open access

Vol 74, No 2 (2015)
ORIGINAL ARTICLES
Published online: 2015-05-28
Submitted: 2014-09-14
Accepted: 2014-10-07
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The abducens nerve: its topography and anatomical variations in intracranial course with clinical commentary

G. Wysiadecki, S. Orkisz, M. Gałązkiewicz-Stolarczyk, P. Brzeziński, M. Polguj, M. Topol
DOI: 10.5603/FM.2015.0037
·
Pubmed: 26050813
·
Folia Morphol 2015;74(2):236-244.

open access

Vol 74, No 2 (2015)
ORIGINAL ARTICLES
Published online: 2015-05-28
Submitted: 2014-09-14
Accepted: 2014-10-07

Abstract

Background: The sixth cranial nerve (CN VI) — or the abducens nerve — in humans supplies only the lateral rectus muscle. Due to its topographic conditions, including angulations and fixation points along its course from the brainstem to the lateral rectus muscle, the CN VI is vulnerable to injury. Every case of CN VI palsy requires precise diagnostics, which is facilitated by an understanding of the anatomy. The present article’s aims include a detailed study of the intracranial course of the CN VI, determination of occurrence of its particular anatomical variations, as well as presentation of some essential anatomical conditions which may conduce to CN VI palsy. Special emphasis was put on the correlation between craniometric measurements and a particular variation of the CN VI, which complements the data that can be found in literature.

Materials and methods: Twenty randomly selected specimens of cadaveric heads fixed in a 10% formalin solution were studied. The study used 40 specimens of the CN VI in order to examine its course variations within the section between the pontomedullary sulcus and the superior orbital fissure.

Results: Detailed analysis of the CN VI topography and anatomy in its intracranial course revealed 3 anatomical variations of the nerve in the studied specimens. Variation I, found in 70% of cases, covers those cases in which the CN VI was found to be a single trunk. Those cases in which there was a branching of the CN VI exclusively inside the cavernous sinus were classified as variation II, occurring in 20% of cases. Cases of duplication of the CN VI were classified as variation III, found in 10% of the specimens. In 75% of cases of CN VI duplication one of the nerve trunks ran upwards from the petrosphenoidal ligament, outside Dorello’s canal.

Conclusions: The CN VI throughout its intracranial course usually runs as a single trunk, however, common variations include also branching of the nerve in the cavernous sinus or duplication. Topographic relations of the CN VI with adjacent structures account for the risk of injuries which may be caused to the nerve as a result of a disease or surgical procedures.  

Abstract

Background: The sixth cranial nerve (CN VI) — or the abducens nerve — in humans supplies only the lateral rectus muscle. Due to its topographic conditions, including angulations and fixation points along its course from the brainstem to the lateral rectus muscle, the CN VI is vulnerable to injury. Every case of CN VI palsy requires precise diagnostics, which is facilitated by an understanding of the anatomy. The present article’s aims include a detailed study of the intracranial course of the CN VI, determination of occurrence of its particular anatomical variations, as well as presentation of some essential anatomical conditions which may conduce to CN VI palsy. Special emphasis was put on the correlation between craniometric measurements and a particular variation of the CN VI, which complements the data that can be found in literature.

Materials and methods: Twenty randomly selected specimens of cadaveric heads fixed in a 10% formalin solution were studied. The study used 40 specimens of the CN VI in order to examine its course variations within the section between the pontomedullary sulcus and the superior orbital fissure.

Results: Detailed analysis of the CN VI topography and anatomy in its intracranial course revealed 3 anatomical variations of the nerve in the studied specimens. Variation I, found in 70% of cases, covers those cases in which the CN VI was found to be a single trunk. Those cases in which there was a branching of the CN VI exclusively inside the cavernous sinus were classified as variation II, occurring in 20% of cases. Cases of duplication of the CN VI were classified as variation III, found in 10% of the specimens. In 75% of cases of CN VI duplication one of the nerve trunks ran upwards from the petrosphenoidal ligament, outside Dorello’s canal.

Conclusions: The CN VI throughout its intracranial course usually runs as a single trunk, however, common variations include also branching of the nerve in the cavernous sinus or duplication. Topographic relations of the CN VI with adjacent structures account for the risk of injuries which may be caused to the nerve as a result of a disease or surgical procedures.  

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Keywords

abducens nerve palsy, cavernous sinus, duplicated abducens nerve, petrosphenoidal (Gruber’s) ligament, petroclival region, posterior clinoid process

About this article
Title

The abducens nerve: its topography and anatomical variations in intracranial course with clinical commentary

Journal

Folia Morphologica

Issue

Vol 74, No 2 (2015)

Pages

236-244

Published online

2015-05-28

DOI

10.5603/FM.2015.0037

Pubmed

26050813

Bibliographic record

Folia Morphol 2015;74(2):236-244.

Keywords

abducens nerve palsy
cavernous sinus
duplicated abducens nerve
petrosphenoidal (Gruber’s) ligament
petroclival region
posterior clinoid process

Authors

G. Wysiadecki
S. Orkisz
M. Gałązkiewicz-Stolarczyk
P. Brzeziński
M. Polguj
M. Topol

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