The facial dermato-muscular system consists of highly specialized muscles tightly adhering to the overlaying skin and thus form a complex morphological conglomerate. This is the anatomical and functional basis for versatile facial expressions, which are essential for human social interaction. The neural innervation of the facial skin and muscles occurs via branches of the trigeminal and facial nerves. These are also the most commonly pathologically affected cranial nerves, often requiring surgical treatment. Hence, experimental models for researching these nerves and their pathologies are highly relevant to study pathophysiology and nerve regeneration. Experimental models for the distinctive investigation of the complex afferent and efferent interplay within facial structures are scarce. In this study, we established a robust surgical model for distinctive exploration of facial structures after complete elimination of afferent or efferent innervation in the rat. Animals were allocated into two groups according to the surgical procedure. In the first group, the facial nerve and in the second all distal cutaneous branches of the trigeminal nerve were transected unilaterally. All animals survived and no higher burden was caused by the procedures. Whisker pad movements were documented with video recordings 4 weeks after surgery and showed successful denervation. Whole-mount immunofluorescent staining of facial muscles was performed to visualize the innervation pattern of the neuromuscular junctions. Comprehensive quantitative analysis revealed large differences in afferent axon counts in the cutaneous branches of the trigeminal nerve. Axon number was the highest in the infraorbital nerve (28625±2519), followed by the supraorbital nerve (2131±413), the mental nerve (3062±341) and the cutaneous branch of the mylohyoid nerve (343±78). Overall, this surgical model is robust and reliable for distinctive surgical deafferentation or deafferentation of the face. It may be used for investigating cortical plasticity, the neurobiological mechanisms behind various clinically relevant conditions like facial paralysis or trigeminal neuralgia as well as local anesthesia in the face and oral cavity.

中文翻译：

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大鼠面部皮肤-肌肉复合体的选择性去神经作用：实验模型和解剖学基础

面部皮肤肌肉系统由紧密附着在皮肤上的高度专业化的肌肉组成，因此形成了复杂的形态集团。这是多种面部表情的解剖学和功能基础，这些面部表情对于人类社交互动至关重要。面部皮肤和肌肉的神经支配是通过三叉神经和面部神经的分支发生的。这些也是最常受到病理影响的颅神经，通常需要手术治疗。因此，用于研究这些神经及其病理的实验模型与研究病理生理和神经再生高度相关。缺乏用于面部结构内复杂的传入和传出相互作用的独特研究的实验模型。在这项研究中，在完全消除大鼠传入或传出的神经支配之后，我们建立了一个强大的外科手术模型，用于面部结构的独特探索。根据手术程序将动物分为两组。在第一组中，三叉神经的面神经和第二端所有远端皮肤分支均单侧切开。所有动物均存活，并且该程序不会引起更高的负担。手术后4周的视频记录了胡须垫的运动，并显示了成功的去神经支配。进行了面部肌肉的全量免疫荧光染色，以可视化神经肌肉接头的神经支配模式。全面的定量分析显示，三叉神经的皮肤分支中传入轴突计数存在很大差异。轴突数在眶下神经中最高（28625±2519），其次是眶上神经（2131±413），精神神经（3062±341）和类肌舌神经的皮肤分支（343±78）。总体而言，该手术模型对于面部的独特的手术除皱或面部除皱均具有鲁棒性和可靠性。它可用于研究皮质可塑性，各种临床相关病症（例如面瘫或三叉神经痛）以及面部和口腔局部麻醉背后的神经生物学机制。该手术模型对于面部的独特手术除皱或除皱效果是可靠且可靠的。它可用于研究皮质可塑性，各种临床相关病症（例如面瘫或三叉神经痛）以及面部和口腔局部麻醉背后的神经生物学机制。该手术模型对于面部的独特手术除皱或除皱效果是可靠且可靠的。它可用于研究皮质可塑性，各种临床相关病症（如面瘫或三叉神经痛）以及面部和口腔局部麻醉背后的神经生物学机制。