CAVirr OF THE ORBIT 



859 



an anterior and a posterior; the former continues a forward course, forming a 

 complete funnel-shaped investment all round, passing ultimately to the eyelids and 

 or))ital margin — whilst the latter turns backwards, covering the hinder third of the 

 globe. 



The anterior lainlna is a well-marked membrane everywhere, liut in certain 

 situations it presents si)ecial bands of thickening, corresponding to the direct c(»n- 

 tinuation forwards of the sheath of each rectus n)uscle. Above and below, this 

 lamina spreads out in the form of two large men)l)ranes, which are finally ap'i>lied 

 to the deep surface of the palt)ebral fascia; the lower membrane constitutes what 

 has been described as ' the suspensory ligament of the eyeball.' The upi>er mem- 

 brane recjuires a fuller description, as its distribution is modified by the presence of 

 the levator palpebrie muscle. 



The upper part of the sheath of the superior rectus (along Avith the adjoining 



Fig. 486.— Horizontal Section Through Left Orbit, viewed feoji auove. 

 (After Von Gerlach. To show check ligaments, etc. ) 



CONJUNCTIVAL FORNIX 

 LACHRYMAL GLAND 



Outer palpebral 

 ligament 



External cheek 

 ligament 



OUTER ORBITAL WALL 



External rectus 



ORBICULARIS 

 PALPEBRARUM 



SPACE OCCUPIED BY 

 SUBCONJUNCTIVAL 

 TISSUE, AND BY 

 TENON'S CAPSULE 

 FURTHER BACK 

 Upper part of 

 Horner's muscle 

 Palpebral fascia 



Internal check 

 ligament 



TENON'S SPACE 

 INNER WALL OF ORBIT 



OPTIC NERVE 

 Internal rectus 



ETHMOIDAL CELLS 



ni'jmbrane on each side of it) passes to the deep surface of the levator, to which it 

 closely adheres, and completely ensheaths this tendon by extending round its 

 borders to its upper surface. The lower part of this levator-sheath is api>lied to the 

 inferior surface of the deeper of the two divisions of the muscle (orbito-jxilpebral 

 muscle of Sappey, superior palpebral muscle of ^liiller), and is attached to the upjjcr 

 border of the tarsus of the upper lid, reaching laterally to the outer and inner angles 

 of the orbit. The upper part of the sheath of the orl)ito-palpel)ralis muscle reaches 

 to the middle of the jialpcbral fascia, and is mainly continued forward between the 

 muscle and the fascia to the anterior surface of the tarsus. 



The lower membrane (susi)ensory ligament of the eycl)all). joined by the sheath 

 of the inferior rectus, reaches forward to the attached (hinder) l)order of the tarsus 

 of the lower lid, where it is mainly attached, wliile a i«\rt of it extends to the lower 

 palpeljral fascia. 



