Anatomy of the External Nasal Nerve

Abstract

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 the midline of the nose and the size of the nerve were measured. The course and the running plane of the nerve 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 mm. Most of the nerves (95 percent) passed through the deep fatty layer directly under 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 not 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 an onlay graft, implants or grafts less than 13 mm wide at the rhinion level should be used.

Minimally Painful Local Anesthetic Injection for Cleft Lip/Nasal Repair in Grown Patients

“…9–11 Eberlin et al 9 reported primary cleft lip repair and primary rhinoplasty on 22 adolescents/adults under pure local anesthesia in 2003. After ethyl chloride spray, they all received infraorbital 12 and external nasal nerve blockade 13 and 5–10 ml of subcutaneous infiltration for the epinephrine effect. Ahmad 10 also described cleft lip repair under local anesthesia in 39 adults in 2008.…”

A Complete Subperichondrial Dissection Technique for Rhinoplasty With Management of the Nasal Ligaments

“…Dissection through the nasal soft tissue and the associated damage to the structural components responsible for tip support can result in loss of tip height and projection, loss of tip rotation, changes in the silhouettes of the nasal cartilages, supratip deformity, and a hanging columella. 11,12 Soft Tissue Envelope…”

Comparison of nasal senses following open and closed rhinoplasty

“…In order to avoid sensory damage, it is essential to perform the dissection, excision, and grafting with great care, keeping in mind that the external nasal nerve in the rhinion region is 6.5-8.5 mm away from the midline (9). It is recommended that, in order to protect the infraorbital nerve truncus or branches, osteotomy be performed only with a chisel, and that if a saw is required, it should be placed with the help of an elevator and remain in the right tunnel (10).…”