An Anatomical and Histological Study of the Vastus Lateralis Muscle Nerve and Application for Functional Muscle Transfer in Upper Lip Reconstruction.

OBJECTIVES

Motor neurotization is essential for functional muscle transfer. The aims of this anatomical study were to map the course of the vastus lateralis muscle motor nerve and determine the axonal counts of the main trunk and its branches to assess its suitability as a free functional muscle transfer.

METHODS

Ten cadaveric thighs were dissected. The length of the nerve and its branches were measured, harvested en bloc, and cross-sectioned at its origin and each branch. Their calibers and axonal counts were analyzed. The vastus lateralis muscle was used for a functional muscle transfer in a clinical case of upper lip reconstruction.

RESULTS

The branches of the vastus lateralis muscle motor nerve coursed adjacent to the branches of the lateral circumflex femoral artery. Two nerve branching patterns were identified. Type 1 (70%) consisted of two branches, the transverse and descending. Type 2 (30%) consisted of three branches, the transverse, oblique, and descending. The average lengths and axonal counts of the transverse, oblique, and descending branches were 7.1, 6.7, and 15.2 cm and 1021, 545, and 1158, respectively. The average lengths of the accompanying transverse, oblique, and descending branches of the lateral circumflex femoral artery were 5.7, 9.0, and 10.3 cm, respectively. Our clinical case regained muscle function and oral sphincter competency.

CONCLUSIONS

Three types of muscle segments of the vastus lateralis muscle may be harvested for functional muscle transfer based on the descending (type A), oblique (type B), and transverse (type C) nerve branches. Types A and C have axonal counts matching the buccal branches of the facial nerve. Clinically, type A functional muscle transfer for lip reconstruction was validated.