Al-Redouan Azzat, Benes Michal, Abbaspour Ehsan, Kunc Vojtech, Kachlik David
Department of Anatomy, Second Faculty of Medicine, Charles University, Prague, Czech Republic.
Ann Anat. 2023 Apr;247:152046. doi: 10.1016/j.aanat.2023.152046. Epub 2023 Jan 20.
The subclavius muscle runs underneath the clavicle. However, there have been a few reports of a duplicated subclavius muscle which is commonly referred to as subclavius posticus muscle due to its orientation being posterior to the proper subclavius muscle. Its occurrence seems to potentially create a narrowing interval at the superior thoracic aperture as it crosses over the brachial plexus. It might also have functional influence on the shoulder girdle.
To provide comprehensive gross anatomy description of the variant "subclavius posticus muscle" and to investigate its reported clinical implications with emphasis on its involvement in causing brachial plexus compression.
A scoping review with meta-analysis of the gross anatomy of the subclavius posticus muscle was conducted along with investigating its correlation to the thoracic outlet syndrome. Forty-seven articles were pooled through two rounds of the selection process. The relevant information was extracted and meta-analyzed.
The scoping review and meta-analysis of the 47 articles revealed a total prevalence of 11/2069 (4.9%); 10/1369 (5.1%) in cadaveric studies, and 1/700 (5.0%) in MRI studies. The subclavius posticus muscle is a short triangular muscle with an average length of 12 cm and an average width of 1 cm. It originates from the sternal end of the first rib in most cases with reported variants of one case originating from the costoclavicular ligament and one case where it was fused with the proper subclavius muscle. Its insertion is more variable: on the superior border of the scapula with variable length in 71.35%, on the coracoid process of the scapula in 25.42%, and on the clavicle in 0.90%. The subclavian nerve seems to be the dominant nerve supply with a 57.6% prevalence, while 25.8% are innervated by the suprascapular nerve. Other reported nerves were the nerve to the myolohyoid (4.5%), accessory phrenic nerve (4.5%), and a direct branch from the brachial plexus (2.0%). The blood supply was reported (only once) to be from the suprascapular artery. However, the venous drainage was not established at all.
The subclavius posticus muscle is a variant muscle occurring with a reported overall prevalence of 4.9%. It can compress the brachial plexus as it runs across at the space of the superior thoracic aperture with exquisite contact, and this can lead to a neurogenic thoracic outlet syndrome. It also can be involved in the vascular thoracic outlet syndrome. Lastly, it is important not to omit its potential influence in shoulder joint instability to some extent.
锁骨下肌走行于锁骨下方。然而，有少数关于锁骨下肌重复出现的报道，因其走行于正常锁骨下肌后方，通常被称为后锁骨下肌。该肌的出现似乎有可能在上胸廓入口处跨过臂丛神经时造成间隙变窄。它也可能对肩带产生功能影响。
提供对变异的“后锁骨下肌”的全面大体解剖学描述，并研究其已报道的临床意义，重点关注其与臂丛神经受压的关系。
对后锁骨下肌的大体解剖进行了范围综述和荟萃分析，并研究其与胸廓出口综合征的相关性。通过两轮筛选过程汇集了47篇文章。提取相关信息并进行荟萃分析。
对47篇文章的范围综述和荟萃分析显示，总体发生率为11/2069（4.9%）；尸体研究中为10/1369（5.1%），MRI研究中为1/700（5.0%）。后锁骨下肌是一块短三角形肌肉，平均长度为12厘米，平均宽度为1厘米。在大多数情况下，它起自第一肋的胸骨端，有报道称1例变异起自肋锁韧带，1例与正常锁骨下肌融合。其止点变化更大：71.35%止于肩胛骨上缘，长度不一；25.42%止于肩胛骨喙突；0.90%止于锁骨。锁骨下神经似乎是主要的神经支配，发生率为57.6%，而25.8%由肩胛上神经支配。其他报道的神经有颏舌骨肌神经（4.5%）、副膈神经（4.5%）和臂丛神经的直接分支（2.0%）。有报道称（仅1次）其血液供应来自肩胛上动脉。然而，静脉引流情况完全未明确。
后锁骨下肌是一种变异肌肉，报道的总体发生率为4.9%。它在上胸廓入口处跨过臂丛神经时可紧密接触并压迫臂丛神经，这可能导致神经源性胸廓出口综合征。它也可能与血管性胸廓出口综合征有关。最后，重要的是不要忽略其在某种程度上对肩关节不稳定的潜在影响。
