Abstract:

Objective　to study the location of chorda tympani, and provide relevant anatomical data for facial nerve decompression surgery and other mastoid surgery.　Methods　From April 2005 to October 2009, there were 216 adult Han nationality patients with peripheral facial paralysis receiving  facial nerve decompression, in the surgery, under NC4 surgical  microscope, the chorda tympani location and the type of issue were observed and analyzed.　Results　69.0%(149 cases) of chorda tympani nerve issues from the facial nerve in the form of a single root, and 19.4%(42cases) of chorda tympani nerve issues in the form of double roots, while 3.2%(7cases) of chorda tympani nerve has 3 roots, there is no pattern in 4 roots or more, all roots converge into a chorda tympani nerve on the top of the facial nerve recess and then go into the middle tympanum.  Due to our surgical approach, chorda tympani roots were not found in 18 cases(8.3%). Single chorda tympani nerve by the issuing site is divided into: from the cone-shaped fascia of stylomastoid foramen region in 82 cases, accounting for 55.0%, from the mastoid segment of the facial nerve in 64 cases, accounting for 43.0%, from the second genu of the facial nerve in 3 cases, accounting for 2%.　Conclusion　In adult Han population, the branch form of the chorda tympani nerve is more complex than that in our traditional knowledge. There is the phenomenon of multiple roots. 69% of the chorda tympanis have single root, while 22.6% have multi-roots phenomenon, only 29.6% of chorda tympani nerves issues from the mastoid segment of facial nerve. In addition, in this survey, we found that three cases of chorda tympani issued from the second genu of the facial nerve, these phenomena should arise the doctor's attention, so that we can avoid accidental injury to this malformation of chorda tympani during the surgery.

Key words: Chorda tympani, Anatomy, Facial nerve, Decompression, Malformation