INNERVATION OF THE MEDIAN NERVE MOTOR BRANCHES IN THE FOREARM AND ITS CLINICAL SIGNIFICANCE

ABSTRACT Objective: To analyse the anatomical variations of the median nerve motor branches in the elbow region. Methods: Twenty upper limbs of 10 adult male cadavers were prepared by intra-arterial injection of a solution of 10% glycerol and formaldehyde. All cadavers belonged to the institution anatomy laboratory. Results: We found a great variability within the distribution of median nerve branches leading to forearm muscles. Only three limbs (14%) presented the normal standard of innervation described in anatomy treatises. The pronator teres muscle (PTM), flexor carpi radialis (FCR), palmaris longus (PL), and the flexor digitorum superficialis (FDS) received exclusive innervation from the median nerve in all forearms. The anterior interosseous nerve (AIN) also originated from the median nerve in all dissected limbs. Conclusion: A thorough understanding of the anatomy of the median nerve branches is important for performing surgeries such as: approach to the proximal third of the forearm, alleviation of pronator teres and anterior interosseous nerve compression syndromes, and distal nerve transfers. It also enables a better understanding the recovery of muscle function after a nerve injury. Level of Evidence IV, Case series.

摘要
研究目的：分析肘部区域正中神经（median nerve）运动分支的解剖变异。
方法：纳入10具成年男性尸体的20侧上肢，通过动脉内注射10%甘油甲醛溶液进行标本制备，所有尸体均取自本机构解剖实验室。
结果：前臂肌的正中神经分支分布存在显著变异；仅3侧上肢（14%）符合解剖学专著中描述的标准神经支配模式。所有前臂的旋前圆肌（pronator teres muscle, PTM）、桡侧腕屈肌（flexor carpi radialis, FCR）、掌长肌（palmaris longus, PL）以及指浅屈肌（flexor digitorum superficialis, FDS）均接受正中神经的单一神经支配；所有解剖标本的前骨间神经（anterior interosseous nerve, AIN）均起自正中神经。
结论：充分掌握正中神经分支的解剖结构，对开展前臂近端三分之一入路手术、缓解旋前圆肌及前骨间神经卡压综合征、实施远端神经移位术等操作具有重要意义，同时也有助于更好地理解神经损伤后肌肉功能的恢复过程。本研究证据等级为IV级，属于病例系列研究。