Cavernous sinus (mnemonic)

The structures inside and beside the cavernous sinus and their relative position can be recalled with the following mnemonic:

• O TOM CAT

Consider a coronal view of the cavernous sinus.

'O TOM' are the first letters of components of lateral wall of cavernous sinus considered vertically, from the top to the bottom. CA are the first letters of the structures located within the sinus. CA continues virtually at the level of the T of 'O TOM'. So that the T represents the point of conjunction of the two words. See below for further illustration:

              O                   O
              T A C           C A T
              O                   O
              M                   M

Mnemonics

O TOM CAT

• O - oculomotor nerve

• T - trochlear nerve
• O - opthalmic branch of trigeminal nerve
• M - maxillary branch of trigeminal nerve

• C - internal carotid artery
• A - abducent nerve
• T - trochlear nerve

Remember two things:

1. the mandibular branch of trigeminal nerve is not associated with the cavernous sinus since it has descended vertically through the foramen ovale underneath the trigeminal ganglion (Gasser ganglion), which is anatomically posteriorly to the cavernous sinus
2. the two branches, opthalmic and maxillary of trigeminal nerve are located externally to the wall of the cavernous sinus, which becomes important in the differential diagnosis of lesions of the cavernous sinus - lesions of these nerves tend to distort the sinus rather than occupy it