An Anatomical Study of the Length of the Neural Pedicle after the Bifurcation of the Thoracodorsal Nerve

Document Type : Original Article

Authors

1 Department of Anatomy and Embryology, Faculty of Medicine, Alexandria University. Corresponding Author.

2 Department of Plastic Surgery, Faculty of Medicine, Menofia University.

Abstract

ABSTRACT
Background: Latissimus dorsi muscle is considered as a key stone most important muscle in plastic surgery used for many reconstructive surgical procedures varying from facial reanimation and breast reconstruction to lower limb reconstruction. it is essential to have knowledge about The branching pattern and length of the thoracodorsal nerve which is the nerve supply of this precious latissimus dorsi distal to the splitting of this nerve. For innervated functional muscle transplant procedures, the length of nerve pedicles available for nerve anastomosis is crucial
Aim of the Work: Is to investigate the topography and branching pattern of the thoracodorsal and also measure its length distal to its splitting.
Materials and Methods: Sixteen latissimus dorsi muscles were dissected in eight adult embalmed human specimens in Anatomy department Faculty of medicine Alexandria university. The thoracodorsal neurovascular bundle was dissected and the pattern of branching of the thoracodorsal nerve was identified The branches were dissected up to the latissimus dorsi muscle and further intramuscularly. All lengths were measured using a vernier caliber. Surgically, in total, 10 patients with recurrent squamous cell carcinoma were undergone surgery permitting simultaneous cancer resection and harvesting of latissimus dorsi flap in Plastic surgery department, Faculty of medicine, Menufia University, Informed written individual consent was obtained for all the patients.
Results: The median length of the medial branch was 3.45 cm (range, 1.80 to 5.5 cm; mean, 3.60 cm; SD, 1.04 cm). As regard the branching pattern of the thoracodorsal nerve distal to its splitting it varied from three branches pattern in 75%, two branches pattern in 23% of the specimens and in one case continued as one branch on the lateral border of latissimus dorsi muscle In one other specimen thoracodorsal nerve distal to its split gave many branches and in this specimen abreast mass was noticed on the corresponding side of this thoraco dorsal nerve. The veins and arteries showed a similar pattern, with a median length that is similar to that of the thoracodorsal nerve.
The median length of the middle branch was3.50 cm (range, 2.4 5 to 4.65 cm; mean3.45 cm; SD, 0.88 cm), The lateral branch showed a median length of 3.99 cm (range, 2.5 5 to 5.95 cm; mean, 3.85 cm; SD, 0.95 cm). The mean length of the thoracodorsal nerve measured from the posterior root to the split was 12.5 cm.Surgically, by surface area the latissimus dorsi is the largest muscle in the body. It can be as large as 20 x 40cms, enabling latissimus dorsi flaps to cover very large defects after resection of squamous cell carcinoma in head and neck region especially in temporal and scalp regions.
Conclusions: The separate neurovascular branches and its minimal pedicle length make the latissimus dorsi muscle very suitable for single functional free muscle transfer, using only the lateral part of the latissimus dorsi muscle, and double functional free muscle transfer using only one vascular pedicle. This suggests the possibility of a multiple, segmentally innervated latissimus dorsi muscle transfer. And actually this is facilitated by this branching pattern of the thoracodorsal nerve.There may be association between the multiple branch pattern of the thoracodorsal nerve and presence of breast mass, an issue which need more research. From surgical points of view, there is strong need for preoperative diagnostic tools to predict the pattern of branching of neuro vascular bundle of latissimus muscle, to help preoperative planning especially in cases as facial reanimation, also in cases that we need more than one muscular functional units, also in cases that we might need to leave portion of muscle for better esthetics and better function of limb movements.

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