DEEP DISSECTION OF THE FACE. 1057 



of the orbit the insertions of these muscles may be more fully displayed. 

 The contents of the orbit may be afterwards divided behind and turned 

 forward, to admit of the tensor tarsi muscle and the lachrymal sac being 

 dissected. Finally, if the subject be favourable, the nasal nerve may be 

 traced through the ethmoid bone to its distribution in the interior of the 

 nares, and its external twig to the tip of the nose examined. 



8. Deep view of the Fifth Nerve. Spheno-palatine and Otic Ganglia. 

 Internal Ear. After the dissection of the orbit has been completed, the 

 foramen rotundum and infraorbital canal are to be laid open, and the supe- 

 rior maxillary nerve and its orbital and dental branches dissected (p. 600). 

 Remove with the saw a further portion of the skull towards the meatus 

 externus, reaching as far as the foramen spinosum, and with the chisel or 

 nippers cut down close to the foramen ovale ; remove also a portion of the 

 bone above the pterygoid processes so as to open up the spheuo- maxillary 

 fossa, and the spheno-palatine ganglion will be brought into view. The con- 

 nection of the ganglion with the superior maxillary nerve may then be made 

 out. Trace the nasal and naso-palatine branches of the ganglion through the 

 ppheno-palatine foramen, and the palatine branches passing downwards. Lay 

 open the Vidian canal and dissect the Vidian nerve back to the great 

 superficial petrosal nerve (p. 603). At the same time the infraorbital, 

 spheno-palatine, descending palatine, and Vidian branches of the internal 

 maxillary artery will be noted (p. 356). The otic ganglion may also be 

 in part seen by breaking open the foramen ovale, following upwards the 

 nerve of the internal pterygoid muscle, and slightly everting the trunk of 

 the inferior maxillary nerve (p. 608). The twigs from this ganglion to the 

 tensor palati and tensor tympani muscles may be found. The otic ganglion, 

 however, can only be seen to advantage in dissections made from the 

 inner side of the internal pterygoid muscle and inferior maxillary nerve. 

 The Eustachian tube may be laid bare in the posterior part of its course, 

 and may be opened, and the attachment of the tensor tympaui above it 

 shown (p. 747). 



By now sawing the wall of the skull down to the margin of the external 

 auditory meatus, and removing with the bone-nippers, cautiously, the ante- 

 rior wall of the meatus externus, the membrana tympani may be exposed ; 

 and by unroofing the tympanic cavity in continuation of the Eustachian 

 tube backwards, the malleus, incus, and st ipes, as well as the tendon of the 

 tensor tympani muscle, will be brought into view (p. 748). The mode of 

 action of the latter on the membrana tympani may be studied ; also the 

 chorda tympani nerve will be seen traversing the cavity. The malleus and 

 incus are to be carefully removed ; then, placing one point of the bone- 

 nippers in the internal auditory meatus, lay open with the other the vesti- 

 bule and cochlea, and let the relation of the portio mollis and portio dura 

 nerves to these cavities be observed (pp. 610 and 615). The manner in 

 which the stapes fits into the fenestra ovalis may now be seen to ad- 

 vantage, the tendon of the stapedius muscle requiring, however, to be 

 cut across before that ossicle can be removed. With the aid of the 

 bone-nippers, the fleshy part of the stapedius may be laid bare, 

 descending in the mastoid part of the temporal bone, close to the facial 

 nerve ; and, in favourable circumstances, the chorda tympani may be traced 

 back to the facial nerve. 



9. Submaxillary and SuUingual Regions. Let the lower jaw be divided 

 in front of the masseter muscle, and let the gustatory and mylo-hyoid 

 nerves be followed from the pterygoid into the submaxillary region. The 



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