Cavernous Sinus 360°29-9-20168.12 pm

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TEPS [ Trans-ethmoid pterygoid sphenoid ] approach to cavernous sinus

Lateral sellar compartment ( = Cavernous sinus )

Safe location for opening the meckels cave – inferior to V2 , lateral to paraclival carotid because it is far inferior to 6th nerve – find safe location to open the cavernous

sinus

Front door

The maxillary strut is identified as a really constant bony landmark useful for indicating the superior orbital fissure and

the “front door” to the cavernous sinus.

CS cavernous sinus, IRM inferior rectus muscle, lOCR lateral optico-carotid recess, MM Muller’s muscle,MRM medial rectus muscle, ON optic nerve, pwMS posterior wall of the maxillary sinus, VN vidian

nerve, V2 second branch of the trigeminal nerve, white asterisk indicates lateral optico-carotid recess,black asterisks indicate the nasal part of the superior orbital fi ssure, black arrow indicates the divisionof the oculomotor nerve, red arrow indicates ophthalmic artery, yellow arrow indicates maxillary strut

To know SOF [ Superior Orbital Fissure ] click http://www.slideshare.net/muralichandnallamothu/superior-

orbital-fissure-360

Yellow line = “nasal” part of SOF Clinically, the SOF and CS apex represents a continuum.

Roof

Roof - two triangles: 1. clinoid (anterior)

2. oculomotor (posterior)

ACP anterior clinoid process, APCF anterior petroclinoid fold, DS dorsum sellae, ICF interclinoidfold, PF pituitary fossa, PLL petrolingual ligament (inferior sphenopetrosal ligament),

PPCF posterior petroclinoid fold, PS planum sphenoidale, SSPL superior sphenopetrosalligament (Gruber’s ligament), TS tuberculum sellae, black asterisk middle clinoid process , CSR

cavernous sinus roof , white asterisk oculomotor nerve

If the Gruber’s ligament is ossificated it is called Wegener’s bridge.

Interclinoidal ligament/fold [ ICF ] after pituitary extracapsular extraction

Roof - two triangles: 1. clinoid (anterior)

2. oculomotor (posterior)Anterior skull base approach – see clinoid triangle in below photo

Occulomotor triangle – courtesy by Dr. Sukhdeep Jhawar

The lower dural ring is given by the COM, that lines the inferior surface of the ACP. It can be visible, through a transcranial route, only by removing the ACP. The lower duralring 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 of the anterior clinoid region. The rightportion of the planum sphenoidale is seen from above. The anterior clinoid process has been removed. Vision obtained through a right supraorbital approach with a 30°

down-facing lens focusing on the cavernous sinus roof. ACP anterior clinoid process (removed), COM carotid oculomotor membrane, ICAc

cavernous portion of the internal carotid artery, ICAi intracranial portion of the internal carotid artery, OA ophthalmic artery, ON optic nerve, LWS lesser wing of the

sphenoid, IIIcn oculomotor nerve

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

COM = carotico–oculomotormembrane

Superior view of the rightophthalmic artery in the right paraclinoid area. The anteriorclinoid process, which is situated on the lateral side of theoptic nerve, has been removed. The optic canal has been

unroofed, the optic sheath opened, and the optic nerve elevatedto expose the origin of the ophthalmic artery under the

medial half of the optic nerve. In the optic canal, the ophthalmicartery courses within the dural sheath of the optic

nerve. It exits the optic canal and the optic sheath to enter theorbital apex on the inferolateral aspect of the optic nerve.

The oculomotor nerve courses just below the dura coveringthe lower margin of the anterior clinoid process. The clinoidsegment of the internal carotid artery is the segment that

courses on the medial side of the anterior clinoid process andis exposed by removing the anterior clinoid process. The

upper edge of the clinoid segment is defined by a dural ring,called the upper dural ring, formed by the dura, which

extends medially from the upper surface of the anterior clinoidprocess. The lower edge of the clinoid segment is

defined by the lower dural ring, which is formed by the durathat line1 the lower surface of the anterior clinoid process and

separates the clinoid process from the upper surface of theoculomotor nerve and continues medially as the carotid-

oculomotor membrane to surround the carotid artery The ophthalmic

artery usually arises just above the clinoid segmenlHowever, it may infrequently arise from the clinoid segment.

Anatomically speaking, the paraclinoid segment of the internal carotid artery is not fully intracavernous, and it is separated from the cavernous sinus by the extension of the dura

covering the inferior surface of the anterior clinoid process (Reisch et al. 2002 ) .

Note carotid cave , cavernous sinus , upper & lower dural rings

Aneurysms of initial intracranial carotid

Fig. 22.31 Clinoidal and oculomotor triangleshave been opened and the anterior clinoid removed up to the optic strut, exposing the carotido-oculomotor membrane. The optic strut has two neural-facing surfaces( yellow dotted lines) and one vascular-facing surface (red dotted line). CN: cranial nerve; Falc.: falciform; ICA: internal carotid artery; Inf.:inferior; Lig.: ligament; Pet.: petrosal; V1: first division; V2: second division; V3: third division of trigeminal nerve.

ACP anterior clinoid process, APCF anterior petroclinoid fold, DS dorsum sellae, ICF interclinoid fold, PF pituitary fossa, PLL petrolingual ligament (inferior sphenopetrosalligament), PPCF posterior petroclinoid fold, PS planum sphenoidale, SSPL superior sphenopetrosal ligament (Gruber’s ligament), TS tuberculum sellae, black asterisk middle clinoidprocess

See the Gasserian ( V , VI ) emerge through the posterior petroclinoidal ligament , ( III , IV ) through triangle between the anterior petroclinoidal and interclinoidal ligamentnext show how the both interclinoidal ligament give sleeves of upper and lower duralrings these ligaments with attachment to petrous edge and clinoid processes( anterior

and posterior ) , stabilizing and held the cranial nerves and carotid , reinforcing the dural wall of sinuses

Rahul Kumar The ILT is an important vessel in this region, vascularising many of the tumours and fistulas, as well as cranial nerves. It can be seen hooking around the sixth nerve in the panel on the right. It has rich anastomoses with many branches from the

external carotid

Roof

Oculomotor cistern Cranial nerve III enters the roof included in its own cistern

(oculomotor cistern).

Oculomotor cistern goes uptoanterior clinoid tip

The optic strut has two neural-facing surfaces( yellow dotted lines) and one vascular-facing surface (red dotted line).

[ COM= Lower dural ring – Carotico-Occulomotor membrane seperates3rd N from Clinoidal carotid ]

Medial wall

yellow arrow inferior part ( Sphenoidal part ) of the medial wall of the cavernous sinus ( yellow line ), blue-sky arrow superior ( Sellar part ) of the medial wall of the cavernous

sinus ( blue-sky line )

In the upper part, the medial wall is given by the meningeal layer, that is a continuation of the diaphragma sellae, which surrounds the pituitary capsule inferiorly (Yasuda et al. 2005 ; Martins et al. 2011 ) . In the inferior part, the medial wall is given by the endosteal layer that covers the

body of the sphenoid bone.

The medial and lateral walls join inferiorly in a ‘keel- like’ formation at the level of the superior margin of the maxillary

nerve.

Lateral wall

In FTOZ APPROACH - From Surgical anatomy of the petrous apex and petroclival region book -H.-D. FOURNIER2, P. MERCIER2, and P.-H. ROCHE1

Fig. 23. Exposure of the epidural temporopolar space (Head cadaver dissection, rightside): the meningoorbital band is the thick fibrous band that connect the periorbital

fascia to the temporopolar dura. At the right bottom corner, the same view is shown inan operative case

From book Analomy and Surgery of the Cavernous Sinus - Vinko V. Dolene old book Fig. 15. In the anterior area of the anterolateral triangle a huge vein enters the lateral wall of the CS. The intense blue color of the lateral wall of the CS indicates that there

is abundant blood between its layers

From book Analomy and Surgery of the Cavernous Sinus - Vinko V. Dolene old bookFig. 63. Further removal of the outer layer of the lateral wall of the CS from the vein

entering the CS shows a huge collection of »venous blood« between the two layers of the lateral wall of the CS. The venous injection is also seen in the paramedial triangle

and laterally in the lateral triangle

http://www.slideshare.net/INUB/endoscopic-anatomy-and-approaches-of-the-cavernous-sinus-cadaver-study - Endoscopic view of the right cavernous sinus and neurovascular relations,

demonstrating the ‘S’ shaped configuration formed by the oculomotor, the abducens , carotid nerve ( paraclival carotid ) and the vidian nerves.

III oculomotor nerve, V1 ophthalmic nerve, V2 maxillary nerve, V3 mandibular nerve, VI abducensnerve, 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

VI nerve is parallel & medial to V1 –in the same direction of V1 [ Mneumonic – VI & V1 in same direction ]

Meningo-hypophyseal trunk & carotid nerve

1. 6th N. crossing carotid at Petro-clival junction when viewing in lateral skull base - The lateral aspect of the parasellar & paraclival carotid junction is crossed by the

abducent nerve (VI) at the entrance of both [ 6th nerve & carotid ] structures into the cavernous sinus.

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 ).

1. 6th N. crossing carotid at Petro-clival junction when viewing in lateral skull base - The lateral aspect of the parasellar & paraclival carotid junction is crossed by the abducent nerve (VI) at the entrance of both [ 6th nerve &

carotid ] structures into the cavernous sinus.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 ).

Carotid nerve –part of S’ shaped configuration formed by the

oculomotor, the abducens , carotid nerve ( paraclival carotid ) and the vidian nerves.

VI nerve is parallel & medial to V1 – in the same direction of V1 [ Mneumonic – VI & V1 in same direction ]

STA is devided into 1. Supra-Trochlear triangle 2. Infra-Trochlear triangle

STA is devided into 1. Supra-Trochlear triangle 2. Infra-Trochlear triangle

1.Supra Trochanteric & Infratrochanteric Triangles2. Upper & lower dural rings

3. lower dural ring is COM ( Carotico-Oculomotor Membrane )

In the below picture superior cerebellar artery mislabelled as meningohypophyseal trunk .

STA is devided into 1. Supra-Trochlear triangle 2. Infra-Trochlear triangle

1.Supra Trochanteric & Infratrochanteric Triangles2. Upper & lower dural rings

3. lower dural ring is COM ( Carotico-Oculomotor Membrane ) Right lateral view of the inferolateral trunk or artery of the inferior cavernous sinus, a branch of the horizontal part of the internal carotid artery (ICA) that provides blood to the dura of the lateral wall of the cavernous sinus as well as to the cranial nerves running along the lateral wall of the cavernous sinus. The trochlear nerve has been displaced inferiorly and the oculomotor nerve has been displaced superiorly. A recurrent branch from the inferolateral trunk is observed in this specimen. This branch heads back toward the tentorium cerebelli forming the so-called marginal tentorial artery. 1=horizontal segment of cavernous ICA, 2=clinoid segment of ICA, 3=supraclinoid ICA, 4=inferolateral trunk or artery of the inferior cavernous sinus, 5=marginal tentorial artery, 6=optic nerve, 7=oculomotor nerve, 8=trochlear nerve, 9=ophthalmic nerve, 10=abducent nerve, and 11=sphenoid sinus.

http://posterng.netkey.at/esr/viewing/index.php?module=viewing_poster&task=viewsection&pi=122476&ti=402607&si=1380&searchkey=#poster

Fig. 1: Schematic drawing of the inferolateral trunk (ILT). The ILT arises from lateral surface of the C4 segment of the internal carotid artery. The ILT gives rise to three

branches: tentorial branch, anterior branch, and posterior branch. The anterior branch divides into the anteromedial branch and anterolateral branch. The posterior branch divides into posteromedial branch and posterolateral branch. ; AB, anterior branch;

ALB, anterolateral branch; AMB, anteromedial branch; ICA, internal carotid artery; ILT, inferolateral trunk; OpA, ophthalmic artery; PB, posterior branch; PLB, posterolateralbranch; PLB,posterolateral branch; TB, tentorial branch References: Radiology, Oita

University - Yufu city/JP

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.

From lateral skull base - The lateral aspect of the parasellar & paraclival carotid junction is crossed by the abducent nerve (VI)

The abducens nerve in most case is a single trunk throughout its entire course (Zhang et al. 2012 ) . There are some variants, and one should be aware that the nerve can fuse with the oculomotor nerve for all its course (Zhang et al. 2012 ) . The surgeon must be prepared to face other rare variations, such as different fasciculi within the CS. Globally, the incidence of a duplicated abducens nerve has been reported, ranging

from 8 % to 18 % (Nathan et al. 1974 ; Iaconetta et al. 2001 ; Ozveren et al. 2003 ) . In the prepontine cistern, when the duplication is present, AICA passes through the bundles. Furthermore, the incidence of a

bilaterally duplicated nerve has been reported as frequently as 8 % of the time (Nathan et al. 1974 ; Ozverenet al. 2003 ) . The abducens nerve can pass above the Gruber’s ligament in 12 % of cases (Lang 1995 ) .

Endoscopic vision of the cavernous sinus. Vision obtained through a right supraorbitalapproach with a 30° down-facing lens focusing on the cavernous sinus

ICAc cavernous portion of the internal carotid artery, lwCS lateral wall of the cavernous sinus, SCA superior cerebellar artery, IIIcn oculomotor nerve, IVcn trochlear nerve, Vcn root of the trigeminal nerve,

VIcn abducens nerve, blue arrow Gruber’s ligament, white asterisk Dorello’s canal.

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

http://www.slideshare.net/INUB/endoscopic-anatomy-and-approaches-of-the-cavernous-sinus-cadaver-study- Endoscopic view of the right cavernous sinus and its

neurovascular relations, demonstrating the triangular area formed by the medial pterygoid process laterally, the parasellar ICA medially and the vidian nerve inferiorly

at the base. 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

http://www.slideshare.net/INUB/endoscopic-anatomy-and-approaches-of-the-cavernous-sinus-cadaver-study -Endoscopic view of the right cavernous sinus showing its neurovascular

relations and the main anatomic areas. III 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, STA superior triangular area, SQA

superior quadrangular area, IQA inferior quadrangular area

1.Supra Trochanteric & Infratrochanteric Triangles2. Upper & lower dural rings

C2 , C3 , C4 – QS is wrongly mentioned here . QS in below photo is actually antero-medial triangle

QS = Quadrangular space

Quadrangular space

http://www.slideshare.net/INUB/endoscopic-anatomy-and-approaches-of-the-cavernous-sinus-cadaver-study - Endoscopic view (a), and a drawing (b) of the right cavernous sinus demonstrating its neurovascular relations. c A drawing of the right cavernous sinus demonstrating the exposure of the trochlear nerve after retracting

the oculomotor nerve. III oculomotor nerve, IV trochlear nerve, V1 ophthalmic nerve, VI abducens nerve, ICA internal carotid artery, OA ophthalmic artery, OCh optic

chiasm, ON optic nerve, PG pituitary gland

L-OCR – Triangle 1. Upper boarder – Optic nerve & Opthalmic artery

2. Posterior boarder – Clinoidal carotid 3. Lower boarder – 3rd N. [ COM – Carotico-Occulomotor

membrane seperates 3rd N from Clinoidal carotid ] [ 6th N. & 4th N. & V1 present inferior to 3rd N. ]

Cutting the maxillary nerve to gain access to the lateral wallof the cavernous sinus in infratemporal fossa approach type C – ITFA-C

Cutting the maxillary nerve to gain access to the lateral wall of the cavernous sinus.

The abducent nerve (VI) crosses from the medial to the lateral aspect of the internal carotid artery (ICA) before entering thecavernous sinus.

V2 also included in the cavernous sinus or not – find

CS virtual compartments

CS divided into four virtual compartments: 1. medial, 2. lateral,

3. posterosuperior, and4. anteroinferior

Right cavernous sinus dissection. The quadrilateral delimits the right cavernous sinus area.a Before periosteal layer removal. b After periosteal layer removal. c Cavernous sinus

compartments.L = Lateral; AI = antero- inferior; PS = posterosuperior compartment of the cavernous sinus (the

medial is a virtual space in continuity with the AI and PS).

Medial and posterosuperior compartments are in strict continuity and do not contain nerves, representing a surgical corridor without risk of neural damage. The anteroinferior and lateral

compartments contain the abducens nerve and, as surgical corridors, they are exposed to the risk of injury to the VIth nerve.

Medial compartment

Medial compartment - By opening the dura of the medial wall of the cavernous sinus, the

space between the internal carotid artery and the PG is exposed. In this space, the MHT is usually evident.

BCA Bernasconi-Cassinari artery, CF cavernous fat, CR clival recess, DMA dorsal meningeal artery, GR gyrus rectus, ICAc cavernous portion of the internal carotid artery, IHA inferior

hypophyseal artery, MHT meningohypophyseal trunk,PG pituitary gland

DMA dorsal meningeal artery, ICAc cavernous portion of internal carotid artery, IHA inferiorhypophyseal artery, MHT meningohypophyseal trunk, PCFd dura and periosteum of the

posterior cranial fossa, PG pituitary gland, VIcn abducens nerve

The MHT is traditionally described as having three branches: the inferior hypophyseal artery, thedorsal meningeal artery (also called the dorsal clival artery), and the tentorial artery (also called theBernasconi-Cassinari artery). The DMA is in close relationship with the abducens nerve at the levelof petrous apex (Cavallo et al. 2011 ) . The DMA is the main feeder of the Dorello’s segment of VIcn

(Martins et al. 2011 ) .

?McConnell’s artery [ Rhoton 2002] / MHT

ACP anterior clinoid process, BCA Bernasconi-Cassinari artery, DMA dorsal meningeal artery, DS dorsum sellae, FO foramen ovale, FR foramen rotundum, ICAc cavernous portion of the internal carotid artery, ICAh horizontal portion of the internal carotid artery, IHA inferior hypophyseal artery, MHT meningohypophyseal trunk, OA ophthalmic artery, PS

planum sphenoiodale, TS tuberculum sellae, white arrow MHT, red asterisk lingula of the sphenoid The MHT is present in most cases. Not in all cases does it give off all the typical braches: dorsal meningeal artery (or

dorsal clival artery), tentorial artery (or Bernasconi-Cassinari artery), and the inferior hypophyseal arteries. In about half of the cases, some branches arise directly from the ICAc (Jittapiromsak et al. 2010 ) . The tentorial artery is the main feeder of the oculomotor nerve (d’Avella et al. 2008 ) , and usually it is located on the inferior surface of the nerve.

Moreover, it can be the feeder of the distal part of the trochlear nerve; in these cases, the vessel runs in close proximity of this nerve to the superior orbital fi ssure. Other authors show that BCA feeds cranial nerve IV along its course within

the tentorium cerebelli (Martins et al. 2011 ) .

Posterosuperior compartment

Posterosuperior compartment –Oculomotor triangle is seen – 3rd N. , 4th N. & Pcom

seen.

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.

Antero-inferior compartment

Antero-inferior compartment 1. The abducens nerve and the sympathetic plexus around the intracavernous carotid artery are

the only nerves which have a real intracavernous course.2. The anteroinferior and lateral compartments contain the abducens nerve and, as surgical

corridors, they are exposed to the risk of injury to the VIth nerve.

BS basisphenoid, CS cavernous sinus, CSd dura of the cavernous sinus, ET eustachian tube, ICAc cavernous portion of the internal carotid artery, ICAh horizontal portion of the internal carotid artery, ICAp parapharyngeal portion of the internal carotid artery, ILT inferolateral

trunk, LVPM levator veli palatini muscle, MHT meningohypophyseal trunk, PAp petrous apex, PCFd posterior cranial fossa dura and periosteum, PG pituitary gland, TVPM tensor veli palatini muscle, VN vidian nerve, IIIcn oculomotor nerve, IVcn trochlear nerve, V1 fi rstbranch of the trigeminal nerve, V2 second branch of the trigeminal nerve, V3 third branch of the trigeminal nerve, VIcn abducens nerve,

XIIcn hypoglossal nerve, white asterisks sympathetic fi bresconnecting the VIcn

In rare situation we have to anticipate OA in Antero-inferior & Lateral compartments of CS . Opthalmic artery – Retrograde branch of

Intracranial carotid

Branches of the cavernous internalcarotid artery ( ICA ), a rare variation: ophthalmicartery passing through the superiororbital fissure

Normal OA above upper duralring

Between VN & V2

• 1. lateral recess of sphenoid

• 2. petrous apex

VI nerve is parallel & medial to V1 – in the same direction of V1 [ Mneumonic – VI & V1 in same

direction ]

Lateral compartment

Lateral compartment ACP anterior clinoid process, ChS chiasmatic sulcus, DS dorsum sellae, FO foramen ovale, ICAc cavernous

portion of the internal carotid artery, ICAh horizontal portion of the internal carotid artery, ILT inferolateraltrunk, MHT meningohypophyseal trunk, OS optic strut, PCP posterior clinoid process, PF pituitary fossa, PG

pituitary gland, TS tuberculum sellae, VIcn abducens nerve, white arrow s branches of the ILT

The ILT is present in most cases (Krisht et al. 1994 ; Tran-Dinh 1987 ) . It may arise as a common trunk with the MHT (Reisch et al. 2002 ) . It is a single trunk in most cases. More often, it arises from the lateral aspect of the horizontal segment of the ICAc, and in most cases it passes superiorly to the abducens nerve (Inoue et al. 1990

; Jittapiromsak et al. 2010 ) . It usually gives rise to 3 or 4 branches supplying the dura and the cranial nerves within the cavernous sinus (Lasjaunias et al. 1977 ; Tran - Dinh 1987 ) . The main trunk of the ILT with small

secondary branches is the feeder of the ophthalmic nerve (V1). Usually, these vessels reach the inferior surface of the nerve. Obviously, the ILT also supplies the abducens nerve with several small branches.

In rare situation we have to anticipate OA in Antero-inferior & Lateral compartments of CS . Opthalmic artery – Retrograde branch of

Intracranial carotid

Branches of the cavernous internalcarotid artery ( ICA ), a rare variation: ophthalmicartery passing through the superiororbital fissure

Normal OA above upper duralring

Sympathetic fibres

Sympathetic fibresWithin the CS, the sympathetic fi bres are observed mainly in the anterior part of the artery, and usually they are placed inferiorly. Most of these fi bres run together with V1 (Jittapiromsak et al.

2010 ) . The sympathetic fi bres diverge from the ICAc to adhere to the abducens nerve while crossing to join the ophthalmic nerve (V1). The main target exit is V1 on the lateral wall of the CS (Jittapiromsak et al. 2010 ) . Within the CS, the abducens nerve typically courses medially to the

V1 before it exits through the superior orbital fissure.

ICAc cavernous portion of the internal carotid artery, lwCS lateral wall of the CS, SF sympathetic fi ber, IIIcn oculomotor nerve, IVcn trochlear nerve, VIcn abducens nerve, white asterisks branches of the

inferolateral trunkThe largest sympathetic fi ber runs close (within 8 mm) to the ILT, posteroinferiorly and medially located

to it (Zhang et al. 2012 ) . After crossing the superior petrosal sinus the trochlear nerve can pierce the roof of the cavernous sinus and runs through its lateral wall. The trochlear nerve, within the cavernous sinus, passes upward the oculomotor nerve (more or less at the level of the optic strut) and becomes the most

superior structure of the CS (Iaconetta et al. 2012). Within the CS course the trochlear nerve is surrounded by an arachnoidal sheath (Lang 1995 ) and it is always superior to V1.

Carotid

1. Paraclival carotid

2. Parasellar carotid

Paraclival carotid

1. caudal part, the lacerumsegment 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 Gasserianganglion is posterior to it and the trigeminal divisions are lateral to it.

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 ApproachCarotid-Clival window – Mid clivus

a. Petrosal faceb.Clival face

Upper half of paraclival carotid – rostral part, the trigeminalsegment of the paraclival carotid

TG ( Trigeminal ganglion ) is lateral to upper half [ rostral part ] of Paraclival carotid

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.

Parasellar carotid

• It covers four segments of the ICA:

1. the hidden segment = Posterior Genu–most common injure area .

2. the inferior horizontal segment – The inferior

horizontal segment appears short due to the perspective view, but is the longest segment of the intracavernous ICA.

3. the anterior vertical segment, and

4. the superior horizontal segment ( = Clinioidal segment )

Diameter of parasellar carotid is more than intracerebral carotid – Prof. Gardner

Add intracerebral carotid photo

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

Triangles of cavernous sinus

10 Triangles = 4 Cavernous Sinus Triangles + 6 Middle Fossa Triangles

4 Cavernous Sinus Triangles1. Clinoidal (Anteromedial) Triangle2. Oculomotor (Medial or Hakuba's) Triangle3. Supratrochlear (Paramedian) Triangle4. Parkinson's (Infratrochlear) Triangle

6 Middle Fossa Triangles1. Anteromedial (Mullan's) Triangle 2. Anterolateral Triangle3. Posterolateral (Glasscock's) Triangle4. Posteromedial (Kawase's) Triangle5. Inferolateral Triangle6. Inferomedial Triangle

Cavernous Sinus Triangles

1. Clinoidal (Anteromedial) Triangle· Borders:1. Optic Nerve2. Occulomotor Nerve3. Tentorial Edge· Contents:1. Anterior Clinoid Process2. Clinoidal ICA

2. Oculomotor (Medial or Hakuba's) Triangle· Borders:1. Anterior petroclinoid dural fold.2. Posterior petroclinoid dural fold.3. Interclinoid dural fold.· Contents:1. Occulomotor Nerve2. Horizontal Segment of ICA

Cavernous Sinus Triangles

3. Supratrochlear (Paramedian) Triangle· Borders:1. Occulomotor Nerve2. Trochlear Nerve3. Tentorial Edge· Contents:1. Meningohypophyseal Trunk

4. Parkinson's (Infratrochlear) Triangle· Borders:1. Trochelar NerveMiddle_fossa_trianglesClinoidal (Anteromedial) Triangle 2

2. Opthalmic Division (V1)3. Tentorial Edge· Contents:1. Cavernous ICA2. Abducens Nerve

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