260 HEAD AND NECK 



the four recti muscles pass are prolonged backwards upon the 

 muscles, in the form of sheaths, much in the same manner 

 that the internal spermatic fascia is prolonged upon the 

 spermatic cord from the abdominal inguinal ring. The 

 sheaths gradually become more and more attenuated, until at 

 last they blend with the perimysium of the muscular bellies. 

 In the case of the superior oblique muscle the corresponding 

 prolongation is related only to the reflected portion of the 

 tendon ; and it ends by becoming attached to the fibrous 

 pulley through which the tendon passes. The sheath of the 

 inferior oblique may be traced upon the muscle as far as the 

 floor of the orbit. The ocular edge of each of the four 

 apertures through which the recti muscles pass is strengthened 

 by a slip of fibrous tissue (Lockwood), and as the fascia bulbi 

 is firmly bound to the bony wall of the orbit at various 

 points these slips act as pulleys, and protect the globe of the 

 eye from pressure during contraction of the muscles. .The 

 aperture for the superior oblique is not furnished with such 

 a slip, and it is doubtful if the opening for the inferior oblique 

 muscle possesses one. 



Dissection. An admirable view of the relations which the 

 fascia bulbi presents to the eyeball and the tendons of the ocular 

 muscles can be obtained by the following dissection : Divide 

 the lateral commissure of the eyelid up to the margin of the 

 orbital opening. Pull the eyelids widely apart, so as to expose 

 as much as possible of the anterior face of the eyeball. Next, 

 divide the conjunctiva, by a circular incision, just beyond the 

 cornea. Along that line the fascia bulbi is so intimately con- 

 nected with the conjunctiva that it is divided at the same time. 

 Now raise carefully both conjunctiva and fascia bulbi from the 

 surface of the eyeball, and spread them out round the orbital 

 opening, as is depicted in Fig. 98. The openings in the fascia 

 bulbi for the tendons of the ocular muscles and the thickened 

 margins of the apertures are well seen. Note also the sheaths 

 which are given to the muscles. 



Check and Suspensory Ligaments. The connections of 

 the fascia bulbi to the walls of the orbital cavity are 

 somewhat complicated. The suspensory ligament (Lockwood) 

 plays an important part in supporting the eyeball. It 

 stretches across the anterior part of the orbit, after the 

 fashion of a hammock ; its two extremities are narrow, 

 and are attached respectively to the zygomatic and lacrimal 

 bones. Below the eyeball it widens out and blends with 

 the fascia bulbi. The lateral and medial check ligaments 



