the facial nerve trunk exits through the stylomastoid foramen , and enters the parotid gland where it divides into the cervicofacial and temporofacial divisions . then divides into five peripheral branches to supply the muscles of facial expression ( 1 ) . the branches arising from the rami form to parotid plexus in parotid gland . the superior buccal nerve arising from temporofacial ramus and the inferior buccal nerve arising from the cervicofacial ramus form to the buccal plexus without parotid gland ( 1 ) . the zygomatic ( 2 ) , the marginal mandibular ( 3 - 5 ) , the buccal ( 6 ) , and the temporal branches ( 7 ) of the facial nerve were investigated by many researchers . different surgical approaches and landmarks to the trunk of the facial nerve have been reported ( 8 - 12 ) . many landmarks such as the mastoid process ( 8 - 10 ) , the transverse process of the atlas ( 8) and axis ( 11 ) , the temporomandibular joint , the angle of the mandible ( 9 , 11 ) , insertion of the sternocleidomastoid muscle , pointer cartilage of the ear ( 10 ) , tragal pointer ( 11 ) and the marginal mandibular branch of the facial nerve ( 12 ) can be used to identify the trunk of the facial nerve . but identification of this trunk may be difficult because it is encompassed by dense connective tissue ( 13 ) . in this paper the double facial nerve trunk emerged from the stylomastoid foramen and petrotympanic fissure was found in a 65-yr - old caucasian male cadaver during a routine dissection course . firstly , the skin and superficial fascia between the mastoid process and ramus of the mandible were reflected in all subjects . the anterior border of the parotid gland was carefully elevated and the rami of the nerves followed proximally up to the stylomastoid foramen under a stereomicroscope ( stemi 2000 ; carl zeiss , jena , germany ) . finally , magnetic resonance ( mr ) imaging was performed by using 1.5 t scanner to this cadaver . to be able to demonstrate the stylomastoid foramen and the petrotympanic fissure in same section , we obtained t1 and t2 weighted oblique sagittal scans . in the present cadaver , difference with the exit point of the facial nerve was observed . in this specimen , in this side , although cervicofacial ramus of the facial nerve exited from the stylomastoid foramen , temporofacial ramus of the facial nerve exited from petrotympanic fissure ( fig . the buccal branch dividing from temporal branch of temporofacial ramus and first buccal branch dividing from cervicofacial ramus formed to first buccal plexus . the buccal branch dividing from zygomatic branch of temporofacial ramus and second buccal branch dividing from cervicofacial ramus formed to second buccal plexus ( fig . 2 ) . these two buccal plexuses and other branches formed to structures like to polygon ( fig . the temporofacial ramus exiting from petrotympanic fissure was seen on magnetic resonance image ( fig . several studies relating to the trunk of the facial nerve have been reported in the literature ( 14 - 19 ) . katz and catalano ( 14 ) reported three cases ( 3% ) presenting two main trunks , known as the major and minor trunks , with the latter joining the larger temporofacial division , the origin of the main buccal branch . the minor trunk of the facial nerve was noted in eight of 30 cases ( 26.7% ) and , in all of them , the minor trunk entered the lower division of the facial nerve ( 15 ) . botman and jongkees ( 16 ) reported that the facial nerve within the mastoid segment of the temporal bone can split into two or three branches , and each branch exits through a separate osseous foramen . in this study , a trunk of the facial nerve exiting from the petrotympanic fissure is present one case . in addition , baker and conley ( 17 ) reported the possibilities of trifurcation , quadrifurcation , or even a plexiform branching pattern of the trunk of the facial nerve . salame et al . ( 18 ) identified one case of trifurcation out of 46 cases . but we did not identify any case of trifurcation , quadrifurcation or a plexiform branching pattern of the trunk . the facial nerve can easily be injured by sharp or penetrating trauma to the cheek . there are number of studies concerning protection extracranial branches of the facial nerve during plastic surgery procedures and operations intended for the parotid gland , but relatively little care has been given exit point of the facial nerve . knowledge of the trunk of the facial nerve is essential for preserving the nerve during surgical procedures of the mastoid process , parotid gland , the cranial base and the facial nerve ( 13 , 17 ) . in this study , we exposed exit point of the trunk of the facial nerve through the cranium . surgeons should be aware of the possible anatomical variations of the trunk of the facial nerve , because a trunk of the facial nerve exiting from the petrotympanic fissure may also be present .
there are several studies concerning branches of the facial nerve , but we encountered less information about the trunk of the facial nerve in the literature . during the routine dissection of a 65-yr - old caucasian male cadaver , double facial nerve trunk emerged from the stylomastoid foramen and petrotympanic fissure were encountered . 
 because of an extremely rare variation , we presented this case report . 
 in addition this cadaver had two buccal plexuses . 
 these plexuses and other branches were formed to structures like to polygon . 
 these anatomic peculiarities were described , photographed and illustrated . 
 finally , magnetic resonance imaging was performed by using 1.5 t scanner to this cadaver . 
 the facial nerve trunk can be damaged during surgical procedures of the parotid gland tumours and submandibular region . 
 surgeons who are willing to operate on this area should be aware of the possible anatomical variations of the facial nerve trunk .