Alltriangles0triangles360SKULLBASEapl.pdf

Retangulos base do cranio Craniotomias possiveis

1. 10 Triangles 360°
26-11-2015
10.06pm

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. For Other powerpointpresentatioins
of
“ Skull base 360°”
I will update continuoslywith date tag at the end as I am
getting more & more information
click
www.skullbase360.in
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account for downloading.

4. 10 Triangles = 4 Cavernous Sinus Triangles + 6 Middle Fossa
Triangles
4 Cavernous Sinus Triangles
1.Clinoidal(Anteromedial) Triangle
2.Oculomotor(Medial or Hakuba's) Triangle
3.Supratrochlear(Paramedian) Triangle
4.Parkinson's (Infratrochlear) Triangle
6 Middle Fossa Triangles
1.Anteromedial(Mullan's) Triangle
2.Anterolateral Triangle
3.Posterolateral(Glasscock's) Triangle
4.Posteromedial (Kawase's) Triangle
5.InferolateralTriangle
6.InferomedialTriangle

5. Cavernous Sinus Triangles
1.Clinoidal(Anteromedial) Triangle
· Borders:
1. Optic Nerve
2. OcculomotorNerve
3. TentorialEdge
· Contents:
1. Anterior ClinoidProcess
2. ClinoidalICA
2. Oculomotor(Medial or Hakuba's) Triangle
· Borders:
1. Anterior petroclinoidduralfold.
2. Posterior petroclinoidduralfold.
3. Interclinoidduralfold.
· Contents:
1. OcculomotorNerve
2. Horizontal Segment of ICA

6. cavernous Roof has -two triangles:
1. clinoid(anterior)
2. oculomotor(posterior)
ACP anterior clinoidprocess, APCF anterior petroclinoidfold, DS dorsum sellae, ICF interclinoid
fold, PF pituitary fossa, PLL petrolingualligament (inferior sphenopetrosalligament),
PPCF posterior petroclinoidfold, PS planumsphenoidale, SSPL superior sphenopetrosal
ligament (Gruber’s ligament), TS tuberculumsellae, black asterisk middle clinoidprocess , CSR
cavernous sinus roof , white asterisk oculomotornerve
If the Gruber’s ligament is ossificatedit is called Wegener’s
bridge.

7. Schematic diagram of cavernous sinus roof

8. 1. LDR=COM
2. 3
rd
nerve below COM after ACP drilling
3. COM present below ACP

9. Anterior clinoiddrilling 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

10. Clinoidhas three roots of attachment
1. Anterirorroot = Anterior Clinoidprocess attachemntto planum
2. Posterior root = Optic struct= L-OCR
3. 3
rd
root = Anterior Clinoidprocess attachment to Lesser wing of sphenoid

11. Clinoidhas three roots of attachment
1. Anterirorroot = Anterior Clinoidprocess attachemntto planum
2. Posterior root = Optic struct= L-OCR
3. 3
rd
root = Anterior Clinoidprocess attachment to Lesser wing of sphenoid

12. Three surgical attachments of the right anterior clinoidprocess.
(a, sphenoid ridge; b, roof of optic canal; c, optic strut.)

13. 1. SOF present between two structs
2. OS [ optic structseparates optic canal from SOF ]

14. 1. SOF present between two structs
2. OS [ optic structseparates optic canal from SOF ]

15. SOF & IOF are in C-shape when you
see through orbit /maxilla/nose

16. Anterior clinoidprocess [ ACP ] has 3 roots of attachements:
1. Anterior root –ACP attachment to sphenoid planummedial
to falciformligament
2. posterior root = OS = L-OCR
3. 3
rd
root to lesser wing of sphenoid

17. Optic strut [ OS ] =
L-OCR
[ Pneumatisation
of OS ] =
Posterior root of
Anterior clinoid
process [ ACP ]
OS = L-OCR =
posterior root of
ACP

18. 1. Surpa-optic pneumatisationstarts from anterior root of ACP & goes to ACP
, infra-optic pneumatizationstarts in posterior root of ACP [ = OS = L-OCR ] &
may goes into ACP
2. In ACP drilling if there is pneumatizationwe will directly open into sphenoid
so we have to plug with fat after ACP drilling in neurosurgical skull base

19. Surpa-optic pneumatisationstarts from anterior root of ACP & goes to
ACP , infra-optic pneumatizationstarts in posterior root of ACP [ = OS
= L-OCR ] & may goes into ACP

20. The lower duralring is given by the COM, that lines the inferior surface of the ACP. It
can be visible, through a transcranialroute, only by removing the ACP. The lower dural
ring is also called Perneczky’sring. Medially the COM blends with the durathat lines
the carotid sulcus (Yasuda et al. 2005 )
Endoscopic supraorbital view of the anterior clinoidregion. The right
portion of the planumsphenoidaleis seen from above. The anterior clinoidprocess
has been removed. Vision obtained through a right supraorbital approach with a 30°
down-facing lens focusing on the cavernous sinus roof.
ACP anterior clinoidprocess (removed), COM carotid oculomotormembrane, ICAc
cavernous portion of the internal carotid artery, ICAiintracranial portion of the
internal carotid artery, OA ophthalmic artery, ON optic nerve, LWS lesser wing of the
sphenoid, IIIcnoculomotornerve

21. The lower duralring is given by the COM [ Carotid-oculomotor
membrane ] , that lines the inferior surface of the ACP. It can be visible, through a
transcranialroute, only by removing the ACP. The lower duralring is also called
Perneczky’sring. Medially the COM blends with the durathat lines the carotid sulcus
(Yasuda et al. 2005 )
Endoscopic supraorbitalview with a 30°
down-facing lens -The right portion of the
planumsphenoidaleis seen from above.
Right side

22. COM = carotico–oculomotor
membrane
Superior view of the right
ophthalmic artery in the right paraclinoidarea. The anterior
clinoidprocess, which is situated on the lateral side of the
optic nerve, has been removed. The optic canal has been
unroofed, the optic sheath opened, and the optic nerve elevated
to expose the origin of the ophthalmic artery under the
medial half of the optic nerve. In the optic canal, the ophthalmic
artery courses within the duralsheath of the optic
nerve. It exits the optic canal and the optic sheath to enter the
orbital apex on the inferolateralaspect of the optic nerve.
The oculomotornerve courses just below the duracovering
the lower margin of the anterior clinoidprocess. The clinoid
segment of the internal carotid artery is the segment that
courses on the medial side of the anterior clinoidprocess and
is exposed by removing the anterior clinoidprocess. The
upper edge of the clinoidsegment is defined by a duralring,
called the upper duralring, formed by the dura, which
extends medially from the upper surface of the anterior clinoid
process. The lower edge of the clinoidsegment is
defined by the lower duralring, which is formed by the dura
that line1 the lower surface of the anterior clinoidprocess and
separates the clinoidprocess from the upper surface of the
oculomotornerve and continues medially as the carotid-
oculomotormembrane to surround the carotid artery The
ophthalmic
artery usually arises just above the clinoidsegmenl
However, it may infrequently arise from the clinoidsegment.

23. Fig. 22.31 Clinoidaland oculomotortriangles
have been opened and the anterior clinoidremoved
up to the optic strut, exposing the carotido-
oculomotormembrane. The optic strut has two
neural-facing surfaces( yellow dotted lines) and one
vascular-facing surface (red dotted line). CN: cranial
nerve; Falc.: falciform; ICA: internal carotid artery;
Inf.:inferior; Lig.: ligament; Pet.: petrosal; V1: first
division; V2: second division; V3: third division of
trigeminal nerve.
ACP anterior clinoidprocess, APCF anterior
petroclinoidfold, DS dorsum sellae, ICF
interclinoidfold, PF pituitary fossa, PLL
petrolingualligament (inferior sphenopetrosal
ligament), PPCF posterior petroclinoidfold, PS
planumsphenoidale, SSPL superior
sphenopetrosalligament (Gruber’s ligament), TS
tuberculumsellae, black asterisk middle clinoid
process

25. The optic strut has two neural-
facing surfaces( yellow dotted
lines) and one vascular-facing
surface (red dotted line).
[ COM= Lower duralring –Carotico-
Occulomotormembrane seperates
3
rd
N from Clinoidalcarotid ]

26. 3
rd
& 4
th
nerves below optic nerve

29. Roof -two triangles:
1. clinoid(anterior)
2. oculomotor(posterior)
Anterior skull base approach –see
clinoidtriangle in below photo

30. Oculomotortriangle [ 3
rd
N. , 4
th
N. & Pcom] is seen in Posterosuperior
compartment [ virtual compartment ] of cavernous sinus –better
understanding see cavernous sinus PPT
http://www.slideshare.net/muralichandnallamothu/cavernous-sinus-360

32. Note the aperture for 3
rd
nerve & 4
th
nerve anterior & posterior to
posterior petro-clivalfold [ PPCF ]

34. Oculomotorcistern
Cranial nerve III enters the roof included in its own cistern
(oculomotorcistern).
Oculomotorcistern goes upto
anterior clinoidtip

35. The lower duralring is given by the COM [ Carotid-oculomotor
membrane ] , that lines the inferior surface of the ACP. It can be visible, through a
transcranialroute, only by removing the ACP. The lower duralring is also called
Perneczky’sring. Medially the COM blends with the durathat lines the carotid sulcus
(Yasuda et al. 2005 )
Endoscopic supraorbitalview with a 30°
down-facing lens -The right portion of the
planumsphenoidaleis seen from above.
Right side

36. The trochlear nerve in 80 % of cases enters at the posterior end
of the roof of the cavernous sinus ( CS ) and in 20 % at the lower
surface of the TC (Lang 1995 ) .
80 % of cases enters at the posterior end
of the roof of the cavernous sinus ( CS ) ---
---Note the aperture for 3
rd
nerve & 4
th
nerve anterior & posterior to posterior
petro-clivalfold [ PPCF ]
in 20 % at the lower surface of
the TC (Lang 1995 )

37. The trochlear nerve is divided into 5 segments: cisternal, tentorial,
cavernous, fissural( in superior orbital fissure ) and orbital.
The cisternalsegment exits the midbrain and courses through the
quadrigeminaland ambienscisterns towards the TC. The tentorialsegment
starts when the nerve pierces the TC, usually posterior to the postero-lateral
margin of the oculomotortriangle. This segment ends at the level of the
anterior petroclinoidfold. This portion is in close relationship with the
spheno-petro-clivalvenous gulf and the petrous apex (Iaconettaet al. 2012 ).

38. The TC [ tentoriumcerebelli], with the trochlearnerve inside,
can be visualized passing inferiorly to the IIIcn.
endoscopic transclivalview

39. 1. In the posterior part of the CS the trochlearnerve is below the oculomotornerve,
while anteriorlyit turns upward and becomes the most superior structure of the CS
(at the level of the optic strut) (Iaconettaet al. 2012 ) .
2. Trochlearnerve is always
superior to V1.

40. L-OCR –Triangle
1. Upper boarder –Optic nerve & Opthalmicartery
2. Posterior boarder –Clinoidalcarotid
3. Lower boarder –3
rd
N. [ COM –Carotico-Occulomotor
membrane seperates3
rd
N from Clinoidalcarotid ]
[ 6
th
N. & 4
th
N. & V1 present inferior to 3
rd
N. ]

41. Oculomotortriangle is seen [ 3
rd
N. , 4
th
N. & Pcom] seen in
Posterosuperiorcompartment [ virtual compartment ] of cavernous sinus –
better understanding see cavernous sinus PPT
http://www.slideshare.net/muralichandnallamothu/cavernous-sinus-360

42. Antero-inferior compartment [ virtual compartment ] of cavernous sinus
–for better understanding see cavernous sinus PPT
http://www.slideshare.net/muralichandnallamothu/cavernous-sinus-360
1. The abducensnerve and the sympathetic plexus around the intracavernouscarotid artery are the only
nerves which have a real intracavernouscourse.
2. The anteroinferiorand lateral compartments contain the abducensnerve and, as surgical corridors, they
are exposed to the risk of injury to the VIthnerve.
BS basisphenoid, CS cavernous sinus, CSdduraof the cavernous sinus, ET eustachiantube, ICAccavernous portion of the internal carotid
artery, ICAhhorizontal portion of the internal carotid artery, ICApparapharyngealportion of the internal carotid artery, ILT inferolateral
trunk, LVPM levatorvelipalatinimuscle, MHT meningohypophysealtrunk, PAppetrous apex, PCFdposterior cranial fossa duraand
periosteum, PG pituitary gland, TVPM tensor velipalatinimuscle, VN vidiannerve, IIIcnoculomotornerve, IVcntrochlear nerve, V1 fi rst
branch of the trigeminal nerve, V2 second branch of the trigeminal nerve, V3 third branch of the trigeminal nerve, VIcnabducensnerve,
XIIcnhypoglossal nerve, white asterisks sympathetic fi bres
connecting the VIcn

43. Anterior clinoiddrilling 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

44. Cavernous Sinus Triangles
3. Supratrochlear(Paramedian) Triangle
· Borders:
1. OcculomotorNerve
2. Trochlear Nerve
3. TentorialEdge
· Contents:
1. MeningohypophysealTrunk
4. Parkinson's (Infratrochlear) Triangle
· Borders:
1. TrochelarNerve
Middle_fossa_triangles
Clinoidal(Anteromedial) Triangle 2
2. OpthalmicDivision (V1)
3. TentorialEdge
· Contents:
1.Cavernous ICA
2. AbducensNerve

45. Supra-trochlear triangle Infra-trochlear triangle

46. http://www.slideshare.net/INUB/endoscopic-anatomy-and-approaches-of-the-cavernous-sinus-
cadaver-study -Endoscopic view of the right cavernous sinus and neurovascular relations,
demonstrating the ‘S’ shaped configuration formed by the oculomotor, the abducensand the
vidiannerves. III oculomotornerve, V1 ophthalmic nerve, V2 maxillary nerve, V3 mandibular nerve, VI
abducensnerve, C clivus, ICA-Sa anterior bend of the internal carotid artery–parasellarsegment, ICA-Sp
posterior bend of the internal carotid artery–parasellarsegment, ICA-C paraclivalsegment of the
internal carotid artery, ICA-L lacerumsegment of the internal carotid artery, ICA-P petrous segment of
the internal carotid artery, PG pituitary gland, VC vidiancanal, VN vidiannerve
6
th
nerve is parallel to V1 –in the
same direction of V1

47. 6
th
nerve is parallel to V1 –in the same direction of V1

48. STA is devidedinto 1. Supra-Trochlear triangle
2. Infra-Trochlear triangle

49. http://www.slideshare.net/INUB/endoscopic-anatomy-and-approaches-of-the-
cavernous-sinus-cadaver-study-Endoscopic view of the right cavernous sinus and its
neurovascular relations, demonstrating the triangulararea formed by the medial
pterygoidprocess laterally, the parasellarICA medially and the vidiannerve inferiorly
at the base. III oculomotornerve, V1 ophthalmic nerve, V2 maxillary nerve, V3
mandibular nerve, VI abducensnerve, C clivus, ICA-Sa anterior bend of the internal
carotid artery–parasellarsegment, ICA-Spposterior bend of the internal carotid
artery–parasellarsegment, ICA-C paraclivalsegment of the internal carotid artery, ICA-
L lacerumsegment of the internal carotid artery, ICA-P petrous segment of the
internal carotid artery, PG pituitary gland, VC vidiancanal, VN vidiannerve

50. 1.Supra Trochanteric& InfratrochantericTriangles
2. Upper & lower duralrings

51. http://www.slideshare.net/INUB/endoscopic-anatomy-and-approaches-of-the-cavernous-
sinus-cadaver-study -Endoscopic view of the right cavernous sinus showing its neurovascular
relations and the main anatomic areas. III oculomotornerve, V1 ophthalmic nerve, V2
maxillary nerve, V3 mandibular nerve, VI abducensnerve, C clivus, ICA-Sa anterior bend of
the internal carotid artery–parasellarsegment, ICA Spposterior bend of the internal carotid
artery–parasellarsegment, ICA-C paraclivalsegment of the internal carotid artery, ICA-L
lacerumsegment of the internal carotid artery, ICA-P petrous segment of the internal carotid
artery, PG pituitary gland, VC vidiancanal, VN vidiannerve, STA superior triangular area, SQA
superior quadrangular area, IQA inferior quadrangular area
1.Supra Trochanteric & InfratrochantericTriangles
2. Upper & lower duralrings

52. http://www.slideshare.net/INUB/endoscopic-anatomy-and-approaches-of-the-
cavernous-sinus-cadaver-study -Endoscopic view (a), and a drawing (b) of the right
cavernous sinus demonstrating its neurovascular relations. c A drawing of the right
cavernous sinus demonstrating the exposure of the trochlear nerve after retracting
the oculomotornerve. III oculomotornerve, IV trochlear nerve, V1 ophthalmic nerve,
VI abducensnerve, ICA internal carotid artery, OA ophthalmic artery, OChoptic
chiasm, ON optic nerve, PG pituitary gland

53. http://www.slideshare.net/INUB/endoscopic-anatomy-and-approaches-of-the-cavernous-sinus-
cadaver-study -Endoscopic view of the right cavernous sinus and neurovascular relations,
demonstrating the ‘S’ shaped configuration formed by the oculomotor, the
abducens, carotid nerve ( paraclivalcarotid ) and the vidiannerves.
III oculomotornerve, V1 ophthalmic nerve, V2 maxillary nerve, V3 mandibular nerve, VI abducens
nerve, C clivus, ICA-Sa anterior bend of the internal carotid artery–parasellarsegment, ICA-Spposterior
bend of the internal carotid artery–parasellarsegment, ICA-C paraclivalsegment of the internal carotid
artery, ICA-L lacerumsegment of the internal carotid artery, ICA-P petrous segment of the internal
carotid artery, PG pituitary gland, VC vidiancanal, VN vidiannerve
VI nerve is parallel & medial to V1 –
in the same direction of V1 [
Mneumonic–VI & V1 in same
direction ]

54. Meningo-hypophysealtrunk & carotid nerve

55. 1. 6
th
N. crossing carotid at Petro-clivaljunction when viewing in lateral skull base -The
lateral aspect of the parasellar& paraclivalcarotid junction is crossed by the
abducentnerve (VI) at the entrance of both [ 6
th
nerve & carotid ] structures into the
cavernous sinus.
2. The gulfarsegment can be identified at the intersection of the sellarfloor and the
proximal parasellarinternal carotid artery (ICA) (Barges-Collet al. 2010 ).

56. 1. 6
th
N. crossing carotid at Petro-clivaljunction when viewing in lateral skull
base -The lateral aspect of the parasellar& paraclivalcarotid junction is
crossed by the abducentnerve (VI) at the entrance of both [ 6
th
nerve &
carotid ] structures into the cavernous sinus.
2. The gulfarsegment can be identified at the intersection of the sellarfloor
and the proximal parasellarinternal carotid artery (ICA) (Barges-Collet al.
2010 ).

57. Carotid nerve –
part of S’ shaped configuration formed by the
oculomotor, the abducens, carotid nerve (
paraclivalcarotid ) and the vidiannerves.

58. VI nerve is parallel & medialto V1 –in the same direction of V1 [ Mneumonic–VI &
V1 in same direction ]

59. STA is devidedinto 1. Supra-Trochlear triangle
2. Infra-Trochlear triangle
1.Supra Trochanteric & InfratrochantericTriangles
2. Upper & lower duralrings
3. lower duralring is COM ( Carotico-OculomotorMembrane )
In the below picture superior
cerebellar artery mislabelledas
meningohypophysealtrunk .

60. STA is devidedinto 1. Supra-Trochlear triangle
2. Infra-Trochlear triangle
1.Supra Trochanteric & InfratrochantericTriangles
2. Upper & lower duralrings
3. lower duralring is COM ( Carotico-OculomotorMembrane )
Right lateral view of the inferolateraltrunk or artery of the inferior
cavernous sinus, a branch of the horizontal part of the internal carotid
artery (ICA) that provides blood to the duraof the lateral wall of the
cavernous sinus as well as to the cranial nerves running along the lateral
wall of the cavernous sinus. The trochlear nerve has been displaced
inferiorly and the oculomotornerve has been displaced superiorly. A
recurrent branch from the inferolateraltrunk is observed in this specimen.
This branch heads back toward the tentorium cerebelliforming the so-
called marginal tentorialartery. 1=horizontal segment of cavernous ICA,
2=clinoidsegment of ICA, 3=supraclinoidICA, 4=inferolateraltrunk or
artery of the inferior cavernous sinus, 5=marginal tentorialartery, 6=optic
nerve, 7=oculomotornerve, 8=trochlear nerve, 9=ophthalmic nerve,
10=abducentnerve, and 11=sphenoid sinus.

61. 1. In the posterior part of the CS the trochlearnerve is below the oculomotornerve, while
anteriorlyit turns upward and becomes the most superior structure of the CS (at the level of
the optic strut) (Iaconettaet al. 2012 ) .
2. Trochlearnerve is always superior to V1.

62. From lateral skull base -The lateral aspect of the parasellar&
paraclivalcarotid junction is crossed by the abducentnerve (VI)

63. The abducensnerve in most case is a single trunk throughout its entire course (Zhang et al. 2012 ) . There
are some variants, and one should be aware that the nerve can fuse with the oculomotornerve for all its
course (Zhang et al. 2012 ) . The surgeon must be prepared to face other rare variations, such as different
fasciculi within the CS. Globally, the incidence of a duplicated abducensnerve has been reported, ranging
from 8 % to 18 % (Nathan et al. 1974 ; Iaconettaet al. 2001 ; Ozverenet al. 2003 ) . In the prepontinecistern,
when the duplication is present, AICA passes through the bundles. Furthermore, the incidence of a
bilaterally duplicated nerve has been reported as frequently as 8 % of the time (Nathan et al. 1974 ; Ozveren
et al. 2003 ) . The abducensnerve can pass above the Gruber’s ligament in 12 % of cases (Lang 1995 ) .
Endoscopic vision of the cavernous sinus. Vision obtained through a right supraorbital
approach with a 30°down-facing lens focusing on the cavernous sinus
ICAccavernous portion of the internal carotid artery, lwCSlateral wall of the cavernous sinus, SCA
superior cerebellar artery, IIIcnoculomotornerve, IVcntrochlear nerve, Vcnroot of the trigeminal nerve,
VIcnabducensnerve, blue arrow Gruber’s ligament, white asterisk Dorello’scanal.

64. Blue arrow in Left picture ; * in Right
picture -Gruber’s ligament

65. http://www.slideshare.net/INUB/endoscopic-anatomy-and-approaches-of-the-
cavernous-sinus-cadaver-study -Endoscopic view (a), and a drawing (b) of the right
cavernous sinus demonstrating its neurovascular relations. c A drawing of the right
cavernous sinus demonstrating the exposure of the trochlear nerve after retracting
the oculomotornerve. III oculomotornerve, IV trochlear nerve, V1 ophthalmic nerve,
VI abducensnerve, ICA internal carotid artery, OA ophthalmic artery, OChoptic
chiasm, ON optic nerve, PG pituitary gland

66. Middle Fossa Triangles
5.Anteromedial(Mullan's) Triangle
· Borders:
1. OpthalmicNerve (V1)
2. Maxillary Nerve (V2)
3. A line connecting Superior Orbital Fissure and Foramen Rotundum
· Contents:
1. Sphenoid Sinus
2. OpthalmicVein
3. AbducensNerve
6. Anterolateral Triangle
· Borders:
1. Maxillary Nerve (V2)
2. Mandibular Nerve (V3)
3. A line connecting Foramen Rotundumand Foramen Ovale
· Contents:
1. Lateral sphenoid wing
2. Spenoidemmissaryvein
3. Cavernous-PterygoidVenous Anastamosis

67. The space between V1 & V 2 and V2 & V3
is sphenoid sinus
Middle cranial fossa approach –
the nerve between V2 & V3 is VN
Anateriorskull base

69. http://www.slideshare.net/INUB/endoscopic-anatomy-and-approaches-of-the-
cavernous-sinus-cadaver-study-Endoscopic view of the right cavernous sinus and its
neurovascular relations, demonstrating the triangulararea formed by the medial
pterygoidprocess laterally, the parasellarICA medially and the vidiannerve inferiorly
at the base. III oculomotornerve, V1 ophthalmic nerve, V2 maxillary nerve, V3
mandibular nerve, VI abducensnerve, C clivus, ICA-Sa anterior bend of the internal
carotid artery–parasellarsegment, ICA-Spposterior bend of the internal carotid
artery–parasellarsegment, ICA-C paraclivalsegment of the internal carotid artery, ICA-
L lacerumsegment of the internal carotid artery, ICA-P petrous segment of the
internal carotid artery, PG pituitary gland, VC vidiancanal, VN vidiannerve

70. JNA DISSECTION IN ANTEROLATERAL TRIANGLE .. NOTE V3

71. VI nerve is parallel & medialto V1 –in the same
direction of V1 [ Mneumonic–VI & V1 in same
direction ]

72. Middle Fossa Triangles
7. Posterolateral(Glasscock's) Triangle
· Borders:
1. Mandibular Nerve (V3)
2. Greater Superficial PetrosalNerve
3. A line from Foramen Spinosumto ArcuateEminence
· Contents:
1. Foramen Spinosum
2. Horizontal Petrous ICA (for anastamosis)
3. InfratemporalFossa
8. Posteromedial (Kawase's) Triangle
This area is also known as The Rhomboid. Removal of the petrous bone within this triangle/quadrangle is an
anterior petrosectomy.
· Borders:
1. Mandibular Nerve (V3)
2. GSPN
3. ArcuateEminence
4. Superior PetrosalSinus
-or-
1. GSPN
2. ArcuateEminence
3. A line connecting the hiatus fallopiiand Meckel'sCave
· Contents:
1. Petrous Apex
2. IAC
3. VertebrobasilarJunction
Contains cochlea

73. Posterolateral(Glasscock's)
Triangle

74. 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
infratemporalfossa 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
eustachiantube (ET).

75. Infratemporalfossa anatomy
line diagram in both anterior
& lateral skull base (
Infratemporalfossa approach
A, B, C , D )

76. Iatrogenic chances of injury of cochlea
in infratemporalfossa transpetrous
approach

77. The skin incision.
The external auditory canal
(arrow) is closed as cul-de-sac.

78. The temporalis muscle is
detached anteriorly.
The zygomaticarch is transected.
Arrows point to the transection sites.

79. Subtotal petrosectomy.
The facial nerve (FN) is skeletonized and the
vertical internal carotid artery (ICA) is identified.

80. A minicraniotomyhelps positioning
the infratemporalfossa retractor.
Identification of the middle meningeal artery (MMA)
crossing lateral to the eustachiantube (ET).

81. Coagulation of the middle
meningeal artery (MMA).
Cutting the middle meningeal
artery (MMA).

82. Identification of the mandibular
nerve (V3). The mandibular nerve (V3) is cut.

83. Suturing the eustachiantube (ET)
at the end of the procedure.Closure and drain insertion.

84. Infratemporalfossa approach B
in cadaver

85. 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

86. The periosteum(P) overlying the
zygomaticarch (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

87. The zygomaticarch 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

88. After complete removal of the external
auditory canal skin
and tympanic membrane, the
incudostapedialjoint is disarticulated in
order to remove the ossicularchain. 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

89. A radical mastoidectomyhas 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 retrofacialand infralabyrinthineair 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 Endolymphaticsac, FN(m)
Mastoid segment of the
facial nerve, ICA Internal carotid artery, SS
Sigmoid sinus

90. 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. ACWAnteriorcanal wall, SB
Squamous bone, ZR Zygomatic
root

91. A small craniotomy (CT) has
been created in the squamous
bone. ACWAnteriorcanal wall,
AD Articular disk
A self-retaining retractor is used
to keep the mandible retracted
inferiorly. ACWAnteriorcanal
wall, AZT Anterior zygomatic
tubercle, GF Glenoidfossa

92. 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 eustachiantube (ET),
glenoidfossa bone (GF), and the
anterior zygomatictubercle (AZT) have to
be carefully drilled away.
ICA Vertical segment of the internal carotid
artery

93. 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

94. 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

95. The stumps of the mandibular
nerve (*). ET Eustachian tube,
ICA Internal carotid artery,
MFP Middle fossa plate
The eustachiantube (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

96. The lateral, thin part of the
eustachiantube (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
eustachiantube, ICA Internal
carotid
artery, MFP Middle fossa plate

97. 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 durawill lead to
stress on the
facial nerve at the geniculate ganglion (GG) level. Thus, if
duralretraction
is needed, cutting the petrosalnerve will prevent this
injury. C Basal turn
of the cochlea (promontory), CL Clivusbone, G Genu,
ICA(v) Vertical
segment of the internal carotid artery

98. 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 petrosalnerve, MFP Middle fossa plate,
MMA middle
meningeal artery stump
Drilling of the clivushas 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 petrosalnerve, ICA
Internal carotid artery, RW Round
window

99. The full course of the intratemporalinternal
carotid artery has
been freed. AFL Anterior foramen lacerum,
CF Carotid foramen, CL Dura
overlying the clivusarea, 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.

100. 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

101. Kawasetriangle

102. Two bissectionsin 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

103. Triangles of Middle cranial fossa –see Ant. Medial & Ant. Lateral triangles in both photos.
http://www.eneurosurgery.com/surgicaltrianglesofthecavernoussinus.html
Postero-medial Triangle = KAWASE triangle [Prof.KAWASE, JAPAN Neurosurgeon -below photo]

104. Neurosurgeons are doing FTOZ + kawaseapproach to
get control of middle cranial fossa & posterior cranial
fossa respectively
For FTOZ + Kawaseapproach click
1. https://www.youtube.com/watch?v=qgItZDwRYjk
2. https://www.youtube.com/watch?v=M89uijtuzQA
3. https://www.youtube.com/watch?v=es-U3QitxdY
4. https://www.youtube.com/watch?v=vDGO4kVy0Gc
5. http://www.aiimsnets.org/skull_base_tumors.asp
6. http://aiimsnets.org/AnteriorTranspetrosalapproach.asp#
others
https://www.youtube.com/results?search_query=frontotemporal+orbitozygo
matic+approach
https://www.youtube.com/results?search_query=kawase+approach

105. FTOZ + kawaseapprochcadaver
albums
•https://www.facebook.com/groups/38350835
5070291/permalink/896897763731345/
•https://www.facebook.com/groups/38350835
5070291/permalink/897122833708838/

106. Modified Anterior TranspetrosalPosterior Cavernous Posteromedial
Rhomboid (Dolenc-KawaseRhomboid) Approach to Posterior Cavernous
and PetroclivalLesions –AIIMS , INDIA
https://www.thieme-
connect.com/products/ejournals/abstract/10.10
55/s-0034-1370530

107. The same approach what you get in
FTOZ + KAWASE approach , you get
in Type C Modified transcochlear
approach without any brain
retraction

108. Various types of Modified
transcochlearapproach
Don't give too much
importance to the jargon
of approaches .
Approaches developed
from anatomy . Anatomy
not developed from
approaches. Know the
www.skullbase360.inanat
omy. Automatically you
can individualize the
approach for the tumor .

109. a Schematic drawing showing the extent of the modified
transcochleartype C approach. Note the superior extent of the craniotomy
and the cut of the tentorium. b The markings of the skin incision
to be made.

110. Drawing showing the structures
exposed.
Incision of the middle fossa dura. The vein of Labbé(vL)
is
clearly seen.

111. Cutting the tentorium (Ten).
The last part of the tentorium is still to
be cut to reach the tentorialnotch.

112. The different structures seen
after completion of the approach.
With mild retraction of the temporal lobe, the
bifurcation of
the internal carotid artery (ICA) into the anterior
(ACA) and middle cerebral
(MCA) arteries is seen. The ipsilateral(ON) and
contralateral (ONc)
optic nerves are seen. The oculomotornerve (III)
is embraced by the
posterior cerebral artery (PCA) superiorly and the
superior cerebellar
artery (SCA) inferiorly.

113. Petroclivalmeningiomassurgery by
Modified transcochlearapproach
Click video
https://www.youtube.com/watch?v=
kUa9fQ4_aQY

114. Middle Fossa Triangles
•9. InferolateralTriangle
· Borders:
1. A line from the duralentries of the Trochlear and AbducensNerve
2. A line from the duralentries of the AbducensNerve and the PetrosalVein
3. The petrous apex
Middle_fossa_triangles
Posterolateral(Glasscock's) Triangle
· Contents:
1. Porous Trigeminii(Dural opening into Meckel'sCave)
10. InferomedialTriangle
· Borders:
1. A line from the duralentries of the Trochlear and AbducensNerve
2. A line from the duralentries of the AbducensNerve and the Posterior Clinoid
3. The petrous apex
· Contents:
1. Porous Abducens(Dural opening into Dorello'sCanal)
2. Gruber's Ligament

115. inferomedialtriangle –remember that 6
th
nerve below the
grubersligament passes in this triangle
· Borders:
1. A line from the dural
entries of the Trochlear and
AbducensNerve
2. A line from the dural
entries of the Abducens
Nerve and the Posterior
Clinoid
3. The petrous apex
· Contents:
1. Porous Abducens(Dural
opening into Dorello'sCanal)
2. Gruber's Ligament

116. Anterior skull base view of Inferomedialtriangle -6
th
nerve –enters the dorelloscanal –Intraduralcourse
clinical importance = GradenigoSyndrome -Infection & inflammation of petrous apex involves
6
th
cranial nerve at the Dorello'scanal and 5
th
cranial nerve in the Meckel'scave

117. The basilar artery (BA) can be seen
very tortuous.

118. Cadaveric dissection of the middle third of the clivuswith removal of the basilar
plexus and exposing the dura. The abducens
nerves (CN VI) can be seen bilaterally as they perforate the meningeal duraand
become the interduralsegments of CN VI. CS,
cavernous sinus; PCA, paraclivalcarotid arteries; P, pituitary gland.

119. Gulfarsegment of 6
th
nerve (GS in left picture ) ( gVIcnin right picture ) -The
gulfarsegment can be identified at the intersection of the sellarfloorand the
proximalparasellarinternal carotid artery (ICA) (Barges-Collet al. 2010 ).
6
th
nerve enters dorello’scanal between
the meningeal layer of duraand the
periosteal layer of dura(POD).

120. 1. 6
th
N. crossing carotid at Petro-clivaljunction when viewing in lateral skull base -The
lateral aspect of the parasellar& paraclivalcarotid junction is crossed by the
abducentnerve (VI) at the entrance of both [ 6
th
nerve & carotid ] structures into the
cavernous sinus.
2. The gulfarsegment can be identified at the intersection of the sellarfloor and the
proximal parasellarinternal carotid artery (ICA) (Barges-Collet al. 2010 ).

121. 1. 6
th
N. crossing carotid at Petro-clivaljunction when viewing in lateral skull
base -The lateral aspect of the parasellar& paraclivalcarotid junction is
crossed by the abducentnerve (VI) at the entrance of both [ 6
th
nerve &
carotid ] structures into the cavernous sinus.
2. The gulfarsegment can be identified at the intersection of the sellarfloor
and the proximal parasellarinternal carotid artery (ICA) (Barges-Collet al.
2010 ).

122. AICA anterior-inferior cerebellarartery, Clclivus, CS cavernous sinus, ICAccavernous portion
of the internal carotid artery, IPS inferior petrosalsinus, LPMVN lateropontomesencephalic
venous network, PBs pontinebranches, PG pituitary gland, TPV transverse pontinevein, VA
vertebral artery, VN vidiannerve (bordered in yellow ), Vcntrigeminal nerve, VIcnabducens
nerve, yellow arrow cavernous portion of the abducensnerve

123. Blue arrow in Left picture ; * in Right
picture -Gruber’s ligament

124. inferolateraltriangle –remember that 5
th
nerve
passes in this triangle
· Borders:
1. A line from the dural
entries of the Trochlear and
AbducensNerve
2. A line from the dural
entries of the Abducens
Nerve and the PetrosalVein
3. The petrous apex
Middle_fossa_triangles
Posterolateral(Glasscock's)
Triangle
· Contents:
1. Porous Trigeminii(Dural
opening into Meckel'sCave)

125. Anterior skull base view of Inferolateraltriangle -“Front door” to
Meckel’scave –the space between trigeminal ganglion & laceralcarotid is
called quadrangular space –suprapetrousapproach
PLL -It can be considered the border between the horizontal and cavernous
portions of the internal carotid artery.

126. For Other powerpointpresentatioins
of
“ Skull base 360°”
I will update continuoslywith date tag at the end as I am
getting more & more information
click
www.skullbase360.in
-you have to login toslideshare.netwith Facebook
account for downloading.