338 



HEAD AND NECK 



posteriorly. The levator palpebne superioris also may be cut midway 

 between its origin and insertion. On raising the posterior portion a 

 minute nerve twig will be seen entering its deep or ocular surface. 

 This comes from the superior division of the third or oculo-motor nerve. 



The eyeball should now be inflated. This may be done from the 

 front or from behind. If the latter method is selected, gently separate 

 the fat under cover of the superior rectus muscle, and push the ciliary 

 vessels and nerves away from the optic nerve. Next make a small incision 

 through the sheath of the nerve. Pass a ligature round the nerve anterior 

 to the opening, and then pass a blowpipe, provided with a stylet, through 

 the incision and along the nerve into the interior of the eyeball. When the 

 globe of the eye is fully inflated, the ligature may be tightened as the blow- 

 pipe is withdrawn. A very much better plan, however, is to inflate the 



eyeball from the front. For this 

 purpose make an oblique valvular 

 aperture in the sclero-corneal junc- 

 tion, with the point of a sharp 

 narrow - bladed knife. Through 

 this the blow-pipe may be intro- 

 duced, and on its withdrawal after 

 the inflation of the eyeball the 

 valvular character of the opening 

 is sufficient to prevent the escape 

 of the air. 



Posterior to the eyeball the dis- 

 sector will notice a quantity of 

 loose bursal-like tissue. This is 

 the fascia bulbi (O.T. capsule of 

 Tenon). Seize the upper part of 

 this with the forceps, and remove 

 a small portion with a pair of 



Diagram of the Superior scissors. An aperture is thus 

 (From Hermann ma de into the fascia, and the 

 handle of the knife can be intro- 

 duced into the space between it 

 and the eyeball. In favourable 



FIG. 134 



Oblique Muscle. 

 Meyer. ) 



a. Trochlea and synovial sheath. 



cases the extent of the fascia can be gauged, and perhaps even the pro- 

 longations or sheaths which it gives to the tendons of the ocular muscles 

 may be made out. The description of the fascia bulbi is given on p. 347. 



Musculus Rectus Superior. The rectus superior, which 

 lies under cover of the levator palpebrse superioris, is now 

 fully exposed. It arises from the upper margin of the optic 

 foramen, passes anteriorly above the optic nerve, and ends 

 upon the upper aspect of the eyeball in a thin, delicate tendon, 

 which expands somewhat to be inserted into the sclera about 

 three or four lines posterior to the sclero-corneal junction. 

 It is supplied by a branch from the superior division of the 

 oculo-motor nerve. 



Musculus Obliquus Superior. This muscle arises from the 

 roof of the orbit immediately anterior to the upper and 

 medial part of the optic foramen. It passes anteriorly, along 



