ABSTRACT
Objective To explore on location of the segments of the facial nerve being easy to damage in mastoid surgery.Methods Retrospective analysis was conducted according to the clinical data of 97cases with chronic suppurative otitis media performed with radical mastoidectomy (or radical mastoidectomy + tympanoplasty) from May 2010 to September 2012,and summarized the methods to locate the segment of the facial nerve being easy to damage in operation.Results ①One case of congenital defect of facial nerve canal was found in 97 cases.②The horizontal segments of the facial nerve of 97 cases were successfully located depending on combined/partial anatomic landmarks including eminence of the lateral semicircular canal,short limb of incus,cochlearform process,tympanic tegmen,stapes.③The pyramidal segment of facial nerve of 97 cases were successfully located depending on combined/partial anatomic landmarks including eminence of the lateral semicircular canal,short limb of incus.④The proximal part of vertical segment of the facial nerve of 97 cases were successfully located depending on combined /partial anatomic landmarks including short limb of incus,chorda tympani nerve,pyramidal eminence,eminence of the lateral semicircular canal.Conclusion The eminence of the lateral semicircular canal,short limb of incus,cochlearform process,tympanic tegmen,stapes,pyramidal eminence,chorda tympani nerve in the area in which the facial nerve being easy to damage are important landmarks by which the segment of facial nerve easy to damage might be located in mastoid surgery.
ABSTRACT
Objective To study the microanatomy of the area in which the facial nerve being easy to damage in mastoid surgery, in order to provide microanatomical datas for the clinical works. Methods In 20 adult wet skull specimens (40 temporal bones), the segments of facial nerve and their adjacent structures in the area in which the facial nerve being easy to damage were observed according to operation of mastoid surgery. Results The length of the horizontal segment was (8.85 ± 1.01) mm (7.10-11.25 nun), the diameter was (1.88 ± 0.65) mm (1.55-1.90 mm); The angle opening towards anterior direction between horizontal segment and vertical segment was (115.50 ± 6.89°) (109.5°-128.6°); The vertical distance from the cochlearform process to this segment was (1.89 ± 0.58) mm (0.90-3.05 mm); The vertical distance from the midpoint of the base of stapes to this segment was (1.92 ± 0.52) mm (1.44-2.56 mm); The vertical distance from the head of the stapes to this segment was (2.30 ± 0.85) mm (1.97-3.11 mm); The angle towards posterior direction between horizontal segment of facial nerve and tympanic tegmen was (28.5°± 3.66°) (25.8°-31.5°); The diameter of the pyramidal segment of facial nerve was (1.89 ± 0.65) mm (1.56-1.88 mm); The distance between the su mmit of pyramidal segment of facial nerve and the apex of shor limb of incus was (2.55 ± 0.21) mm (2.10-2.90 mm); The distance from the su mmit to the eminence of the lateral semicircular canal was (2.86 ± 0.31) mm (2.23-3.56 mm); The diameter of the proximal part of vertical segment of facial nerve was (2.13 ± 0.13) mm (1.90-2.40 mm); The angle towards superior direction between verical segment of facial nerve and chorda tympani nerve was (38.60 ± 1.99°) (28.5°-52.5°); The vertical distance from the top of the pyramidal eminence to the vertical segment of the facial nerve was (2.05 ± 0.65) mm (1.85-2.36 mm). Conclusions The eminence of the lateral semicircular canal, short limb of incus, cochlearform process, tympanic tegmen, stapes, pyramidal eminence, chorda tympani nerve in the area are important landmarks to be located in mastoid surgery. The anatomic relations in this area are complicated and compact. Anatomical knowledge is very important to the surgery of this area.