Page 132 - Manual of Equine Field Surgery
P. 132

128                       HEAD  AND  NECK  SURGERIES



  I·


                                                                                                                                                Conchofrontal  sinus



































                                                                     Rostral  maxillary  sinus                               Caudal  maxillary  sinus



                                                                                                                                                                 7:Jler-,v:,t;_.£a,,;1e,  -,.




                       Figure 21-1  Lateral view of skull with bone removed over the frontal and maxillary sinuses. Note position  of infra-


                       orbital  canal and  nasolacrimal  duct  (dotted  lines).
















                                                                                                                                                  a point halfway between  the  infraorbital  foramen


                                                                                                                                                  and  the  orbit  at the  approximate  level of the  fifth



                                                                                                                                                  cheek tooth.  The  caudal  limit  is at the level of the


                                                                                                                                                  caudal  border  of the  orbit.  The  lateral  extent  is


                                                                                                                                                  near  the  level of the  medial  canthus.  The  medial


                                                                                                                                                   extent  is  on  midline.  In  the  horse,  the  dorsal


                                                                                                                                                   conchal  sinus  has  an  extensive  communication



                                                                                                                                                  with the frontal  sinus, and  together  they are com-


                                                                                                                                                   monly  referred  to as the conchofrontal  sinus. The


                                                                                                                                                   rostral  extent  of the  conchal  sinus is at the level of


                                                                                             ~  Conchofrontal                                      the  facial tubercle.


                                                                                                    sinus                                                The  caudal  maxillary  and  frontal  sinuses

                                                                                                     lnfraorbital

                                                                                                    canal                                          communicate  through  a  large  frontal  maxillary

                                                                                                                                                   opening  and  drain  into  the  nasal  cavity  through


                                                                                                 ,  Caudal  maxillary                              the  nasomaxillary  opening  in  the middle  meatus.
                                             \                                                       sinus
                                              '                                             ...;.;.- Rostral  maxillary                            The  rostral  maxillary  sinus  drains  into  the  nasal





                                                                                                     sinus                                         cavity  through  a separate  opening  in  the  middle
                                                                                                                                                   meatus.



                                                  I                                                  Facial

                                                  I                                                  tubercle

                                                                                                                                                   PROCEDURE AND PREPARATION




                                                                           ~-           Nasolacrimal


                                                 ii  ,                                 duct                                                        Several sites are recommended  for sinus trephina-

                                                                                                                                                   tion  in  the  horse.  The  trephine  portal  for  the



                                                                                                                                                   frontal  sinus is 3 to 4 cm caudal to the most  rostral


                                                                                                                                                   aspect  of the frontal  sinus  and  3 to 4 cm lateral  to


                                                                                                                                                   midline.  The  trephine  portal  for  the  caudal  max-


                                                                                                                                                   illary  sinus  is  1  to  2  cm  dorsal  to  the  facial crest


                                                                                                                                                   and  7 to 8 cm caudal to the  most  rostral  aspect of



                                                                                                                                                   the facial crest. The trephine  portal  for the cranial



                                                           ~.Q(l),-::,d~~                                                                          maxillary  sinus  is  1  to  2  cm  dorsal  to  the  facial

                                                                                                                                                   crest  and  3  to  4 cm  caudal  to the  facial tubercle.
                        Figure 21-2  Overview  of skull with  bone  removed


                        over  the  frontal  and  maxillary  sinuses.  Note  relative                                                               As the  septum  dividing  the  maxillary  sinuses  is


                        positions  of  infraorbital  canal  and  nasolacrimal  duct                                                                variable,  these  locations  are guidelines  only.


                        (dotted  lines).                                                                                                                  The  infraorbital  foramen  and  the  levator

                                                                                                                                                   nasolabialis  and  levator  labii  maxillaris  muscles
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