Sakamoto Kazuaki, Nasu Hisayo, Nimura Akimoto, Hamada Junichiro, Akita Keiichi
Department of Clinical Anatomy, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo, 113-8510, Japan.
Anat Sci Int. 2015 Mar;90(2):82-8. doi: 10.1007/s12565-014-0234-1. Epub 2014 Apr 12.
The pronator quadratus muscle is composed of the superficial and deep heads. However, to date there is no consensus on the variations of each head. To add to this enigma, the innervation patterns of each head have not been thoroughly studied. The present study was conducted to clarify the structure and innervation of the pronator quadratus muscle by minute dissection of 46 forearms from 26 cadavers. The origin, insertion, shape, and direction of the muscle fascicles in each head were observed. The intramuscular distribution and the innervation patterns to each head were investigated. The attachment of the deep head was examined using Masson's trichrome staining technique. Each head consisted of various muscle fascicles which differed in shape and direction. The most distal muscle fascicle extended toward the head of the ulna. On microscopic study, this most distal fascicle was observed to reach the base of the ulnar styloid process. The nerves innervating the superficial head penetrated through the deep head and ran on the anterior surface of the radius from medial to lateral. This tendency was common to all of the forearms studied. We confirmed that each head of the pronator quadratus muscle consisted of various muscle fascicles. The attachment to the base of the ulnar styloid process is considered to be an important structure that prevents the head of the ulna from impacting against the carpal bones. Knowledge of the innervation pattern to each head is critical for preserving the function of the pronator quadratus muscle during surgery for distal radial fracture.
旋前方肌由浅头和深头组成。然而，迄今为止，关于每个头的变异尚无共识。更令人困惑的是，每个头的神经支配模式尚未得到充分研究。本研究通过对26具尸体的46条前臂进行细致解剖，以阐明旋前方肌的结构和神经支配。观察了每个头的起点、止点、肌束形状和方向。研究了肌内分布以及每个头的神经支配模式。使用马松三色染色技术检查深头的附着情况。每个头由形状和方向各异的肌束组成。最远端的肌束向尺骨头延伸。在显微镜下观察到，这个最远端的肌束到达尺骨茎突基部。支配浅头的神经穿过深头，并从内侧向外侧走行于桡骨前表面。这种趋势在所有研究的前臂中都很常见。我们证实旋前方肌的每个头都由不同的肌束组成。附着于尺骨茎突基部被认为是防止尺骨头撞击腕骨的重要结构。了解每个头的神经支配模式对于在桡骨远端骨折手术中保留旋前方肌的功能至关重要。
