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SKULL BASE 360°
Below presentation is
SKULL BASE 360°-Part 2
For
SKULL BASE 360°-Part 1
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Great teachers – All this is their work .
I am just the reader of their books .
Prof. Paolo castelnuovo
Prof. Aldo Stamm P...
For Other powerpoint presentatioins
of
“ Skull base 360° ”
I will update continuosly with date tag at the end as I am
gett...
Below presentation is
SKULL BASE 360°-Part 2
Indetail eloborate description for
each part of skullbase360 done at
www.skul...
Orbit
Orbital fascia = Periorbita
Bulbar fascia includes
1. Tenon’s capsule 2. Tubular sheat for each orbital muscle 3. medial & lateral
check ligament 4. s...
Superior oblique tendon goes underneath the superior rectus
where are inferior oblique muscle goes below the inferior rect...
Parts of SOF
1. Lateral part- LFT [ Liver functional tests ] Menumonic – Lacrimal N., Frontal
N.,Trochlear N.
2.Middle par...
Parts of SOF
1. Lateral part- LFT [ Liver functional tests ] Menumonic – Lacrimal N., Frontal
N.,Trochlear N.
2.Middle par...
Branches of V 1
1. Lacrimal N.
2.Frontal N.
3. Nasociliary N.
Immediately after removing the
periorbita
Frontal N. devides into Sup.Troch.N.
& Supraorb.N. – NOTE Fal.Lig
A segment of the orbital portion of the optic
nerve has been removed. This exposes the
branch of the inferior division of ...
When you are approaching endoscopically
the upper most one is Sup.Orb.M
superiorly & Medial rectus inferiorly
The medial a...
Nasociliary N. [ 3rd branch of V1 ]
devides into AEN & PEN
Inferior orbital muscle is completely
muscle , whereas Sup.Obl.M is muscle &
tendinous
Medial
Orbital
Approach-
Periorbita
elevated
from
bone
Accessing intraconal lesions endonasally requires manipulation of the extraocular
muscles. The nerve branches that supply ...
OPTIC NERVE DECOMPRESSION
Optic tubercle
In 83% the OA passes around the lateral aspect of the optic
nerve (b, left); in the remaining cases the OA stays medial to...
One artery in the head which we can’t move – is
OA – Central retinal artery is avulsed
Relation of PEA & ON
Anterior limit of Transplanum approach is
PEA – when we are removing a triangular
piece of bone in Tr...
when we are removing a triangular piece of bone in
Transplanum approach , the base of traingle is PEA
The sphenoid ostium (SO) is first opened inferiorly (black arrow, 1) then laterally (black
arrow, 2). This should afford a...
Opthalmic artery – Retrograde branch of Intracranial carotid
Branches of the cavernous internal
carotid artery ( ICA ), a ...
classification of the ophthalmic artery types
http://www.springerimages.com/Images/MedicineAndPublicHealth/1-
10.1007_s101...
In both type a = intradural type,
b = extradural supra-optic strut types Opthalmic
foramen is in Optic canal
In Type c = extradural trans-optic strut type , the Opthalmic
foramen in Optic strut
http://www.nature.com/eye/journal/v20/n10/fig_tab/6702377f3.html#figure
-title
The upper diagram is Type a or b Opthalmic ...
Origin and intracranial and
intracanalicular course of
the ophthalmic artery and its
subdivisions, as seen on opening
the ...
Schematic drawing origin (a medial, b central, c lateral) and exit
(d lateral, emedial) of superior wall of the ophthalmic...
A diagrammatic representation of variations in origin and intraorbital course of ophthalmic artery.
(a) Normal pattern. (b...
Origin, course, and branches of the ophthalmic artery in two adult specimens. Segment Y
disappeared in (a) and segment Z d...
Various relations of OA [ Opthalmic artery ] to ON
left figure when it crosses under the optic
nerve (in 17.4%) and right ...
The dura over the ACP passes over the
ON, giving the falciform ligament
Fibrous tissue
FCB-Fibrocartilago basalis at junction
of petrous & paraclival carotid
Fibrous tissue surrounds the entrance of
the verteb...
Fibrous tissue surrounds the entrance of
the vertebral artery into the CPA.
Left side. Combined transsigmoid, suboccipital...
Laceral carotid lies over the Foramen lacerum not passing through
Foramen lacerum - Foramen lacerum floor is occupied by F...
A nontoothed forceps is used to hold the soft tissues (ST) surrounding
the nerve at the level of the stylomastoid foramen ...
Rerouting of the facial nerve. FN(m) Mastoid
segment of the
facial nerve, FN(p) Intraparotid facial nerve, SM
Facial nerve...
Styloid process
Styloid apparatus – superior
view Styloid apparatus – lateral view
After the attached muscles have been dissected away, the
styloid process (SP) is fractured using a rongeur. FC Fallopian c...
Fig. 9.21 To obtain control over the vascular structures as they enter
the temporal bone, the tympanic bone (TB), the fall...
The view after completely uncovering the lateral surfaces of
the vascular structures. C Basal turn of the cochlea (promont...
Fig. 9.29 The plane of dissection between the internal carotid artery
(ICA) and the overlying periosteum (P) is best devel...
Internal carotid artery is deeper to styloid process when we see from laterally &
medial to styloid process when we see fr...
Two things protect the parapharyngeal carotid anteriorly
1. Tensor veli palatini & 2. SPHA [ = stylopharyngeal
aponeurosis...
Inferior petrosal sinus
HVP hypoglossal
venous plexus
The Petro-occipital Fissure- contains IPS
The Petro-occipital Fissure- contains
IPS
Exocranial & Endocranial views of Jugular Foramen : Within the JF
area 2 venous compartement can be identified: a large po...
Usually inferior petrosal sinus
opens into jugular bulb
Sometimes along with jugular
bulb opening , it opens into
internal...
Inferior petrosal sinus
a. IPS inferior to nerve IX and
superior to nerves X and XII.
b. IPS inferior and medial to all
four nerves.
c. IPS superi...
An anatomical classification according to the level of the inferior
petrosal sinus–internal jugular vein junction has been...
3. Junction at the level of the
lower extracranial jugular vein
• CoC - level of the condylar
canal
• IJV- internal jugula...
4. Multiple junctions: upper junction at the level of the jugular bulb and
lower junction at the level of the anterior con...
In Transcochlear approach
In infratemporal fossa [=intact
cochlear approach –
Dr.Morwani ] type B
approach
See IPS in Kawase approach
Right sided anterior petrosectomy on a cadaver dissection: intradural exposure
and operative field. PCA Petrous carotid ar...
NOTE Inferior petrosal sinus at CLIVUS
ICAc cavernous portion of the internal carotid artery, IPS inferior petrosal sinus,...
In middle cranial fossa approach
In middle cranial fossa approach
3rd nerve
3rd nerve is sandwiched between posterior
cerebral artery & superior cerebellar artery
3rd nerve is sandwiched between posterior cerebral artery &
superior cerebellar artery
3rd nerve is sandwiched between posterior cerebral artery &
superior cerebellar artery
Through endoscopic lateral skull
ba...
3rd nerve is sandwiched between posterior cerebral
artery & superior cerebellar artery
Through endoscopic lateral skull
ba...
P1 in relation to 3rd nerve P2 in relation to 3rd nerve
Relationship of PcomA & 3rd nerve –
parallel to each other
In parasellar pituitary 3rd n & 4th n & Pcom present
in Postero-superior cavernous compartment
Relationship of PcomA & 3rd nerve
Relationship of PcomA & 3rd nerve
a,b Intraoperative image of the fenestration of deep cystic membrane using different microsurgical
instruments (forceps an...
Right supraorbital approach (0 optic). 1 Diaphragma sellae, 2 cn II, 3 optic
tract, 4 ICA, 5 A1, 6 M1, 7 C. N.III, 8 anter...
Note the aperture for 3rd nerve & 4th nerve anterior & posterior to
posterior petro-clival fold [ PPCF ]
Oculomotor cistern
Cranial nerve III enters the roof included in its own cistern
(oculomotor cistern).
Oculomotor cistern ...
The lower dural ring is given by the COM [ Carotid-oculomotor
membrane ] , that lines the inferior surface of the ACP. It ...
Fronto-temporal orbitozygomatic
transcavernous approach
COM= Caratico-occulomotor
membrane , DR = dural ring
The oculomotor nerve divides into a
small superior and large inferior division just before passing
through the superior or...
4th nerve
4th nerve – 5 components – a. cisternal b. tentorial –
see paolo castelneovo book
Endoscopic lateral skull base
The TC [ tentorium cerebelli ], with the trochlear nerve inside,
can be visualized passing inferiorly to the IIIcn.
endosc...
1. In the posterior part of the CS the trochlear nerve is below the oculomotor nerve,
while anteriorly it turns upward and...
1. In the posterior part of the CS the trochlear nerve is below the oculomotor nerve, while
anteriorly it turns upward and...
(A) Intraoperative endoscopic close-up view showing the trigeminal nenre and the related neurovascular
anatomy. a Trigemin...
5th nerve
Trigeminal area at Cerebello Pontine
Angle – along with my voice
Click
http://www.youtube.com/watch?
v=YBqk4Jdnxic
171
175
6th nerve
The pontomedullary junction.
1. The exit zones of the hypoglossal and abducent nerves are at
the same level [ same vertica...
6th nerve origin is above or below AICA or has two
rootlets of origin
6th is appresiated in TA-II [ Transapical type II ]
approach when 360 degrees IAC drilled
6th nerve – enters the dorellos canal –
Intradural course
6th nerve – enters the dorellos canal – Intradural course
clinical importance = Gradenigo Syndrome - Infection & inflammat...
The DMA is in close relationship with the abducens nerve at the level
of petrous apex (Cavallo et al. 2011 ) . The DMA is ...
When we are doing clival chordoma we have to
anticipate 6th nerve medial to paraclival carotid
which is present in dorello...
Courtesy Dr. Tomasz Skibinski
The basilar artery (BA) can be seen
very tortuous.
Gulfar segment of 6th nerve (GS in left picture ) ( gVIcn in right picture ) - The
gulfar segment can be identified at the...
ICAc cavernous portion of the internal carotid artery, IPS inferior petrosal sinus, PAp petrous apex, SPCG sphenopetrocliv...
1. 6th N. crossing carotid at Petro-clival junction when viewing in lateral skull base
2. The gulfar segment can be identi...
Inferior boarder of L-OCR is by 6th
nerve & V1
AICA anterior-inferior cerebellar artery, Cl clivus, CS cavernous sinus, ICAc cavernous portion
of the internal carotid ar...
Blue arrow in Left picture ; * in Right
picture - Gruber’s ligament
Usually, the IPS passes beneath the superior petro-sphenoidal
ligament (l. of Gruber) with the abducens nerve.
Grubers ligament
6th nerve passing below gruber’s
ligament
ACP anterior clinoid process, APCF anterior petroclinoid fold, DS dorsum sellae, ICF interclinoid
fold, PF pituitary fossa...
6th nerve is parallel to V1 – in the same
direction of V1
6th nerve is parallel to V1 – in the same direction of V1
http://www.slideshare.net/INUB/endoscopic-anatomy-and-approaches-of-the-cavernous-sinus-
cadaver-study - Endoscopic view o...
Upper part of S-shaped configuration –
3rd & 6th nerves.
6th nerve is freely hanging in the cavernous injury when
compared to 3rd & 4th nerve – so postential for injury in
tumor d...
7th nerve
Vertical part of 7th nerve bissects the
jugular bulb
In 50% of the cases mastoid segment of Facial nerve travels
lateral to level of annulus – This is important while removing...
3rd GENU
When facial nerve exists the temporal bone , the main trunk of
the facial nerve is the perpendicular bisection of...
9th nerve
A closer view of the pars nervosa of
the jugular
foramen. The glossopharyngeal nerve
has its own dural
porus, which is sit...
Note the bone (>, <) left to protect the
dura from the drill.
AC Supralabyrinthine air cells, CA
Cochlear aqueduct, FN Fac...
Fig. 2.57 After rerouting the facial nerve and drilling away the fallopian canal of a
left temporal bone, the cochlear aqu...
The cochlear aqueduct is a bony channel with a pyramidal shape
connecting the perilymphatic space of the scala tympani in ...
Drilling has been carried out more
inferiorly to identify the
cochlear aqueduct (CA). Note the
proximity of the aqueduct t...
The bone overlying the transitional zone from the jugular
bulb (JB) to the internal jugular vein (IJV) has been drilled aw...
9th nerve present between internal carotid & jugular
bulb at carotid canal area[extra-cranially]
View from anterior skull ...
9th nerve – in cadaver
Jugular foramen area [
9,10,11,12 nerves]
Superior & inferior ganglion of vagus
at jugular foramen
Jugular tubercle [ JT ] , star = foramen lacerum
In the cerebello-medullary cistern the LCNs cross the
posterior surface of the JT on their way to JF (Fernandez-
Miranda e...
Note the relationship of clivus &
jugular tubercle
Jugular tubercle [ JT ]
AICA antero-inferior cerebellar artery, ASC anterior semicircular canal, BA basilar artery, HC
hyp...
Jugular tubercle [ JT ]
Exocranial & Endocranial views of Jugular Foramen : Within the JF
area 2 venous compartement can be identified: a large po...
The glossopharyngeal nerve has its
own dural porus, which is situated 0-
3 mm upwards from the duralporus
of the tenth cra...
Jugular fossa is just lateral to
hypoglossal canal
12th nerve
The pontomedullary junction.
1. The exit zones of the hypoglossal and abducent nerves are at
the same level [ same vertica...
A closer view of the anterior border
of the pontomedullary stem and the
vertebral artery junction and origin
of the basila...
Fig. 26a, b Right side. The root fibers of the hypoglossal
nerve (12) collect in two bundles, which pierce the dura in
two...
Through lateral skull base - The
curved vertebral artery displaces
and stretches the hypoglossal
nerve fibers.
Through ant...
Through lateral skull base - The curved
vertebral artery displaces and stretches the
hypoglossal nerve fibers.
Through lat...
HC = hypoglossal canal , JT= Jugular Tubercle
SCG = Supracondylar groove
Jugular fossa is just lateral to
hypoglossal canal
Hypoglossal canals
From front – through nose From back
Coronal cut – hypoglossal canal
1. The SCG [Supracondylar groove] represents a reliable landmark for hypoglossal canal (HC)
identification (red arrow) (Mo...
Transoral approach to SUPERO-MEDIAL Parapharyngeal
tumors – incision anterior to anterior pillar of tonsil
In infrapetrous approach there are chances of injury to 6th nerve [ in dorello’s
canal medial to paraclival carotid ] & 12...
12th nerve bissecting internal & external carotid
Vertebral artery
Robbins level II. 1 Sternocleidomastoid muscle, 2
posterior belly of digastric muscle, 3
spinal accessory nerve (common tr...
Superior view of the atlas and the axis.
The atlas consists of two thick lateral masses situated
at the anteromedial part ...
The entrance of the vertebral artery is the boundary between the foramen
magnum and the spinal part of the accessory nerve...
Fibrous tissue surrounds the entrance of
the vertebral artery into the CPA.
Left side. Combined transsigmoid, suboccipital...
In transcochlear approach
Anterior cranial fossa
Anterior & Posterior perforated
substance
Anterior perforated substance &
olfactory track relation
Fronto-polar artery
Superior hypophyseal artery =
SHA
Superior Hypophyseal Arteries [ SHAs ]
- more commonly arise from the paraclinoid ICA - In rare cases SHAs originate
from ...
Cisterns
Oculomotor cistern
Oculomotor cistern
Cranial nerve III enters the roof included in its own cistern
(oculomotor cistern).
Oculomotor cistern ...
LT lamina terminalis cistern=
Suprachiasmatic cistern
LT lamina terminalis cistern –
The lamina terminalis cistern is situated above the optic chiasm (Martins etal.
2011 ) . Wi...
The space between a & oc is Lamina terminalis
Neuroendoscopic view of the third ventricle floor-----Infundibular recess (i...
Endoscopic third ventricle from
posteriorly -- a. Infundibular
recess b. tuber cinereum c.
mammillary bodies
left posterio...
Endoscopic third
ventricle from
posteriorly --
a. Infundibular recess b.
tuber cinereum c.
mammillary bodies
From front – ...
In the descriptive analysis of the 20 specimens, the PCoAs
distance was 9 to 18.9 mm, mean of 12.5 mm, median of 12.2
mm, ...
Optic chiasma – infundibulum – Mamillary
bodies
Chiasmatic cistern
The AcomA complex is usually above the optic chiasm (70 % of cases)
(Rhoton 2003 ) . The AcomA is similar to the textbook ...
1. The transplanum route may also facilitate exposing the
anterior incisural space. On the center of this space the chiasm...
Below the OT & A1 you will see PComA
Endoscopic view of the anterior part of the Left Suprasellar area [ = Sub-
Chiasmatic...
Chiasmatic cistern –
The chiasmatic cistern is located in front of the
optic chiasm and above the sella turcica. In the la...
CSF rhinorrhoea case
Closed with hadad flap
lt ICA SEEN ON LT SIDE.. A HOLE IN THE ARACHNOID..
THE STALK JUST BEHIND IT.. ...
Sub-chiasmatic cistern = Supra
sellar area = Supr-sellar cistern
Observe here the Pcom (here labelled as ACoP in some language ) is parallel
to 3rd nerve in infrachiasmatic cistern . Exce...
Retrosellar
Interpeduncular cistern[ = basal
cistern ]
Interpeduncular cistern
Interpeduncular cistern
IR = infundibulum
Interpeduncular cistern -- Removal of the upper clivus (dorsum sella and
posterior clinoids) provides an excellent view of...
Right supraorbital approach (30 optic).
Window between cn II and ICA: 1 left
PCoA, 2 left P2, 3 left cn III, 4 left P1, 5
...
Mammillary bodies
Without removing the DS ,
Subchiasmatic view downwards
After removing the DS &
midclivus
Craniopharyngioma
https://www.facebook.com/groups/4
05175366256295/permalink/552393
251534505/?stream_ref=2
CRANIOPHARYNGIOMAS-Removal corridors.
https://www.scienceopen.com/document_file/84699ab2-4980-4f70-a5b0-
c8d95a1fb6a2/PubMedCentral/84699ab2-4980-4f70-a5b0-c8d9...
FIGURE 2. In this cystic craniopharyngioma (Patient 5), the stalk was centrally
infiltrated close to the pituitary and cou...
FIGURE 3. Large craniopharyngioma (Patient 3) produced unilateral hydrocephalus
by obstructing the right formen of Monro A...
Supratentorial arteries
• http://dc496.4shared.com/doc/2vRIALeU/pre
view.html
Optic pathway
Interpeduncular cistern
3rd ventricle is visualised
..through the tuber cinereum
Recurrent artery of Heubner
Recurrent artery of Anterior cerebral
artery = Recurrent artery of Heubner
The recurrent artery of Heubner usually origins from the post-communicating segment of the anterior
cerebral artery (ACA)....
3rd ventricle
3rd ventricle entered through
1. Supra optic chiasmic route – by Lamina terminalis
2. Infra optic chiasmic route – by Tube...
3rd ventricle entry by - Supra optic chiasmic route – by
Lamina terminalis
FM – Foramen of Monro
FM – Foramen of Monro
CC corpus callosum, CP choroid plexus, MI massa intermedia, PC posterior commissure, T
thalamus, ThV fl floor of the third...
Intradural Anatomy
Different positions of the anterior inferior cerebellar artery (AICA) in relation to the
internal auditory meatus.
1st & 2nd cervical vertebrae
Don’t use cutting bur while drilling “Frontal T” in
Draf 3 – Use only diamond bur – we may injure
the dura .
HADAD FLAP ---1, area
of origin of the nasoseptal flap (dotted line); 1b, area of origin of the
extended nasoseptal flap, ...
anterolateral endonasal flap.
Pituitary surgery
pituitary tumors schematic diagram.
Fig. 13.17 Classification of Knosp et al.10 grading the cavernous sinus extension
when compared with lines drawn medial th...
Cavernous Sinus MRI anatomy
Liliequist membrane [LM]
Liliequist membrane - Interpeduncolar cistern separated from prepontine
cistern by the mesencephalic leaf of LM.
Liliequist
Craniopharyngioma removal -
Lilliquest membrane & Basillar artery
LM through subtemporal approach
APPROACHES
DRAF III
1st olfactory neuron seen in draft 3
Outside-in approach of draf III –
similar like outside-in mastoid
Inside-out approach of draf III –
similar like Inside-ou...
Trans-ptyregoid approach
The wedge bone between V2 & Vidian nerve
decreases as we go posteriorly towards petrous
carotid
The wedge bone between V2 & Vidian nerve decreases
as we go posteriorly towards petrous carotid
Accessories
anterior ethmoidal artery ( AEA) and nerve
(AEN) , anterior falcine artery (AFA)
Deep temporal artery
Trigeminal area at Cerebello Pontine
Angle – along with my voice
Click
http://www.youtube
.com/watch?v=YBqk
4Jdnxic
CAROTID COURSE
Click
http://www.youtube.c
om/watch?v=JlNmSI3t
S8Q
PETROCLIVAL MENINGIOMA DECISION
MAKING
•Click
http://www.youtube.com
/watch?v=kUa9fQ4_aQY
Frontal sinus surgery concepts – must for to do DRAF-III
– Don’t use cutting burr while drilling the Frontal-T ,
high chan...
Hemifacial spasm
Video-1
http://www.youtube.com/watc
h?v=-zlymD2LYsM
Video-2
http://www.youtube.com/watc
h?v=gGyQFh3PqPg
Subfrontal craniotomy.
Subfrontal craniotomy.
Mandibulotomy [ Mental nerve
bilaterally ]
AFB area
Fig. 74a, b The reference level is the acousticofacial nerve
bundle. The anterior inferior cerebellar artery, lying betwee...
7up- 7th is above
Coca cola – cochlear n. is cola[=lower]
SKULL BASE 360°
Above presentation is
SKULL BASE 360°-Part 2
For
SKULL BASE 360°-Part 1
Please click or copy/paste in URL ...
Skull base 360°- part 2
Skull base 360°- part 2
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Skull base 360°- part 2

  1. 1. SKULL BASE 360° Below presentation is SKULL BASE 360°-Part 2 For SKULL BASE 360°-Part 1 Please click or copy/paste in URL or weblink area http://www.slideshare.net/muralichandnallamoth u/skull-base-360-part-1-39394198 [ Dated: 1-11-14 ] I will update continuosly with date tag at the end as I am getting more & more information
  2. 2. Great teachers – All this is their work . I am just the reader of their books . Prof. Paolo castelnuovo Prof. Aldo Stamm Prof. Mario Sanna Prof. Magnan
  3. 3. For Other powerpoint presentatioins of “ Skull base 360° ” I will update continuosly with date tag at the end as I am getting more & more information click www.skullbase360.in - you have to login to slideshare.net with Facebook account for downloading.
  4. 4. Below presentation is SKULL BASE 360°-Part 2 Indetail eloborate description for each part of skullbase360 done at www.skullbase360.in » Presentation by » Dr. N. Murali Chand DLO MS (ENT) FHM » Fellowship in HIV medicine, MAMC, New Delhi » My website = www.integratedmedicine.co.in • www.skullbase360.in » Cell= +91 99496 77605
  5. 5. Orbit
  6. 6. Orbital fascia = Periorbita
  7. 7. Bulbar fascia includes 1. Tenon’s capsule 2. Tubular sheat for each orbital muscle 3. medial & lateral check ligament 4. suspensory ligament of lockwood
  8. 8. Superior oblique tendon goes underneath the superior rectus where are inferior oblique muscle goes below the inferior rectus
  9. 9. Parts of SOF 1. Lateral part- LFT [ Liver functional tests ] Menumonic – Lacrimal N., Frontal N.,Trochlear N. 2.Middle part 3. Medial/Inferior part
  10. 10. Parts of SOF 1. Lateral part- LFT [ Liver functional tests ] Menumonic – Lacrimal N., Frontal N.,Trochlear N. 2.Middle part 3. Medial/Inferior part
  11. 11. Branches of V 1 1. Lacrimal N. 2.Frontal N. 3. Nasociliary N. Immediately after removing the periorbita
  12. 12. Frontal N. devides into Sup.Troch.N. & Supraorb.N. – NOTE Fal.Lig
  13. 13. A segment of the orbital portion of the optic nerve has been removed. This exposes the branch of the inferior division of the oculomotor nerve, which passes below the optic nerve and enters the medial rectus muscle.
  14. 14. When you are approaching endoscopically the upper most one is Sup.Orb.M superiorly & Medial rectus inferiorly The medial approach is directed through the interval between the superior oblique and the levator muscles.
  15. 15. Nasociliary N. [ 3rd branch of V1 ] devides into AEN & PEN
  16. 16. Inferior orbital muscle is completely muscle , whereas Sup.Obl.M is muscle & tendinous
  17. 17. Medial Orbital Approach- Periorbita elevated from bone
  18. 18. Accessing intraconal lesions endonasally requires manipulation of the extraocular muscles. The nerve branches that supply the oculomotor muscles run in the medial surface of the muscles. Thus, try to avoid excessive retraction of the extraocular muscles to avoid inadvertent muscle paresis.
  19. 19. OPTIC NERVE DECOMPRESSION
  20. 20. Optic tubercle
  21. 21. In 83% the OA passes around the lateral aspect of the optic nerve (b, left); in the remaining cases the OA stays medial to the optic nerve, 17% - this point important in optic nerve decompression
  22. 22. One artery in the head which we can’t move – is OA – Central retinal artery is avulsed
  23. 23. Relation of PEA & ON Anterior limit of Transplanum approach is PEA – when we are removing a triangular piece of bone in Transplanum approach , the base of traingle is PEA
  24. 24. when we are removing a triangular piece of bone in Transplanum approach , the base of traingle is PEA
  25. 25. The sphenoid ostium (SO) is first opened inferiorly (black arrow, 1) then laterally (black arrow, 2). This should afford a clear view into the sphenoid sinus and the remaining anterior face of the sphenoid can be removed up toward the optic tubercle (OT) but usually stopping short of the tubercle to lessen the potential risk to the optic nerve.
  26. 26. Opthalmic artery – Retrograde branch of Intracranial carotid Branches of the cavernous internal carotid artery ( ICA ), a rare variation: ophthalmic artery passing through the superior orbital fissure
  27. 27. classification of the ophthalmic artery types http://www.springerimages.com/Images/MedicineAndPublicHealth/1- 10.1007_s10143-006-0028-6-1 a = intradural type, b = extradural supra-optic strut type [ Optic strut = L-OCR ] c = extradural trans-optic strut type on optic nerve, pr proximal ring, cdr carotid dural ring= upper dural ring , ica internal carotid artery I think this variation is type c
  28. 28. In both type a = intradural type, b = extradural supra-optic strut types Opthalmic foramen is in Optic canal
  29. 29. In Type c = extradural trans-optic strut type , the Opthalmic foramen in Optic strut
  30. 30. http://www.nature.com/eye/journal/v20/n10/fig_tab/6702377f3.html#figure -title The upper diagram is Type a or b Opthalmic artery , the lower diagram is Type c Opthalmic artery Dup OC = Duplicate Opthalmic canal
  31. 31. Origin and intracranial and intracanalicular course of the ophthalmic artery and its subdivisions, as seen on opening the optic canal (reproduced from Hayreh67). Both from one specimen. (a) The extradural origin of the right ophthalmic artery, so that no ophthalmic artery is seen even on opening theoptic canal; a thinning of the dural sheath is seen at 'X', indicating the position of the artery. (b) The ophthalmic artery is seen after removing the dural sheath covering it (reproduced from Hayreh and Dass2).
  32. 32. Schematic drawing origin (a medial, b central, c lateral) and exit (d lateral, emedial) of superior wall of the ophthalmic artery
  33. 33. A diagrammatic representation of variations in origin and intraorbital course of ophthalmic artery. (a) Normal pattern. (b–e) The ophthalmic artery arises from the internal carotid artery as usual, but the major contribution comes from the middle meningeal artery. (f and g) The only source of blood supply to the ophthalmic artery is the middle meningeal artery, as the connection with the internal carotid artery is either absent (f) or obliterated (g) (reproduced from Hayreh and Dass3).
  34. 34. Origin, course, and branches of the ophthalmic artery in two adult specimens. Segment Y disappeared in (a) and segment Z disappeared in (b), resulting in the ophthalmic artery crossing under the optic nerve in both. In (b) an anastomosis is seen in lateral wall of the cavernous sinus between the part of the internal carotid artery lying in proximal part of the cavernous sinus and a branch from the ophthalmic artery passing through the superior orbital fissure (reproduced from Hayreh67).
  35. 35. Various relations of OA [ Opthalmic artery ] to ON left figure when it crosses under the optic nerve (in 17.4%) and right figure when it crosses over the optic nerve (in 82.6%).
  36. 36. The dura over the ACP passes over the ON, giving the falciform ligament
  37. 37. Fibrous tissue
  38. 38. FCB-Fibrocartilago basalis at junction of petrous & paraclival carotid Fibrous tissue surrounds the entrance of the vertebral artery into the CPA.
  39. 39. Fibrous tissue surrounds the entrance of the vertebral artery into the CPA. Left side. Combined transsigmoid, suboccipital and extreme lateral approaches provide an overview off the craniocervical junction, the foramen magnum area, and the surrounding structures of the medullary stem.
  40. 40. Laceral carotid lies over the Foramen lacerum not passing through Foramen lacerum - Foramen lacerum floor is occupied by FCB [ Fibrocartilagenous basalis ] -- Note Fibrocartilagenous basalis at laceral segment in both photos
  41. 41. A nontoothed forceps is used to hold the soft tissues (ST) surrounding the nerve at the level of the stylomastoid foramen (SMF), and sharp scissors are used to dissect the soft tissues from the bone at that level. C Cochlea, FN(m) Mastoid segment of the facial nerve, LSC Lateral semicircular canal, NC New canal, SS Sigmoid sinus
  42. 42. Rerouting of the facial nerve. FN(m) Mastoid segment of the facial nerve, FN(p) Intraparotid facial nerve, SM Facial nerve at the stylomastoid level, ST Soft tissues The facial nerve has been rerouted into the new canal (*). FC Fallopian canal, FN(p) Rerouted part of the intratemporal facial nerve, FN(t) Rerouted part of the tympanic segment of the facial nerve, ST Soft tissues
  43. 43. Styloid process
  44. 44. Styloid apparatus – superior view Styloid apparatus – lateral view
  45. 45. After the attached muscles have been dissected away, the styloid process (SP) is fractured using a rongeur. FC Fallopian canal, FN Facial nerve, FN(p) Rerouted part of the intraparotid facial nerve, TB Temporal bone
  46. 46. Fig. 9.21 To obtain control over the vascular structures as they enter the temporal bone, the tympanic bone (TB), the fallopian canal remnants (FC), and the infralabyrinthine air cells are all to be removed. C Basal turn of the cochlea (promontory), IJV Internal jugular vein, JB Jugular bulb, SS Sigmoid sinus
  47. 47. The view after completely uncovering the lateral surfaces of the vascular structures. C Basal turn of the cochlea (promontory), ICA Internal carotid artery, IJV Internal jugular vein, JB Jugular bulb, SS Sigmoid sinus
  48. 48. Fig. 9.29 The plane of dissection between the internal carotid artery (ICA) and the overlying periosteum (P) is best developed at the entrance of the artery into its canal. C Basal turn of the cochlea (promontory)
  49. 49. Internal carotid artery is deeper to styloid process when we see from laterally & medial to styloid process when we see from anteriorly – [SP- Styloid process]
  50. 50. Two things protect the parapharyngeal carotid anteriorly 1. Tensor veli palatini & 2. SPHA [ = stylopharyngeal aponeurosis ]
  51. 51. Inferior petrosal sinus
  52. 52. HVP hypoglossal venous plexus
  53. 53. The Petro-occipital Fissure- contains IPS
  54. 54. The Petro-occipital Fissure- contains IPS
  55. 55. Exocranial & Endocranial views of Jugular Foramen : Within the JF area 2 venous compartement can be identified: a large postero- lateral_SIGMOID_venous channel and a small antero-medial_PETROSAL_venous channel which can receive the drainage of the inferior petrosal sinus (IPS). An intermediary neural compartment is located between the venous ones and houses lower cranial nerves (IX, X, XI). CC carotid canal, CR carotid ridge, ESF endolymphatic sac fossa, FS foramen spinosum, IAM internal acoustic meatus, JT jugular tubercle, OC occipital condyle, PCF petroclival fi ssure, SAF subarcuate fossa, SP styloid process, SSG sigmoid sinus groove, TB tympanic bone, VPTB vaginal process of the tympanic bone, white arrow intrajugular process of the temporal bone, red arrow external ori fi ce of the hypoglossal canal, violet arrow petroclival fi ssure, blue-sky arrow tubal isthmus, black arrow endocranial orifice of the hypoglossal canal, orange arrow trigeminal impression, green arrow pyramidal fossa, black asterisks intrajugular ridge, black circle intrajugularprocess of the occipital bone
  56. 56. Usually inferior petrosal sinus opens into jugular bulb Sometimes along with jugular bulb opening , it opens into internal jugular vein also [ lower single arrow in below photo ]
  57. 57. Inferior petrosal sinus
  58. 58. a. IPS inferior to nerve IX and superior to nerves X and XII. b. IPS inferior and medial to all four nerves. c. IPS superior and lateral to all four nerves d. A second IPS joining the internal jugular vein passing medial to IX and lateral to X, XI, and XII
  59. 59. An anatomical classification according to the level of the inferior petrosal sinus–internal jugular vein junction has been developed 1. Junction at the level of the jugular bulb 2. Junction at the level of the anterior condylar vein junction (extracranial opening of the hypoglossal canal)
  60. 60. 3. Junction at the level of the lower extracranial jugular vein • CoC - level of the condylar canal • IJV- internal jugular vein • JF- level of the jugular foramen • SS- sigmoid sinus • VVP- vertebral venous plexus
  61. 61. 4. Multiple junctions: upper junction at the level of the jugular bulb and lower junction at the level of the anterior condylar vein a )Multiple upper junctions at the level of the jugular bulb (JB). b )Multiple junctions: upper junctions at the level of the jugular bulb and lower junction at the level of the anterior condylar vein. c) No connection between the internal petrosal sinus and the internal jugular vein. The sinus drains in the vertebral venous plexus.
  62. 62. In Transcochlear approach
  63. 63. In infratemporal fossa [=intact cochlear approach – Dr.Morwani ] type B approach See IPS in Kawase approach
  64. 64. Right sided anterior petrosectomy on a cadaver dissection: intradural exposure and operative field. PCA Petrous carotid artery; DPA drilled petrous apex; IPS inferior petrosal sinus; BA basilar artery; VI 6th cranial nerve; AICA anterior inferior cerebellar artery; P pons; V 5th cranial nerve
  65. 65. NOTE Inferior petrosal sinus at CLIVUS ICAc cavernous portion of the internal carotid artery, IPS inferior petrosal sinus, PAp petrous apex, SPCG sphenopetroclival gulf, cVIcn cisternal segment of the abducens nerve, gVIcn gulfar segment of the abducens nerve, pVIcn petrosal segment of the abducens nerve, white asterisks dura of the posterior cranial fossa
  66. 66. In middle cranial fossa approach
  67. 67. In middle cranial fossa approach
  68. 68. 3rd nerve
  69. 69. 3rd nerve is sandwiched between posterior cerebral artery & superior cerebellar artery
  70. 70. 3rd nerve is sandwiched between posterior cerebral artery & superior cerebellar artery
  71. 71. 3rd nerve is sandwiched between posterior cerebral artery & superior cerebellar artery Through endoscopic lateral skull base Through endoscopic anterior skull base
  72. 72. 3rd nerve is sandwiched between posterior cerebral artery & superior cerebellar artery Through endoscopic lateral skull base Through endoscopic anterior skull base
  73. 73. P1 in relation to 3rd nerve P2 in relation to 3rd nerve
  74. 74. Relationship of PcomA & 3rd nerve – parallel to each other
  75. 75. In parasellar pituitary 3rd n & 4th n & Pcom present in Postero-superior cavernous compartment
  76. 76. Relationship of PcomA & 3rd nerve
  77. 77. Relationship of PcomA & 3rd nerve
  78. 78. a,b Intraoperative image of the fenestration of deep cystic membrane using different microsurgical instruments (forceps and scissors). Asterisks posterior communicating artery and anterior choroidal artery. c Fenestration of the cisternal layer (cross Liliequist’s membrane). d Intraoperative picture at the end of the procedure http://www.springerimages.com/Images/MedicineAndPublicHealth/1-10.1007_s00381-004-0940-4-0
  79. 79. Right supraorbital approach (0 optic). 1 Diaphragma sellae, 2 cn II, 3 optic tract, 4 ICA, 5 A1, 6 M1, 7 C. N.III, 8 anterior petroclinoid fold, 9 anterior clinoid process. A Optocarotid window, B window between ICA and cn III –I think B is nothing but posterior clinoid process C window lateral of cn III Right supraorbital approach (30 optic). Window between ICA and cn III : 1 tuber cinereum, 2 left P1, 3 left cn III, 4 BA, 5 right P1, 6 right SCA, 7 right cn III
  80. 80. Note the aperture for 3rd nerve & 4th nerve anterior & posterior to posterior petro-clival fold [ PPCF ]
  81. 81. Oculomotor cistern Cranial nerve III enters the roof included in its own cistern (oculomotor cistern). Oculomotor cistern goes upto anterior clinoid tip
  82. 82. The lower dural ring is given by the COM [ Carotid-oculomotor membrane ] , that lines the inferior surface of the ACP. It can be visible, through a transcranial route, only by removing the ACP. The lower dural ring is also called Perneczky’s ring. Medially the COM blends with the dura that lines the carotid sulcus (Yasuda et al. 2005 ) Endoscopic supraorbital view with a 30° down-facing lens -The right portion of the planum sphenoidale is seen from above. Right side
  83. 83. Fronto-temporal orbitozygomatic transcavernous approach COM= Caratico-occulomotor membrane , DR = dural ring
  84. 84. The oculomotor nerve divides into a small superior and large inferior division just before passing through the superior orbital fi ssure.
  85. 85. 4th nerve
  86. 86. 4th nerve – 5 components – a. cisternal b. tentorial – see paolo castelneovo book
  87. 87. Endoscopic lateral skull base
  88. 88. The TC [ tentorium cerebelli ], with the trochlear nerve inside, can be visualized passing inferiorly to the IIIcn. endoscopic transclival view
  89. 89. 1. In the posterior part of the CS the trochlear nerve is below the oculomotor nerve, while anteriorly it turns upward and becomes the most superior structure of the CS (at the level of the optic strut) (Iaconetta et al. 2012 ) . 2. Trochlear nerve is always superior to V1.
  90. 90. 1. In the posterior part of the CS the trochlear nerve is below the oculomotor nerve, while anteriorly it turns upward and becomes the most superior structure of the CS (at the level of the optic strut) (Iaconetta et al. 2012 ) . 2. Trochlear nerve is always superior to V1.
  91. 91. (A) Intraoperative endoscopic close-up view showing the trigeminal nenre and the related neurovascular anatomy. a Trigeminal nerve (V). b Superior aspect of cerebellum. c Petrosal veins. d Petrous apex. e Dense araclmoid adhesions (post-Gamma KnifeX2). f Trochlear nerve (IV). g Brainstem. h Tentorium. i Tentorial incisura. From Prof.shahanian endoskull base book pg 127
  92. 92. 5th nerve
  93. 93. Trigeminal area at Cerebello Pontine Angle – along with my voice Click http://www.youtube.com/watch? v=YBqk4Jdnxic
  94. 94. 171
  95. 95. 175
  96. 96. 6th nerve
  97. 97. The pontomedullary junction. 1. The exit zones of the hypoglossal and abducent nerves are at the same level [ same vertical line when view from Transclival approah ( through lower clivus ) ] 2. The abducent nerve exits from the pontomedullary junction, and ascends in a rostral and lateral direction toward the clivus.
  98. 98. 6th nerve origin is above or below AICA or has two rootlets of origin
  99. 99. 6th is appresiated in TA-II [ Transapical type II ] approach when 360 degrees IAC drilled
  100. 100. 6th nerve – enters the dorellos canal – Intradural course
  101. 101. 6th nerve – enters the dorellos canal – Intradural course clinical importance = Gradenigo Syndrome - Infection & inflammation of petrous apex involves 6th cranial nerve at the Dorello's canal and 5th cranial nerve in the Meckel's cave
  102. 102. The DMA is in close relationship with the abducens nerve at the level of petrous apex (Cavallo et al. 2011 ) . The DMA is the main feeder of the Dorello’s segment of Vicn (Martins et al. 2011 ) . DMA & 6TH NERVE DMA & 6TH NERVE
  103. 103. When we are doing clival chordoma we have to anticipate 6th nerve medial to paraclival carotid which is present in dorellos canal
  104. 104. Courtesy Dr. Tomasz Skibinski
  105. 105. The basilar artery (BA) can be seen very tortuous.
  106. 106. Gulfar segment of 6th nerve (GS in left picture ) ( gVIcn in right picture ) - The gulfar segment can be identified at the intersection of the sellar floor and the proximal parasellar internal carotid artery (ICA) (Barges-Coll et al. 2010 ).
  107. 107. ICAc cavernous portion of the internal carotid artery, IPS inferior petrosal sinus, PAp petrous apex, SPCG sphenopetroclival gulf, cVIcn cisternal segment of the abducens nerve, gVIcn gulfar segment of the abducens nerve, pVIcn petrosal segment of the abducens nerve, white asterisks dura of the posterior cranial fossa – The gulfar segment can be identified at the intersection of the sellar floor and the proximal parasellar internal carotid artery (ICA) (Barges-Coll et al. 2010 ).
  108. 108. 1. 6th N. crossing carotid at Petro-clival junction when viewing in lateral skull base 2. The gulfar segment can be identified at the intersection of the sellar floor and the proximal parasellar internal carotid artery (ICA) (Barges-Coll et al. 2010 ).
  109. 109. Inferior boarder of L-OCR is by 6th nerve & V1
  110. 110. AICA anterior-inferior cerebellar artery, Cl clivus, CS cavernous sinus, ICAc cavernous portion of the internal carotid artery, IPS inferior petrosal sinus, LPMVN lateropontomesencephalic venous network, PBs pontine branches, PG pituitary gland, TPV transverse pontine vein, VA vertebral artery, VN vidian nerve (bordered in yellow ), Vcn trigeminal nerve, VIcn abducens nerve, yellow arrow cavernous portion of the abducens nerve
  111. 111. Blue arrow in Left picture ; * in Right picture - Gruber’s ligament
  112. 112. Usually, the IPS passes beneath the superior petro-sphenoidal ligament (l. of Gruber) with the abducens nerve.
  113. 113. Grubers ligament
  114. 114. 6th nerve passing below gruber’s ligament
  115. 115. ACP anterior clinoid process, APCF anterior petroclinoid fold, DS dorsum sellae, ICF interclinoid fold, PF pituitary fossa, PLL petrolingual ligament (inferior sphenopetrosal ligament), PPCF posterior petroclinoid fold, PS planum sphenoidale, SSPL superior sphenopetrosal ligament (Gruber’s ligament), TS tuberculum sellae, black asterisk middle clinoid process
  116. 116. 6th nerve is parallel to V1 – in the same direction of V1
  117. 117. 6th nerve is parallel to V1 – in the same direction of V1
  118. 118. 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 and the vidian nerves. III oculomotor nerve, V1 ophthalmic nerve, V2 maxillary nerve, V3 mandibular nerve, VI abducens nerve, C clivus, ICA-Sa anterior bend of the internal carotid artery–parasellar segment, ICA-Sp posterior bend of the internal carotid artery–parasellar segment, ICA-C paraclival segment of the internal carotid artery, ICA-L lacerum segment of the internal carotid artery, ICA-P petrous segment of the internal carotid artery, PG pituitary gland, VC vidian canal, VN vidian nerve 6th nerve is parallel to V1 – in the same direction of V1
  119. 119. Upper part of S-shaped configuration – 3rd & 6th nerves.
  120. 120. 6th nerve is freely hanging in the cavernous injury when compared to 3rd & 4th nerve – so postential for injury in tumor dissection
  121. 121. 7th nerve
  122. 122. Vertical part of 7th nerve bissects the jugular bulb
  123. 123. In 50% of the cases mastoid segment of Facial nerve travels lateral to level of annulus – This is important while removing the 1. EAC in temporal bone malignancy 2. while decompressing the nerve in malignant otitis externa 3. very careful in children Click http://www.youtube.com/ watch?v=f0cblTWJQ4k
  124. 124. 3rd GENU When facial nerve exists the temporal bone , the main trunk of the facial nerve is the perpendicular bisection of a line joining the cartilagenous pointer to the mastoid tip – some surgeons call this bend as 3rd genu.
  125. 125. 9th nerve
  126. 126. A closer view of the pars nervosa of the jugular foramen. The glossopharyngeal nerve has its own dural porus, which is situated 0-3 mm upwards from the dural porus of the tenth cranial nerve. The vagus and the accessory nerve exit the posterior fossa together in a sleeve of dura through the jugular foramen. Left side. The 30° angled endoscope provides an overview of the inferior part of the CPA. On the right lies the acousticofacial nerve bundle, with the anterior inferior cerebellar artery; the glossopharyngeal nerve and the vagus nerve, as multiple filaments, form three to five major nerve bundles and the accessory nerve.
  127. 127. Note the bone (>, <) left to protect the dura from the drill. AC Supralabyrinthine air cells, CA Cochlear aqueduct, FN Facial nerve, SA Ampulla of the superior canal, V Vestibule Fig. 4.30 The internal auditory canal (IAC) has been identified, but the overlying bone needs to be thinned further. CA Cochlear aqueduct, FN Facial nerve, V Vestibule
  128. 128. Fig. 2.57 After rerouting the facial nerve and drilling away the fallopian canal of a left temporal bone, the cochlear aqueduct (CA) has been opened. The proximity of the glossopharyngeal nerve (IX) can be well appreciated. Since the nerve lies just inferior to the cochlear aqueduct, the latter is used as a landmark to the nerve in the translabyrinthine approach, indicating the lower limit of drilling in order to avoid injury to the glossopharyngeal nerve. ICA Internal carotid artery, JB Jugular bulb, SMF Stylomastoid foramen Retrosigmoid approach – observe 9th nerve near cochlear aqueduct [CA]
  129. 129. The cochlear aqueduct is a bony channel with a pyramidal shape connecting the perilymphatic space of the scala tympani in close proximity to the round window with the subarachnoid space at the level of the JF
  130. 130. Drilling has been carried out more inferiorly to identify the cochlear aqueduct (CA). Note the proximity of the aqueduct to the glossopharyngeal nerve (IX).
  131. 131. The bone overlying the transitional zone from the jugular bulb (JB) to the internal jugular vein (IJV) has been drilled away. The hook can be seen underneath the fibrous band covering the exit of the bulb from the bone. The jugulocarotid spine of bone (<) can be seen lying between the internal carotid artery (ICA) and the jugular bulb. * The fibrous band covering the entrance of the internal carotid artery into the temporal bone.
  132. 132. 9th nerve present between internal carotid & jugular bulb at carotid canal area[extra-cranially] View from anterior skull base approach View from Lateral skull base approach
  133. 133. 9th nerve – in cadaver
  134. 134. Jugular foramen area [ 9,10,11,12 nerves]
  135. 135. Superior & inferior ganglion of vagus at jugular foramen
  136. 136. Jugular tubercle [ JT ] , star = foramen lacerum
  137. 137. In the cerebello-medullary cistern the LCNs cross the posterior surface of the JT on their way to JF (Fernandez- Miranda et al. 2012 ). Trans-clival approach Retrosigmoid approach Lateral skull base approach
  138. 138. Note the relationship of clivus & jugular tubercle
  139. 139. Jugular tubercle [ JT ] AICA antero-inferior cerebellar artery, ASC anterior semicircular canal, BA basilar artery, HC hypoglossal canal, IAC internal acoustic canal, ICAh horizontal portion of the internal carotid artery, JT jugular tubercle, LCNs lower cranial nerves, LSC lateral semicircular canal, P pons, PICA postero-inferior cerebellar artery, PSC posterior semicircular canal, VIcn abducens nerve, VIIcn facial nerve, white arrow vestibolocochlear nerve
  140. 140. Jugular tubercle [ JT ]
  141. 141. Exocranial & Endocranial views of Jugular Foramen : Within the JF area 2 venous compartement can be identified: a large postero- lateral_SIGMOID_venous channel and a small antero-medial_PETROSAL_venous channel which can receive the drainage of the inferior petrosal sinus (IPS). An intermediary neural compartment is located between the venous ones and houses lower cranial nerves (IX, X, XI). CC carotid canal, CR carotid ridge, ESF endolymphatic sac fossa, FS foramen spinosum, IAM internal acoustic meatus, JT jugular tubercle, OC occipital condyle, PCF petroclival fi ssure, SAF subarcuate fossa, SP styloid process, SSG sigmoid sinus groove, TB tympanic bone, VPTB vaginal process of the tympanic bone, white arrow intrajugular process of the temporal bone, red arrow external ori fi ce of the hypoglossal canal, violet arrow petroclival fi ssure, blue-sky arrow tubal isthmus, black arrow endocranial orifice of the hypoglossal canal, orange arrow trigeminal impression, green arrow pyramidal fossa, black asterisks intrajugular ridge, black circle intrajugularprocess of the occipital bone
  142. 142. The glossopharyngeal nerve has its own dural porus, which is situated 0- 3 mm upwards from the duralporus of the tenth cranial nerve. The vagus and the accessory nerve exit the posterior fossa together in a sleeve of dura through the jugular foramen.
  143. 143. Jugular fossa is just lateral to hypoglossal canal
  144. 144. 12th nerve
  145. 145. The pontomedullary junction. 1. The exit zones of the hypoglossal and abducent nerves are at the same level [ same vertical line when view from Transclival approah ( through lower clivus ) ] 2. The abducent nerve exits from the pontomedullary junction, and ascends in a rostral and lateral direction toward the clivus.
  146. 146. A closer view of the anterior border of the pontomedullary stem and the vertebral artery junction and origin of the basilar artery. Perforating arteries arise from the vertebral and basilar arteries. The endoscope is focusing on the hypoglossal nerve area. The posterior inferior cerebellar artery arises from the vertebral artery in the background, and runs between the two bundles of the hypoglossal nerve.
  147. 147. Fig. 26a, b Right side. The root fibers of the hypoglossal nerve (12) collect in two bundles, which pierce the dura in two dural pori. The hypoglossal nerve is situated more anteriorly and medially than the root fibers of the lower cranial nerves. The arterial relationship is the vertebral artery, with perforating arteries to the brain stem. The curved vertebral artery displaces and stretches the hypoglossal nerve fibers.
  148. 148. Through lateral skull base - The curved vertebral artery displaces and stretches the hypoglossal nerve fibers. Through anterior skull base
  149. 149. Through lateral skull base - The curved vertebral artery displaces and stretches the hypoglossal nerve fibers. Through lateral skull base - The opposite vertebral artery exits from the dural porus and stretches /raises the hypoglossal nerve.
  150. 150. HC = hypoglossal canal , JT= Jugular Tubercle
  151. 151. SCG = Supracondylar groove
  152. 152. Jugular fossa is just lateral to hypoglossal canal
  153. 153. Hypoglossal canals From front – through nose From back
  154. 154. Coronal cut – hypoglossal canal
  155. 155. 1. The SCG [Supracondylar groove] represents a reliable landmark for hypoglossal canal (HC) identification (red arrow) (Morera et al. 2010 ) . 2. The HC divides the condylar region into the tubercular compartment (superior) and the condylar compartment (inferior). Tubercular compartment contains LPT lateral pharyngeal tubercle, PT pharyngeal tubercle,
  156. 156. Transoral approach to SUPERO-MEDIAL Parapharyngeal tumors – incision anterior to anterior pillar of tonsil
  157. 157. In infrapetrous approach there are chances of injury to 6th nerve [ in dorello’s canal medial to paraclival carotid ] & 12th nerve
  158. 158. 12th nerve bissecting internal & external carotid
  159. 159. Vertebral artery
  160. 160. Robbins level II. 1 Sternocleidomastoid muscle, 2 posterior belly of digastric muscle, 3 spinal accessory nerve (common trunk), 4 internal jugular vein, 5 splenius capitis muscle, 6 levator scapulae muscle, 7 anterior scalene muscle, 8 transverse process of atlas, 9 hypoglossal nerve, 10 carotid bifurcation, 11 branches of cervical plexus
  161. 161. Superior view of the atlas and the axis. The atlas consists of two thick lateral masses situated at the anteromedial part of the ring, which are connected in front by a short anterior arch and posteriorly by a longer curved posterior arch. 1, anterior arch of the atlas; 2, superior articular facet is an oval, concave facet that articulates with the occipital condyle; 3, posterior arch of the atlas; 4, vertebral artery (VA); 5, transverse foramina; 6, transverse process; 7, dens of the axis.
  162. 162. The entrance of the vertebral artery is the boundary between the foramen magnum and the spinal part of the accessory nerve. The root fibers of the spinal accessory nerve and the fibres of C1 and C2
  163. 163. Fibrous tissue surrounds the entrance of the vertebral artery into the CPA. Left side. Combined transsigmoid, suboccipital and extreme lateral approaches provide an overview off the craniocervical junction, the foramen magnum area, and the surrounding structures of the medullary stem.
  164. 164. In transcochlear approach
  165. 165. Anterior cranial fossa
  166. 166. Anterior & Posterior perforated substance
  167. 167. Anterior perforated substance & olfactory track relation
  168. 168. Fronto-polar artery
  169. 169. Superior hypophyseal artery = SHA
  170. 170. Superior Hypophyseal Arteries [ SHAs ] - more commonly arise from the paraclinoid ICA - In rare cases SHAs originate from the intracavernous segment of the ICA
  171. 171. Cisterns
  172. 172. Oculomotor cistern
  173. 173. Oculomotor cistern Cranial nerve III enters the roof included in its own cistern (oculomotor cistern). Oculomotor cistern goes upto anterior clinoid tip
  174. 174. LT lamina terminalis cistern= Suprachiasmatic cistern
  175. 175. LT lamina terminalis cistern – The lamina terminalis cistern is situated above the optic chiasm (Martins etal. 2011 ) . Within this cistern, A1 and A2, as well as the anterior communicating artery and the first part of the recurrent artery of Heubner, are evident.
  176. 176. The space between a & oc is Lamina terminalis Neuroendoscopic view of the third ventricle floor-----Infundibular recess (i), optic chiasm (oc) and a prominent anterior commissure (a) are seen anterior to the opaque and narrow tuber cinereum (t). B Neuroendoscopic view of the third ventricle floor in another myelomeningocele patient. A non-transparent tuber cinereum (t) and a dilated infundibular recess (i) are seen anterior to the mamillary bodies (m). Note to the vascular structure of the third ventricle floor. cNeuroendoscopic view showing a steep third ventricle floor in a myelomeningocele patient. A narrow tuber cinereum (t) is visible just anterior to the mamillary bodies (m). dNeuroendoscopic view through a very narrow prepontine cistern. Note the close proximity of the basillary artery (ba) and clivus (cl)
  177. 177. Endoscopic third ventricle from posteriorly -- a. Infundibular recess b. tuber cinereum c. mammillary bodies left posterior communicating artery (a), mammillary body (b), and right posterior hypoplasic communicating artery (c) --- measurement performed between the posterior communicating arteries using Geogebra software (a-b = 11.3 mm),
  178. 178. Endoscopic third ventricle from posteriorly -- a. Infundibular recess b. tuber cinereum c. mammillary bodies From front – through lamina terminalis
  179. 179. In the descriptive analysis of the 20 specimens, the PCoAs distance was 9 to 18.9 mm, mean of 12.5 mm, median of 12.2 mm, standard deviation of 2.3 mm.
  180. 180. Optic chiasma – infundibulum – Mamillary bodies
  181. 181. Chiasmatic cistern
  182. 182. The AcomA complex is usually above the optic chiasm (70 % of cases) (Rhoton 2003 ) . The AcomA is similar to the textbook description in three- fourths of cases. In about 10 % of cases, it can be hypoplastic or even duplicated and triplicated (Lang 1995 ) . • 1. Supra-chiasmatic cistern • 2. Chiasmatic cistern • 3. Sub -chiasmatic cistern
  183. 183. 1. The transplanum route may also facilitate exposing the anterior incisural space. On the center of this space the chiasm helps separate the two major cisternal compartments. Below the chiasm is the chiasmatic cistern, and above it is the center of the lamina terminalis cistern. 2. The pituitary stalk and superior hypophyseal arteries are located into the chiasmatic cistern.
  184. 184. Below the OT & A1 you will see PComA Endoscopic view of the anterior part of the Left Suprasellar area [ = Sub- Chiasmatic Cisttern ] . A1 first segment of the anterior cerebral artery, AChA anterior choroidal artery, GR gyrus rectus, ICA internal carotid artery, OC optic chiasm, ON optic nerve, OT optic tract, PCoA posterior communicating artery, PG pituitary gland, PitS pituitary stalk, MB midbrain, U uncus
  185. 185. Chiasmatic cistern – The chiasmatic cistern is located in front of the optic chiasm and above the sella turcica. In the lateral border of the chiasmatic cistern the first part of the ICAi is visible. lt ICA SEEN ON LT SIDE.. A HOLE IN THE ARACHNOID.. THE STALK JUST BEHIND IT.. THE DIAPHRAGM SEEN IN 5/6 O CLOCK POSITION..
  186. 186. CSF rhinorrhoea case Closed with hadad flap lt ICA SEEN ON LT SIDE.. A HOLE IN THE ARACHNOID.. THE STALK JUST BEHIND IT.. THE DIAPHRAGM SEEN IN 5/6 O CLOCK POSITION..
  187. 187. Sub-chiasmatic cistern = Supra sellar area = Supr-sellar cistern
  188. 188. Observe here the Pcom (here labelled as ACoP in some language ) is parallel to 3rd nerve in infrachiasmatic cistern . Excellent photo . Other points to note 1. 3rd nerve sandwitched between posterior cerebral artery & superior cerebellar artery . 2. On the left side 2 superior cerebellar arteries present from the origin itself. 3. Diameter of Pcom varies on two sides. 4. Infra-chiasmastic cistern is nothing but suprasellar area
  189. 189. Retrosellar
  190. 190. Interpeduncular cistern[ = basal cistern ]
  191. 191. Interpeduncular cistern
  192. 192. Interpeduncular cistern IR = infundibulum
  193. 193. Interpeduncular cistern -- Removal of the upper clivus (dorsum sella and posterior clinoids) provides an excellent view of the interpeduncular cistern Once the gland has been completely dissected from the surrounding dura, the pituitary aperture or diaphragm should be transected along with the superior intercavernous sinus. This allows the transposition of the gland into the suprasellar space, between the optic nerves. This maneuver exposes the dorsum sella and posterior clinoids that can now be safely removed. An osteotomy between the dorsum sella and the posterior clinoids is advised to avoid excessive traction while removing the clinoid, which can be risky for the third nerve and carotid artery.
  194. 194. Right supraorbital approach (30 optic). Window between cn II and ICA: 1 left PCoA, 2 left P2, 3 left cn III, 4 left P1, 5 left SCA, 6 BA, 7 doubled right SCA, 8 right cn III, 9 right P1, 10 mammillary bodies, 11 tuber cinereum, 12 right PCoA, 13 right M1.* sucker
  195. 195. Mammillary bodies Without removing the DS , Subchiasmatic view downwards After removing the DS & midclivus
  196. 196. Craniopharyngioma https://www.facebook.com/groups/4 05175366256295/permalink/552393 251534505/?stream_ref=2
  197. 197. CRANIOPHARYNGIOMAS-Removal corridors.
  198. 198. https://www.scienceopen.com/document_file/84699ab2-4980-4f70-a5b0- c8d95a1fb6a2/PubMedCentral/84699ab2-4980-4f70-a5b0-c8d95a1fb6a2.pdf FIGURE 4. The capsule of the cystic craniopharyngioma was firmly attached to the left hypothalamus, the stalk was dislocated to the right side (Patient 6). The outgrowth of the craniopharyngioma from proximal stalk is recognizable A. Complete removal of the capsule was possible, but produced subpial blood injection over the left hypothalamic surface B. MRI scan revealed a small ischemic injury in the left hypothalamus C. This patient had transient sleep disorder, moderate hyperphagia and memory problems (see also a supplemented video material 1).
  199. 199. FIGURE 2. In this cystic craniopharyngioma (Patient 5), the stalk was centrally infiltrated close to the pituitary and could not be preserved A. The incipient third ventricle entrance is seen from intracavitary view. The slit into the third ventricle is still covered with tumour capsule B. Complete removal of the capsule opened the third ventricle C. Petehiae in the hypothalamus bilaterally resulted from apparently gentle traction and blunt dissection of the capsule away from the hypothalamus D. Psychoorganic change, disorientation and memory deficits were noticed in less than a week after surgery, the transient sleep disorder become apparent in the second week postoperatively (see also a supplemented video material 2).
  200. 200. FIGURE 3. Large craniopharyngioma (Patient 3) produced unilateral hydrocephalus by obstructing the right formen of Monro A. The dome was filled with soft cholesterine cristals B, which were easily removed. Lower limbus of the right foramen of Monro is seen through the empty third ventricle D. Despite bilateral preservation of anteromedial hypothalamus C and stalk preservation E, the patient developed panhypopituitarism and diabetes insipidus with long lasting psychoorganic change
  201. 201. Supratentorial arteries • http://dc496.4shared.com/doc/2vRIALeU/pre view.html
  202. 202. Optic pathway
  203. 203. Interpeduncular cistern 3rd ventricle is visualised ..through the tuber cinereum
  204. 204. Recurrent artery of Heubner
  205. 205. Recurrent artery of Anterior cerebral artery = Recurrent artery of Heubner
  206. 206. The recurrent artery of Heubner usually origins from the post-communicating segment of the anterior cerebral artery (ACA). It doubles back the ACA to reach the medial part of the Sylvian fi ssure, below the anterior perforated substance. Sometimes its path is so long that the artery loops below the basal surface of the frontal lobes. Not frequently more than one recurrent arteries can be present (Rhoton 2003 ). According to Lang the artery is double in about 30% of cases (Lang 1995 ) .
  207. 207. 3rd ventricle
  208. 208. 3rd ventricle entered through 1. Supra optic chiasmic route – by Lamina terminalis 2. Infra optic chiasmic route – by Tuber cinerereum Infra optic chiasmic route – by Tuber cinerereum
  209. 209. 3rd ventricle entry by - Supra optic chiasmic route – by Lamina terminalis
  210. 210. FM – Foramen of Monro
  211. 211. FM – Foramen of Monro
  212. 212. CC corpus callosum, CP choroid plexus, MI massa intermedia, PC posterior commissure, T thalamus, ThV fl floor of the third ventricle, yellow arrow opening of the Silvius aqueduct, red asterisk suprapineal recess, white asterisk ( left ) lateral ventricle, white circles foramen of Monro
  213. 213. Intradural Anatomy
  214. 214. Different positions of the anterior inferior cerebellar artery (AICA) in relation to the internal auditory meatus.
  215. 215. 1st & 2nd cervical vertebrae
  216. 216. Don’t use cutting bur while drilling “Frontal T” in Draf 3 – Use only diamond bur – we may injure the dura .
  217. 217. HADAD FLAP ---1, area of origin of the nasoseptal flap (dotted line); 1b, area of origin of the extended nasoseptal flap, including the floor of the nasal fossa, and if necessary, the mucosa of the inferior meatus; 2, position of the nasoseptal flap used for repair of the anterior and posterior ethmoid roof and cribriform plate; when bilateral flaps are taken, the anterior skull base can be repaired from orbit to orbit; 3, position of the nasoseptal flap used for repair of the sellar and parasellar regions; 4, position of the nasoseptal flap used for repair of the region of the clivus; the arrows indicate the different ways in which the nasoseptal flap (HBF) can be rotated from the nasal septum for repair of different zones of the cranial base.
  218. 218. anterolateral endonasal flap.
  219. 219. Pituitary surgery
  220. 220. pituitary tumors schematic diagram.
  221. 221. Fig. 13.17 Classification of Knosp et al.10 grading the cavernous sinus extension when compared with lines drawn medial through the middle and on the lateral aspect of the carotid arteries—grades 0 to 3. Grade 4 encases the carotid.
  222. 222. Cavernous Sinus MRI anatomy
  223. 223. Liliequist membrane [LM]
  224. 224. Liliequist membrane - Interpeduncolar cistern separated from prepontine cistern by the mesencephalic leaf of LM. Liliequist
  225. 225. Craniopharyngioma removal - Lilliquest membrane & Basillar artery
  226. 226. LM through subtemporal approach
  227. 227. APPROACHES
  228. 228. DRAF III
  229. 229. 1st olfactory neuron seen in draft 3
  230. 230. Outside-in approach of draf III – similar like outside-in mastoid Inside-out approach of draf III – similar like Inside-out mastoid
  231. 231. Trans-ptyregoid approach
  232. 232. The wedge bone between V2 & Vidian nerve decreases as we go posteriorly towards petrous carotid
  233. 233. The wedge bone between V2 & Vidian nerve decreases as we go posteriorly towards petrous carotid
  234. 234. Accessories
  235. 235. anterior ethmoidal artery ( AEA) and nerve (AEN) , anterior falcine artery (AFA)
  236. 236. Deep temporal artery
  237. 237. Trigeminal area at Cerebello Pontine Angle – along with my voice Click http://www.youtube .com/watch?v=YBqk 4Jdnxic
  238. 238. CAROTID COURSE Click http://www.youtube.c om/watch?v=JlNmSI3t S8Q
  239. 239. PETROCLIVAL MENINGIOMA DECISION MAKING •Click http://www.youtube.com /watch?v=kUa9fQ4_aQY
  240. 240. Frontal sinus surgery concepts – must for to do DRAF-III – Don’t use cutting burr while drilling the Frontal-T , high chances of injuring the dura -- use only dimond drill Click http://www.youtube.com /watch?v=2rhafq3Ur0s
  241. 241. Hemifacial spasm Video-1 http://www.youtube.com/watc h?v=-zlymD2LYsM Video-2 http://www.youtube.com/watc h?v=gGyQFh3PqPg
  242. 242. Subfrontal craniotomy.
  243. 243. Subfrontal craniotomy.
  244. 244. Mandibulotomy [ Mental nerve bilaterally ]
  245. 245. AFB area
  246. 246. Fig. 74a, b The reference level is the acousticofacial nerve bundle. The anterior inferior cerebellar artery, lying between the auditory and facial nerves, is found in 38% of cases.
  247. 247. 7up- 7th is above Coca cola – cochlear n. is cola[=lower]
  248. 248. SKULL BASE 360° Above presentation is SKULL BASE 360°-Part 2 For SKULL BASE 360°-Part 1 Please click or copy/paste in URL or weblink area http://www.slideshare.net/muralichandnallamoth u/edit_my_uploads [ Dated: 19-4-14 ] I will update continuosly with date tag at the end as I am getting more & more information

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