What structures are found in Dorello's canal?

Structures in Dorello's Canal

Dorello's canal contains the abducens nerve (cranial nerve VI) and the inferior petrosal sinus, enclosed within a rigid osteofibrous tunnel at the petrous apex. 1, 2

Anatomical Components

• Dorello's canal is a narrow osteofibrous channel located near the apex of the petrous bone 1
• The canal forms a "tube within a tube" structure, with the inner tube exclusively containing the abducens nerve, creating a rigid fixation that prevents nerve movement 2
• The abducens nerve (CN VI) passes through this canal before entering the cavernous sinus 1, 3
• The inferior petrosal sinus surrounds the nerve within the canal, creating a venous confluence between the dural leaves of the petroclival area 3
• The petrosphenoidal ligament (also called Gruber's ligament) forms the posteromedial wall of the canal and appears as a fibrous trabecula surrounded by venous blood 3

Clinical Significance

• The rigid tethering of the abducens nerve within Dorello's canal makes it particularly vulnerable to compression and injury 1, 2
• The canal's anatomy explains the high incidence of abducens nerve palsy following head trauma, as the nerve cannot move with brainstem motion due to its fixed position 2
• Compression of structures within Dorello's canal can cause abducent nerve palsy, which may present as diplopia (double vision) due to lateral rectus muscle weakness 4
• The canal is a key landmark in skull base surgery of the petroclival region 1
• Pathologies affecting this region, such as meningiomas at the entrance of Dorello's canal, can cause compression of the abducens nerve resulting in CN VI palsy 4

Anatomical Relationships

• Dorello's canal is located between the petrous apex and the clivus 1, 3
• The canal has a bow-shaped configuration 3
• The abducens nerve shows variable degrees of angulation in its course inside and outside the canal, contributing to its vulnerability 3
• The canal is in close proximity to the cavernous sinus, which the abducens nerve enters after traversing the canal 1, 3
• The trigeminal ganglion and posterior clinoid process are important neighboring structures to Dorello's canal 5

Historical Context

• The canal was first described by Austrian anatomist Wenzel Leopold Gruber in 1859 1
• It was later studied in detail by Italian anatomist Primo Dorello, after whom the canal is named 1
• Harris Holmes Vail, an otolaryngologist from Harvard Medical School, was the first to describe Dorello's canal in English literature in 1922, immortalizing the eponym "Dorello's canal" 1