Anatomic grounds for the transposition of the thoracodorsal nerve in case of neurotization of brachial plexus nerve damage

 The goal is to identify topographic, anatomic, and constitutional features of thoracodorsal and musculocutaneous nerves of brachial plexus.

Materials and methods. Anthropometry of 45 corpses was carried out to determine growth; length of the trunk and upper extremities; circumference of neck, thoracic cage, shoulder and forearm; lateral dimensions of shoulders, thoracic cage and pelvis; anteroposterior size of thoracic cage; neck circumference. Morphometry of all brachial plexus components (length, thickness of nerves and angles of their origin) was performed after its  anatomic preparation.

Results. The cephalic type of brachial plexus with participation of C4 spinal nerve was found in 7% of cases. The caudal type with inclusion of Th2 spinal nerve was found in 4% of cases. In 4% of cases, there was no musculocutaneous nerve, at the same time shoulder biceps innervates median nerve. In 93% of cases, the thoracodorsal nerve originates from posterior secondary bundle along lower posterior surface, in 7% it is an axillary nerve branch. Neck circumference is directly correlated with thoracodorsal nerve length: the larger the neck circumference is, the greater is the nerve length. In females, linear regression equations were derived, which allow estimating thoracodorsal nerve length knowing the thoracic cage width.

Conclusion. The length of the thoracodorsal nerve determines the possibility of its transplantation into the musculocutaneous position. The size of neck circumference and, in females, the width of the thoracic cage, for reliability, should be used as external size biomarkers for donor and recipient nerves. 

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