Extra and Intramuscular Distribution of the Thoracodorsal Nerve with Regard to Nerve Reconstruction Surgeries

Background The lateral branch of the thoracodorsal nerve (LBTN) is used for nerve transfer in facial, musculocutaneous, axillary nerve injuries and for irreparable C5, C6 spinal nerve lesions and accessory nerve defects. For a successful surgical outcome, the nerve to be used in nerve transfer should be of adequate length and thickness for nerve coaptation. Aim Our objective was to evaluate the length of the LBTN that could be obtained as a donor nerve, externally and within the muscle. Method Eight (8) cadavers with intact upper limbs and thorax which could be positioned in the anatomical position were selected for the study. Cadavers with dissected axillae, brachial plexus or upper limbs were excluded. The thoracodorsal neurovascular bundle was dissected and the number of branches of the thoracodorsal nerve was identified along with its lateral branch. The lateral branch was dissected up to the latissimus dorsi muscle and further intramuscularly. All lengths were measured using a vernier caliper. Results The mean length of the LBTN, up to its first intramuscular branch, is 8.14 cm (range 5.99-12.29 cm). Beyond this, the intramuscular nerve branched further and was of very minute diameter. The mean unbranched intramuscular length of the nerve is 3.36 cm (range 1.3-7.71 cm) which is 41.28% of the total length of the LBTN. Conclusion A significant proportion of the LBTN is found within the latissimus dorsi muscle. This length could potentially be used for direct nerve coaptation by intrafascicular dissection.