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Infratemporal fossa 360°

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Infratemporal fossa 360°

  1. 1. Infratemporal fossa 360° 10-12-2015 8.34pm
  2. 2. Great teachers – All this is their work . I am just the reader of their books . Prof. Paolo castelnuovo Prof. Aldo Stamm Prof. Mario Sanna Prof. Magnan
  3. 3. For Other powerpoint presentatioins of “ Skull base 360° ” I will update continuosly with date tag at the end as I am getting more & more information click www.skullbase360.in - you have to login to slideshare.net with Facebook account for downloading.
  4. 4. Infratemporal fossa anatomy video – Prof. Carrau – click https://www.youtube.com /watch?v=gnGcxC7pSy4
  5. 5. HTTPS://WWW.YOUTUBE.COM/WATCH ?V=2FXF0Z5DDB8 & HTTP://WWW.YOUTUBE.COM/WATCH? V=X-6YKLY84T4&SNS=FB Pterygopalatine Fossa - Gross Anatomy
  6. 6. Do we approach infratemporal fossa through ear ???? Answer : YES – by infratemporal fossa approaches A,B,C ,D [ ITFA-A,B,C ,D ]
  7. 7. Infratemporal fossa anatomy line diagram in both anterior & lateral skull base ( Infratemporal fossa approach A, B, C , D )
  8. 8. Pterygo-palatine fossa
  9. 9. Posterior wall of maxilla & pterygoid process is curved anteriorly
  10. 10. PPF is at supero-medial area of posterior wall of maxilla
  11. 11. PPF & palatine bone relation
  12. 12. Lateral to infraorbital nerve & V2 is Infratemporal fossa , Medial to ION & V2 is Pterygopalatine fossa
  13. 13. Pterygopalatine ganglion in PPF
  14. 14. Tracking of infraorbital nerve leads to V2 & tracking of V2 leads to Trigeminal ganglion/ Middle cranial fossa [ one of the best way to track middle crannial fossa is to track V 2 ]
  15. 15. Medial wall of PPF is perpendicular plate of palatine bone – foramen in it is sphenopalatine foramen
  16. 16. foramen rotandum is 5 mm to middle cranial fossa dura where as vidian nerve from vidial canal to laceral carotid is 2 cm – listen 4.00 time in this video https://www.youtube.com/watch?v=Uk57MEgkde8
  17. 17. PPF extended into orbital apex
  18. 18. The PPF extended to superior orbital fissure ( SOF ) / Orbital apex , inferior to the cavernous sinus and Muller’s muscle. – anterior skull base view
  19. 19. The PPF extended to superior orbital fissure ( SOF ) / Orbital apex , inferior to the cavernous sinus and Muller’s muscle. – Lateral skull base view
  20. 20. The PPF extended to superior orbital fissure ( SOF ) / Orbital apex , inferior to the cavernous sinus and Muller’s muscle. Anterior skull base Lateral skull base
  21. 21. Infratemporal fossa
  22. 22. Infratemporal fossa anatomy line diagram in both anterior & lateral skull base ( Infratemporal fossa approach A, B, C , D )
  23. 23. 1. One line along Vidian nerve & another line along V2 2. Lateral to LPP & infra-orbital nerve [ or V2 ] is Infratemporal fossa 3. One transverse line from Vidian nerve connecting vertical line of V 2 & another transverse line from V2 4. The space above transverse line of Vidian nerve is Pterygoid Recess of sphenoid 5. The space above transverse line of V2 is Middle cranial fossa ( Meckel’s cave )
  24. 24. 1. Pterygoid recess [= sphenoid recess ] is pneumatisation of pterygoid trigone – spac between V2 & VN [ Vidian nerve ] 2. The space above transverse line of Vidian nerve is Pterygoid Recess of sphenoid
  25. 25. Pvc, vc, FR are in a 45 degree angle
  26. 26. SOF also comes in the 45 degree angle – my observation
  27. 27. MPP[ medial pterygoid plate ] present at lateral surface of posterior choana – which is in line with paraclival carotid
  28. 28. Vidian canal is funnel shaped
  29. 29. 1. V1,V2,V3 of 5th nerve – V3 is 90° to V1 & V2 and anterior to petrous carotid like horse rider leg [ V3 ] [ mneumonic ] on saddle of horse [ petrous carotid & paraclival carotid junction ] 2. Vidian nerve is continuation of GSPN crosses laterally the laceral carotid
  30. 30. V1,V2,V3 of 5th nerve – V3 is 90° to V1 & V2 and anterior to petrous carotid like horse rider leg [ V3 ] [ mneumonic ] on saddle of horse [ petrous carotid & paraclival carotid junction ]
  31. 31. LPP if you look anteriorly (radiologically ) is in line with FR (V2) , if you look laterally posterior border of LPP leads to V3 . So when you are removing recurrent nasopharyngeal carcinoma transnasally you can observe LPP leads to V3 . This V3 seperates pre & post styloid compartments.
  32. 32. Posterior boarder of lateral pterygoid plate leads to foramen ovale
  33. 33. GSPN bisects V3 & petrous carotid
  34. 34. In the floor of sphenoid sinus you will get Vidian nerve when you approach by antero-lateral triangle
  35. 35. Hand model -- left hand = medial & lateral pterygoid right hand = index is parapharyngeal carotid , middle is IJV , ring is styloid & stylopharyngeal muscles , thumb is horizontal carotid
  36. 36. IAN = inferior alveolar nerve , LN = lingual nerve , MPM = medial pterygoid muscle , LPM = lateral pterygoid muscle Different layers of muscles & aponeurosis protecting great vessels in infratemporal fossa – Main protectors are medial & lateral pterygoid mucles & temporalis muscle - great vessels are posterior to these 3 muscles – small contribution of protection of great vessels are done by tensor veli palatini & styloid muscles & stylopharyngeal aponeurosis
  37. 37. IAN = inferior alveolar nerve , LN = lingual nerve , MPM = medial pterygoid muscle , LPM = lateral pterygoid muscle
  38. 38. TVPM is triangular muscle , LVPM is cylindrical muscle
  39. 39. SPM attached to superior constrictor , SGM attached to tongue , SHM attached to lesser cornu of hyoid bone
  40. 40. After drilling LPP & MPP longissmus capitis & superior constrictor seen .
  41. 41. Incision anterior to anterior to anterior pillar of tonsil for “Trans - Oral approach to infratemporal fossa”
  42. 42. Two planes posterior to MPM which have greater surgical importance ...... …..1. Nasopharyngeal carcinoma/JNA excision - plane between medial pterygoid muscle ( MPM ) & ET tube/TVPM ( tensor veli palatini muscle)........ 2 . Trans-oral exposure of Infratemporal fossa (ITF) - incision anterior to anterior pillar of tonsil - leads to - plane between MPM & superior constrictor / styloid muscles............In the below diagrams MPM reflected back for understanding purpose
  43. 43. Two planes posterior to MPM which have greater surgical importance ...... …..1. Nasopharyngeal carcinoma/JNA excision - plane between medial pterygoid muscle ( MPM ) & ET tube/TVPM ( tensor veli palatini muscle)........ 2 . Trans-oral exposure of Infratemporal fossa (ITF) - incision anterior to anterior pillar of tonsil - leads to - plane between MPM & superior constrictor / styloid muscles............In the below diagrams MPM reflected back for understanding purpose
  44. 44. 1. Each styloid muscle accompanied by one nerve – SPM by 9th nerve , SGM by lingual nerve , SHM by 12th nerve 2. SPM & SGM protects ICA whereas SHM protects both ECA & ICA 3. ECA & ICA & CCA are like tuning fork – caricature diagram
  45. 45. Each styloid muscle accompanied by one nerve – SPM by 9th nerve , SGM by lingual nerve , SHM by 12th nerve
  46. 46. MPM is reflected back – which shows the structures seen in trans-oral approach of ITF – incision anterior to anterior pillar of tonsil
  47. 47. Apex of infratemporal fossa
  48. 48. V3 & mma are together
  49. 49. Schematic diagram for infratemporal fossa approach – MMA & V3 & pterygoid plate from posterior to anterior
  50. 50. V3[MN] & MMA & ET in lateral & Anterior skull base – see the relationship of ET tube which is medial to V3 & MMA
  51. 51. V3 & mma are together 2. V3 accompanied by mma whereas IAN [ inferior alveolar nerve ] is accompanied by PSAA [ postero- superior alveolar nerve ] Lateral skull base Anterior skull base
  52. 52. After drilling the tympanic bone & styloid process inbetween jugular bulb & carotid , 9th nerve is seen
  53. 53. Cochlear aqueduct is a pyramidal shape structure present in between round window & jugular bulb – which is an important landmark for identification of 9th nerve in retrofacial mastoid air cells area .
  54. 54. Sympathetic trunk is posterior to vagus – below photo right side
  55. 55. SCG anastamosed with all the lower cranial nerves – below photo right side
  56. 56. Superior cervical ganglion is posterior to inferior ganglion of vagus – SCG lies over prevertebral facia over longus capitis – below photo left side
  57. 57. 11th nerve present inbetween vertebral artery & IJV
  58. 58. 11th nerve is postero-medial & antero- lateral to IJV Postero-medial to IJV Antero-lateral to IJV
  59. 59. 1. Anterior to IPS - 9th nerve seen , posterior IPS - 10th & 11th seen 2. 12th nerve crosses 10th nerve laterally
  60. 60. 1. Anterior to IPS - 9th nerve seen , posterior IPS - 10th & 11th seen 2. 12th nerve crosses 10th nerve laterally
  61. 61. 1. 9th & 12th nerves crosses parapharyngeal carotid above & below 2. supracondylar groove leads to Hypoglossal canal
  62. 62. 12th nerve seen in infra-petrous approach in anterior skull base
  63. 63. 9th & 12th nerves Anterior skull base Lateral skull base
  64. 64. 9th nerve is the most lateral nerve & 12th nerve is most medial nerve in skull base
  65. 65. ITFA with Transcondylar [ = TC ] Transtubercular [ = TT ] approach Here Transcondylar is through Occipital Condyle ; Transtubercular is through Jugular tubercle & lateral pharyngeal tubercle
  66. 66. Endoscopic endonasal view of a cadaveric dissection showing transection of the right eustachian tube (ET) attachment to foramen lacerum (FL). The hypoglossal nerve (XII) enters the hypoglossal canal just deep to the ET and separates the occipital condyle (OC) and the jugular tubercle (JT). (BA, basilar artery; ICA, internal carotid artery [paraclival segment]; IPS, inferior petrosal sinus; VN, vidian nerve.) B. Endoscopic endonasal view of cadaveric dissection showing the parapharyngeal internal carotid artery (ICA) and jugular foramen (JF) following transection and removal of the eustachian tube. (BA, basilar artery; IPS, inferior petrosal sinus; FL, foramen lacerum; JT, jugular tubercle; OC, occipital condyle; XII, hypoglossal nerve.)
  67. 67. Note 12th nerve in between JT ( Jugular tubercle ) & OC ( Occipital condyle ) in both lateral & anterior skull base Lateral skull base Anterior skull base
  68. 68. 1. Laceral carotid & jugular tubercle & lower cranial nerves 9th ,10th ,11th are in the same line . 2. hypoglossal canal present between occipital condyle/foramen magnum & jugular tubercle
  69. 69. 1. 9th & 12th nerves crosses parapharyngeal carotid above & below 2. 12th nerves originates medial to apex of parapharyngeal carotid 3. 11th nerve hinges the transverse process of C 1 4. 11 th nerve between vertebral artery & IJV 5. 9th nerve anterior to origin of IPS whereas 10th & 11th nerve posterior to origin of IPS 6. superior ganglion of vagus [ SGV ] is inside the jugular foramen where as inferior ganglion of vagus [ IGV ] is outside skull base
  70. 70. 1. 9th & 12th nerves crosses parapharyngeal carotid above & below 2. 12th nerves originates medial to apex of parapharyngeal carotid 3. 11th nerve hinges the transverse process of C 1 4. 11th nerve between vertebral artery & IJV 5. 9th nerve anterior to origin of IPS whereas 10th & 11th nerve posterior to origin of IPS 6. superior ganglion of vagus [ SGV ] is inside the jugular foramen where as inferior ganglion of vagus [ IGV ] is outside skull base
  71. 71. Incision anterior to anterior pillar of tonsil for “Trans - Oral approach of infratemporal fossa”
  72. 72. Incision of trans-oral approach of ITF is – anterior to anterior pillar of tonsil – pathway is between MPM & superior constrictor
  73. 73. 1. Each styloid muscle accompanied by one nerve – SPM by 9th nerve , SGM by lingual nerve , SHM by 12th nerve 2. SPM & SGM protects ICA whereas SHM protects both ECA & ICA 3. ECA & ICA & CCA are like tuning fork – caricature diagram
  74. 74. Each styloid muscle accompanied by one nerve – SPM by 9th nerve , SGM by lingual nerve , SHM by 12th nerve
  75. 75. MPM is reflected back – which shows the structures seen in trans-oral approach of ITF – incision anterior to anterior pillar of tonsil
  76. 76. Transoral approach to SUPERO-MEDIAL Parapharyngeal tumors – incision anterior to anterior pillar of tonsil
  77. 77. Infratemporal fossa approach A ITFA-A
  78. 78. The skin incision is made as shown. A cadaveric dissection, showing the facial nerve trunk (FNT) as it exits the stylomastoid foramen and the start of the pes anserinus (PA). IJV Internal jugular vein, MT Mastoid tip
  79. 79. In a right temporal bone, the intraparotid segment of the facial nerve (FNp) has been identified. An extended mastoidectomy has been carried out, removing the bony covering of the sigmoid sinus (SS) and revealing the posterior fossa and middle fossa dura (MFD). Skeletonization of the mastoid and tympanic segments of the facial nerve (FN) has been carried out. C Basal turn of the cochlea (promontory), DR Digastric ridge, LSC Lateral semicircular canal The superstructure of the stapes (S) is being cut using straight scissors. FN Facial nerve, LSC Lateral semicircular canal
  80. 80. Decompression of the nerve is being carried out. C Basal turn of the cochlea (promontory), FN(m) Mastoid segment of the facial nerve, FN(t) Tympanic segment of the facial nerve, G Facial nerve genu, LSC Lateral semicircular canal, SS Sigmoid sinus The mastoid tip (MT) is being removed by avulsing it posteriorly away from the stylomastoid foramen (SMF), to avoid injuring the nerve at this level. FN(m) Mastoid segment of the facial nerve, SS Sigmoid sinus, T Tympanic bone
  81. 81. The last shell of bone covering the mastoid (FNm) and tympanic (FNt) segments of the facial nerve is now ready to be removed. The new fallopian canal (NC) drilled into the root of the zygoma can be seen. LSC Lateral semicircular canal, PD Posterior belly of the digastric muscle, SMF Stylomastoid foramen, TB Tympanic bone The last shell of bone covering the mastoid segment of the facial nerve (FNm) is being removed. ET Eustachian tube, FN(p) Intraparotid facial nerve, G Genu, SM Stylomastoid foramen, SS Sigmoid sinus
  82. 82. The bony covering of the tympanic segment of the facial nerve is being removed. FN(m) Mastoid segment of the facial nerve, G Genu, LSC Lateral semicircular canal, NC New fallopian canal The bone overlying the proximal part of the tympanic segment (FNt) and the geniculate ganglion is being removed, although the nerve is not to be rerouted at this level. The reason for removing bone here is to prevent it from injuring the rerouted part of the nerve. ET Eustachian tube, LSC Lateral semicircular canal, MFD Middle fossa dura, NC New fallopian canal
  83. 83. A tunnel is being created in the soft tissues of the parotid gland (PT) to accommodate the distal part of the rerouted nerve. FN(m) Mastoid segment of the facial nerve, NC New canal, PD Posterior belly of the digastric muscle, SM Stylomastoid foramen A nontoothed forceps is used to hold the soft tissues (ST) surrounding the nerve at the level of the stylomastoid foramen (SMF), and sharp scissors are used to dissect the soft tissues from the bone at that level. C Cochlea, FN(m) Mastoid segment of the facial nerve, LSC Lateral semicircular canal, NC New canal, SS Sigmoid sinus
  84. 84. The fibrovascular attachments (<) between the mastoid segment of the facial nerve (FNm) and the fallopian canal (FC) should be sharply cut. The attachments shown in Fig. 9.14 are being sharply cut to avoid injuring the mastoid segment (FNm) of the nerve. FC Fallopian canal
  85. 85. The required length of the facial nerve has been dissected away from the fallopian canal; the arrows (> <) show the limit. Keeping this proximal part of the tympanic segment of the nerve (FNt) and the geniculate ganglion attached to the canal medially will help preserve part of the blood supply, resulting in better facial nerve function. FN(m) Mastoid segment of the facial nerve, LSC Lateral semicircular canal, NC New canal In preparation for rerouting, the soft tissues (ST) surrounding the facial nerve at the stylomastoid foramen are being held by a nontoothed forceps. FN(m) Mastoid segment of the facial nerve, FN(p) Intraparotid facial nerve, FN(t) Tympanic segment of the facial nerve, NC New canal
  86. 86. Rerouting of the facial nerve. FN(m) Mastoid segment of the facial nerve, FN(p) Intraparotid facial nerve, SM Facial nerve at the stylomastoid level, ST Soft tissues The facial nerve has been rerouted into the new canal (*). FC Fallopian canal, FN(p) Rerouted part of the intratemporal facial nerve, FN(t) Rerouted part of the tympanic segment of the facial nerve, ST Soft tissues
  87. 87. After the attached muscles have been dissected away, the styloid process (SP) is fractured using a rongeur. FC Fallopian canal, FN Facial nerve, FN(p) Rerouted part of the intraparotid facial nerve, TB Temporal bone To obtain control over the vascular structures as they enter the temporal bone, the tympanic bone (TB), the fallopian canal remnants (FC), and the infralabyrinthine air cells are all to be removed. C Basal turn of the cochlea (promontory), IJV Internal jugular vein, JB Jugular bulb, SS Sigmoid sinus
  88. 88. The view after completely uncovering the lateral surfaces of the vascular structures. C Basal turn of the cochlea (promontory), ICA Internal carotid artery, IJV Internal jugular vein, JB Jugular bulb, SS Sigmoid sinus If further anterior exposure of the internal carotid artery (ICA) is required, a retractor is used to keep the mandibular condyle displaced anteriorly. C Basal turn of the cochlea (promontory), FN Rerouted facial nerve, IJV Internal jugular vein, JB Jugular bulb, LSC Lateral semicircular canal, RW Round window, SS Sigmoid sinus
  89. 89. The proximal end of the sigmoid sinus is closed by extraluminal packing of connective tissue (CT). FN Rerouted facial nerve, ICA Internal carotid artery, JB Jugular bulb, MFD Middle fossa dura, SS Sigmoid sinus The lateral wall of the sigmoid sinus (SS) has been opened. CT Connective tissue, IJV Internal jugular vein, L Lumen of the sigmoid sinus
  90. 90. The distal portion of the opened sigmoid sinus is packed with connective tissue (CT). ICA Internal carotid artery, IJV Internal jugular vein, JB Jugular bulb, L Lumen of the sigmoid sinus The internal jugular vein (IJV) is being dissected away. ICA Internal carotid artery, JB Jugular bulb
  91. 91. The view after removal of the internal jugular vein and jugular bulb. Note that in live surgery, the opening of the inferior petrosal sinus (IPS) will start bleeding, requiring it to be packed. IX Hypoglossal nerve, X Vagus nerve, C Basal turn of the cochlea (promontory), ICA Internal carotid artery The plane of dissection between the internal carotid artery (ICA) and the overlying periosteum (P) is best developed at the entrance of the artery into its canal. C Basal turn of the cochlea (promontory)
  92. 92. A suction tube is used to displace the internal carotid artery (ICA) laterally while the medially lying bone is being drilled. C Basal turn of the cochlea (promontory), IPS Inferior petrosal sinus The suction tube is used here both to displace the artery and to protect it during drilling of the anteriorly lying bone. ICA(h) horizontal segment of the internal carotid artery, ICA(v) vertical segment of the internal carotid artery
  93. 93. Infratemporal fossa approach B ITFA-B
  94. 94. Posterolateral (Glasscock's) Triangle approach in Trans-temporal skull base approaches is called “ Infra- temporal fossa B approach “ by Prof. Mario sanna The petrous apex as viewed through the infratemporal fossa type B approach. Structures lying lateral to the internal carotid artery (ICA). The mandibular nerve (V3) and the middle meningeal artery have been cut. The instrument points to the position of the already drilled bony eustachian tube (ET).
  95. 95. Iatrogenic chances of injury of cochlea in infratemporal fossa transpetrous approach
  96. 96. The skin incision. The external auditory canal (arrow) is closed as cul-de-sac.
  97. 97. The temporalis muscle is detached anteriorly. The zygomatic arch is transected. Arrows point to the transection sites.
  98. 98. Subtotal petrosectomy. The facial nerve (FN) is skeletonized and the vertical internal carotid artery (ICA) is identified.
  99. 99. A minicraniotomy helps positioning the infratemporal fossa retractor. Identification of the middle meningeal artery (MMA) crossing lateral to the eustachian tube (ET).
  100. 100. Coagulation of the middle meningeal artery (MMA). Cutting the middle meningeal artery (MMA).
  101. 101. Identification of the mandibular nerve (V3). The mandibular nerve (V3) is cut.
  102. 102. Suturing the eustachian tube (ET) at the end of the procedure. Closure and drain insertion.
  103. 103. Infratemporal fossa approach B in cadaver
  104. 104. The temporalis muscle (TM ) of a left temporal bone has been reflected anteriorly after it has been dissected from the squamous bone (S). TL Temporalis line, ZR Root of the zygomatic process
  105. 105. The periosteum (P) overlying the zygomatic arch (ZA) is being dissected away. This step helps avoid the laterally lying frontal branch of the facial nerve. SB Squamous bone The view after dissection of the periosteum (P) from the zygomatic arch (ZA). SB Squamous bone, TM Temporalis muscle
  106. 106. The zygomatic arch has been transected. EAC External auditory canal, SB Squamous bone, TM Temporalis muscle, ZR Zygomatic root The skin of the external auditory canal (S) is being dissected away under the microscope. TM Tympanic membrane
  107. 107. After complete removal of the external auditory canal skin and tympanic membrane, the incudostapedial joint is disarticulated in order to remove the ossicular chain. C Chorda tympani, I Incus, M Malleus, S Stapes The mastoid cavity and the posterior and superior walls of the external auditory canal have been partially drilled. FB Facial bridge, FR Facial ridge, MFP Middle fossa plate, SS Sigmoid sinus
  108. 108. A radical mastoidectomy has been carried out, and the facial nerve has been skeletonized. AR Anterior attic recess, C Basal turn of the cochlea (promontory), DR Digastric ridge, FN(m) Mastoid segment of the facial nerve, FN(t) Tympanic segment of the facial nerve, LSC Lateral semicircular canal, MFP Middle fossa plate, PSC Posterior semicircular canal, RW Round window, S Stapes, SS Sigmoid sinus, SSC Superior semicircular canal, TT Tensor tympani The retrofacial and infralabyrinthine air cells are being drilled using an appropriately sized diamond drill. Attention must be paid during this step to avoid injuring the laterally lying facial nerve with the burr or the shaft. ELS Endolymphatic sac, FN(m) Mastoid segment of the facial nerve, ICA Internal carotid artery, SS Sigmoid sinus
  109. 109. The anterior wall of the external auditory canal has been partially drilled, and the vertical segment of the internal carotid artery (ICA) has been identified. FN(m) Mastoid segment of the facial nerve, FN(t) Tympanic segment of the facial nerve, JB Jugular bulb, LSC Lateral semicircular canal, S Stapes, SS Sigmoid sinus, TT Tensor tympani Dissecting the articular disk (AD) of the temporomandibular joint. ACWAnterior canal wall, SB Squamous bone, ZR Zygomatic root
  110. 110. A small craniotomy (CT) has been created in the squamous bone. ACWAnterior canal wall, AD Articular disk A self-retaining retractor is used to keep the mandible retracted inferiorly. ACWAnterior canal wall, AZT Anterior zygomatic tubercle, GF Glenoid fossa
  111. 111. The rest of the anterior canal wall has been drilled away, and the internal carotid artery is better skeletonized. C Basal turn of the cochlea (promontory), ET Eustachian tube, FN(m) Mastoid segment of the facial nerve. G Genu of the internal carotid artery, ICA(v) Vertical segment of the internal carotid artery To obtain control of the horizontal segment of the internal carotid artery, the eustachian tube (ET), glenoid fossa bone (GF), and the anterior zygomatic tubercle (AZT) have to be carefully drilled away. ICA Vertical segment of the internal carotid artery
  112. 112. In live surgery, the middle meningeal artery (MMA) should be coagulated to prevent bleeding. ICA Internal carotid artery, MFP Middle fossa plate The middle meningeal artery (MMA) is being sharply cut. ET Eustachian tube, ICA Internal carotid artery, MFP Middle fossa plate
  113. 113. Further anterior drilling uncovers the mandibular nerve (MN). This nerve also has to be coagulated in live surgery before it is cut. ET Eustachian tube, ICA Internal carotid artery, MFP Middle fossa plate Sharply cutting the mandibular nerve (MN). ET Eustachian tube, ICA Internal carotid artery, MFP Middle fossa plate
  114. 114. The stumps of the mandibular nerve (*). ET Eustachian tube, ICA Internal carotid artery, MFP Middle fossa plate The eustachian tube (ET) and tensor tympani muscles (TT) are the last structures lying lateral to the horizontal segment of the facial nerve and should be removed. ICA Internal carotid artery, JB Jugular bulb, MN The cut end of the mandibular nerve
  115. 115. The lateral, thin part of the eustachian tube (ET) that remains can be removed with forceps. C Basal turn of the cochlea (promontory), ICA Internal carotid artery, MFP Middle fossa plate The tensor tympani muscle has been dissected away from its canal (TTC). ET Medial wall of the eustachian tube, ICA Internal carotid artery, MFP Middle fossa plate
  116. 116. A large diamond burr is used to remove the remaining bone overlying the horizontal segment of the internal carotid artery. C Basal turn of the cochlea (promontory), ICA Vertical segment of the internal carotid artery, MFP Middle fossa plate, MMA Stump of the middle meningeal artery, MN Stump of the mandibular nerve The horizontal segment of the internal carotid artery (ICAh) has been skeletonized. Note that the greater petrosal nerve (GPN) is adherent to the dura, and that retracting the dura will lead to stress on the facial nerve at the geniculate ganglion (GG) level. Thus, if dural retraction is needed, cutting the petrosal nerve will prevent this injury. C Basal turn of the cochlea (promontory), CL Clivus bone, G Genu, ICA(v) Vertical segment of the internal carotid artery
  117. 117. The tip of the suction is used to displace the internal carotid artery (ICA) laterally while the medially lying bone is being drilled. C Basal turn of the cochlea (promontory), FN(m) Mastoid segment of the facial nerve, FN(t) Tympanic segment of the facial nerve, GPN Greater petrosal nerve, MFP Middle fossa plate, MMA middle meningeal artery stump Drilling of the clivus has been completed. C Basal turn of the cochlea (promontory), FN(m) Mastoid segment of the facial nerve, FN(t) Tympanic segment of the facial nerve, GG Geniculate ganglion, GPN Greater petrosal nerve, ICA Internal carotid artery, RW Round window
  118. 118. The full course of the intratemporal internal carotid artery has been freed. AFL Anterior foramen lacerum, CF Carotid foramen, CL Dura overlying the clivus area, ICA(h) Horizontal segment of the internal carotid artery, ICA(v) Vertical segment of the internal carotid artery, MN Stump of the mandibular nerve The view after completion of the approach.
  119. 119. The relationship of the internal carotid artery (ICA) to the tympanic membrane (TM) and middle ear in a right temporal bone. A Annulus, FN(m) Mastoid segment of the facial nerve, I Incus, JB Jugular bulb, LSC Lateral semicircular canal, M Malleus, MFD Middle fossa dura, PSC Posterior semicircular canal, SSC Superior semicircular canal
  120. 120. Infratemporal fossa approach C ITFA-C This is an anterior extension of the type B approach, in which the pterygoid process is drilled, providing control of the nasopharynx, the pterygopalatine fossa, and the sphenoid sinus (Fig. 9.18). The approach is designed to give lateral access for the extirpation of extradural lesions involving the infratemporal fossa, the nasopharynx, the pterygopalatine fossa, the sphenoid sinus, and minimal extension into the cavernous sinus.
  121. 121. The sphenoid (SphS) sinus lies superomedial to the base of the pterygoid. The bony anatomy of the base of the skull. The hatched line represents the pharyngobasilar fascia.
  122. 122. Cutting the fibrous attachments of the eustachian tube (ET). The petro-occipital synchondrosis (arrow) separating the clivus from the petrous apex.
  123. 123. Exposure of the base and lateral process (PtP) of the pterygoid. Opening the nasopharynx (NP).
  124. 124. Locating the sphenoid sinus (SphS). The maxillary nerve (V2) runs roughly at the level of the sinus roof. Retracting the middle fossa dura allows complete control of the horizontal internal carotid artery (ICA) to the foramen lacerum. AFL, anterior foramen lacerum.
  125. 125. Opening the sphenoid sinus (SphS). Cutting the maxillary nerve to gain access to the lateral wall of the cavernous sinus.
  126. 126. The abducent nerve (VI) crosses from the medial to the lateral aspect of the internal carotid artery (ICA) before entering the cavernous sinus.
  127. 127. The Group of Preauricular Transzygomatic Approaches 1. Type D Infratemporal Fossa Approach 2. Preauricular Infratemporal Transzygomatic Approach 3. Preauricular FTOZ = Frontotemporal Orbitozygomatic Approach
  128. 128. Type D Infratemporal Fossa Approach Rationale The type D approach is like the type C but is performed through a preauricular incision. Mastoidectomy is not performed and the middle ear is left intact. The eustachian tube is not sacrificed. The approach is designed for infratemporal fossa lesions with or without extension to the pterygopalatine fossa, sphenoid sinus, and/or minimal cavernous sinus extension; for example, trigeminal neurinomas with predominant infratemporal fossa component and minimal middle fossa extension. The approach will be discussed together with the more extensive preauricular approaches, namely, the preauricular infratemporal fossa
  129. 129. Preauricular Infratemporal Transzygomatic Approach Rationale The preauricular infratemporal approach is a variant of theinfratemporal approach in which a large frontotemporal craniotomy is performed. This approach is suitable for infratemporal fossa lesions with or without extension to the petrous apex, sphenoid sinus, or upper clivus or minimal cavernous sinus extension. It is suitable for both intradural and extradural lesions affecting the upper clivus and parasellar regions. The craniotomy allows tumor removal with minimal brain retraction.
  130. 130. Skin incision. A semilunar incision (arrows) is made in the superficial layer of the deep temporal fascia.
  131. 131. The temporalis muscle, zygomatic arch, and orbital rim are fully exposed. The temporalis muscle (TeM) is incised in a line about 1 cm along its attachment. Drawing showing the zygomatic cuts for the pure transzygomatic approach.
  132. 132. Orbitozygomatic osteotomy performed. Drawing showing the partial orbitozygomatic osteotomy.
  133. 133. Zygomatic and Orbitozygomatic Osteotomy The zygomatic osteotomy is performed according to the extension of the lesions as follows: a) In limited cases, only the zygomatic arch is displaced inferiorly. The zygomatic bone and the lateral orbital rim are left intact . b) For the majority of lesions only an “extended” zygomatic osteotomy is performed in which the zygomatic arch and part of the zygomatic bone are included in the zygomatic osteotomy . The orbitozygomatic osteotomy in more advanced cases in which the tumor extends into the orbital apex through the inferior or superior orbital fissures: The frontal and temporal dura are detached from the periorbita exposing the bony orbit.
  134. 134. Standard orbitozygomatic osteotomy. Standard orbitozygomatic osteotomy.
  135. 135. Drawing outlining the lines of the standard orbitozygomatic osteotomy.
  136. 136. The removed orbitozygomatic bone to be placed in saline.
  137. 137. The bone is drilled to the base of the middle fossa (MFD). The temporal lobe is retracted for further bone removal. The hatched lines represent the bone that needs to be removed for the standard orbitozygomatic osteotomy.
  138. 138. With temporal lobe retraction, the three branches of the trigeminal nerve (V1, V2, V3) are exposed. More exposure can be gained by further performing the standard orbitozygomatic osteotomy.
  139. 139. Approach of infratemporal fossa by anterior skull base
  140. 140. 1. External corridor doesn’t matter except cosmesis , only internal corridor matters – so in Open approaches of skull base also use endoscope to get best results – see this video how the Dr. Dugani Suresh ; Neurosurgeon is using endoscope in Weber Fergusson incision https://www.youtube.com/watch?v=Y95Jf3u8S8o&feature=y outu.be 2. Most of the times “Don’t cross the NERVES”
  141. 141. Only to lesion lateral to meridian of pupil in frontal sinus we have to do osteoplastic flap The landmarks for canine fossa puncture/trephine are the intersection between a vertical line through the pupil and a horizontal line drawn through the floor of the nose.
  142. 142. Enhanced T1-weighted magnetic resonance imaging (MRI), coronal section demonstrates a right nasoethmoidal lesion (adenocarcinoma) with an “hourglass” intradural extension through the ethmoidal roof. Diffuse enhancement of the dural layer (arrowheads) over the orbital roof is suspicious for neoplastic spread. The vertical lines limit the area of the dura safely resectable by a pure endoscopic approach.
  143. 143. “Up & below” approach to frontal sinus
  144. 144. Illustration of the septal incisions necessary to achieve good access to the entire anterior wall of the maxillary sinus for tumors either originating from this region or with a significant anterior wall attachment. (B) Cadaveric image demonstrating the access to the anterior wall (AW) of the maxillary sinus with a 70-degree diamond drill (D).
  145. 145. (A) The microdebrider blade has been passed through an inferior meatal antrostomy. Note the anterior fulcrum (nasal vestibule, broken white arrow) and the posterior fulcrum (inferior meatal antrostomy, white arrow). The region of the maxillary sinus that can be cleared through this access is shaded. This shaded region is smaller with a middle meatal antrostomy. The single fulcrum of the canine fossa puncture is indicated (white arrow) (B,C,D), illustrating how the entire maxillary sinus can be accessed as the blade only has a single fulcrum.Medial , posterior & Lateral walls approached through Caldwel-luc
  146. 146. The red arrows demonstrate the endonasal approach, and the green arrows represents the transmaxillary approach. The blue rectangle shows the parasellar structures. A more perpendicular angle of attack is achieved in the transmaxillary approach, and the distance to the target from this route is equal to or smaller than that in the endonasal approach. Temp.: temporal.
  147. 147. Note that in the transmaxillary approach the structures in the lateral wall of the sphenoid sinus are seen in a more perpendicular way, facilitating dissection of this region.
  148. 148. Close-up view of the cavernous sinus through the transmaxillary approach. Gasser.: gasserian.
  149. 149. The pink and orange lines demonstrate the possible angles of maneuver in transmaxillary approach. In green is emphasized the possibilities of resection through transmaxillary approach.
  150. 150. General view of the radial endoscopic accesses to the skull base --- The green arrows represent the endonasal approaches, the red arrows represent the transmaxillary approaches, and the purple arrows represent the subtemporal approaches. Note the multiple possibilities of combination of these approaches.
  151. 151. Modified denkers approach - Blue dotted line shows the medial maxillary wall. (B) Panoramic view after removing the medial maxillary wall. Yellow dotted line shows the connected nasal cavity with maxillary sinus the maxillary sinus.
  152. 152. Schematic demonstrating how the removal of the lateral aspect of the piriform overture (in the red circle) enables a wider approach (the green cone compared with the yellow cone) to the lateral regions (pterygopalatine and infratemporal fossa).
  153. 153. Use combination of approaches when ever it is necessary - Combined Transmastoid Middle Cranial Fossa Approach
  154. 154. Rt lower cranial nerve shwannoma, which approach will be better ,which approach will be better considering this side is dominant sinus.
  155. 155. Answer • Amit Keshri says - eight nerve was normal,so was 7th,removed tumor completely with retrolab approach and to get space,the sigmoid plate was decompressed and sinus retracted posteriorly after RMSO [ Retro mastoid sub-occipital ] craniotomy without opening dura posteriorioly. • Murali Chand Nallamothu For lower cranial nerve schawnnoma POTS approach is the best - but here you are saying it is dominent sinus , no need to sacrifice sigmoid sinus -- so in this case we can use extended translabyrinthine approach for the AFB area part & at carotid canal area part of the tumor can be removed by externally which is included in the lower C - shaped incision • Murali Chand Nallamothu if the 8 th nerve is good we can try retrolabyrinthinne & retrosigmoid approach & take the help of endoscope. • Post-op :
  156. 156. Approaches to Infratemporal fossa
  157. 157. B, approach to infratemporal fossa. A, approach to MCF through greater wing of sphenoid bone.
  158. 158. MPP/VN LPP/V2
  159. 159. Anteriorly MPP & LPP are fused & posterioly only they are divided .
  160. 160. Anteriorly MPP & LPP are fused & posterioly only they are divided .
  161. 161. Erosion of right greater wing of sphenoid in a case of maxillary carcinoma
  162. 162. Medial pterygoid is in line with lateral wall of Sphenoid -- The superior vertical limb represents the paraclival ascending carotid and the descending vertical limb is represents the medial pterygoid plate. The horizontal bar of the ‘H’ is represented by the sphenoid sinus floor.
  163. 163. Lateral part of Posterior choanae is MPP
  164. 164. ET is just posterior to MPP
  165. 165. Lateral part of Posterior choanae is MPP
  166. 166. Medial pterygoid is in line with Paraclival carotid
  167. 167. Tracking of infraorbital nerve leads to V2 & tracking of V2 leads to Trigeminal ganglion/ Middle cranial fossa [ one of the best way to track middle crannial fossa is to track V 2 ]
  168. 168. Zygomatic nerve [ ZN ]
  169. 169. Infraorbital groove near inferior orbital fissure – If we drill supero-lateral to infraorbital nerve it is nothing but Inferior orbital fissure .
  170. 170. Infraorbital groove near inferior orbital fissure – If we drill supero-lateral to infraorbital nerve it is nothing but Inferior orbital fissure .
  171. 171. Red ring = V2
  172. 172. Inferior orbital foramen continues as pterygomaxillary fissure .
  173. 173. One line along Vidian nerve & another line along V2
  174. 174. Lateral to LPP & infra-orbital nerve [ or V2 ] is Infratemporal fossa
  175. 175. One transverse line from Vidian nerve connecting vertical line of V 2 & another transverse line from V2
  176. 176. The space above transverse line of Vidian nerve is Pterygoid Recess of sphenoid – Read the CT – scan/ Plane the surgery by using these lines
  177. 177. The space above transverse line of V2 is Middle cranial fossa ( Meckel’s cave ) – Read the CT – scan/ Plane the surgery by using these lines
  178. 178. Pterygo-palatine fossa
  179. 179. Pterygopalatine fossa. A, V2 (blue dotted line) coming out from the foramen rotundum; B, green-yellow dotted line shows the pterygopalatine ganglion; C, yellow dotted line shows the vidian nerve; D, red dotted line shows the sphenopalatine artery; E, light blue dotted line shows the great palatine nerve; F, white dotted line showing the infraorbital artery.
  180. 180. EC – Ethmoidal crest – left nose
  181. 181. Vidian canal is funnel shapped
  182. 182. PVC , VC & FR are in 45 degree angle line
  183. 183. Endoscopic view of PPG
  184. 184. Tracking of infraorbital nerve leads to V2 & tracking of V2 leads to Trigeminal ganglion/ Middle cranial fossa [ one of the best way to track middle crannial fossa is to track V 2 ]
  185. 185. Zygomatic nerve [ ZN ]
  186. 186. Endoscopic view of foramen rotundum area
  187. 187. Infratemporal fossa
  188. 188. Lateral pterygoid muscle devides internal maxillary artery into 3 parts - 1 . Mandibular part 2. lateral pterygoid [ infratemporal fossa ] part 3. pteygo-palatine fossa part
  189. 189. Dissection done by Dr.Janakiram , india
  190. 190. 1. The maxillary artery & Buccal nerve enters the infratemporal fossa between the superior and inferior head of the lateral pterygoid muscles. 2. Lingual nerve & Inferior alveolar nerve comes between medial pterygoid & lateral pterygoid mucles .
  191. 191. .
  192. 192. Anteriorly lingual nerve & posteriorly Inferior Alveolar nerve coming lateral to medial pterygoid muscle – Lingual nerve is just submucous & palpable just posterior to 3rd molar
  193. 193. Forceps behind IAN Forceps behind LN
  194. 194. IAN = Inferior alveolar nerve
  195. 195. Triangle formed by temporalis muscle , MPM & LPM Mandibulotomy approach Endospic view
  196. 196. Post-maxillectomy “Fat pad” over temporalis muscle – which is seen as Fat Pad [ FP ] in the triangle formed by temporalis mucle , MTM & LPM endoscopically
  197. 197. Internal carotid artery going medial & posterior to medial pterygoid muscle into Parapharyngeal space & becoming Parapharyngeal carotid
  198. 198. Internal carotid artery going medial & posterior to medial pterygoid muscle into Parapharyngeal space & becoming Parapharyngeal carotid
  199. 199. After removing the LPM you will see Tensor veli palatini muscle (TVPM) coming vertically downwards from anterior surface of ET , protecting parapharyngeal carotid & after TVPM , thick Stylopharyngeal apneurosis (SPHA ) present ANTERIOR to Parapharyngeal carotid [ So 2 structures ( TVPM & SPHA ) protecting parapharyngeal carotid ]
  200. 200. After removing the LPM you will see Tensor veli palatini muscle (TVPM) coming vertically downwards from anterior surface of ET , protecting parapharyngeal carotid & after TVPM thick Stylopharyngeal apneurosis present ANTERIOR to Parapharyngeal carotid -- Attached to this ET cartilage [ TP/ET attachment ] is the tensor palatini (TP) fibrous aponeurosis (solid white line) with its muscle fibers seen below (broken white line).
  201. 201. Hand model -- left hand = medial & lateral pterygoid right hand = index is parapharyngeal carotid , middle is IJV , ring is styloid & stylopharyngeal muscles , thumb is horizontal carotid
  202. 202. Hypoglossal is just behind the upper end of parapharyngel carotid – very easy way to identify 12th nerve in paraphayrngeal space – Dr.Satish jain
  203. 203. Parapharyngeal space
  204. 204. Devided into • Pre-styloid compartment – no vital structures • Post-styloid compartment = carotid space – contains last 4 cranial nerves & great vessels & sympathetic chain
  205. 205. prestyloid mass originating from parotid deep lobe
  206. 206. Note : Glossopharygeal nerve & styloglossus in the bed of tonsil
  207. 207. Internal carotid artery going medial & posterior to medial pterygoid muscle into Parapharyngeal space & becoming Parapharyngeal carotid
  208. 208. Internal carotid with aberrant loop lying in the sagittal plane of the neck. The normal internal carotid artery runs in a straight course to the skull base. The pharynx lies anteromedial and is normally at least 1.5 cm away with fatty areolar tissue and pharyngeal veins in between. In the embryo, the internal carotid artery, derived from the third aortic arch and dorsal aortic root, is normally coiled. Straightening occurs when the foetal heart and great vessels descend into the mediastinum. Failure of or incomplete uncoiling can result in the vessel assuming a wide loop in the coronal, saggital or, rarely, transverse plane of the neck .Such an anomaly is rare but well recognized. This emphasizes the importance of palpating for pulsating vessels while undertaking an adenoidectomy. A medialized internal carotid artery is a well-described entity associated with velocardiofacial syndrome. In this syndrome, where pharyngoplasty may be undertaken for velopharyngeal insufficiency, this internal carotid anomaly is particularly relevant.
  209. 209. Internal carotid with aberrant loop lying in the coronal plane of the neck. – add pulsating internal carotid artery video link here
  210. 210. Post-styloid compartment = carotid space – contains last 4 cranial nerves & great vessels & sympathetic chain
  211. 211. PVC – is occupied by Ascending palatine artery (APA)
  212. 212. Transoral approach to SUPERO-MEDIAL Parapharyngeal tumors – incision anterior to anterior pillar of tonsil
  213. 213. Paraphayrngeal JNA removal by Endoscopic trans-oral approach by Dr.Janakiram
  214. 214. The jugular bulb lies beneath the fl oor of the middle ear cavity (Roche et al. 2008 ) . It can be of variable shape and size. All the lower cranial nerves ( LCNs ) exit the foramen anteromedially to the jugular bulb, separated from it by connective tissue. The superior ganglion of the vagus nerve is within the jugular foramen ( JF ). At the level of the intraforaminal course, there is a strict connection between the LCNs. The vagus nerve exits the JF vertically, behind IXcn and ICAp (Roche et al. 2008 ) and gives its inferior ganglion on the outer skull base surface. The accessory nerve lies immediately lateral to the vagus nerve. CR carotid ridge, DM digastric muscle (posterior belly), ICAp parapharyngeal portion of the internal carotid artery, IJV internal jugular vein, JB jugular bulb, MMA middle meningeal artery, VIIcn facial nerve, IX glossopharyngeal nerve, X vagus nerve, XI accessory nerve, XII hypoglossal nerve, black arrow inferior ganglion of vagus nerve
  215. 215. Internal Jugular foramen External jugular foramen
  216. 216. Right side. The acousticofacial nerve bundle, posterior inferior cerebellar artery, and lower cranial nerves are seen in the lower part. The inferior cerebellar vein (not constant) enters the jugular bulb. As the posterior fossa is approached from behind the sigmoid sinus, the jugular dural fold appears as a white linear structure overlying the lower cranial nerves. Right side. The acousticofacial nerve bundle, posterior inferior cerebellar artery, and lower cranial nerves are seen in the lower part. The inferior cerebellar vein (not constant) enters the jugular bulb. As the posterior fossa is approached from behind the sigmoid sinus, the jugular dural fold appears as a white linear structure overlying the lower cranial nerves.
  217. 217. A closer view of the pars nervosa of the jugular foramen. The glossopharyngeal nerve has its own dural porus, which is situated 0-3 mm upwards from the dural porus of the tenth cranial nerve. The vagus and the accessory nerve exit the posterior fossa together in a sleeve of dura through the jugular foramen. Closer view of the inferior area of the left CPA, with the tip of the endoscope just over the flocculus. The vagus nerve (X) and spinal accessory nerve (XI) arise as a widely separatedseries of rootlets that originate from the lower medulla and from theupper cervical cord. The rootlets of the hypoglossal nerve (XII) runhorizontally and are displaced and stretched by the curved vertebral artery (VA). The posterior-inferior cerebellar artery (PICA) arisesfrom the vertebral artery and forms a vascular loop inferior to the root exit /entry zone of the acoustic-facial nerve bundle (VII/ VIII).
  218. 218. When they exit from the skull base, the glossopharyngeal nerve is the most lateral, while the hypoglossal nerve is the most medial. The glossopharyngeal nerve crosses the internal carotid artery shortly after exiting the skull base.Thehypoglossal nerve turns inferiorly to run together with the vagus nerve for a short distance in the upper neck (Fig. 8.4).
  219. 219. The glossopharyngeal nerve is seen crossing the internal carotid artery. More inferiorly, the hypoglossal nerve crosses the artery and passes anteriorly. The vagus nerve is seen coursing between the internal jugular vein and the internal carotid artery. The accessory nerve crosses anterolateral to the internal jugular vein and travels posteriorly (Fig. 8.5).
  220. 220. In about half the cases, the accessory nerve crosses posteromedial to the internal jugular vein. In all cases, it passes anterolateral to the transverse process of the atlas. Note the close relation between the vertebral artery and the internal jugular vein. In extensive cases of posteriorly located glomus tumors, the vertebral artery may be involved .
  221. 221. In infrapetrous approach there are chances of injury to 6th nerve [ in dorello’s canal medial to paraclival carotid ] & 12th nerve
  222. 222. V3 & MMA
  223. 223. V 3 falls like niagara falls from middle cranial fossa to infratemporal fossa 90 degrees away from V1 & V2 – it is anterior to all the 3 structures , Petrous carotid & ET tube & Parapharyngeal carotid
  224. 224. ATN = Auriculotemporal nerve
  225. 225. MMA
  226. 226. IAN = Inferior alveolar nerve
  227. 227. My forceps touched the lingual nerve , posterior to this LN is Inferior alveolar nerve – These two nerves present in triangle formed by medial pterygoid , lateral pterygoid & temporalis muscle
  228. 228. Chorda[CT] attached to LN
  229. 229. Chorda[CT] attached to LN
  230. 230. Schematic diagram for infratemporal fossa approach
  231. 231. Sometimes V3 can be seen in the sphenoid sinus – in “pneumosinus dilatans multiplex”
  232. 232. The greater wing of sphenoidal is almost completely pnematised. So is the temporal bone on the left.the Left carotid can be traced from the middle ear to the sphenoid - in “pneumosinus dilatans multiplex”
  233. 233. V3 & MMA
  234. 234. V3 & MMA
  235. 235. V3[MN] & MMA & ET in lateral & Anterior skull base – see the relationship of ET tube which is medial to V3 & MMA
  236. 236. Posterior boarder of Lateral pterygoid bone leads to Foramen Ovale [ FO ] – Dr.Kuriakose
  237. 237. Posterior boarder of Lateral Pterygoid bone leads to Foramen Ovale [ FO ] – Dr.Kuriakose
  238. 238. Endoscopically [ Anterior skull base ] if we follow upper end of LPT posteriorly we can reach V3 [ Posterior boarder of Lateral Pterygoid bone leads to Foramen Ovale – Dr.Kuriakose ] View in nasopharyngectomy of recurrent nasopharyngeal carcinoma
  239. 239. In Infratemporal fossa approach- Posterior boarder of Lateral pterygoid bone leads to Foramen Ovale [ FO ] – Dr.Kuriakose
  240. 240. V3 is anterior (infront) to Horizontal carotid (= Petrous carotid ) & ET – It cause indentation on the ET also .
  241. 241. In open approaches in maxillary swing approach as long as you stay lateral to ET you will not injure the horizontal part of carotid
  242. 242. Petrous carotid & paraclival carotid is SADDLE shape – LEG of the rider is V3
  243. 243. V 3 is anteriror to all the 3 structures - Petrous carotid & ET & Parapharyngeal carotid [ very imp ]
  244. 244. Cochlea in anterior skull base b is cochlea in middle cranial fossa – cochlear angle between GSPN & IAC
  245. 245. 1. V3 is an important landmark to locate the post-styloid compartment, as it is anterior to this space (Falcon et al. 2011 ) . 2. styloid process & tensor veli palatini seperates pre-styloid & post-styloid compartments .
  246. 246. TP & LP
  247. 247. See the relationship of MPP & TP which is just posterior
  248. 248. Sinus of Morgagni - In nasopharyngeal carcinoma, the tumor may extend laterally and involve this sinus involving the Mandibular nerve. This produces a triad of symptoms known as Trotter's triad [ 1) Conductive deafness ( due to eustachian tube involvement) 2) Ipsilateral immobility of soft palate 3) Neuralgic pain in the distribution of V3 ] Add fossa of rosenmullar diagram photo present in scott brown text book
  249. 249. See the relationship between LPP & V3 which is just posterior
  250. 250. Eustachian tube
  251. 251. ET is just posterior to MPP [ Lateral part of Posterior choanae is MPP ]
  252. 252. ET is just posterior to MPP
  253. 253. ET is pointing like an ARROW the posterior genu of internal carotid [ ICAp & CF is parapharyngeal carotid ]
  254. 254. Sinus of Morgagni - In nasopharyngeal carcinoma, the tumor may extend laterally and involve this sinus involving the Mandibular nerve. This produces a triad of symptoms known as Trotter's triad [ 1) Conductive deafness ( due to eustachian tube involvement) 2) Ipsilateral immobility of soft palate 3) Neuralgic pain in the distribution of V3 ]
  255. 255. black asterisks medial corridor to ICAp – TVPM attached to anterior surface of ET – so if we go inbetween MPM & TVPM we reach to ICAp
  256. 256. Bony-cartilagenous junction of ET tube is at posterior genu of carotid - ET is pointing like an ARROW the posterior genu of internal carotid
  257. 257. Yellow arrow - Bony-cartilagenous junction of ET tube is at posterior genu of carotid - ET is pointing like an ARROW the posterior genu of internal carotid
  258. 258. V 3 is anteriror to all the 3 structures - Petrous carotid & ET & Parapharyngeal carotid [ very imp ]
  259. 259. ET tube in SPF [Spheno-petrosal fissure]
  260. 260. At bony-cartilagenous junction of ET tube – Horizonal carotid & Parapharyngeal carotid is above & below ET - My understanding
  261. 261. In open approaches in maxillary swing approach as long as you stay lateral to ET you will not injure the horizontal part of carotid
  262. 262. Fossa of Rossenmuller apex is laceral carotid [ Foramen Lacerum ] pharyngeal recess (fossa of Rosenmüller), which projects laterally from the posterolateral corner of the nasopharynx with its lateral apex facing the internal carotid artery laterally and the foramen lacerum above;
  263. 263. endonasal approaches to expose the area between the ICAs belong to the sagittal plane, and the approaches around the ICA define the coronal plane modules.
  264. 264. Note that the eustachian tube indicates the carotid canal only approximately. In other words, it lies on a different CORONAL plane in respect of the vessel, and from an anterior viewpoint, it covers the vessel for all its length. -- Medially the space between these two CORONAL planes is nothing but Fossa of Rosenmuller [ My understanding ]
  265. 265. Note that the eustachian tube indicates the carotid canal only approximately. In other words, it lies on a different CORONAL plane in respect of the vessel, and from an anterior viewpoint, it covers the vessel for all its length. -- Medially the space between these two CORONAL planes is nothing but Fossa of Rosenmuller [ My understanding ]
  266. 266. Surgeons should have in mind that the external orifi ce of the carotid canal is not on the same coronal plane of the foramen lacerum (anterior genu). It is by far more posteriorly located.
  267. 267. GSPN-VIDIAN NERVE
  268. 268. Vidian canal is 2 cm to foramen lacerum – Amin kassam – refer paolo castelnuovo book , Foramen rotundum is 5mm to dura – listen 4.00 time in this video https://www.youtube.com/watch?v=Uk57MEgkde8
  269. 269. Gasserian ganglion is intradural – it is not extradural or intradural – listen 4.00 time in this video https://www.youtube.com/watch?v=Uk57MEgkde8
  270. 270. GSPN passes above Horizontal [=petrous] carotid & passes underneath V3 & crosses petro-paraclival carotid junction at foramen lacerum before becoming vidian nerve
  271. 271. The bone overlying the internal auditory canal has been removed and the dura of the canal has been removed near the fundus. The facial nerve (FN) can be seen entering its labyrinthine segment to form the geniculate ganglion (GG) more laterally. V Trigeminal nerve, < Acousticofacial bundle, C Cochlea, ET Eustachian tube, GPN Greater petrosal nerve, I Incus, IAC Internal auditory canal, ICA Internal carotid artery, M Malleus, SSC Superior semicircular canal, SV Superior vestibular nerve Observe the relationship between GSPN & horizontal carotid
  272. 272. Fig. 2.62 The course of the horizontal segment of the internal carotid artery (ICAh), as seen from the middle cranial fossa of a left temporal bone. VI Abducent nerve, C Cochlea, GPN Greater petrosal nerve, IAC Internal auditory canal, ICA(ic) Intracranial internal carotid, M Mandibular nerve, MMA Middle meningeal artery, MX Maxillary nerve
  273. 273. Fig. 5.47 The view after completion of the middle crannial fossa approach. AE Arcuate eminence, BB Bill’s bar, C Cochlea, FN(iac) Internal auditory canal segment of the facial nerve, FN(t) Tympanic segment of the facial nerve, G Geniculate ganglion, GPN Greater petrosal nerve, I Body of the incus, L Labyrinthine segment of the facial nerve, M Head of the malleus, MFD Middle fossa dura, SVN Superior vestibular nerve
  274. 274. In Infratemporal fossa - Note that the greater petrosal nerve (GPN) is adherent to the dura, and that retracting the dura will lead to stress on the facial nerve at the geniculate ganglion (GG) level. Thus, if dural retraction is needed, cutting the petrosal nerve will prevent this injury. In middle cranial fossa – same point
  275. 275. Foramen lacerum AFL = Anterior foramen lacerum * [ black asterisk ] = foramen lacerum Petrolingual area = foramen lacerum
  276. 276. After elevating V3 anterior[infront] to ET & petrous carotid observe -- GSPN continues as VN [ VN is lateral to paraclival carotid ]
  277. 277. GSPN & GSPN groove in Surpra petrous window ET eustachian tube, GPN greater petrosal nerve, MCFd dura of the middle cranial fossa, MMA middle meningeal artery, SPS superior petrosal surface, TI trigeminal impression, V3 third branch of the trigeminal nerve, yellow arrow accessory middle meningeal artery, white asterisks greater petrosal nerve groove
  278. 278. Vidian nerve is formed by GSPN & Deep petrosal nerve – so GSPN (passes underneath V3) crosses laterally the Horizontal carotid and paraclival carotid junction (Prof.Kassam) & continues as Vidian nerve Blue arrow – LPN & Yellow arrow – GPN
  279. 279. Trans-pterygoid approch-- Vidian Artery present in 60% & enters at the junction of Horizontal carotid & paraclival carotid – it is present above the Vidian nerve so while drilling vidian canal in JNA first we have to drill inferior half and then upper half [the bone around the vidian canal is drilled along its inferior half (from 3 o’clock to 9 o’clock) until the carotid artery is identified at the lacerum segment ]
  280. 280. Vidian nerve - lateral to paraclival carotid & medial to FO [ Foramen Ovale ]- actually it is GSPN
  281. 281. Vidian canal & Spheno-palatine foramen are in 90 degrees
  282. 282. Vidian nerve - lateral to paraclival carotid
  283. 283. Vidian nerve - lateral to paraclival carotid
  284. 284. Vidian nerve - lateral to paraclival carotid
  285. 285. Vidian nerve - lateral to paraclival carotid Close vision of the middle cranial fossa. The gasserian ganglion has been removed
  286. 286. Vidian nerve - lateral to paraclival carotid
  287. 287. Axial T2-weighted magnetic resonance imaging (MRI) sequence at the level of the vidian canal: 1, clivus; 2, pterygoid; 3, horizontal tract of the internal carotid artery (ICA); 4, vidian canal.
  288. 288. The space between V1 & V 2 and V2 & V3 is sphenoid sinus Middle cranial fossa approach – the nerve between V2 & V3 is VN Anterior skull base
  289. 289. Infratemporal fossa approach type C Middle cranial fossa approach – the nerve between V2 & V3 is VN
  290. 290. Foramen lacerum AFL = Anterior foramen lacerum * [ black asterisk ] = foramen lacerum Petrolingual area = foramen lacerum
  291. 291. Vidian artery – origin from Laceral segment
  292. 292. Lateral Recess is the space between V2 & Vidian nerve .
  293. 293. Courtesy – Dr. Satish Jain , Jaipur
  294. 294. Lateral Recess is the space between V2 & Vidian nerve .
  295. 295. Here TI [ trigeminal impression ] is V2
  296. 296. LRSS = Lateral recess of the sphenoid sinus
  297. 297. Floor of Lateral recess is by ET ---- BS basisphenoid, ET eustachian tube, LRSS lateral recess of the sphenoid sinus, OPPB orbital process of the palatine bone, PVA(s) palatovaginal artery(ies), RPm rhinopharyngeal mucosa, SPAib inferior branch of the sphenopalatine artery, SPPB sphenoidal process of the palatine bone, SS sphenoid sinus, RS rostrum sphenoidale, VN vidian nerve
  298. 298. Surpra petrous window ET eustachian tube, GPN greater petrosal nerve, MCFd dura of the middle cranial fossa, MMA middle meningeal artery, SPS superior petrosal surface, TI trigeminal impression, V3 third branch of the trigeminal nerve, yellow arrow accessory middle meningeal artery, white asterisks greater petrosal nerve groove
  299. 299. Carotid nerve
  300. 300. Transmaxillary infratemporal fossa approach – Endoscopic assisted microscopic approach – mainly useful for stage 4 JNAs & cavernous extensions • Click video : https://www.youtube.com/watch?v=Uk57ME gkde8
  301. 301. For Other powerpoint presentatioins of “ Skull base 360° ” I will update continuosly with date tag at the end as I am getting more & more information click www.skullbase360.in - you have to login to slideshare.net with Facebook account for downloading.

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