open access

Vol 82, No 3 (2023)
Original article
Submitted: 2022-05-18
Accepted: 2022-06-02
Published online: 2022-06-10
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Microanatomy of the central myelin portion and transitional zone of the oculomotor and abducens nerves

W. Quanchareonsap1, S. Jariyakosol2, S. Apinyawasisuk2, A. Roumwong1, V. Chentanez1
·
Pubmed: 35692113
·
Folia Morphol 2023;82(3):543-550.
Affiliations
  1. Department of Anatomy, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand
  2. Department of Ophthalmology, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand

open access

Vol 82, No 3 (2023)
ORIGINAL ARTICLES
Submitted: 2022-05-18
Accepted: 2022-06-02
Published online: 2022-06-10

Abstract

Background: The microanatomy of the central myelin portion and transitional
zone of several cranial nerves including trigeminal, facial, vestibulocochlear,
glossopharyngeal, and vagus nerves have been clearly demonstrated to provide
information for neurovascular compression syndrome such as trigeminal neuralgia
and hemifacial spasm. However, the study of oculomotor and abducens nerve
is limited.
Materials and methods: Oculomotor and abducens nerves were harvested with
a portion of brainstem and embedded in paraffin. Longitudinal and serial sections
from ten of each cranial nerve were stained and a photomicrograph was taken
to make the following observations and measurements: 1) patterns of central
myelin portion, 2) length of central myelin portion, and 3) depth of central myelin-
peripheral myelin transitional zone.
Results: For oculomotor nerve, the longest central myelin bundle was always
seen on the first nerve bundle and that the length of central myelin decreased
gradually. For abducens nerve, morphological patterns were classified into four
types based on number of nerve rootlets emerging from the brainstem and number
of nerve bundles in each rootlet. Length of central myelin portion was between
0.36–6.10 mm (2.75 ± 0.83 mm) and 0.13–5.01 mm (1.66 ± 1.39 mm) for
oculomotor and abducens nerves, respectively. The oculomotor nerve transitional
zone depth was 0.07–058 mm (0.23 ± 0.07 mm), while for abducens nerve,
depth was 0.05–0.40 mm (0.16 ± 0.07 mm). Positive weak correlations between
central myelin and depth of TZ were found in oculomotor nerve (r +0.310,
p < 0.05) and abducens nerves (r +0.413, p < 0.05).
Conclusions: Detailed microanatomy of the central myelin and transitional zone
might be beneficial for locating the site of compression in neurovascular conflicts
at oculomotor and abducens nerves.

Abstract

Background: The microanatomy of the central myelin portion and transitional
zone of several cranial nerves including trigeminal, facial, vestibulocochlear,
glossopharyngeal, and vagus nerves have been clearly demonstrated to provide
information for neurovascular compression syndrome such as trigeminal neuralgia
and hemifacial spasm. However, the study of oculomotor and abducens nerve
is limited.
Materials and methods: Oculomotor and abducens nerves were harvested with
a portion of brainstem and embedded in paraffin. Longitudinal and serial sections
from ten of each cranial nerve were stained and a photomicrograph was taken
to make the following observations and measurements: 1) patterns of central
myelin portion, 2) length of central myelin portion, and 3) depth of central myelin-
peripheral myelin transitional zone.
Results: For oculomotor nerve, the longest central myelin bundle was always
seen on the first nerve bundle and that the length of central myelin decreased
gradually. For abducens nerve, morphological patterns were classified into four
types based on number of nerve rootlets emerging from the brainstem and number
of nerve bundles in each rootlet. Length of central myelin portion was between
0.36–6.10 mm (2.75 ± 0.83 mm) and 0.13–5.01 mm (1.66 ± 1.39 mm) for
oculomotor and abducens nerves, respectively. The oculomotor nerve transitional
zone depth was 0.07–058 mm (0.23 ± 0.07 mm), while for abducens nerve,
depth was 0.05–0.40 mm (0.16 ± 0.07 mm). Positive weak correlations between
central myelin and depth of TZ were found in oculomotor nerve (r +0.310,
p < 0.05) and abducens nerves (r +0.413, p < 0.05).
Conclusions: Detailed microanatomy of the central myelin and transitional zone
might be beneficial for locating the site of compression in neurovascular conflicts
at oculomotor and abducens nerves.

Get Citation

Keywords

abducens nerve, central myelin, oculomotor nerve, transitional zone, nerve compression syndrome

About this article
Title

Microanatomy of the central myelin portion and transitional zone of the oculomotor and abducens nerves

Journal

Folia Morphologica

Issue

Vol 82, No 3 (2023)

Article type

Original article

Pages

543-550

Published online

2022-06-10

Page views

1065

Article views/downloads

688

DOI

10.5603/FM.a2022.0057

Pubmed

35692113

Bibliographic record

Folia Morphol 2023;82(3):543-550.

Keywords

abducens nerve
central myelin
oculomotor nerve
transitional zone
nerve compression syndrome

Authors

W. Quanchareonsap
S. Jariyakosol
S. Apinyawasisuk
A. Roumwong
V. Chentanez

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