Anatomical substantiation of the thoracodorsal nerve as a donor nerve and the musculocutaneous nerve as a recipient nerve

Aim. To identify the correspondence in the diameter of the thoracodorsal and musculocutaneous nerves, depending on the level of branching.

Materials and мethods. Using 121 preparations of the brachial plexus from 105 corpses of men and women aged 40–97 years, the diameter of the thoracodorsal nerve was measured at five levels, and the diameter of the musculocutaneous nerve was determined at two levels. For each parameter, the median and the interquartile range Me [Q1; Q3] were determined. The significance of differences between the groups was found by the Mann – Whitney test. The differences were considered significant at p < 0.05. The correlation was evaluated by the Spearman’s rank correlation coefficient. At 0.7 ≤ rs < 0.9, the correlation was regarded as strong, at 0.5 ≤ rs < 0.7 – as moderate.

Results. The diameter of the thoracodorsal nerve varied throughout its length: in the initial section, it was 1.66 [1.66; 1.99] mm, before branching – 3.00 [2.65; 3.50] mm, at the firstand second-order extramuscular branches – 4.2 [3.2; 5.0] mm and 5.25 [4.50; 6.50] mm, at the first-order intramuscular branches – 4.00 [3.50; 4.66] mm. The diameter of the musculocutaneous nerve in the initial section was 3.0 [2.6; 3.3] mm, and before the coracobrachialis muscle – 2.7 [2.4; 3.0] mm.

The total diameter of the extraand intramuscular branches of the thoracodorsal nerve was equal to or greater than the thickness of the musculocutaneous nerve in 90.1–95.0% of cases. Excess total diameter of the branches of the thoracodorsal nerve (0.05–8.0 mm) and fascicular dissection make it possible to preserve 1–2 firstand secondorder extramuscular branches and 1–4 first-order intramuscular branches.

Conclusion. The diameter of the thoracodorsal nerve in the initial section is smaller than that of the musculoskeletal nerve, but the total thickness of its extraand intramuscular branches is equal to or greater by 0.05–8.0 mm in 90.1–95.0% of cases. Different levels of branching of the thoracodorsal nerve contribute to extended transfer, and an excess diameter with fascicular dissection will preserve the function of the latissimus dorsi muscle.

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