Scutuloauricularis muscle of the rabbit: a new model for free functional muscle transplantation in the mimic system.

There is little information on the specific process of free, functional muscle transplantation to the face trying to restore mimic function. Up to now one of the main reasons was the impossibility of functional assessment of mimic muscles as well as their transplanted substitutes. The scutuloauricularis muscle provides an ideal model for quantitative assessment of muscle function because of its circumscript tendinous insertion and is suitable for microsurgical transplantation. In a series of 26 adult, female New Zealand rabbits the anatomical and microsurgical details were studied. The scutuloauricularis muscle weighs 1.018 +/- 0.106 g, it is supplied by the auricularis rostralis artery (diameter 0.4 +/- 0.1 mm) and the auricularis rostralis vein (diameter 1.3 +/- 0.1 mm) and one oligofascicular (2-3 fascicles) branch of the facial nerve. During isometric contraction under supramaximal electrostimulation the maximal tetanic tension was 2.995 +/- 0.928 N. Histomorphometric studies in ATP-ase stained cross-sections showed 40.5 +/- 4.6% type I fibres, 32.3 +/- 5.2% type IIA fibres, and 27.2 +/- 7.1% type IIB fibres.