Department of Normal and Clinical Anatomy, Chair of Anatomy and Histology, Medical University of Lodz, Poland.
Folia Morphol (Warsz). 2021;80(1):63-69. doi: 10.5603/FM.a2020.0017. Epub 2020 Feb 19.
This study aims to revisit the anatomy of orbital segment of the third cranial nerve (CN III). The study also involved morphometric measurements of CN III muscular branches. Detailed description of observed anatomical variations and their incidence was also included. The study supplements earlier findings with detailed observations of the neuromuscular relations.
The study was conducted on 52 orbits taken from 26 cadaveric heads (10 males and 16 females; Central European population).
Anatomical variations of the orbital segment of the CN III observed on the examined material involved both the superior and inferior branch of this nerve. The muscular branch innervating the levator palpebrae superioris muscle occasionally pierces the superior rectus muscle. The nerve to the inferior oblique muscle may pierce and innervate the inferior rectus muscle. In rare instances, duplication of the parasympathetic root of the ciliary ganglion may also occur. Among the muscular branches, the smallest diameter reached the branch to the levator palpebrae superioris muscle. Among the three muscular branches derived from the inferior branch of the CN III, the nerve to the inferior oblique was the longest one. Its length varied from 28.9 mm to 37.4 mm. The shortest was the muscular branch to the inferior rectus muscle. Its length varied from 0 mm (when muscular sub-branches arose directly from the nerve to the inferior oblique muscle) to 7.58 mm.
This study presented the characteristic of orbital segment of the CN III, including anatomical variations and morphometric measurements relevant to intraorbital procedures.
本研究旨在重新审视第三颅神经（CN III）的眶段解剖结构。该研究还涉及 CN III 肌支的形态测量。还包括观察到的解剖变异及其发生率的详细描述。该研究通过对神经肌肉关系的详细观察，补充了早期的发现。
本研究在 26 个头骨（10 名男性和 16 名女性；中欧人群）的 52 个眼眶上进行。
在所检查的材料上观察到的 CN III 眶段解剖变异涉及该神经的上支和下支。支配上睑提肌的肌支偶尔穿过上直肌。支配下斜肌的神经可能穿过并支配下直肌。在极少数情况下，睫状神经节副交感根也可能发生重复。在肌支中，直径最小的到达上睑提肌支。在 CN III 下支分出的三个肌支中，支配下斜肌的神经最长。其长度从 28.9 毫米到 37.4 毫米不等。最短的是支配下直肌的肌支。其长度从 0 毫米（当肌支从小支直接从下斜肌神经分出时）到 7.58 毫米不等。
本研究介绍了 CN III 的眶段特征，包括与眶内手术相关的解剖变异和形态测量。
