The Elementary Anatomical Study And Three-dimensional Reconstruction Of The Facial Modiolus

Objective: To indentify the location, histological composition of modiolus and its characteristics in morphology by gross anatomy of the facial modiolus, histological observation and three-dimensional recons- truction, in order to provide anatomical foundation for facial plastic surgery.Method:①Dissected 15 (30sides) cadaveric head which had been fixed by formalin., and done measurements which were made from horizontal (x axis) and vertical (y axis) lines drawn through the angle oris,the x axis is parallel with the line through tragion and infraorbital point. Recorded the levels and features of muscles which contributed to the modiolus.②Take 4 tissues samples lateral to the angle oris, the size was 25mm×35mm×10mm, paraffin imbedding,15μm thick serial sections were taken parallel to the skin, we kept the every other slice, totally 680 slices, then stained with Verhoeff iodine- Hematoxylin, observed under the microscope.③153 slices among them been grabed large image by image analyzer with 4 times magnification, after image registration and image segmentation by man-power with photoshop within the cross-section images, gave individual color to every single structure and input the color images into Winsurf software on PC, and then three-dimensional recons- tructed images displayed perfectly.Results:1,Results of gross anatomy (definition in broad sense): ⑴Muscles that join in modiolus are as follows: orbicularis oris, zy- gomaticus major muscles, levator anguli oris, depressor anguli oris ,buccinator,platysma pars modiolus and risorius. Risorius is not constantly occurrence, the frequency of its occurrence is 57%.⑵There are three planes of muscles which contributed to the modiolus,: risorius constantly occurred in the first plane, platysma pars modiolus constantly occurred in the second plane, buccinator constantly occurred in the third plane; zygomaticus major muscles and depressor anguli oris occurred in the first or second plane, levator anguli oris occurred in the second or third plane; orbicularis oris join in every plane of modiolus.⑶The center point of apex moduli is 11.7mm±2.3mm in horizontal; and location of modiolus can be divided into three types in vertical according to the relationship between center point of apex moduli and angle oris, the criterion is:①Lateral to the angle oris, occurred in 17 sides (56.7%),which center point of modiolus is in the area between 5mm superior and 5 mm inferior to the horizontal line drawn from angle oris.(contain 5mm)②Superior to the angle oris, occurred in 7 sides (23.3%),which center point of modiolus is superior to the parallel line,and the parallel line is5mm above the horizontal line drawn from angle oris.;③Inferior to the angle orisoccurred in 6 sides(20%), which center point of modiolus is inferior to the parallel line, and the parallel line is 5mm below the horizontal line drawn from angle oris.⑷Zygomaticus major muscles join in the modiolus in four different types.①Zygomaticus major muscles with one band. just as it join in the modiolus as a single muscle band.(4 sides);②TypeⅠof zygomaticus major muscle with two bands, the superior band interlaced with levator anguli oris and the inferior band join in the modiolus.(8 sides);③TypeⅡof zygoma- ticus major muscle with two bands, the superior band interlaced with levator anguli oris and the inferior band join in the modiolus with two bundles.(2 sides);④TypeⅢof zygomaticus major muscle with two bands, the superior band join in orbicularis oris passing through both superior and deep of levator anguli oris the inferior band join in the modiolus.(16 sides).⑸The lengths of zygomaticus major muscle,risorius,depressor anguli oris,levator anguli oris from their originations to where they join in the modiolus are 59.4mm±3.5mm,43.9mm±7.4mm,40.4mm±7.4mm,27.4mm±2.8mm;and the widths are 6.8mm±1.8mm,4mm±1.3mm,8mm±1.9mm,8.3mm±1.8 mm.2,Result of histological sections observation and 3-D reconstruction (definition in narrow sense):⑴We can see muscles converged in the superficial layer of buccinator lateral to the angle of the mouth that were orbicularis oris,zygomaticus major muscles,levator anguli oris,depressor anguli oris,platysma pars modiolus and risorius. We can find collagens being thick conspicuously where the muscles converged, and elastic fibers intermix in it.⑵Apex moduli is ellipse like, and the thickness of modiolus is 2.52mm.⑶Measurements of 3-D reconstruction are: distance between center point of apex moduli and angle oris is 11.96mm; volume of modiolus is 84.10mm3; perimeter of apex moduli is 27.13mm, area is 18.41mm2;perimeter of base moduli is 33.39mm, area is 28.86mm2.Conclusion:1,As refer to definition of modiolus in broad sense:①Muscles that join in modiolus are as follows: orbicularis oris , zygomaticus major muscles,levator anguli oris,depressor anguli oris,buccinator,platysma pars modiolus and risorius. Risorius is not constantly occurrence, the frequency of its occurrence is 57%.②Zygomaticus major muscles join in the modiolus in four different types.③Modiolus can be divided into three types in vertical according to the relationship between center point of apex moduli and angle oris, the calibration line is the parallel line 5mm both superior and inferior with horizontal line drawing from angle oris.2,According to histological construction of modiolus, we put forward the definition of modiolus in narrow sense. Relative to the familiar defini- tion of modiolus in broad sense.We definited modiolus in narrow sense observed under the microscope.As we can see muscles interlaced in the position adjacent to angle oris, and collagens being thick conspicuously and elastic fibers intermix in it because of muscular fascia coalesced, we definited it as modiolus in narrow sense.The base of modiolus that defined in narrow sense is superficial layer of buccinator, and apex is interlaced area of superficial muscles.3,Measurements of 3-D reconstruction are(definition in narrow sense): thickness of modiolus is 2.52mm.distance between center point of modiolus and angle oris is 11.96mm, volume of modiolus is 84.10mm3; perimeter of apex moduli is 27.13mm,area is 18.41mm2;perimeter of basis moduli is 33.39mm, area is 28.86mm2.4,Computerized three-dimensiona1 reconstruction by serial thin cross- sections is a practicable research method for stereoscopic observation of small and complicated structure, applicable with modiolus which tridi- mensional structure is so complicated.