348 HEAD AND NECK 



with the conjunctiva close to the margin of the cornea. 

 Posteriorly, it fuses with the sheath of the optic nerve where 

 the nerve pierces the sclera. The internal surface of the 

 membrane (i.e. the surface towards the globe of the eye) is 

 smooth, and is connected to the eyeball by some soft yielding 

 and humid areolar tissue, the interval between them con- 

 stituting, in fact, an extensive lymph space called the spat in m 

 interfasdale. Its external surface is in contact posteriorly 

 with the orbital fat, to which it is loosely adherent ; and it is 

 firmly attached to the ocular conjunctiva more anteriorly. It 

 obviously, therefore, forms a membranous socket in which 

 the eyeball can glide with the greatest freedom. 



The tendons of the various ocular muscles are inserted 

 into the eyeball within this fascia, and they gain its interior 

 by piercing the membrane opposite the equator of the globe 

 (Fig. 139). The lips of the openings through which the four 

 recti muscles pass are prolonged posteriorly upon the muscles, 

 in the form of sheaths, very much in the same manner that 

 the infundibuliform fascia is prolonged upon the spermatic 

 cord from the abdominal inguinal ring. These 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 its reflected portion ; when it 

 reaches the pulley it ends, by becoming attached to its 

 margins. The sheath of the inferior oblique may be traced 

 upon the muscle as far as the floor of the orbit. The medial 

 or 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 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. At this point the fascia bulbi is so intimately connected 

 with the conjunctiva that it is divided at the same time. Now raise care- 



