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Line diagrams - skull base 360 - part 1

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Line diagrams - skull base 360 - part 1

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Line diagrams - skull base 360 - part 1

  1. 1. Dr.B.D.CHAURASIA - Great anatomist of india whose books inspired me to take up surgical field . Simplified the anatomy with line diagrams . Line diagrams - Skull base 360°- Part 1 9-5-2017 12.43 pm
  2. 2. Chaurasia book weblink http://www.amazon.in/s/?ie=UTF8&keywords=human+anatomy+by+chaurasia&tag=googinhydr1- 21&index=aps&hvadid=64937120410&hvpos=1t1&hvexid=&hvnetw=g&hvrand=13828071178419120710&hvpone=&h vptwo=&hvqmt=b&hvdev=c&ref=pd_sl_1zkx9qygk2_b
  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. Anterior skull base line diagram video – updated further time to time – click https://www.youtube.com/watch?v= cLxLSyAo-KY
  5. 5. ORBIT • 1. Two Ice cream cones in orbit -mnemonic - SOF & IOF - superior orbital fissure & inferior orbital fissure. • 2. Bone between OC ( optic canal ) & SOF is optic strut ( OS) • 3. Bone between SOF & V2 ( foramen rotundum ) is MS ( maxillary strut ) - front door of cavernous sinus • 4. So SOF is presents between two struts - OS & MS • 5. Bone above SOF is LWS ( leader wing of sphenoid ) • 6. Bone between SOF & IOF is GWS ( greater wing of sphenoid ) • 7. Four semilunar lines 1, 2, 3, 4 are - orbital surface of frontal bone , orbital surface of zygomatic none , orbital surface of maxillary none , laminae papyracea resp. • 8. Medial wall of SOF is nothing but nasal surface of SOF which is just anterior to cavernous sinus
  6. 6. Total anterior skull base
  7. 7. Two bisections in whole skull base
  8. 8. Two bissections in skull base 1. vertical part of facial nerve bisects jugular bulb 2. GSPN bisects V3& petrous carotid Vertical part of facial nerve bisects jugular bulb GSPN bisects V3 & petrous carotid
  9. 9. Two bissections in whole skull base 1. facial nerve bissects jugular bulb 2. GSPN bissects V3 & Petrous carotid
  10. 10. Pterygo-palatine fossa
  11. 11. Posterior wall of maxilla & pterygoid process is curved anteriorly
  12. 12. PPF is at supero-medial area of posterior wall of maxilla
  13. 13. PPF & palatine bone relation
  14. 14. Lateral to infraorbital nerve & V2 is Infratemporal fossa , Medial to ION & V2 is Pterygopalatine fossa
  15. 15. Pterygopalatine ganglion in PPF
  16. 16. 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 ]
  17. 17. Medial wall of PPF is perpendicular plate of palatine bone – foramen in it is sphenopalatine foramen
  18. 18. 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
  19. 19. PPF extended into orbital apex
  20. 20. The PPF extended to superior orbital fissure ( SOF ) / Orbital apex , inferior to the cavernous sinus and Muller’s muscle. – anterior skull base view
  21. 21. The PPF extended to superior orbital fissure ( SOF ) / Orbital apex , inferior to the cavernous sinus and Muller’s muscle. – Lateral skull base view
  22. 22. 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
  23. 23. Infratemporal fossa
  24. 24. INFRA-TEMPORAL FOSSA ANATOMY in both anterior & lateral skull base 1. When you go from MPP to jugular bulb it is anterior skull base 2 . When you go from jugular bulb to MPP it is lateral skull base In CT - scan 1. The space below transverse line of V2 & lateral to LPP is infra- temporal fossa 2 . The upper half of space between MPP & LPP is pterygo-palatine fossa . 3. The space above transverse line of V2 is MCF ( middle cranial fossa ) 4. The space above transverse line of VN is pterygoid recess
  25. 25. Infratemporal fossa anatomy line diagram in both anterior & lateral skull base ( Infratemporal fossa approach A, B, C , D )
  26. 26. I Max = Internal maxillary artery
  27. 27. 1st & 2nd & 3rd part of I-MAX
  28. 28. Temporalis muscle flap is based on posterior ( PDTA ) & anterior deep temporal arteries (ADTA)
  29. 29. Anteior skull base Lateral skull base
  30. 30. Anterior skull base view
  31. 31. Lateral skull base view
  32. 32. 1 = Nasal component , 2 = Infratemporal fossa component , 3 = Parapharyngeal component - for nasal & Infratemporal component of JNA we don’t need external carotid artery control , just coblator is enough . Where as parapharyngeal part of JNA we need external carotid artery control because the vascularity comes posteriorly from external carotid arterial system
  33. 33. The position of MA in respect to the LPM is hightly variable – Paolo Castelnuovo Photo Courtesy – Dr.Janakiram
  34. 34. 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 )
  35. 35. 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
  36. 36. LACERAL CAROTID in relation to PTERYGOID RECESS -Both diagrams right side 1. VN inline with MPP ( Medial pterygoid plate ) 2. V2 inline with LPP ( lateral pterygoid plate ) 3. Pterygoid recess present inbetween V2 & VN endoscopically 4. Laceral carotid present just behind the posterior wall of pterygoid recess ( sphenoid recess ) - very important vital structure in clearing pterygoid recess pathology
  37. 37. Pvc, vc, FR are in a 45 degree angle
  38. 38. SOF also comes in the 45 degree angle – my observation
  39. 39. MPP[ medial pterygoid plate ] present at lateral surface of posterior choana – which is in line with paraclival carotid
  40. 40. Vidian canal is funnel shaped
  41. 41. 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
  42. 42. 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 ]
  43. 43. 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.
  44. 44. Posterior boarder of lateral pterygoid plate leads to foramen ovale
  45. 45. GSPN bisects V3 & petrous carotid
  46. 46. Petrous bone has three surfaces with three boarders & divided into three 1/3rds
  47. 47. In the floor of sphenoid sinus you will get Vidian nerve when you approach by antero-lateral triangle
  48. 48. 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
  49. 49. 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
  50. 50. IAN = inferior alveolar nerve , LN = lingual nerve , MPM = medial pterygoid muscle , LPM = lateral pterygoid muscle
  51. 51. TVPM is triangular muscle , LVPM is cylindrical muscle
  52. 52. SPM attached to superior constrictor , SGM attached to tongue , SHM attached to lesser cornu of hyoid bone
  53. 53. After drilling LPP & MPP longissmus capitis & superior constrictor seen .
  54. 54. Incision anterior to anterior to anterior pillar of tonsil for “Trans - Oral approach to infratemporal fossa”
  55. 55. 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
  56. 56. 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
  57. 57. 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
  58. 58. Each styloid muscle accompanied by one nerve – SPM by 9th nerve , SGM by lingual nerve , SHM by 12th nerve
  59. 59. MPM is reflected back – which shows the structures seen in trans-oral approach of ITF – incision anterior to anterior pillar of tonsil
  60. 60. Apex of infratemporal fossa
  61. 61. V3 & mma are together
  62. 62. Schematic diagram for infratemporal fossa approach – MMA & V3 & pterygoid plate from posterior to anterior
  63. 63. V3[MN] & MMA & ET in lateral & Anterior skull base – see the relationship of ET tube which is medial to V3 & MMA
  64. 64. V3 & mma are together 2. V3 accompanied by mma whereas IAN [ inferior alveolar nerve ] is accompanied by PSAA [ postero- superior alveolar artery ] Lateral skull base Anterior skull base
  65. 65. After drilling the tympanic bone & styloid process inbetween jugular bulb & carotid , 9th nerve is seen
  66. 66. 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 .
  67. 67. The cochlear aqueduct: An important landmark in lateral skull base surgery http://booksc.or g/book/1766130 2 EO [ external opening of cochlear aqueduct ]
  68. 68. Complete exposure of CA in its entire length (right side). Lateral walls of jugular bulb (JB) and IPS were removed. In this case IPS is only structure crossing external opening of CA. Ninth nerve is located slightly anterior and inferior to opening. ICA is seen anterolateral to CA.
  69. 69. Sympathetic trunk is posterior to vagus – below photo right side
  70. 70. SCG anastamosed with all the lower cranial nerves – below photo right side
  71. 71. Superior cervical ganglion is posterior to inferior ganglion of vagus – SCG lies over prevertebral facia over longus capitis – below photo left side
  72. 72. 11th nerve present in between vertebral artery & IJV
  73. 73. 11th nerve is postero-medial & antero- lateral to IJV Postero-medial to IJV Antero-lateral to IJV
  74. 74. 1. Anterior to IPS - 9th nerve seen , posterior IPS - 10th & 11th seen 2. 12th nerve crosses 10th nerve laterally
  75. 75. 1. Anterior to IPS - 9th nerve seen , posterior IPS - 10th & 11th seen 2. 12th nerve crosses 10th nerve laterally
  76. 76. 1. 9th & 12th nerves crosses parapharyngeal carotid above & below 2. supracondylar groove leads to Hypoglossal canal
  77. 77. 12th nerve seen in infra-petrous approach in anterior skull base
  78. 78. 9th & 12th nerves Anterior skull base Lateral skull base
  79. 79. 9th nerve is the most lateral nerve & 12th nerve is most medial nerve in skull base
  80. 80. ITFA with Transcondylar [ = TC ] Transtubercular [ = TT ] approach Here Transcondylar is through Occipital Condyle ; Transtubercular is through Jugular tubercle & lateral pharyngeal tubercle
  81. 81. 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.)
  82. 82. Note 12th nerve in between JT ( Jugular tubercle ) & OC ( Occipital condyle ) in both lateral & anterior skull base Lateral skull base Anterior skull base
  83. 83. 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
  84. 84. 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
  85. 85. 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
  86. 86. Incision anterior to anterior pillar of tonsil for “Trans - Oral approach of infratemporal fossa”
  87. 87. Incision of trans-oral approach of ITF is – anterior to anterior pillar of tonsil – pathway is between MPM & superior constrictor
  88. 88. 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
  89. 89. Each styloid muscle accompanied by one nerve – SPM by 9th nerve , SGM by lingual nerve , SHM by 12th nerve
  90. 90. MPM is reflected back – which shows the structures seen in trans-oral approach of ITF – incision anterior to anterior pillar of tonsil
  91. 91. Transoral approach to SUPERO-MEDIAL Parapharyngeal tumors – incision anterior to anterior pillar of tonsil
  92. 92. Modified transcochlear approach
  93. 93. Don't give too much importance to the jargon of approaches . Approaches developed from anatomy . Anatomy not developed from approaches. Know the www.skullbase360.in anatom y. Automatically you can individualize the approach for the tumor .
  94. 94. PARISIER'S TRIANGLE (DANGEROUS TRIANGLE) Perisier's triangle is very important triangle in endoscopic ear surgery 1) Superior limb is formed by inferior part of HFN 2) The apex is formed by the geniculate ganglion 3) The base is formed by the anterior commissure (end) of oval window 4) Inferior limb is formed by tunning point of jocobson's nerve to the the geniculate ganglion.
  95. 95. PARISIER'S TRIANGLE (DANGEROUS TRIANGLE)
  96. 96. Iatrogenic cochlear injury
  97. 97. Iatrogenic chances of injury of cochlea in infratemporal fossa transpetrous approach , kawase approach & anterior skull base approach. For better understanding visit www.skullbase360.in -- Here the cochlea is actually postero-medial to vertical part of carotid – wrongly depicted here medial to pre-cochlear carotid
  98. 98. Orbit
  99. 99. Orbital apex
  100. 100. ORBITAL APEX [ SOF = ALSC + Orbital apex] Extraconal & intraconal compartmements
  101. 101. ORBIT • 1. Two Ice cream cones in orbit -mnemonic - SOF & IOF - superior orbital fissure & inferior orbital fissure. • 2. Bone between OC ( optic canal ) & SOF is optic strut ( OS) • 3. Bone between SOF & V2 ( foramen rotundum ) is MS ( maxillary strut ) - front door of cavernous sinus • 4. So SOF is presents between two struts - OS & MS • 5. Bone above SOF is LWS ( leader wing of sphenoid ) • 6. Bone between SOF & IOF is GWS ( greater wing of sphenoid ) • 7. Four semilunar lines 1, 2, 3, 4 are - orbital surface of frontal bone , orbital surface of zygomatic none , orbital surface of maxillary none , laminae papyracea resp. • 8. Medial wall of SOF is nothing but nasal surface of SOF which is just anterior to cavernous sinus
  102. 102. A - trajectory leads to middle cranial fossa B - trajectory leads to infra-temporal fossa
  103. 103. GWS=Greater wing of sphenoid LWS = Lesser wing of sphenoid
  104. 104. Carotid
  105. 105. All odd numbers of the carotid are VERTICAL C7 = Parapharyngeal carotid C6 = petrous carotid C5 = paraclival carotid C4 = lower horizontal part of parasellar carotid C3 = vertical part of parasellar carotid C2 = upper horizontal part of parasellar carotid C1 = intracerebral carotid
  106. 106. Endoscopic view of the internal carotid artery showing 3 types of angles (black lines) between the posterior ascending and horizontal portions of the C4 segment. (A) angle <80; (B) angle >100; and (C) angle between 80 and 100. PG, pituitary gland; ON, optic nerve. *C4 bend. (Printed with permission from Mayfield Clinic.)
  107. 107. See video lecture at https://www.youtube.com/watch?v=4tiRfPLYkBo
  108. 108. Transnasal transsphenoidal endoscopic view of the parasellar region illustrate that types I- III are symmetric and type IV is asymmetric. (A) Type I angle between the posterior ascending and horizontal portions of C4 segment is <80, resulting in direct contact between the pituitary gland and the internal carotid artery (ICA) and a tortuous ICA configuration. (B) Type II angle between the posterior ascending and the horizontal portions of the C4 segment is between 80 and 100. (C) Type III angle between the posterior ascending and the horizontal portions of the C4 segment is >100. ICA appears slightly curvilinear and less tortuous than the type I or the type II. (D) Type IV angles of the left and right ICAs are asymmetric. PG, pituitary gland; ON, optic nerve. *C4 bend. (Printed with permission from Mayfield Clinic.)
  109. 109. Authors speculate that type I presents the highest risk for vascular injury based on its contact between the ICA and pituitary gland. In 50% of our specimens, the C4 bend was behind the pituitary gland (Figure 4A). Risk of potential vascular injury decreases in types II and III. – Get paper at http://dx.doi.org.sci-hub.cc/10.1016/j.wneu.2014.09.021
  110. 110. core diagram of anterior skull base If we don't know these diagrams posterior genu carotid blowout happens in pituitary & anterior skull base surgery especially when the angle between paraclival carotid & horizontal part of the parasellar carotid is < 80 degrees where pituitary is very adhere to posterior genu
  111. 111. core diagram of anterior skull base If we don't know these diagrams posterior genu carotid blowout happens in pituitary & anterior skull base surgery especially when the angle between paraclival carotid & horizontal part of the parasellar carotid is < 80 degrees where pituitary is very adhere to posterior genu
  112. 112. core diagram of anterior skull base If we don't know these diagrams posterior genu carotid blowout happens in pituitary & anterior skull base surgery especially when the angle between paraclival carotid & horizontal part of the parasellar carotid is < 80 degrees where pituitary is very adhere to posterior genu
  113. 113. Transnasal transsphenoidal endoscopic view of a type II angle (between 80 and 100) that has no contact with the pituitary gland. Angle allows a corridor to the posterior aspect of the cavernous sinus and the oculomotor nerve without retraction of the internal carotid artery or the pituitary gland. CN III, oculomotor nerve; CS, cavernous sinus; PG, pituitary gland. (Printed with permission from Mayfield Clinic.)
  114. 114. Transnasal transsphenoidal endoscopic view between the C3 and the C4 segments of the internal carotid artery at the lacerum and clivus levels. Two distinct shapes (green) were identified as trapezoid (A) in 80%or hourglass (B) in20%of specimens. (Printed with permission from Mayfield Clinic.)
  115. 115. Conceptual illustration of the endoscopic perspective depicts the various internal carotid artery (ICA) classifications. (Left) Bouthillier et al. (2) used 7 segments: C1 ¼ cervical, C2 ¼ petrous, C3 ¼ lacerum, C4 ¼ cavernous, C5 ¼ clinoid, C6 ¼ ophthalmic, and C7 ¼ communicating. (Right) De Powell et al. (5) modification includes C3-C4 bend, C4 bend, and C4-C5 bend. Depending on the angle of the C4 bend (green plane), a potential corridor between the ICA and the pituitary allows access to the posterior cavernous sinus (yellow arrow). SOF, superior orbital fissure; OS, optic strut; OCR, opticocarotid recess; TS, tuberculum sellae. (Printed with permission Mayfield Clinic.)
  116. 116. Anatomic measurements between the internal carotid arteries and the pituitary gland in 20 specimens. (A) (aee) Intercarotid distances between the left and right ICAs. (B) Measurements (a’, b’, c’) of the space between the ICA and the pituitary gland at 3 levels (cephalic, middle, caudal). (Printed with permission from Mayfield Clinic.)
  117. 117. Sphenoid bone LWS = lesser wing of sphenoid , GWS = greater wing of sphenoid
  118. 118. 1. Vertical part of facial nerve bissects jugular bulb . 2. Both facial nerve & temporal part of carotid has vertical & horizontal ( Petrous carotid ) parts . 3. horizontal & labyrinthine part of facial nerve junction [ 1st genu ] is V-shaped while vertical part of facial nerve & diagastric tendon junction is U-shaped
  119. 119. Paraphayngeal carotid behind adenoids Paraphayngeal carotid behind tonsils
  120. 120. Petrous carotid & paraclival carotid junction is saddle shapped – not perpendicular to each other – This is where the carotid-clival window – infra-petrous approach
  121. 121. LACERAL CAROTID in relation to PTERYGOID RECESS -Both diagrams right side 1. VN inline with MPP ( Medial pterygoid plate ) 2. V2 inline with LPP ( lateral pterygoid plate ) 3. Pterygoid recess present inbetween V2 & VN endoscopically 4. Laceral carotid present just behind the posterior wall of pterygoid recess ( sphenoid recess ) - very important vital structure in clearing pterygoid recess pathology
  122. 122. 1. Vidian artery ( VA ) is branch of laceral carotid . The bone around the vidian canal ( VC ) is drilled along its inferior half (from 3 o’clock to 9 o’clock) until the carotid artery is identified at the lacerum segment . VC is funnel shapped . 2. You have to simply cauterize VA to stop bleeding . If bleeding not controlled keep muscle plug in VA 3. VN is lateral to laceral carotid which is continuation of GSPN. PCC = Paraclival carotid , PC = Petrous carotid , VN = vidian nerve
  123. 123. Anterior skull base view Lateral skull base view
  124. 124. Vidian canal is funnel shapped
  125. 125. 1. Both sides 6th nerves in dorello’s canals present medial to para-clival carotids in mid-clivus & 2. 6th nerve crosses Para-clival & Para-sellar carotids juction in AI [ antero-inferior ] virtual compartment of cavernous sinus
  126. 126. 1. MPP & ET opening is in line with paraclival carotid . 2. Laceral carotid is in posterior wall of pterygoid recess / sphenoid recess. 3. Transpyerygoid approach is needed to reach parasellar area. 4. Area between LPP & MPP extrapolated lines is cavernous sinus . 5. LPP in line with FR 6. Traiangle between FR & VC is pterygoid trigone or Pterygoid recess / sphenoid recess
  127. 127. Sternberg canal – this figure is not final – still literature has to be searched ------ actually sternberg canal is lateral to V2 – Satish Jain
  128. 128. 1. SHA supplies anterior pituitary originates from first part of intracerebral carotid 2. IHA supplies posterior pituitary , branch of MHT originates from posterior genu of carotid 3. ILT arises from horizontal carotid in parkinsons triangle 4. Strong opponents of extracapsular dissection of pituitary surgery argument is IHA is damaged sothat posterior pituitary compromised & diabetes insipidus develops .
  129. 129. Vasculature of the Brain and Cranial Base – book name Superior hypo-physeal artery CL anterior clinoid DX distal ring IC internal carotid artery ON optic nerve PK pituitary stalk SH superior hypophyseal artery
  130. 130. B, endonasal cadaveric dissection using a zero-degree endoscope after releasing the pituitary gland from the dural fold (DF) that forms the aperture is shown. The SHa runs above the DF, and care should be taken at the last cut when opening the sellar aperture to avoid damaging the SHa. The CS, the IHa, the dorsum sellae (DS), and the clivus (C) are shown. The pituitary stalk (S) can be seen moved to the right side with the pituitary gland (PG) still being tethered by several PLs, preventing complete mobilization.
  131. 131. intraoperative suprasellar view with a zero-degree endoscope showing the pituitary gland (PG) and the pituitary stalk (S) after the opening of the suprasellar and sellar dura, ligation of the SIS, and complete excision of the anterior dural fold (DF) that forms the pituitary aperture. The chiasm (Ch) is visualized superiorly and anteriorly. A small subchiasmatic perforator (SP) branch of the superior hypophyseal artery is shown.
  132. 132. Posterior genu is the most common area of iatrogenic injury of carotid The parasellar carotid protuberance is a C- shaped bone protuberance with the convexity of the C facing anterolaterally. It covers four segments of the ICA: (1) the hidden segment / Posteriori genu ; (2) the inferior horizontal segment; (3) the anterior vertical segment, and (4) the superior horizontal segment. The hidden segment is located at the level of the posterior sellar floor and includes the posterior bend of the ICA.
  133. 133. IATROGENIC CAROTID INJURE AREAS - 1. Upper & Lower point of C-shape of parasellar carotid - mnemonic 2. Upper point is m-OCR ( optico - carotid recess ) - junction of para seller & intra-cerebral carotid 3. Lower point is posterior genu - junction of paraclival & parasellar carotid
  134. 134. Two potential iatrogenic carotid injury areas We have to very careful at m-OCR in transtubercular & transplanum drilling because praclinoidal & supraclinoidal junction is exactly m-OCR Posterior genu is the most common area of iatrogenic injury of carotid
  135. 135. Upper & lower points of C-shaped Parasellar carotid are origins of SHA & MHT -- These two potential iatrogenic carotid injury areas are origins of SHA ( Superior hypophyseal artery ) & MHT ( Meningo-hypophyseal trunk ) ; IHA ( Inferior hypophyseal artery is branch of MHT
  136. 136. Upper half of paraclival carotid is intracavernous while lower half is extracavernous . 1. caudal part, the lacerum segment of the artery corresponding to the extracavernous portion of the vessel, and 2. rostral part, the trigeminal, intracavernous portion of the artery, so- called because the Gasserian ganglion is posterior to it and the trigeminal divisions are lateral to it.
  137. 137. PLL = petro-lingual ligament
  138. 138. Branches of ICA – only retrograde artery is opthalmic artery originates above the upper dural ring
  139. 139. 1. After removing TS ( Tuberculam sellae ) you will appreciate SIS ( Superior intercavernous sinus ) ; 2. SIS & IIS & Right cavernous & Left cavernous is called FOUR blues . IIS = Inferior intercavernous sinus
  140. 140. SHA ( Superior hypophyseal artery ) 1. SHA arises in carotid cave from paraclival carotid or from intracerebral carotid in sub-chiasmatic cistern . 2. UDR little bit exagerated for better understanding of carotid cave 3. Opthalmic artery ,only retrograde artery of carotid arises above the UDR 4. SHA present above the diaphragm ( cut anteriorly in diagram ) 5. Protection of SHA is utmost important in suprasellar tumors & craniopharyngiomas 6. SHA gives upper chiasmatic branches ( injury causes scotomas ) & lower pituitary branches mainly supplying anterior pituitary . 7. SHA may present infero-medial aspect of cisternal part of optic nerve in subchiasmatic cistern . 8. Ophthalmic artery & SHA arises from carotid cave
  141. 141. Carotid cave
  142. 142. Vasculature of the Brain and Cranial Base – from this book Superior view of the right internal carotid (IC) artery with the roof of the cavernous sinus dura removed. Part of the anterior clinoid tip has been removed. III third nerve 21 anterior clinoid DX distal ring ON optic nerve OP ophthalmic artery PX proximal ring
  143. 143. Superior view of the internal carotid artery with more extensive removal of the anterior clinoid exposing the relationship of the third nerve sheath to the proximal ring. A thin veil of dura extends from the third nerve sheath to the lateral internal carotid artery. Also note the at tachment of the third nerve sheath to the proximal ring. III third nerve IIIs third nerve sheath 21 anterior clinoid DX distal ring ON optic nerve OP ophthalmic artery PX proximal ring IC internal carotid artery
  144. 144. 1. Virtual compartments of cavernous sinus – parasellar carotid virtually devides cavernous sinus into L,M,AI,PS compartments 2. 3rd , 4th , 6th , V1 nerves in lateral compartment [ V1 & 6th nerves are in parallel ] 3. 6th nerve in antero-inferior & lateral compartments . Only 6th nerve is freely present in cavernous , that is the reason for high chances of injury to 6th nerve in cavernous surgery . 4. 3rd nerve in postero-superior compartment 5. there is no vital [ nerves or vessesl ] in medial compartment 6. medial & postero-superior compartment are in continuity . 7. 3rd nerve & pcom are in parallel. In the same way V1 & 6th nerve are in parallel
  145. 145. Actually FCB is filled in foramen lacerum
  146. 146. Thick fibrous tissue attached to carotid present at carotid canal & foramen lacerum [ called FCB – fibrocartilagenous basalis ] In all the skull base foramena vital structure (vessel or nerve ) passes through respective foramena. But laceral carotid NOT passing through foramen lacerum . Laceral carotid stays ABOVE the foramen lacerum & fibrocartilageno basalis ( thick fibrocartilagenous tissue ) . Actually FCB fills the foramen lacerum . This point useful in infrapetrous approach in anterior skull base .For details see " carotid 360 " PPT at www.skullbase360.in Lateral skull base view Anterior skull base view
  147. 147. Lower half of paraclival carotid - caudal part, the lacerum segment of the paraclival carotid ”The unsolved surgical problem remains the medial wall of the ICA at the level of the anterior foramen lacerum, until now unreachable with the available surgical approaches." - In lateral skull base by Prof. Mario sanna – this unreachable is Carotid- Clival window which is accessable in Anterior skull base Infrapetrous Approach Carotid-Clival window – Mid clivus a. Petrosal face b.Clival face
  148. 148. In FTOZ paraclival carotid looks horizontal while in anterior skull base paraclival carotid looks vertical – because of angle of view /angle of approach FTOZ view Anterior skull base view
  149. 149. Observe the posterior genu & anterior genu [ parasellar carotid ] of carotid is S-shaped in both anterior & FTOZ view – This posterior genu is most common cause of iatrogenic injury Anterior skull base view FTOZ view
  150. 150. Observe the posterior genu & anterior genu [ parasellar carotid ] of carotid is S-shaped in both anterior & FTOZ view – This posterior genu is most common cause of iatrogenic injury Anterior skull base view Anterior skull base view
  151. 151. Eustachian tube points like an ARROW the APEX of parapharyngeal carotid – infact bony part of ET tube is above the junction of vertical part & horizontal part [ petrous carotid ] of temporal carotid [ in middle ear carotid seen below the ET ] Here the cochlea is actually postero- medial to vertical part of carotid – wrongly depicted here laterally
  152. 152. 1. Cadaveric dissection demonstrating the osteotomies at the base of the posterior clinoids (PC) for separation with the body of the dorsum sella (DS). 2. Cadaveric dissection image demonstrating the close anatomical relationship of the posterior clinoid (PC) with both the intracranial carotid artery (ICCA) and the posterior genu of the intracavernous carotid artery (P. CCA
  153. 153. Cadaveric dissection image demonstrating structures seen following dissection of the lower third of the clivus. Note how the basilar arteries and vertebral arteries can be extremely tortuous in their course.
  154. 154. 1. PCOM & 3RD nerve parallel to each other . 2. Relationship of PcomA & 3rd nerve – parallel or cross each other in Kernochan's Notch diagram http://en.wikipedia.org/wiki/Kernohan%27s_notch In parasellar pituitary 3rd n & 4th n & Pcom present in Postero-superior cavernous compartment
  155. 155. Relationship of PcomA & 3rd nerve – parallel or cross each other in Kernochan's Notch diagram http://en.wikipedia.org/wiki/Kernohan%27s_notch In parasellar pituitary 3rd n & 4th n & Pcom present in Postero- superior cavernous compartment
  156. 156. Schematic diagram of cavernous sinus roof
  157. 157. 1. LDR=COM 2. 3rd nerve below COM after ACP drilling 3. COM present below ACP
  158. 158. " Lateral limit of subchiasmatic cistern is - First part of intracerebral ICA " - This is useful when the tumor fills the whole sphenoid cavity & has no landmarks - then we dissect/drill at planum area & slow identify the optic nerve - so just below the optic nerve laterally [ in subchiasmatic cistern ] you will encounter the First part of intracerebral ICA - ONE OF THE KEY POINT IN ANTERIOR SKULL BASE
  159. 159. Don’t touch these chiasmatic vessels – scotomas develops
  160. 160. Outer wall of cochlea seperates from vertical part of intratemporal carotid
  161. 161. Parapharyngeal carotid is at the same coronal place of anterior arch of atlas – Satish Jain Dr
  162. 162. Paraclival carotids
  163. 163. PARACLIVAL CAROTIDS 1. In 80% cases the space between paraclival carotids is TRAPEZOID & in 20% the space between paraclival carotids is HOURGLASS 2. Laceral carotid area ( paraclival & petrous carotid junction ) is saddle shapped. It is not 90 degrees 3. Paraclival carotid is inline with MPP ( Medial pterygoid plate ) 4. Paraclival carotid can be pushed medially , laterally , anteriorly or posteriorly by the tumor at laceral carotid area . Sometimes total paraclival carotid is encircled by the tumor .
  164. 164. Lower half of paraclival carotid - caudal part, the lacerum segment of the paraclival carotid ”The unsolved surgical problem remains the medial wall of the ICA at the level of the anterior foramen lacerum, until now unreachable with the available surgical approaches." - In lateral skull base by Prof. Mario sanna – this unreachable is Carotid- Clival window which is accessable in Anterior skull base Infrapetrous Approach Carotid-Clival window – Mid clivus a. Petrosal face b.Clival face
  165. 165. Circle of willis
  166. 166. Circle of willis in anterior & lateral skull base view ??? is intracerebral carotid
  167. 167. Pituitary
  168. 168. Pituitary is yellow in color like Jack fruit pulp ; spikes on fruit are pituitary ligaments
  169. 169. Pituitary 1. Jackfruit analogous to pituitary 2. Normal pituitary is yellow in color . Preserve it in surgery . Unless DI / panhypo comes . 3. Jackfruit surface has spikes . Analogous to Pituitary Ligaments which is plane for extracapsular pituitary - between pituitary capsule & meningeal layer . 4. Jackfruit peel is pituitary capsule after periosteal layer & meningeal layer of dura . So total 3 layers to enter into pituitary yellow mass from sphenoid sellar bone. Endosteal layer & Meningeal layer are fused to each other at all places except where the cranial venous sinuses are enclosed between them . 5 . Superior & inferior intercavernous sinus present between periosteal & meningeal layer of dura
  170. 170. Endosteal layer & Meningeal layer are fused to each other at all places except where the cranial venous sinuses are enclosed between them .
  171. 171. Endosteal layer & Meningeal layer are fused to each other at all places except where the cranial venous sinuses are enclosed between them
  172. 172. Saggital section
  173. 173. Therefore, in regions of the cranial base where the dura is not covered by overlying bone, the periosteal layer is absent. This is best exemplified along the superior and lateral portions of the sella, where the lack of bone creates a very unique morphological arrangement of the dura mater. Over the lateral portion of the cavernous sinus, on each side, there is a meningeal layer along the sphenoid ridge. As this then spans medially traveling along the roof of the cavernous sinus and toward the sellar roof, the meningeal layer invaginates into the sella, forming a pouch. As the meningeal layer from both sides progresses centrally and begins to invaginate, a central oval aperture is formed through which the stalk eventually runs (46). Now given that the sella, is completely covered by bone anteriorly, posteriorly, and inferiorly along the sellar floor, the invaginating meningeal layer encounters the periosteal layer in these regions forming the dense double-layered dura mater of the sellar face, which often is interpreted as a single layer (46). Laterally, by virtue of the fact that there is no bone separating the pituitary fossa from the cavernous sinus, the periosteal layer is absent and therefore the meningeal layer alone separates the pituitary gland from the cavernous sinus.
  174. 174. Lateral wall of cavernous sinus has 2 layers – there is clear cut plain between dura propria & inner membranous layer . 1. outer meningeal layer is also called Dura propria which we elevate in dolenc approach . 2. inner membranous layer formed by sheats of nerves of 3 , 4 , V1 .
  175. 175. G & H are present observations
  176. 176. Artist's drawings of different types of cavernous sinus. Left. Normal cavernous sinus. The whole cavernous sinus is enveloped by a thin membranous layer that separates the contents of the lateral wall (third (III), fourth (IV), and ophthalmic division (V~) of the fifth cranial nerves) from the venous channels of the cavernous sinus proper. The abducens nerve (VI) is the only intracavemous cranial nerve. The internal carotid artery (ICA) and second division of the trigeminal nerve (V2) are also depicted. Center: Intracavemous (Type I) tumors (for example, meningiomas) arise within the cavernous sinus, encircle and displace the cranial nerves laterally, and tend to encase and narrow the ICA. Right; Interdural (Type II) tumors (tumors of the lateral wall of the cavernous sinus) arise and remain between the two layers of the lateral wall. The deep membranous layer separates these tumors from the venous channels of the cavernous sinus. The ICA is displaced medially, but not encased or narrowed.
  177. 177. yellow arrow inferior part ( Sphenoidal part ) of the medial wall of the cavernous sinus ( yellow line ), blue-sky arrow superior ( Sellar part ) of the medial wall of the cavernous sinus ( blue-sky line ) In the upper part, the medial wall is given by the meningeal layer, that is a continuation of the diaphragma sellae, which surrounds the pituitary capsule inferiorly (Yasuda et al. 2005 ; Martins et al. 2011 ) . In the inferior part, the medial wall is given by the endosteal layer that covers the body of the sphenoid bone.
  178. 178. 3 layers anteriorly, posteriorly, and inferiorly along the sellar floor 1. periosteal dura [ PD ] 2. meningeal dura [ MD ] 3. pituitary capsule [ PC ] Intraoperative view with a zero- degree endoscope showing the two components of the dura mater located along the face and floor of the sella. The dura here is formed by an inner meningeal dura (MD) and an outer periosteal dura (PD). The intercavernous sinuses run in between both layers as the IIS shown in the picture. Once these layers reach the cavernous sinus, they bifurcate and only the meningeal layer forms the medial wall of the cavernous sinus (CS) along the lateral border of the sella. The pituitary gland is shown with a preserved pituitary capsule (PC).
  179. 179. A, schematic drawing showing the sellar region in a frontal view. The pituitary gland (P) is demonstrated in the center attached to the medial wall of the cavernous sinus (CS) by the pituitary ligaments (PLs). The anterior dura covering the pituitary gland was removed, and the pituitary stalk was freed under the chiasm (Ch). The internal carotid arteries are shown on both sides. The inferior hypophyseal arteries (IHa) originate from the meningohypophyseal trunk of the ICA within the CS, and they travel medially and posteriorly to vascularize the inferior posterior third of the gland. The inferior hypophyseal arteries are ligated and cut along with the IIS and the PLs to allow the gland to be mobilized superiorly. The superior hypophyseal arteries (SHa) are preserved, and care should be taken when opening the dural fold of the aperture to avoid injuring them.
  180. 180. From paper DOI 10.1007/s00701-011-0961-1 – “Transsphenoidal pseudocapsule- based extracapsular resection for pituitary adenomas ” - Xin Qu - – get paper from www.sci-hub.cc or www.sci-hub.bz Diagrams illustrating the pseudocapsule-based intracapsular (a) and extracapsular (b) resection approaches for large pituitary adenomas. A, adenoma; B, pseudocapsule; C, normal pituitary gland; D, pituitary capsule; E, dural envelope
  181. 181. Clivus
  182. 182. Mid clivus
  183. 183. 1. Mid clivus – from floor of pituitary to floor of sphenoid sinus 2. From carotid-clival window we can reach petrous apex by infra-petrous approach 3. Mid clivus is in between paraclival carotids
  184. 184. 1. Mid clivus – from floor of pituitary to floor of sphenoid sinus 2. From carotid-clival window we can reach petrous apex by infra-petrous approach 3. Mid clivus is in between paraclival carotids
  185. 185. 1. Mid clivus – from floor of pituitary to floor of sphenoid sinus 2. From carotid-clival window we can reach petrous apex by infra-petrous approach 3. Mid clivus is in between paraclival carotids
  186. 186. Lower clivus
  187. 187. Just adding two triangles of petrous bone base around foramen magnum , your lower clivus / foramen magnum area completes -- just as simple as that
  188. 188. Lower clivus devided into 1. tubercular compartment [ Above red line ] 2. condylar compartment [ Below red line ] Hypoglossal canal present at the junction of anterior 1/3rd & posterior 2/3rd
  189. 189. Lower clivus + petrous bone [ base ] Petrous bone devided into three 1/3rds
  190. 190. Lower clivus + petrous bone [ base ] + Zygomatic bone Petrous bone devided into three 1/3rds
  191. 191. Lateral skull base view – observe the petrous apex
  192. 192. Lower clivus + petrous apex in anterior skull base 1. observe the petrous apex in both views 2. hypoglossal canal medial to parapharyngeal carotid & jugular fossa
  193. 193. Cranio-vertebral junction in anterior skull base
  194. 194. RCLM = rectus capitis lateral muscle , RCAM = rectus capitis anterior muscle , AIM = anterior intertrasversarius muscle , Lcap = Longus capitis , Lcol = Longus coli – longus capitis anterior to longus coli
  195. 195. 1. Vertebral artery ( VA ) is medial to AIM in between C1 & C2 transverse process 2. ICA anterior to longus capitis . Lcap = Longus capitis , Lcol = Longus coli – longus capitis anterior to longus coli
  196. 196. Jugular foramen is postero-lateral to hypoglossal canal . IJV is posterior to ICA RCLM = rectus capitis lateral muscle , RCAM = rectus capitis anterior muscle , HC = hypoglossal canal , IJV = internal juvular vein , S = styloid process , ICA = internal carotid artery , VA = vertebral artery , AIM = anterior intertrasversarius muscle
  197. 197. Jugular foramen is postero-lateral to hypoglossal canal . IJV is posterior to ICA
  198. 198. Anteior longitudinal ligament attached to PT ( Pharyngeal tubercle ) . AAOM & AAAM present between lower clivus –C1 & C1–C2 respectively
  199. 199. In between eustachian tubes AAA ( anterior arch of atlas ) present .
  200. 200. 1. In between eustachian tubes AAA ( anterior arch of atlas ) present 2. Floor of nasal cavity in line with AAA FM = foramen magnum , MPP = medial pterygoid plate , LPP = lateral pterygoid plate
  201. 201. After drilling AAA ( Anterior arch of atlas ) dens seen .
  202. 202. After dens drilling- cruciate ligament seen - Transverse fibres of cruciate ligament is transverse ligament which embraces dens to prevent it dislocation
  203. 203. After anterior arch of atlas , dens drilling & cruciate ligament removal – tentorial membrane seen – tentorial membrane is upward continuation of posterior longitudinal ligament . Tentorial ligament not attached to dens
  204. 204. After opening dura . Dura present after removal of posterior longitudinal ligament & tentorial membrane . Note two ASAs ( Anterior spinal arteries )
  205. 205. Cranio-vertebral junction in lateral skull base
  206. 206. OC ( occipital condyle ) present at the back side angle of jugular bulb
  207. 207. 11th nerve present in between vertebral artery & IJV
  208. 208. 11th nerve is postero-medial & antero- lateral to IJV Postero-medial to IJV Antero-lateral to IJV
  209. 209. 2 openings in medial wall of jugular bulb – anterior is IPS opening & posterior is PCV opening
  210. 210. 1. 12th nerve between JT & OC 2. vertebral artery below OC
  211. 211. Vertebral artery present in between SO & IO triangle
  212. 212. Vertebral artery present in between SO & IO triangle
  213. 213. 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
  214. 214. Hypoglossal canal at anterior 1/3rd & posterior 2/3rd junction of OC
  215. 215. HC ( hypoglossal canal ) present between JT ( Jugular tubercle ) & OC ( Occipital condyle ) - JT & OC drilled in below diagram in infrapetrous approach
  216. 216. HC ( hypoglossal canal ) present between JT ( Jugular tubercle ) & OC ( Occipital condyle ) ; FM = foramen magnum
  217. 217. 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
  218. 218. HC present between JT & OC approached in behind jugular bulb in lateral skull base ( far lateral approach ) & anterior skull base
  219. 219. ACA complex
  220. 220. Trasnasal endoscopic view FPA = Fronto-polar artery ; FOA = Fronto-orbital artery
  221. 221. Trascranial view FPA = Fronto-polar artery ; FOA = Fronto-orbital artery
  222. 222. FPA = Fronto-polar artery ; FOA = Fronto-orbital artery Transnasal endoscopic view Trascranial view
  223. 223. Bifrontal craniotomy view FPA = Fronto-polar artery ; FOA = Fronto-orbital artery
  224. 224. Superior & inferior orbital fissure
  225. 225. 1. SOF present between two structs 2. OS [ optic struct separates optic canal from SOF ]
  226. 226. 1. SOF present between two structs 2. OS [ optic struct separates optic canal from SOF ]
  227. 227. Anterior wall of Cavernous sinus , SOF , Orbital apex in continnum [ SOF = ALSC + Orbital apex]
  228. 228. The term cavernous sinus addresses only the venous aspect, neglecting the neural and soft tissue components. A more comprehensive and rational term is lateral sellar compartment (Parkinson 1990 ) . • Lateral sellar compartment ( = Cavernous sinus ) is in continuation with SOF & Orbit • SOF devided into [ SOF = ALSC + Orbital apex] 1. ALSC = Anterior lateral sellar compartment – Located anterior to the anterior loop of the cavernous portion of the internal carotid artery. 2. Orbital apex
  229. 229. Anterior lateral sellar compartment [ ALSC ] [ SOF = ALSC + Orbital apex] An important vein travelling the SOF is quite constant. It is immediately under the periorbit, outside the muscular cone, and reaches the cavernous venous compartment. This vein can be a limiting factor for drilling the SOF area (Dallan et al. 2013 ).
  230. 230. Parts of ALSC ( Anterior lateral sellar compartment ) 1. Superior Part – Nervous compartment a. Lateral Group of nerves - from lateral to medial - LFT[ Liver functional tests ] Menumonic – Lacrimal N., Frontal N.,TrochlearN. b. Middle Group of nerves - 3rd , 6th , Nasocilliary N. 2. Inferior part – Venous compartment - Inferior Opthalmic vein – The inferior venous compartment is given by the confluence of the superior ophthalmic vein ( SOV ) and inferior ophthalmic vein ( IOV ), which drain into the cavernous sinus (Froelich et al. 2009 ) .
  231. 231. ORBITAL APEX [ SOF = ALSC + Orbital apex] Orbital apex is divided into the 1. intraconal compartment 2. extraconal compartments - passed by the lacrimal, trochlear, and frontal nerves. The frontal and trochlear nerves ascend above the Levator muscle & superior rectus muscle. Within the intraconal space, the 1. superomedial foramen - optic nerve and the ophthalmic artery pass. 2. superolateral foramen - oculomotor, nasociliary, and abducens nerves pass.
  232. 232. ORBITAL APEX [ SOF = ALSC + Orbital apex] Extraconal & intraconal compartmements
  233. 233. Parts of Orbital Apex Orbital apex is divided into the – intraconal compartment – extraconal compartments - passed by the lacrimal, trochlear, and frontal nerves. The frontal and trochlear nerves ascend above the Levator muscle & superior rectus muscle. Within the intraconal space, the 1. superomedial foramen - optic nerve and the ophthalmic artery pass. 2. superolateral foramen - oculomotor, nasociliary, and abducens nerves pass.
  234. 234. Anterior wall of Cavernous sinus , SOF , Orbital apex in continnum [ SOF = ALSC + Orbital apex]
  235. 235. ORBITAL APEX [ SOF = ALSC + Orbital apex] Orbital apex is divided into the 1. intraconal compartment 2. extraconal compartments - passed by the lacrimal, trochlear, and frontal nerves. The frontal and trochlear nerves ascend above the Levator muscle & superior rectus muscle. Within the intraconal space, the 1. superomedial foramen - optic nerve and the ophthalmic artery pass. 2. superolateral foramen - oculomotor, nasociliary, and abducens nerves pass.
  236. 236. ORBITAL APEX [ SOF = ALSC + Orbital apex] Extraconal & intraconal compartmements
  237. 237. 1. 3rd nerve supplies to the muscles from medially – so when you are doing principle of divergence [ to separate the ocular muscles ] to remove the intraconal tumors , don’t stretch too much , chances of nerve avulsion from the muscle is there sothat muscle palsy 2. SO4 LR6 – all muscles by 3rd nerve , super oblique by 4th nerve , lateral rectus by 6th nerve 3. MG = medial group of nerves – 3rd, 6rth , nasociliary ; LG = lateral group of nerves – LFT [ mneumonic = Lacrimal , frontal , trochlear ] Orbital apex [ SOF = ALSC + Orbital apex]
  238. 238. Nasal part of SOF
  239. 239. SOF & IOF are in C-shape when you see through orbit /maxilla/nose
  240. 240. SOF & IOF are in C-shape when you see through orbit /maxilla/nose
  241. 241. Optic strut [ OS ] = L-OCR [ Pneumatisation of OS ] = Posterior root of Anterior clinoid process [ ACP ] OS = L-OCR = posterior root of ACP
  242. 242. Anterior clinoid process [ ACP ] has 3 roots of attachements : 1. Anterior root – ACP attachment to sphenoid planum medial to falciform ligament 2. posterior root = OS = L-OCR 3. 3rd root to lesser wing of sphenoid
  243. 243. 1. Surpa-optic pneumatisation starts from anterior root of ACP & goes to ACP , infra-optic pneumatization starts in posterior root of ACP [ = OS = L-OCR ] & may goes into ACP 2. In ACP drilling if there is pneumatization we will directly open into sphenoid so we have to plug with fat after ACP drilling in neurosurgical skull base
  244. 244. Surpa-optic pneumatisation starts from anterior root of ACP & goes to ACP , infra-optic pneumatization starts in posterior root of ACP [ = OS = L-OCR ] & may goes into ACP
  245. 245. Carotid is usually not injured in ACP drilling because ICA turns backwards poterior /behind OS ( Optic strut ) Before ACP drilling After ACP drilling
  246. 246. Anterior clinoid drilling videos in FTOZ [ neurosurgery skull base ] 1. https://www.youtube.com/watch?v=wO2cWHiOdO0 2. https://www.youtube.com/watch?v=4dkQY3zxJHU 3. https://www.youtube.com/watch?v=vd4_lPVIUvE 4. https://www.youtube.com/watch?v=_dvYB1InGMc 5. https://www.youtube.com/watch?v=83_VuKHXOmQ 6. https://www.youtube.com/watch?v=0KwBhTqNXA4 7. https://www.youtube.com/watch?v=pCURjQ83HzU 8. https://www.youtube.com/watch?v=DNIy0L3oFgY 9. https://www.youtube.com/watch?v=GT4eBB2x58Q 10. https://www.youtube.com/watch?v=OS4Mc0X8tlU 11. https://www.youtube.com/watch?v=_xq9e3p1cc4
  247. 247. Compare the optic struct/ UDR/LDR/SOF in neurosurgical & anterior skull base 3rd & 6th nerve in SOF
  248. 248. Vasculature of the Brain and Cranial Base – from this book Superior view of the right internal carotid (IC) artery with the roof of the cavernous sinus dura removed. Part of the anterior clinoid tip has been removed. III third nerve 21 anterior clinoid DX distal ring ON optic nerve OP ophthalmic artery PX proximal ring
  249. 249. Superior view of the internal carotid artery with more extensive removal of the anterior clinoid exposing the relationship of the third nerve sheath to the proximal ring. A thin veil of dura extends from the third nerve sheath to the lateral internal carotid artery. Also note the at tachment of the third nerve sheath to the proximal ring. III third nerve IIIs third nerve sheath 21 anterior clinoid DX distal ring ON optic nerve OP ophthalmic artery PX proximal ring IC internal carotid artery
  250. 250. 1. Upper thinner & lower thicker divisions of 3rd nerve 2. 6th nerve is lateral to nasociliary nerve in between two divisisons of 3rd nerve because it has to supply lateral rectus .

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