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Published on: June 2, 2018
Variations in the number of rootlets of the trochlear nerve
Kacper Bąk1, Michał Mordarski1, Tomasz Iskra1
1Department of Anatomy, Jagiellonian University Medical College, Kraków, Poland.
Background:
The trochlear nerve is the fourth cranial nerve with the thinnest and the longest intracranial course of them all. The trochlear nerve is the only cranial nerve that originates from the dorsal part of the midbrain and innervates the contralateral superior oblique muscle. The number of its rootlets can vary, ranging from 1 to 6.
Material And Methods:
In this study of body donors, we dissected and examined 87 trochlear nerves from 44 body donors to determine the number of rootlets. Our results were then combined with data from previously published studies on the same topic.
Results:
Of the 87 nerves analyzed, one rootlet was found 26 times, two rootlets 43 times, three rootlets 13 times and four rootlets 5 times. After combining our results with other articles, the total number of specimens analyzed reached 663, with the following distribution: one rootlet - 35.90 %; two rootlets - 47.21 %; three rootlets - 12.82 %; four rootlets - 3.17 %; five rootlets - 0.75 %; six rootlets - 0.15 %. The longest rootlet was found in the three-rootlet pattern and measured 9.36 mm (SD = 0.22 mm).
Conclusion:
Knowledge of the anatomy of the trochlear nerve and its rootlets plays a decisive role in complex microsurgical and endoscopic transcranial or endonasal procedures in the area of the supracerebellar region and middle cranial fossa.
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