The Facial Nerve Anatomical Study Related With The Face Lift

Objective:Over the years, there has been much conflicting descriptions of the fascial planes surrounding the facial nerve in clinical practice. The Objective of this study was to define the path of the facial nerve and the relationship between the facial nerve and the fascia.Methods:The specimen were chosen inclnding10fresh-frozen cadaver, of which3were male and7were female. Their age range was about20-70years old. Cadaver hemifaces were dissected in a layer-by-layer fashion to evaluate path of the facial nerve and the relationship of the nerve and the fascial planes. Histologic evaluation was performed on the rest cadaver hemifaces.We took the Frankfurt plane as x axis, and the external acoustic foramen midpoint perpendicular as Y axis to establish the coordinate system. Using coordinate points represented the exited position of the facial nerve branch from parotid margin. With the naked eye and the operating microscope observed the distribution of characteristics of the facial nerve. Then established another coordinate system, taking the superior border of the zygomatic arch as X’axis, and the lateral orbital rim perpendicular as the Y’axis, to mark the location where the facial nerve temporal branch transfered from one fascia layer to another. Excised full-thick tissue blocks from superior and inferior of the zygomatic arch, the parotid masseteric region, and the vicinity the mandibular angle to observe the stratification characteristics. Tissues were fixed and sliced, and then observed with a microscope.Results:There are great individual differences in the number of branches of each branch of the facial nerve. The temporal branch of the facial nerve divided into2to4branches that exited from the superior margin of parotid gland called the temporal branch of Ⅰ, Ⅱ,Ⅲ, IV respectively. Below the zygomatic arch temporal branch crossed within the parotid-masseteric fascia,and crossed within the middle temporal fascia across the zygomatic arch. Then temporal branch continued to run in the oblique direction. Along with the middle temporal fascia was more anterosuperior to become thinner, the temporal branch gradually moving towards more superficial temporal fascia.The Zygomatic Branch of the facial nerve divided into1to4branches,called the temporal branch of I, II, III, IV respectively. Zygomatic branch exited from the anterosuperior or anterior margin of parotid gland, which crossd within the Masseter fascia coursing along the inferior margin of the Zygomatic arch. Normally at this point anterior edge of the parotid is most prominent, and the initiation part of the zygomatic muscle is most posterior, so there was short trip to reach the zygomatic muscle for zygomatic branch.The buccal branch of the facial nerve divided into2to4branches called the buccal branch of Ⅰ, Ⅱ, Ⅲ,Ⅳ,Ⅴ, respectively. There are two kinds of relationship between buccal branch and the masseter muscle fascia:Firstly, buccal branch located deep to the fascia, and exited from the anterior edge of the masseter muscle. Secondly, the buccal branch located within the masseter fascia, and then crossed deep to the Superficial Musculoaponeurotic System (SMAS).Marginal mandibular branch of the facial nerve divided into1to2branches. Exited from parotid, most of the marginal mandibular Branch traversed into the masseter fascia above the lower edge of the mandibular body. It crossed the surface and deep layers of the superficial facial vein and artery at the anterior border of the mandibular angle, then traveled forward into the space between the platysma and the body of the mandible and branching into the muscle. Most mandibular branches coursed above the inferior border of the mandible, except in small number of cases coursed below the mandible.Cervical branch of the facial nerve had one branch constantly. A distance just left parotid gland is vertical descent for cervical branch. There was thin loose connective tissue between the superficial surface of the cervical branch and the platysma.Conclusion:1.Subcutaneous temporal soft tissue followed from shallow to deep: superficial temporal fascia,middle temporal fascia,superficial layer of the deep temporal fascia,superficial temporal fat pad,deep layer of the deep temporal fascia,and deep temporal fat pad.2. The temporal branch of the facial nerve crossed within the middle temporal fascia, zygomatic branch, buccal branch, marginal mandibular branch, and cervical branch crossd within or deep to the masseter fascia.3. The superficial surface of the superficial temporal fascia and the superficial surface of the deep temporal fascia is relatively safe separation plane.4. Dissection in the transition zone of the superficial and deep fascia above the zygomatic arch should pay attention.5. The upper zygomatic branch location of shallow and easily damaged. Parotid gland leading edge and the masseter muscle between the zygomatic branch of the most vulnerable.6. Dissection at anterior margin of the parotid gland, upper segment of the masseter muscle,surface buccal fat pad, easy to damage the facial nerve buccal branch.7. At the upper and lower of the mandibular edge2cm,attention to protect the mandibular marginal branch of the facial nerve.8. Avoid to injury cervical branch of facial nerve injury, when dissection deep to platysma at the inferior and anterior border of the mandibular angle need to be cautious.