petrous apex 360°
TRANSCRIPT
Petrous apex 360°29-5-2015
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
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The Petrous pyramid has only 3 surfaces unlike
Egypt pyramid which has 4 surfaces
The petrous portion of the temporal bone or pyramid is pyramidal
Petrous apex =Anterior Triangular ( T ) area + Posterior Quadrangular ( Q ) area
Petrous apex =Anterior Triangular ( T ) area + Posterior Quadrangular ( Q ) area
Petrous apex – Triangular area
Petrous apex – Quadrangular area
Quadrangular ( Q ) space in anterior skull base – where petrous apex is seen – Supra-petrous approach – space
between laceral carotid & Trigeminal ganglion & V3
Quadrangular ( Q ) space – where petrous apex is seen – Supra-petrous approach – space between laceral
carotid & Trigeminal ganglion & V3 Quadrangular ( Q ) area in middle cranial fossa
Quadrangular ( Q ) space in anterior skull base approach
Quadrangular ( Q ) space – where petrous apex is seen – Supra-petrous approach – space between laceral carotid & Trigeminal
ganglion & V3
Quadrangular ( Q ) area in middle cranial fossa
Quadrangular ( Q ) space in anterior skull base approach
JT= Jugular Tubercle – Below this tubercle is hypoglossal canal & above is Internal Jugular foramen
IPS & HVP hypoglossalvenous plexus
Petrous apex - Quadrangular area
Middle cranial fossa approach
the anterior petrosectomy with preoperative embolization of the inferior petrosal sinus is a time-conserving approach giving one of the best routes to reach the ventral brainstem while working in front of the cranial nerves and
preserving hearing.http://www.worldneurosurgery.org/article/S0090-3019(00)00271-8/fulltext
The middle fossa retractor is fixed at the petrous ridge (PR).AE Arcuate eminence, GPN Greater petrosal nerve, M Middle meningealartery
The expected location of the internal auditory canal (IAC).The bar-shaded areas are the locations for drilling. A Anterior, AE Arcuateeminence, GPN Greater petrosal nerve, MMA Middle meningealartery, P Posterior
Middle cranial fossa Transpetrous ( = Transapical )
A right-sided skin incision for the middle cranial fossa approach.
The skin and subcutaneous tissues have been elevated as one flap.
The temporalis fascia has been harvested and the temporalis muscle cut using monopolar diathermy.
The temporalis muscle and periosteum have been elevated as one flap.
The craniotomy has been performed using a small drill.
The craniotomy flap has been elevated and the middle fossa (MFD) can be seen.
The branches of the trigeminal nerve (V1, V2, V3) can beidentified at the anterior part of the approach.
The Fukushima middle cranial fossa retractor has been applied to maintain the elevated dura.
Three-quarters of the canal circumference is skeletonized, leaving a thin shell of bone over it.
The different areas of access for the middle fossa approaches.a Classic middle fossa approach to the internal auditory canal.
b Enlarged middle fossa approach for tumor removal. c−e The middlefossa transpetrous approach.
The landmarks for the internal auditory canal (arrow) in middle fossa approach. AE, arcuate eminence; gspn, greater superficial petrosal nerve; MMA, middle meningeal artery.
A schematic representation of the position of the internal audi tory canal in middle cranial fossa approach. EAC, external auditory canal; IAC, internal auditory canal; SSC, superior semicircular canal; SPS, superior petrosal sinus.
An anatomical dissection carried out through the middle fossa,illustrating the relationships between the various structures in this area.
A closer view of the lateral end of the internal auditory canal.
The posterior rhomboidal area (Q) of the anterior petrous apex.
The anterior triangular area has been uncovered by sectioning the mandibular nerve (V3) and reflecting the gasserian ganglion.
The amount of circumferential exposure of the internal auditory canal near the fundus is only 180°.
Kawase approachThe quadrangular area of the petrous apex anterior to the internalauditory canal is drilled and the horizontal segment of the internalcarotid artery (ICA) is exposed.
the anterior petrosectomy with preoperative embolization of the inferior petrosal sinus is a time-conserving approach giving one of the best routes to reach the ventral brainstem while working in front of the cranial nerves and
preserving hearing.http://www.worldneurosurgery.org/article/S0090-3019(00)00271-8/fulltext
Videos of kawase approach or Anterior Transpetrosal approach
– click
http://aiimsnets.org/AnteriorTranspetrosalapproach.asp
#
The whole length of the horizontal portion of the internal carotid artery (ICA) is exposed up to the anterior foramen lacerum (AFL).
The dura is opened by creating an inferiorly based flap, the dashed lines.
Surgical Anatomy after Opening of the DuraThe middle fossa transpetrous approach.
The anterior inferior cerebellar artery is seen looping around the acousticofacial bundle (AFB).
At a higher magnification a prominent flocculus (Fl) is observed.
The distal part of the vertebral artery (VA) can be seen.
The distal part of the vertebral artery (VA) can be seen.
After removing the remaining bone of the petrous apex, the basilar artery (BA) can be seen in the prepontine cistern.
Opening the dura of the middle cranial fossa exposes the third nerve (III) and intracavernous portion of the internal carotid artery (ICA).
A closer view at the level of the fundus of the internalauditory canal. The facial nerve lies anteriorly and superiorly. The vestibular nerve posteriorly is separated from thefacial nerve by a plane of cleavage. The cochlear nerve islocated inferior to the facial nerve.
The cochlear nerve travels along an inferior coursein the internal auditory canal. Inferior to the vestibular nerveat the porus acusticus, it becomes inferior to the facial nerveat the lateral end of the internal auditory canal. There is alabyrinthine artery coursing between the cochlear and facialnerves.
A closer view at the level of the porus acusticus. The anterior inferior cerebellar artery forms a vascular loop and gives off labyrinthine arteries, which fix the contact between the artery and
the inferior surface of the acousticofacial nerve bundle at the inferior lip of the meatus.
The root exit zone of the facial nerve is anterior to the root of the cochlear nerve and superior to the rootlets of the lower cranial nerves.
7 Facial nerve8 Vestibulocochlear nerve9 Glossopharyngeal nerve10 Vagus nerveAICA Anterior inferior cerebellar arteryIAC Internal auditory canalPICA Posterior inferior cerebellar artery
The pontobulbar junction and the roots of thelower cranial nerves are visualized. The loop of the posterior
inferior cerebellar artery is seen in the background.
Right enlarged middle fossa approach. The internalauditory canal has been opened, revealing the acousticofacial
Perve bundle contained within it. The facial nerve runs anteriorly,and the superior vestibular nerve lies posteriorly. The
loop of the anterior inferior cerebellar artery runs near theMeatus, below the acousticofacial nerve bundle.
Lateral view of CP angle
Posterior view of CP angle 1. level 1 = Trigeminal area
2. Level 2 = AFB area3. Level 3 = Lower cranial nerve area 4. Level 4 = Foramen magnum area
Various Transpetrous approaches to get lateral view of CP angle ( = to reach Lateral part of Posterior cranial fossa dura )
predominently to reach Level 1 = Trigeminal nerve area & Level 2 = AFB area1. Retrolabyrinthine Transpetrous ( =
Transapical )2. Translabyrinthine Transpetrous ( =
Transapical )3. Transcochlear Transpetrous ( =
Transapical )
predominently to reach Level 3 = Lower cranial nerve area4. POTS = Petro-Occipital Trans-
Sigmoid approach predominently to reach Level 4 = Foramen magnum area5. Exrtreme lateral or Far lateral or Transcondylar approach
Photograph of a cadaveric dissection showing an overview of the temporal bone and depicting the posterior surface of the petrous part. The sphenoid bone, which articulates anteriorly with the petrous and squamous
temporal bone, has been removed in this specimen. The pyramidal petrous part, located between the sphenoid and occipital bones, has a base, apex, and three surfaces. The sigmoid sinus descends along the posterior surface of the mastoid part and turns anteriorly toward the jugular foramen. The posterior transpetrosal approaches involve progressive degrees of resection of the petrous temporal bone. The retrolabyrinthine
(green outline) dissection exposes the area between the superior petrosal sinus, the sigmoid sinus, and the posterior semicircular canal. The translabyrinthine approach (pink outline) extends more anteriorly to remove
all three semicircular canals and to expose the anterior wall of the IAC. The transcochlear (blue outline) dissection extends even more anteriorly to the petrous apex, resulting in an almost complete petrosectomy
with the widest and most direct exposure of all the posterior transpetrosal approaches. PET. = petrous/petrosal; POST. = posterior; RETROLAB = retrolabyrinthine; S.C. = semicircular canal; SIG. = sigmoid;
SUP. = superior; TRANSLAB = translabyrinthine.
Middle cranial fossa Transpetrous approach - the anterior petrosectomy with preoperative embolization of the inferior petrosal sinus is a time-conserving approach giving one of the best routes to reach the ventral brainstem while working in front of the cranial nerves and preserving hearing.http://www.worldneurosurgery.org/article/S0090-3019(00)00271-8/fulltext
Retrolabyrinthine Transpetrous ( = Transapical )
Retrolabyrinthine Transpetrous ( = Transapical ) &Translabyrinthine Transpetrous ( = Transapical ) &
Transcochlear Transpetrous ( = Transapical )
predominently to reach
Level 1 = Trigeminal nerve area & Level 2 = AFB area
COMBINED APPROACHES Retrolabyrinthine Transpetrous ( =
Transapical )Subtemporal ApproachRetrolabyrinthine Transpetrous ( =
Transapical )Subtemporal Transtentorial Approach
Retrolabyrinthine Subtemporal Transapical Approach
Retrolabyrinthine Subtemporal Transtentorial Approach
A view of the cerebellopontine angle through the retrolabyrinthine approach Note the narrow field and limited control.
Posterior fossa dura (PFD) structures exposed through the standard retrolabyrinthine approach.
A view of the posterior fossa dura through the combined retrolabyrinthine subtemporal transapical approach.
The middle fossa dura has been cut. The oculomotor nerve (III) is clearly seen.
With more retraction of the temporal lobe and the tentorium(*), the optic nerve (II) is seen.
Retrolabyrinthine Subtemporal Transapical (Transpetrous Apex) Approach
Schematic drawing showing the incision to be performed.
A retrolabyrinthine approach is performed.
The dura of the middle fossa is detached from the superior surface of the temporal bone from posterior to anterior.
With further detachment of the dura, the middle meningeal (MMA) artery is clearly identified.
The middle meningeal artery (MMA) and the three branches(V1, V2, V3) of the trigeminal nerve are identified.
View after cutting the middle meningeal artery (MMA) andthe mandibular branch of the trigeminal nerve (V).
The internal auditory canal (IAC) is identified.
A large diamond burr is used to drill the petrous apex.
The petrous apex has been drilled. The internal carotid artery(ICA) is identified.
At higher magnification, the abducent nerve (VI) is identifiedat the level of the tip of the petrous apex (PA).
Panoramic view showing the structures after opening of theposterior fossa dura.
At higher magnification, the anterior inferior cerebellar artery (AICA)is seen stemming from the basilar artery (BA) at the prepontine cistern. The artery is crossed by the abducent nerve (VI). Note the good control of the prepontine cistern through this approach.
Tilting the microscope downward, the lower cranial nervesare well seen.
Retrolabyrinthine Subtemporal Transtentorial Approach
The retrolabyrinthine craniotomy has been performed. The petrous apex has been partially drilled.
The middle fossa dura (*) is incised.
The tentorium (*) is cut, taking care not to injure thetrochlear nerve.
The tentorium is further cut until the tentorial notch isreached. With retraction of the temporal lobe the optic (II), oculomotor(III) and contralateral oculomotor (IIIc) nerves are seen.
Branches of the trigeminal nerve (V1, V2, V3) at the level ofthe lateral wall of the cavernous sinus.
Endoscopic Retrolabyrinthine approach – The retrolabyrinthine approach consists of a small posterior fossa craniotomy, between the sigmoid sinus and the otic capsule. It provides limited exposure of the posterior fossa, confined to the region of the
entryzone of the trigeminal nerve and acousticofacial nerve
bundle. More lateral structures, such as the porusacusticus and the internal auditory canal, cannot bevisualized directly, since they are blocked by the otic
capsule. In order to reach and inspect the interna)auditory canal, it is necessary first to enlarge the
approach posteriorly, removing the bone overlying thesigmoid sinus and 1-2 cm of the retrosigmoid occipital
bone; and secondly, to use the endoscopic procedure .
Translabyrinthine Transpetrous ( = Transapical )
Retrolabyrinthine Transpetrous ( = Transapical ) &Translabyrinthine Transpetrous ( = Transapical ) &
Transcochlear Transpetrous ( = Transapical )
predominently to reach
Level 1 = Trigeminal nerve area & Level 2 = AFB area
The Enlarged Translabyrinthine Approach with Transpetrous ( = Transapical ) Extension
Schematic drawings showing the amount of bone removalaround the internal auditory canal in the different variants of the
translabyrinthine approach. Note that in the transapical modification theexposure is 320° and about 360° in types I and II, respectively. Abbreviations
as in Fig. 5.1. cn, cranial nerve; CN, cochlear nerve; FN, facial nerve;IV, inferior vestibular nerve; SV, superior vestibular nerve.
Drilling inferior to the right internal auditory canal (IAC).
Further extensive drilling inferior to the internal auditory canal (IAC) toward the petrous apex.
Extensive bone removal inferior and superior to the internal auditory canal (IAC). Bone superior to the canal (*) is still to be removed.
The whole contents of the internal auditory canal (IAC) are pushed inferiorly to allow removal of the remaining bone (*) superior to the canal.
The whole contents of the canal are displaced inferiorly to show the extent of bone removal. The anterior wall of the canal can also be drilled if needed.
Schematic drawing showing the technique and extent of bone removal in the type I (green line) and type II (red line) transapical extension. F, facial nerve; C, cochlear nerve; Vs, superior vestibular nerve; Vi, inferior vestibular nerve.
Schematic drawing showing the technique and extent of bone removal in the type I (green line) and type II (red line) transapical extension. F, facial nerve; C, cochlear
nerve; Vs, superior vestibular nerve; Vi, inferior vestibular nerve.
General view of the structures in the cerebellopontine angleafter opening the dura. Note the enhanced exposure of the angle andthe excellent exposure of the trigeminal nerve (V).
The trigeminal nerve (V) is pushed superiorly. The basilarartery (BA) in the prepontine cistern can be seen well.
With more traction of the tentorium, a panoramic view of thestructures in the angle is available. The trochlear nerve (IV) is
seen before piercing the tentorium to gain access to the middle fossa.
Transcochlear Transpetrous ( = Transapical )
Retrolabyrinthine Transpetrous ( = Transapical ) &Translabyrinthine Transpetrous ( = Transapical ) &
Transcochlear Transpetrous ( = Transapical )
predominently to reach
Level 1 = Trigeminal nerve area & Level 2 = AFB area
An extended mastoidectomy, labyrinthectomy, identificationof the internal auditory canal, and drilling of the cochlea has been performed.
The facial nerve (FN) has been skeletonized.
The facial nerve (FN) has been skeletonized.
Using a diamond burr to uncover the labyrinthine segment ofthe facial nerve (FN).
The facial nerve (FN) is completely uncovered. Note Bill’s bar(BB) separating the nerve from the superior vestibular nerve (SVN) at thelevel of the fundus of the internal auditory canal.
Identification of the greater superficial petrosal nerve (gspn).
The greater superficial petrosal nerve is (gspn) cut.
The geniculate ganglion (GG) and the labyrinthine portion ofthe facial nerve (FN) are elevated.
The tympanic segment is freed.
A beaver knife is used to free the mastoid segment.
The superior vestibular nerve (SVN) is detached from its attachment.
The whole contents of the internal auditory canal are transposed posteriorly with the facial nerve (FN).
New position of the facial nerve (FN) after posterior rerouting
Removal of the fallopian canal with a rongeur.
Surgical Anatomy after Opening the posterior cranial fossa dura
Drilling of the cochlea (Co). Drilling of the petrous apex (PA).
View after complete performance of the approach. Thedashed lines represent the dural incision.
View after opening the dura, showing excellent control of thebasilar artery (BA) and prepontine cistern.
Tilting the microscope downward, both the ipsilateral (VA)and contralateral (VAc) vertebral arteries come into view.
With a slight retraction of the middle fossa dura, the origin ofthe superior cerebellar artery at the basilar artery (BA) can be seen. Notethe excellent control of the trigeminal nerve (V).
Lilliquits membrane present over the basillar artery & 3rd N. origin area
Mild retraction of the tentorium (Ten) provides a good view ofthe oculomotor nerve (III) and its relation to the superior cerebellarartery (SCA) lying inferiorly and the posterior cerebral artery (PCA) lyingsuperiorly. The trochlear nerve (IV) is seen running on the undersurfaceof the tentorium.
Meckel’s cave (MC) can be opened when necessary.
The Type C Modified TranscochlearApproach – after cutting the tentorium
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 oculomotor nerve (III) is embraced by the posterior cerebral artery (PCA) superiorly and the superior cerebellar artery (SCA) inferiorly
POTS = Petro-Occipital Trans-sigmoid approach
POTS = Petro-Occipital Trans-sigmoid approach predominently to reach
Level 3 = Lower cranial nerve area
The C-shaped skin incision. A skin flap is raised.
A U-shaped musculoperiosteal flap is outlined.
Bone exposure. Note that no retractors are used.
The internal jugular vein (IJV) is identified.
The internal jugular vein is liberated.An extended mastoidectomy has been performed.
A wide retrosigmoid craniotomy.The sigmoid sinus (SS) is uncovered. Note that the bone overlyingthe genu from the lateral to the sigmoid sinus is intact (arrowhead).
The dura is separated from the overlying bone.
The dura is separated from the overlying bone.
The endolymphatic sac (ELS) is identified.
Further separation of dura from the overlying bone.
Placement of aluminum to protect the dura from injury.
The cochlear aqueduct (CAq)is identified.
Complete drilling of the retrofacial air cells. The approach has been completed. The
dotted line representsthe dural incision.
The dura has been opened and the tumor (T) can be seen.
Closure of the dura. The remaining defect (white arrowheads), together with the operative cavity, is obliterated with abdominal fat.
Surgical Anatomy after Opening the posterior cranial fossa dura
General view of the structures that can be visualized after opening the dura.
At the superior aspect of the approach, the fourth (IV) and fifth (V) cranial nerves can be appreciated.
The facial nerve can be clearly seen in the middle part of the approach after retracting the posteriorly lying cochlear nerve. Separation of the glossopharyngeal nerve (IX) from the vagus (X) and accessory (XI) nerves at the medial aspect of the jugular foramen.
Further inferiorly, the ninth (IX), tenth (X), and eleventh (XI) cranial nerves can be seen exiting the skull through the jugular foramen
At the inferior part of the approach the lower cranial nerves can be appreciated.
The relation between the inferior petrosal sinus (ips) and the lower cranial nerves.
The origin of the hypoglossal nerve (XII).
.
The drilled occipital condyle (OC) and the hypoglossal canal (HC).
Anterior skull base
Infra-petrous approach
Infra-petrous approach is through Mid Clivus
1. Upper clivus – Upto 6th nerve entry dorello’s canal (petro-clival junction) 2. Middle clivus – from 6th nerve to jugular foramen
3. Lower clivus – from jugular foramen to foramen magnum
Lateral skull base Anterior skull base
The middle third (M. 1/3rd) begins at the sella floor (SF) and extends to the floor of the sphenoid sinus (SSF), and the lower third (L. 1/3rd) extends from
the floor of the sphenoid sinus to the foramen magnum (FM).
Lateral skull base Anterior skull base
Lower half of paraclival carotid - caudal part, the lacerum segment of the paraclival carotid ”The unsolved surgical problem remains the medial wall of the ICA at the level of the anterior foramen lacerum, until now unreachable with the available surgical approaches." - In lateral skull
base by Prof. Mario sanna – this unreachable is Carotid-Clival window which is accessable in Anterior skull base
Infrapetrous Approach
Carotid-Clival window – Mid clivusa. Petrosal face
b.Clival face
JT = jugular tubercle separates the hypoglossal canal from Jugular foramen
IPS & HVP hypoglossalvenous plexus
Jugular tubercle [ JT ] AICA antero-inferior cerebellar artery, ASC anterior semicircular canal, BA basilar artery, HChypoglossal canal, IAC internal acoustic canal, ICAh horizontal portion of the internal carotidartery, 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
The foramen lacerum (FL) is located lateral to the floor of the sphenoid sinus at the level of the spheno-petro-clival confuence.
JT jugular tubercle, HC hypoglossal canal –
addFig 3.78 also
Pontomedullary junction = Vertebro-basillar junction = Junction of Mid clivus & Lower clivus = foramen lacerum area
The pontomedullary junction. The vertebral artery junction is at the level of the junction of the inferior and midclivus. The basilar artery runs in a straight line on the surface of the pons. The exit zones of the hypoglossal and abducent nerves are at the same level. The abducent nerve exits from the pontomedullary junction, and ascends
in a rostral and lateral direction toward the clivus.
Very rare specimen..The vbj is far inferior to floor of sphenoid sinus
Cadaveric dissection demonstrating the osteotomies at the base of the posterior clinoids (PC) for separation with the body of the dorsum sella (DS). P. CCA , posterior
genu of the intracavernous carotid artery; PCA, paraclival carotid artery; ICCA, intracranial carotid artery; BA, basilar artery; PL, posterior lobe of the pituitary gland;
AL, anterior lobe of the pituitary gland.
Cadaveric dissection image demonstrating the close anatomical relationship of the posterior clinoid (PC) with both the intracranial carotid artery (ICCA)
and the posterior genu of the intracavernous carotid artery (P. CCA). AL, anterior lobe of the pituitary gland; PL, posterior lobe of the pituitary gland;
BA, basilar artery.green dotted triangle area for entry of the endoscope into the interpeduncular fossa
Cadaveric dissection of the middle third of the clivus with removal of the basilar plexus and exposing the dura. The abducens
nerves (CN VI) can be seen bilaterally as they perforate the meningeal dura and become the interdural segments of CN VI. CS,
cavernous sinus; PCA, paraclival carotid arteries; P, pituitary gland.
Clival recess
See the relationship between lower boarder of posterior end of vomer & clivus – vomer lower boarder is at junction of mid & lower clivus – my
understanding
http://www.neurosurgicalapproaches.com/2013/08/25/
Anterior cranial fossa dura Posterior cranial fossa dura
Anterior skull base
Supra-petrous approach
Quadrangular ( Q ) space – where petrous apex is seen – Supra-petrous approach – space between laceral
carotid & Trigeminal ganglion & V3
Quadrangular ( Q ) space – where petrous apex is seen – Supra-petrous approach – space between laceral
carotid & Trigeminal ganglion & V3 Quadrangular ( Q ) area in middle cranial fossa
Quadrangular ( Q ) space in anterior skull base approach
Quadrangular ( Q ) space – where petrous apex is seen – Supra-petrous approach – space between laceral carotid & Trigeminal
ganglion & V3
Quadrangular ( Q ) area in middle cranial fossa
Quadrangular ( Q ) space in anterior skull base approach
Paraclival carotid PAp = Petrous apex
1. caudal part, the lacerum segment of the artery corresponding to the extracavernous portion of the vessel, and
2. rostral part, the trigeminal, intracavernous portion of the artery, so- called because the Gasserian ganglion is posterior to it and the trigeminal divisions are lateral to it.
CR clival recess, ICAc cavernous portion of the internal carotid artery, ICAh horizontal portion of the internal carotid
artery, PAp petrous apex, VN vidian nerve , MC Mevkels cave
CR clival recess, ET eustachian tube, ICAc cavernous portion of the internal carotid artery,
ICAh horizontal portion of the internal carotid artery, PAp petrous apex, PLL petrolingual ligament, VN vidian nerve, V2 second branch of the trigeminal nerve, red
arrow artery for the foramen rotundum, yellow arrow greater petrosal nerve.
The petrolingual ligament connects the petrous apex and the lingula of the sphenoid. It can
be considered the border between the horizontal and cavernous portions of the internal carotid artery.
Endoscopic vision of the suprapetrous window. The dura of the middle cranial fossa has been displaced upward, and the greater petrosal nerve coming out from the geniculate ganglion is evident. The black arrow in the small picture
indicates the perspective of the vision in the bigger image
ET eustachian tube, GPN greater petrosal nerve, MCFd dura of the middle cranial fossa, MMAmiddle meningeal artery, SPS superior petrosal surface, TI trigeminal impression, V3 third
branch of the trigeminal nerve, yellow arrow accessory middle meningeal artery, white asterisksgreater petrosal nerve groove
The skull base given by the sphenoid bone has been drilled away, and the third branch of the trigeminalnerve and the MMA have been freed from their canals. An accessory MMA is seen in close relationship
to V3. When present, it passes through the foramen ovale.
The space above transverse line of V2 is Middle cranial fossa ( Meckel’s cave ) –
Read the CT – scan/ Plane the surgery by using these lines
Upper half of paraclival carotid – rostral part, the trigeminal segment of the paraclival carotid
TG ( Trigeminal ganglion ) is lateral to upper half [ rostral part ] of Paraclival carotid
Anterior skull base Lateral skull base
Carotid transposition – need to refer literature regarding “ How far it is SAFE ” in anterior skull
base approach
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.