248 HEAD AND NECK 



muscle of the upper eyelid rests upon the upper surface of 

 the rectus superior. Posteriorly, it is narrow and pointed, 

 but it expands as it passes forwards, above the eyeball, to 

 the upper eyelid. It arises from the under surface of the 

 roof of the orbit, immediately anterior to the optic foramen 

 and, therefore, from the inferior surface of the small wing of 

 the sphenoid bone. In the anterior part of the orbital 

 cavity it widens out into a broad membranous expansion, 

 which splits into three lamellae. The most anterior lamella 

 is attached to the palpebral fascia of the upper eyelid and 

 by it to the upper tarsus. The middle lamella is attached 

 directly to the upper border of the upper tarsus. The 

 posterior lamella is attached to the upper margin of the 

 conjunctiva. The lateral and medial margins of the ex- 

 pansion are fixed to the rim of the orbital opening, in close 

 proximity to the medial palpebral ligament and the lateral 

 palpebrae raphe. By those attachments, excessive action of 

 the muscle upon the upper eyelid is checked. The levator 

 palpebrae superioris is supplied by the upper division of the 

 oculo-motor nerve, and it is the elevator not only of the 

 upper eyelid but also of the upper fornix of the conjunctiva. 



Dissection. Divide the frontal nerve and throw the ends 

 forwards and backwards. The levator palpebrae superioris also 

 may be cut midway between its origin and insertion. When 

 the posterior portion is raised a minute nerve twig will be seen 

 entering its deep or ocular surface ; it is a branch of the superior 

 division of the third or oculo-motor nerve. 



The eyeball should now be inflated. That 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 as the blowpipe is withdrawn. A very much better plan, how- 

 ever, is to inflate the eyeball from the front. For that purpose 

 make an oblique valvular aperture in the sclero-corneal junction, 

 with the point of a sharp narrow-bladed knife. Insert a blow- 

 pipe through the aperture, 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, at the sides of the superior rectus, 

 the dissector will notice a quantity of loose bursal-like tissue. 

 It is the fascia bulbi (O.T. capsule of Tenon}. Seize the upper 

 part of it with the forceps, and remove a small portion with a 

 pair of scissors. An aperture is thus made in the fascia, and the 



