Gross: 8:00-9:00Scribe: Sally Hamissou

Friday, February 20, 2009Proof: Sunita Jagani

Dr. SalterTemporal and Infratemporal FossaePage1 of 7

Abbreviations: MMA = Middle Meningeal Artery, TMJ = Temporomandibular joint, CN = Cranial Nerves

Temporal and Infratemporal Fossae

  1. Temporal and Infratemporal Fossae [S1]
  2. This is a dissection that can be carried out easily within the prescribed time and is important.
  3. Trigeminal nerve is included, we have already looked at V1, today we will look at V3, and V2 will be discussed next week when we talk about the pterygopalatine fossa.
  4. Temporal Fossa [S2]
  5. Depression in side of head and is bounded by superiorly 2 temporal lines and inferiorly by supramastoid crest
  6. All of this is the temporal fossa
  7. Floor: frontal, parietal, vertical portion sphenoid, squamous portion temporal bones (remember there are 5 parts)
  8. 4 cm superior to zygomatic arch is an important area, referred to as a pterion
  9. Deep to it lies the MMA- if you lacerate the skull, you may lacerate the vessel and you will have an epidural hematoma
  10. Temporal Fossa [S3]
  11. Temporal lines
  12. Superior Temporal Line
  13. Attachment of temporalis fascia
  14. Inferior Temporal Line
  15. Superior attachment of temporalis muscle
  16. The temporalis muscle arises from this fossa but has superior attachment to the inferior temporal line
  17. Netter Skull View [S4]
  18. The temporal fossa is bounded superiorly by the two temporal lines and bounded inferiorly by the zygomatic arch, superficially speaking. If we take a horizontal section, you would find the inferior aspect of the temporal fossa more deeply located than the zygomatic arch and that would be represented by removal of zygomatic arch.
  19. Removal of Zygomatic Arch allows one to view the deep, inferior boundary of temporal fossa deeply represented by the infratemporal crest of the greater wing of sphenoid bone.
  20. Bones and what attaches to them are very important
  21. Notice irregular border- temporalis muscle arises from that
  22. Deep temporal nerves and vessels run in between the juts of bones.The roughened edges and these passage ways are filled with deep temporal vessels and nerves, the temporalis muscle arises there.
  23. Infratemproal Fossa [S5]
  24. “An irregular space inferior and deep to the zygomatic arch and posterior to the maxilla” RTW
  25. The fossa is inferior to temporal fossa
  26. Surgical Access to Infratemporal Fossa [S6]
  27. Take off ramus of mandible, that is where the infratemporal fossa is
  28. Here is the surgical access to infratemporal fossa, accessed by mandibular fossa.
  29. The masseter muscle lies right in here.
  30. Today in the dissection, we are asked to remove masseter muscle from zygomatic arch, and when we reflect it inferiorly, you will find the nerves and vessels to the masseter to reach the masseter muscle by way of the mandibular notch and it also allows for surgical access to region as well.
  31. No Title [S7]
  32. However, removing the zygomatic arch & the ramus of the mandible allows greater access to the infratemporal fossa- this is what we will accomplish in the laboratory today
  33. Netter Skull View [S8]
  34. Remove zygomatic arch and ramus of mandible(which is the lateral border), and we encounter the infratemporal fossa
  35. Infratemporal Fossa Boundaries [S9-10]
  36. Medial: lateral surface of lateral pterygoid plate
  37. The lateral surface of the lateral pterygoid plate is the medial boundary here
  38. Lateral: ramus of the mandible
  39. Superior: zygomatic arch and horizontal part of greater wing of sphenoid, including infratemporal crest
  40. Inferior: is open
  41. Anterior: space posterior to the maxilla
  42. Posterior: temporal bone specifically the styloid process- one of five portions of the temporal bone.
  43. The deep portion or deep lobe of parotid gland wraps itself around styloid process, so its possible that the gland is a part of infratemporal fossa
  44. Netter Skull View [S10]
  45. What we will see in lab filled with the components of the infratemporal fossa
  46. Communications of Infratemporal fossa [S11-12]
  47. Communicates medially with pterygopalatine fossa via pterygomaxillary fissure
  48. Here is the maxilla, this is the pterygoid process of the sphenoid bone, so the fissure in between is the pterygomaxillary fissure
  49. Pterygomaxillary fissure leads to the pterygopalatine fossa
  50. [S12] Communicates anterior/superiorly with orbit via inferior orbital fissure
  51. Inferior orbital fissure leads to the orbit
  52. If one injects too much anesthetic into the infratemporal fassa, some will leak through inferior orbital fissure and manifest as eye muscle paralysis, as diplopia because of the communication here.
  53. Communicates superiorly with the middle cranial fossa through both the foramen ovale & the foramen spinosum
  54. Communication here with pterygopalatine fossa through pterygomaxillary fissure (you should realize these words and how you associate these words is important) remember pterygopalatine fossa, and the fissure that leads to that is the pterygomaxillary fissure
  55. Fossa also communications inferior orbit through the inferior orbital fissure.
  56. More than just an anesthetic can get in tooth region.
  57. Also a venous channel that runs into region.
  58. Holes in Roof [S13]
  59. Roof/Tangential view
  60. Foramen of roof communicate with the middle cranial fossa via the two foramen:Foramen spinosum and ovale, which lie in the roof of the infratemporal fossa
  61. Points out the pterygomaxillary fissure and the inferior orbital fossa.
  62. Foramen Spinosum
  63. Called spinosum because ‘spine of sphenoid’ to which a ligament attaches and we will show you the sphenomandibular ligament lies there
  64. Spine of sphenoid sits right there near the foramen, you should know exactly where the spine of the sphenoid is
  65. Figure of the Face [S14, 15]
  66. Components of the infratemporal fossa
  67. Take off venous plexus, you can see the muscles of mastification, V3, maxillary artery, and sphenomandibular ligament- these are the main components.
  68. Primary Contents [S16]
  69. Muscles of Mastication
  70. How many? 4
  71. Maxillary Artery there are two parts divided into 3 parts by a muscle.
  72. We have talked about arteries that have been divided into three parts because of muscles like Anterior scalene muscle divides subclavian artery into 3 parts, proximal, posterior, distal
  73. Pterygoid Plexus of Veins
  74. Important to dentists, abscesses from maxillary and mandibular teeth may drain into the pterygoid plexus of veins and concern is where it goes from there?
  75. Mandibular Nerve (V3)
  76. About all that we will see in the infratemporal fossa, we will see a small branch of V2.
  77. Chorda Tympani Nerve- looks like a cord in the middle ear, after it passes through middle ear into the infratemporal fossa, and carries on different modalities.
  78. Otic Ganglion- can’t identify, even harder to tag on practicals and has never been tagged, and he doesn’t expect us to find the otic ganglion.
  79. Sphenomandibular Ligament
  80. Can be seen and we will talk about it.
  81. Deep Lobe of Parotid Gland
  82. Nerve that runs through the gland is the facial nerve. If one injects into infratemporal fossa too much anesthetic, it may make its way into parotid gland and paralyze the facial nerve and the muscles supplied by the nerve.
  83. Local dentist called and had paralyzed the inferior alveolar nerve of his patient. This is an important issue because if you inject too much anesthetic, it can produces anesthesia in areas that supply the inferior alveolar nerve, lingual nerve, and also the facial nerve, so one has to be careful of that.
  84. Muscles of Mastification [S17]
  85. Temporalis
  86. Origin: temporal fossa
  87. Insertion: into the coronoid process of the ramus of mandible and inserts all the way down posterior to the third molar.
  88. The temporalis insertion is important
  89. It’s a big muscle to remove in lab because of it’s origin.
  90. Action: elevates mandibular and - primary elevator of the mandible and closer of orifice. Posterior fibers (run horizontally) retract mandible, so if the mandible was protruded out, you would use the posterior fibers to bring it back. So it is a retruder or retractor of the mandible.
  91. Masseter
  92. Origin: zygomatic arch, has a superficial origin, and the muscle peaking out deeply is the deep head of the masseter muscle, we won’t be focusing on there being a superficial and deep head of the masseter, but we will be identify this in lab.
  93. Action: Elevates mandible
  94. Medial and Lateral Pterygoid Muscles [S18]
  95. Deeply lined muscles
  96. Lateral Pterygoid Muscle
  97. Superior head arises from the roof of infratemporal fossa ( roof formed by the sphenoid bone). Since muscle arises from greater wing of sphenoid and attaches to the disk of the TMJ and the superior head is sometimes referred to as sphenoid meniscus head.
  98. Inferior head arises from the lateral surface of the lateral pterygoid plate. It is the larger of the 2 heads and arises from lateral surface of the lateral pterygoid plate. You can’t see the medial boundary of the infratemporal fossa of the pterygoid plate because it is covered up by the muscle.
  99. The inferior head runs and attaches to fovea (depression) in the neck of the mandible and this may be tagged on the next exam
  100. Medial pterygoid muscle
  101. Deep head arises from the medial surface of lateral pterygoid plate. The lateral surface of the lateral pterygoid plate arises is the lateral pterygoid muscle. Arising from the medial surface of the lateral pterygoid plate is the medial pterygoid muscle.
  102. Superficial head (we will have to identify this) arises from the maxillary tubercle. Insertion is the same, into the internal aspect of the angle of the mandible. Here is the masseter muscle inserting into the external aspect of the ramus of mandible, particularly at the angle and you can see the internal or medial pterygoid doing the same thing.
  103. Some dentist refer to this as pterygoid masseteric sling, there is the masseter here and underneath the angle is the medial pterygoid maxillary sling.
  104. Muscles involved in Mastification (Deep) [S19]
  105. Lateral Pterygoid- superior & inferior heads- protrude & depress mandible (by the inferior head)
  106. The inferior head depresses the mandible and it doesn’t take much to depress the mandible because gravity will bring it down.
  107. Medial Pterygoid- deep and superficial heads-- they elevate the mandible.
  108. [SQ] clarification on lateral pterygoid muscle. [A]: both heads might protrude the jaw and the inferior head depresses it.
  109. Another View of the Pterygoid Muscles and Another Function [S20]
  110. Another view and another function of the pterygoid muscles: Here is the lateral pterygoid and medial pterygoid muscles, they rise from opposite sides of the lateral plate of the pterygoid process of the sphenoid bone.
  111. Arising from the lateral surface of the lateral pterygoid plate is the inferior head of the lateral pterygoid. The medial surface of lateral pterygoid plate has the origin for the deep head of the medial pterygoid muscle.
  112. Another View & Function of the Pterygoids [S21]
  113. When both muscles contract unilaterally, as in grinding, the mandible moves horizontally in the contralateral direction.
  114. If the muscles contract, it will pull right side of mandible over to the other side, if it contracts and shortens it will pull the mandible, and therefore the other side of the mandible will deviate to the other side, so the muscles contract and will pull the right side of the mandible to the contralateral side
  115. If V3 injured or the muscles themselves are injured, so the muscle contralateral side will pull mandible over to the contralateral side, like the effect of a V3 lesion.
  116. Effect of V3 Lesion [S22]
  117. Opened jaw deviates towards the side of lesion.
  118. Maxillary Artery [S23, S24]
  119. 2 terminal branches around the neck of the mandible, we may have seen these in the dissections already.
  120. Around the head/neck of the mandible, the maxillary artery terminates into its two branches, superficial temporal and maxillary artery.
  121. Remove Ramus of Mandible [S25]
  122. If we remove the mandible, we can see more of the maxillary artery.
  123. Maxillary Artery [S26]
  124. 3 parts are designated because of the relationship of the second part of the artery to the lateral pterygoid muscle.
  125. 2/3 of the time, the second part lies superficial to the lateral pterygoid muscle and 1/3 of the time it lies deep to the lateral pterygoid muscle.
  126. 1st part (mandibular)- part proximal to lateral pterygoid
  127. Branches enter foramina/canals, remember that!
  128. 2nd part (pterygoid)
  129. All muscular branches- artery to masseter, buccinator, and pterygoid muscles all come off the second part of the maxillary artery
  130. Lies superficial to the lateral pterygoid muscle but sometimes it is deep to it and you may see both in the cadavers.
  131. 3rd part (pterygopalatine)- more distal or medial to lateral pterygoid muscle.
  132. Lies within the pterygopalatine fossa
  133. 1st part --Mandibular Part [S27]
  134. Concentrates on MMA, Inferior Alveolar Artery, and Accessory MMA.
  135. Inferior alveolar artery
  136. Passes through the mandibular foramen and passes with the inferior alveolar nerve. Sometimes it is damaged during the TMJ dissection/surgery.
  137. Deep to lateral pterygoid muscles: two branches- MMA and accessory MA
  138. MMA passes through the foramen spinosum, the middle cranial fossa, and the holes in the roof communicate the middle cranium fossa with the infratemporal fossa.
  139. The accessory MMA passes through foramen ovale, so if you see an artery passing through the foramen ovale, then it is the accessory MMA, no matter where it comes from. It can come from MMA or second part of the maxillary artery.
  140. Mandibular Nerve (V3)- Lateral View [S28]
  141. MMA
  142. Seen after removal of lateral pterygoid muscle.
  143. Take out lateral pterygoid muscle in order to see most of MMA.
  144. MMA runs in between the rootlets auriculotemporal nerve, we will identify it as being a large structure in the infratemporal fossa
  145. Usually passes in between the two roots but it may or may not do that.
  146. 2nd part –Pterygoid Part [S29]
  147. Located superficial to lateral pterygoid muscle
  148. All branches are muscular
  149. If we see an artery going to muscle of the buccinator or temporalis muscle and ask you from what part of the maxillary artery do they originate, it is from the 2nd part because all branches from the 2nd part are muscular.
  150. These are the deep temporal arteries that enter the deep aspect of the temporalis muscle.
  151. This is the buccal artery that runs with buccal branch of V3. These are branches to the pterygoid.
  152. 3rd part-Pterygopalatine Part [S30]
  153. 3rd part Is located in the pterygopalatine fossa and the fossa is medial to pterygomaxillary fissure.
  154. Today we will only see one branch of the third part of the maxillary artery, which originates within the pterygopalatine fossa, extends back out of the fossa, and extends thus.
  155. Posterior alveolar nerves which runs with the posterior superior alveolar artery, which you dentists will anesthetize on occasion.
  156. Blood Supply [S31]
  157. Here is the maxillary artery and the Inferior alveolar is seen on the slide also.
  158. From 1st part various branches
  159. MMA seen here, and you will have to remove a lot of lateral pterygoid to see expanse of the artery.
  160. Inferior alveolar artery and accessory MA is not seen here but we will see it in the lab downstairs.
  161. From 2nd part all muscular branches
  162. From 3rd part Posterior superior alveolar Artery
  163. The only one we will have to identify today, it runs and enters foramen on posterior aspect of superior alveolar arch, the arch is part of the maxilla. This is an artery that enters the superior/posterior aspect of the superior arch.
  164. Pterygoid Venous Plexus [S32, S33]
  165. When you take off ramus of mandible, the very first thing we will see is the pterygoid venous plexus
  166. Lateral pterygoid muscle is enveloped by pterygoid venous plexus
  167. The venous plexuses drains lower and upper teeth.
  168. Abscess from teeth, both mandible and maxilla can pass through the venous plexus
  169. Danger Triangle of Face [S34]
  170. Normally blood drains from medial angle of the eye, nose and lips into facial vein, via the deep facial vein back to something else.
  171. Because facial veins and tributaries don’t have valves, blood can drain deeply into pterygoid plexus and eventually into the cavernous sinus
  172. Cavernous Sinus Venus [S35]
  173. Points out : Superior ophthalmic vein, Inferior ophthalmic vein, Angular vein (beginning of facial vein), Facial vein, Deep facial vein (connects facial vein to pterygoid plexus), Pterygoid venous plexus, Cavernous Sinus, Superficial Temporal Vein joins with the Maxillary Vein to form the retromandibular vein
  174. Routes for infection- infection and bacteria from the face, angular vein can lead to the superior ophthalmic vein, carries infection back to cavernous sinus. The veins don’t have valves.
  175. Inferior ophthalmic runs in inferior aspect of the orbit, runs back and connects to cavernous sinus, bringing aboutthrombosis of the cavernous sinus.
  176. Facial vein carries infection by deep facial vein to pterygoid plexus of veins and eventually to cavernous sinus.
  177. Pterygoid plexus of veins drains laterally via maxillary vein, the maxillary vein joins the superficial temporal vein to form the retromandibular vein.
  178. And there is the IJV
  179. Mandibular Nerve V3 [S36]
  180. Very important
  181. Points out V1, V2, V3
  182. CN (Motor and Sensory Distribution): Schema [S37]
  183. V3 eventually goes through the mandible so mandibular branch
  184. Mandibular Nerve [S38]
  185. Four Areas of Supply:
  186. Muscles derived from first pharyngeal arch
  187. 4 muscles of mastification.