Anatomy of the external nasal nerve

초록

After rhinoplasty, many patients report numbness of the nasal tip. This is primarily because Of injury to the external nasal nerve. It is imperative that surgeons performing rhinoplasty be familiar with the anatomy and the common variations of this nerve. Therefore, the purpose of this study was to present an anatomical study of the external nasal nerve. Twenty external nasal nerves were examined by dissecting 10 fresh cadaver noses within 48 hours Of death. On dissection, the exit of the nerve between the nasal bone and Upper lateral cartilage was identified. The distance from the point of exit to tire midline of the nose and the size of the nerve were measured. The course and the running plane of tire new were investigated. The nerve branchings were also classified into three types: type I, only one nerve without any branch; type II, one nerve proximally and then splitting into two main branches at the intercartilaginous junction, and type III, two main branches from the point of exit. The point of exit of the external nasal nerve from the distal nasal bone was located 6.5 to 8.5 mm (7.3 +/- 0.6 mm) lateral to the nasal midline. The average diameter of the nerve at the point of exit was 0.35 +/- 0.036 trim. Most of the nerves (95 percent) passed through the deep fatty layer directly wider the nasal superficial musculoaponeurotic layer, all the way down to the alar cartilages. In terms of the branching type, type I was observed in 10 of 20 nerves (50 percent), type II was observed in six of 20 (30 percent), and type III was seen in four of 20 (20 percent). On the basis of the results; of this study, the following precautions are, suggested during a rhinoplasty to minimize the chance of injury to this nerve. First, it is best to avoid deep intercartilaginous or intracartilaginous incisions so that the deep fatty layer is trot invaded and the dissection is maintained directly on the surface of the cartilage (deep to the nasal superficial musculoaponeurotic layer). Second, dissection at the junction of the nasal bone and upper lateral cartilage area of one side should be limited to within 6.5 mm from the midline. Lastly, when the nasal dorsum is augmented by art onlay graft, implants or grafts less than 13 mm wide at tire rhinion level should be used.

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