BACKGROUND The levator palpebrae superioris muscle (LPS) acts as the upper eyelid's major elevator and retractor and is innervated by the oculomotor nerve. The muscle's paralysis is manifested by ptosis. MATERIAL AND METHODS 70 orbits were dissected. After removing the orbital roof, the LPS' shape and anatomical variations (i.e., the presence of accessory muscular bands or atypical formation of the muscle) were assessed. To visualize the distribution of the oculomotor nerve's intramuscular sub-branches, the isolated levator palpebrae superioris muscles were stained using Sihler's staining technique. RESULTS Several LPS anatomical variations were observed in the specimens examined, in seven of which (7/70; 10%) additional delicate muscular slips arose from the LPS' lateral border and reached the lacrimal gland. Histological examination confirmed the presence of striated skeletal muscle fibers in all those cases. In three other specimens (3/70; 4.28%), supernumerary muscular bands ("tensor trochleae") were found that linked the levator with the superior oblique muscle's trochlea. In the next case, the LPS' origin was double and the muscle was bipartite on its proximal half. In most cases (55/70; 78.6%), muscular branches formed a single bundle that wrapped around the superior rectus muscle's medial border to reach the levator's inferior surface. Intramuscular sub-branches were distributed largely within the proximal two-thirds of the LPS and formed an irregular, tree-like pattern. However, thin sub-branches and small retrograde sub-branches extended as far as the muscle's insertion. CONCLUSIONS Plastic surgeons and ophthalmologists should be aware of the levator palpebrae superioris muscle's anatomic variations both in planning and conducting surgeries on the upper eyelid.

中文翻译：

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上睑提肌的解剖学变化，包括对其神经支配和肌内神经分布模式的观察。

背景技术上睑提肌（LPS）充当上眼睑的主要提升器和牵开器，并由动眼神经支配。肌肉麻痹表现为上睑下垂。材料与方法解剖了70个轨道。移除眼眶顶后，评估LPS的形状和解剖学变化（即，存在辅助性肌肉带或肌肉的非典型形成）。为了可视化动眼神经肌内支的分布，使用Sihler染色技术对孤立的上睑提肌睑上肌进行了染色。结果在所检查的标本中观察到了几种LPS解剖学变化，其中7例（7/70； 10％）从LPS的侧缘出现了另外的细腻的肌肉滑脱并到达了泪腺。组织学检查证实在所有这些情况下均存在横纹肌纤维。在其他三个标本中（3/70； 4.28％），发现了多余的肌肉带（“张肌滑车”）将提肌与上斜肌滑车相连。在下一种情况下，LPS的起源是双重的，而其近端的一半是肌肉。在大多数情况下（55/70； 78.6％），肌肉分支形成单个束，缠绕直肌上肌内侧边界，到达提肌下表面。肌内支行主要分布在LPS的近三分之二内，并形成不规则的树状图案。但是，细的分支和小的逆行分支一直延伸到肌肉的插入。