Skull Base Triangles

Structures in relation w/ CS

CN2 optic → Optic canal
CN3 Oculomotor → SOF
CN4 Trochlear → SOF
CN5
- V1 → SOF
- V2 → f. rotundum
- V3 → f. ovale
CN6 Abducens → dural reflections
Greater petrosal nerve → dural reflections

Ant. Clinoid proc.
Pos. Clinoid proc.
Petrous apex

Three triangles groups:

Medial group
Posterior group
Lateral group

Medial group:

Supero-posterior △ (oculomotor △)
Superior △ (clinoidal/Dolenc's △)
Middle △ (supratrochlear/paramedian △)
Inferior △ (infratrochlear/Parkinson's △)

Posterior group (paraclival △'s):

Medial △ (inferomedial △)
Lateral △ (inferolateral △)

Lateral group:

Anteromedial △ (Mullan's △)
Anterolateral △
Posteromedial △ (Kawase's △)
Posterolateral △ (Glasscock's △)

Medial group

Supero-posterior △ (oculomotor △)

Vertex of the △

ant. clinoid proc.
pos. clinoid proc.
Petrous apex

Borders

(lat. border) Ant. petroclinoid dural fold - b/w ant. clinoid proc. & petrous apex
(base) Pos. petroclinoid dural fold - b/w pos. clinoid proc. & petrous apex
(med. border) Interclinoid dural fold - b/w ant. & pos. clinoid proc.

Content of the △

Oculomotor Nerve
ICA horizontal segment
Interpeduncular fossa

Superior △ (clinoidal/Dolenc's △)

Borders

(med. border) CN2 optic
(lat. border) CN3 oculomotor (b/f entering SOF)
(base) Tentorial edge - b/w entries of CN2 & CN3

Content of the △

Oculomotor Nerve
ICA clinoidal segment

Middle △ (supratrochlear/paramedian △)

Borders

(med. border) CN3 oculomotor
(lat. border) CN4 trochlear
(inf. border) tentorial edge b/w dural entries of CN3 & CN4

Content of the △

Inferior △ (infratrochlear/Parkinson's △)

Borders

(med. border) CN4 trochlear
(lat. border) V1 ophthalmic n.
(base) tentorial edge b/w CN4 & V1

Content of the △

ICA (cavernous)
CN6 abducens
Origin of MHT

Lateral group

Anteromedial △ (Mullan's △)

Borders

(sup. border) V1 ophthalmic n.
(inf. border) V2 maxillary n.
(base) line b/w SOF & f. rotundum

Content of the △

SOF artery
Sphenoid sinus

Anterolateral △

Borders

(sup. border) V1 ophthalmic n.
(inf. border) V2 maxillary n.
(base) line b/w f. rotundum & f. ovale

Content of the △

lat. wing of sphenoid sinus
Vidian n.
pterygoid region

Posterolateral △ (Glasscock's △)

Vertex of the △

f. ovale
hiatus of GSPN
cross b/w V3 mandibular n. & GSPN (f. spinosum)

Borders

(ant. border) V3 mandibular n.
(med. border) GSPN
(lat. border) Line b/w f. ovale & hiatus of GSPN

Content of the △

pos. & lat. ICA loops
GSPN & LSPN
tensor tympani mus.
MMA
infratemporal fossa

Posteromedial △ (Kawase's △)

Vertex of the △

CN5 ganglion/petrus apex
hiatus of GSPN (arcuate Eminence)
cross b/w V3 mandibular n. & GSPN (f. spinosum)

Borders

(lat. border) GSPN
(base) line b/w hiatus of GSPN & petrous apex
(med. border) line b/w f. spinosum & GG (petrous ridge)

Content of the △

pos. CS
cochlea
IAC
clivus & IPS

Use

pos. fossa entry point (ant. petrosectomy)

Posterior group (paraclival △'s)

Lateral △ (inferolateral △)

Vertex of the △

dural entry of CN4 trochlear (incisura into lat. wall of CS)
dural entry of CN6 abducens (Dorello’s canal)
petrous apex

Borders

(pos. border) line b/w dural entery of CN6 abducens (Dorello’s canal) & sup. petrosal vein (⟹ SPS)
(ant. border) line b/w dural entrance CN4 trochlear & CN6 abducens (Dorello’s canal)
(sup. border) line b/w dural entry of CN4 trochlear & sup. petrosal vein (⟹ SPS)

Content of the △

Porus trigemini (the Meckel’s cave)

Medial △ (inferomedial △)

Vertex of the △

dural entry of CN4 trochlear (incisura into lat. wall of CS)
dural entry of CN6 abducens (Dorello’s canal)
pos. clinoid proc.

Content of the △

Dorello’s canal
Gruber’s lig.
Porus trigemini (Meckel’s cave)
intracavernous ICA

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