted learning programme on

the ability to interpret cardiotochography. A before and after study. Sexual &

Reproductive Healthcare, 3(1), 37-41.

Norton, N. S. (2012). Netter's head and neck anatomy for dentistry. Philadelphia, PA:

Elsevier/Saunders.

Rogers, D. A., Regehr, G., Howdieshell, T. R., Yeh, K. A., & Palm, E. (2000). The

impact of external feedback on computer-assisted learning for surgical technical

skill training. The American Journal of Surgery, 179(4), 341-343.

Romans, L. E. (1995). Introduction to computed tomography. Baltimore: Williams &

Wilkins.

Scarfe, W. C., Farman, A. G., & Sukovic, P. (2006). Clinical applications of cone-beam

computed tomography in dental practice. Journal (Canadian Dental Association),

72(1), 75.

Sukovic, P. (2003). Cone beam computed tomography in craniofacial imaging.

Orthodontics & Craniofacial Research, 6(s1), 31-36.

Vichitvejpaisal, P., Sitthikongsak, S., Preechakoon, B., Kraiprasit, K., Parakkamodom,

S., Manon, C., et al. (2001). Does computer-assisted instruction really help to

improve the learning process? Medical Education, 35(10), 983-989.

32 Vuchkova, J., Maybury, T., & Farah, C. S. (2012). Digital interactive learning of oral

radiographic anatomy. European Journal of Dental Education : Official Journal of

the Association for Dental Education in Europe, 16(1), e79-e87.

White, S. C., & Pharoah, M. J. (2009). Oral radiology: Principles and interpretation. St.

Louis, Mo: Mosby/Elsevier.

Yoshida, N., Aso, T., Asaga, T., Okawa, Y., Sakamaki, H., Masumoto, T., et al. (2012).

Introduction and evaluation of computer-assisted education in an undergraduate

dental hygiene course. International Journal of Dental Hygiene, 10(1), 61.

33