Moore Colin W, Rice Charles L
School of Kinesiology, Faculty of Health Sciences, The University of Western Ontario, London, ON, N6A 5B9, Canada.
Department of Anatomy and Cell Biology, Schulich School of Medicine & Dentistry, The University of Western Ontario, London, ON, N6A 3K7, Canada.
Anat Sci Int. 2018 Mar;93(2):311-316. doi: 10.1007/s12565-017-0408-8. Epub 2017 Jul 6.
Supernumerary or accessory heads of the biceps brachii are persistent muscular structures which can vary in number and location in the arm. Variations in other arm muscles, such as the coracobrachialis, can accompany supernumerary biceps brachii musculature in the upper limb. In this case report, we describe two rare muscular variants in a single adult male: a four-headed biceps brachii and the muscular elevator of the latissimus dorsi tendon. Additionally, accessory muscles of the brachialis and flexor digiti minimi brevis were identified in the upper limb. To our knowledge, the muscular variants identified here are considered rare, and their co-occurrence in a single upper limb has not been described previously. Also, a four-headed biceps brachii consisting of both the infero-medial and infero-lateral humeral heads has not been described previously to our knowledge. We postulate that the simultaneous appearance of several muscular variations may indicate a signaling disruption in embryogenesis during muscle patterning of the ventral limb bud. Knowledge of variant musculature in the arm is important for surgeons and clinicians as these muscles and their aberrant innervation patterns can complicate surgical procedures and may compress arteries and nerves producing upper limb pain and paresthesia. The clinical, functional and embryological implications of the upper limb variants are discussed.
肱二头肌的额外头或副头是持续存在的肌肉结构，其数量和在手臂中的位置会有所不同。上肢中肱二头肌额外肌肉组织可能伴有其他手臂肌肉的变异，如喙肱肌。在本病例报告中，我们描述了一名成年男性身上的两种罕见肌肉变异：一个四头肌头的肱二头肌和背阔肌腱的肌肉提升器。此外，在上肢还发现了肱肌和小指短屈肌的副肌。据我们所知，此处发现的肌肉变异被认为是罕见的，且它们在单个上肢中共存的情况此前尚未有过描述。同样，据我们所知，由肱骨下内侧头和下外侧头组成的四头肌头的肱二头肌此前也未被描述过。我们推测，多种肌肉变异同时出现可能表明在腹侧肢芽肌肉形成过程中的胚胎发育信号中断。了解手臂中的变异肌肉组织对外科医生和临床医生很重要，因为这些肌肉及其异常的神经支配模式会使手术程序复杂化，并可能压迫动脉和神经，导致上肢疼痛和感觉异常。本文讨论了上肢变异的临床、功能和胚胎学意义。
