A Variation of the Cords of the Brachial Plexus on the Right and a Communication between the Musculocutaneous and Median Nerves on the Left Upper Limb: A Unique Case

Abstract

During routine anatomical dissection of the upper extremity of a 64-year-old cadaver for educational purposes, we observed variations in the brachial plexus on each side. On the right an anomaly of cord formation was present and on the left there was a communication between the musculocutaneous nerve (MCN) and median nerve (MN). On the right side the brachial plexus showed two trunks, superior (C5 and C6) and inferior (C7, C8, and T1); the middle trunk was absent. The superior trunk bifurcated into anterior and posterior divisions, the anterior division continued as the lateral cord forming the MCN. The posterior division gave off the subscapular branch. The inferior trunk trifurcated into radial, median, and ulnar nerves. The radial nerve gave off the axillary and thoracodorsal nerves. The ulnar nerve gave off the median cutaneous nerves of the arm and forearm. The median nerve received a small ascending branch from the MCN. On the right side, there was a communicating branch from the MCN to the MN in the lower third of the arm region. This communicating branch also gave rise to a muscular branch to the brachialis muscle and the lateral cutaneous nerve of forearm. No additional heads of the biceps brachii muscle were observed in either upper limb. Knowledge of the variations of the brachial plexus in humans can be valuable for operations of the shoulder joint and its repair for providing an effective block or treatment for anesthetists and also for explaining otherwise incomprehensible clinical signs for neurologists.

Multiple variations in the course and motor branching pattern of the musculocutaneous nerve with unusual communication with the median nerve

“…The MCN in the present case did not pierce the coracobrachialis muscle and there was an additional communicating branch from the MN to MCN. Taken together, the present communications between the MCN and MN observed in the left arm of this cadaver did not resemble any variations described previously [3,8,14,16,17,20,28,33]. In this case, injury of the MCN in the upper arm superior to the proximal communication may cause paralysis of the elbow flexor and unexpected paralysis of flexor and/or thenar muscles.…”

“…Kaus and Wotowicz [14] reported two junctions of the MN and MCN similar to the present case but without an additional communicating branch from the MN to the MCN. Kirazli et al [16] reported a case of MCN piercing the coracobrachialis muscle and terminating by giving a communicating branch to the MN. From this branch, the branches to the brachialis muscle and LACN were given.…”

“…Several articles have described patterns of motor branching of the MCN [7,9,15,18,19,23,24,34]. Furthermore, the connection between the MCN and MN has been reported and classified by various criteria [3,8,11,14,16,17,20,28,33]. The MN is formed by the fusion of medial and lateral roots from the medial and lateral cords, respectively.…”

Bilateral anatomic variation in the relation of the upper trunk of the brachial plexus to the anterior scalene muscle

“…Variations in the formation of the BP's trunks [4,7,[23][24][25], as well as in their relation to the scalene muscles [5,18], have been described in the literature. Certain variations are linked to the neurogenic thoracic outlet syndrome (TOS) [9], due to the proximity of the muscle fibres and the nerves.…”

Pitiríase Liquenóide, Dermatose Incomum – Um Relato De Caso

“…No lado direito, havia um ramo comunicante do MCN para o MN no terço inferior da região do braço. Este ramo comunicante também deu origem a um ramo muscular para o músculo braquial e o nervo cutâneo lateral do antebraço(Kirazli et al, 2013).Tais achados, influenciam diretamente na conduta de procedimentos cirúrgicos nas áreas de membros superiores, uma vez que toda a estrutura típica do plexo braquial foi alterada devido à ausência do tronco médio. Nesse contexto, maiores conhecimentos sobre tais variações são imprescindíveis tendo em vista que o seu desconhecimento pode ser um preditor de para piora de desfechos clínicos.CONCLUSÃOObservou-se que as variações anatômicas do plexo braquial não são achados incomuns.…”