Cavernous Sinus Anatomy/Skull Base - ENC

Question 1

What are the borders of the cavernous sinus?

Answer 1

1. Anterior: superior orbital fissure.
2. Medial: sella and both clinoids.
3. Posterior: petroclival ligament/tentorium.
4. Posteromedial: clivus.
5. Inferolateral: funnel-shaped area around foramen lacerum.

Question 2

Which two cranial nerves enter the cavernous sinus superiorly?

Answer 2

1. CNs III and IV.

Question 3

What is the entry point into the cavernous sinus for CN VI called?

Answer 3

1. Dorello’s canal (limited superiorly by the petroclival ligament and the petrous apex inferiorly).

Question 4

Which 3 cranial nerves pierce the cavernous sinus posterioinferiorly?

Answer 4

1. CNs VI, V1, V2.

Question 5

How many triangles are there in the roof of the cavernous sinus?

Answer 5

1. Two - clinoidal and oculomotor.

Question 6

How many triangles are there in the lateral wall of the cavernous sinus?

Answer 6

1. Two - supratrochlear and infratrochlear.

Question 7

What are the limits of the anteromedial (clinoidal) triangle?

Answer 7

1. Medial border: optic nerve.
2. Lateral border: oculomotor nerve.
3. Posterior border: dura between both, which relates to the distal dural ring of the ICA.

Question 8

What structure needs to be drilled to access the clinoidal triangle?

Answer 8

1. Anterior clinoid.

Question 9

What are the contents of the clinoidal triangle?

Answer 9

1. Anterior loop and horizontal segment of the parasellar ICA.
2. Venous trabeculae.
3. Fibrous tissue related to the proximal ring of the carotid artery.

Question 10

What are the limits of the oculomotor triangle?

Answer 10

1. Medial border: interclinoidal dural fold.
2. Posteromedial border: posterior petroclival ligament.
3. Anteromedial border: anterior petroclival ligament.

Question 11

What are the limits of the supratrochlear (paramedian) triangle?

Answer 11

1. Superior: CN III.
2. Inferior: CN IV.
3. Posterior: dura between both.

Question 12

What can you access via the supratrochlear triangle?

Answer 12

1. The medial loop of the cavernous ICA and part of the meningohypophyseal trunk.

Question 13

What are the limits of the infratrochlear triangle (Parkinson’s)?

Answer 13

1. Medial: lateral border of IV.
2. Lateral : medial border of V1.
3. Posterior: dura between entry point of both IV and V1.

Question 14

What are the limits of the anteromedial triangle?

Answer 14

1. V1 and V2.

Question 15

What are the limits of the anterolateral triangle?

Answer 15

1 V2 and V3.

Question 16

What two nerves delineate the limits of the posterolateral (Glasscocks) triangle?

Answer 16

1. GSPN and V3.

Question 17

What artery is included in the floor of Glasscock’s triangle?

Answer 17

1. MMA.

Question 18

What area do you access if you drill through the floor of Glasscock’s triangle?

Answer 18

1. Infratemporal fossa.

Question 19

What are the limits of Kawase’s triangle?

Answer 19

1. Posterior aspect of V3 and greater petrosal nerve.

Question 20

What structures can be accessed via Kawase’s triangle?

Answer 20

1. Cochlea and petrous carotid.

Question 21

What are the limits of the inferolateral triangle?

Answer 21

1. Superolateral: CN IV.
2. Inferomedial: CN VI.
3. Apex: junction between superior petrosal sinus and a vein just lateral to the porus trigeminus.

Question 22

What structure is in the center of the inferolateral triangle?

Answer 22

1. The porus trigeminus.

Question 23

What are the limits of the inferomedial triangle?

Answer 23

1. Superolateral: CN IV.
2. Inferomedial: CN VI.
3. Superomedial: posterior clinoid process.

Question 24

What can be accessed through the inferomedial triangle?

Answer 24

1. CN VI entering Dorello’s canal underneath the petroclival ligament.