1038 



ORGANS OF SPECIAL SENSE 



connected with the dunil sheath of the optic nerve. As it covers the inferior or- 

 bital (spheno-maxillary) fissure its fibres are interwoven with smooth muscle, forming 

 the orbital muscle of Miiller. From its inner surface processes run into the orbital 

 cavity, separating the fat lobules. One important process comes from the periorbita 

 about midway along the roof of the orbit, runs forwards to the back of the upper 

 division of the lachrymal gland, and there splits, helping to form the gland-capsule: 

 this capsule is joined at its inner border by other periorbital bands coming off near 

 the upper orbital rim, and forming the suspensory ligament of the gland. On the 

 inner side of the orbit the periorbita sends fibrous processes to the trochlea of the 

 superior oblique, which keep it in position. On arriving at the lachrymal groove 

 the periorbita divides into two layers, a thin posterior one continuing to line the 

 bone forming the floor of the groove, whilst the thicker anterior layer bridges over 

 the groove and the sac which lies in it, forming the limbs of the inner palpebral 

 ligament (page 1046). 



FIG. 737. VERTICAL SECTION THROUGH THE EYEBALL AND ORBIT IN THE DIRECTION OP 

 THE ORBITAL Axis, WITH CLOSED EYELIDS. 



(Semi-diagrammatic. After Schwalbe, modified to show fasciae.) 

 Periorbita green; muscle-fascia red; Tenon's capsule yellow. 



SKIN OF LOWER LID 

 LOWER TARSUS 



Palpebral fascia and 

 ant. lamina of muscle- 

 fascia 



.Orbicularis oeuli 

 Extension of sheath of - 

 inferior reetus to 

 lower eyelid 



FORNIX CONOUNCTIV/E 



Inferior oblique muscle, cut 

 across 



Posterior lamina of muscle- 

 fascia 



SUPRAVAGIXAL SPACE CONTINUOUS 



WITH TENON'S SPACE 

 SPtCE OCCUPIED BY ORBITAL FAT. PRO- 

 CESSES OF FASCIA SEPARATING THE 

 LOBULES AND ENCLOSING BLOOD- 

 VESSELS Inferior rectus 



SKIN OF UPPER LID 

 UPPER TARSUS 

 CORNEA 



Orbicularis oouli 



UPPER RIM OF ORBIT, WITH 

 Splitting of periorbita 



Upper or anterior insertion 

 of levator palpebras 



Superior palpebral muscle of 



FORNIX CONJUNCTIV/t [Muller 



Connection between levator 



palpebrae and aup. rectus, 



and fibres to conjunctiva 



PROCESS FROM PERIORBITA TO 

 CAPSULE OF LACHRYMAL GLAND 



Superior rectus 



Levator palpebra; superioris 



Posterior lamina of muscle- 

 fascia lined by prolongation of 

 Tenon's capsule 



OPTIC NER VE 



Quite anteriorly, at the rim- of the orbit, the periorbita sends off a membranous 

 process which aids in forming the fibrous tissue of the eyelids (orbito-tarsal liga- 

 ment, or palpebral fascia), and is itself continuous with the periosteum of the 

 bones outside the orbital margin. 



2. The T orbital muscles are connected by a common fascia, which splits at their 

 borders and furnishes a sheath to each. Processes of this fascia give membranous 

 investments for the vessels and nerves (including the optic nerve), splitting similarly 

 to enclose them; these membranous processes also assist in separating the fat lob- 

 ules. Posteriorly, this fascia is thin and loose, and blends with the periorbita at 

 the origin of the muscles. Anteriorly, it becomes thicker and firmer, accompanies 

 the muscles to near the equator of the eyeball, and there divides into two lamina, 

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

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



