- WILLARD: CRANIAL NERVES OF ANOLIS CAROLINENSIS. 31 
I. MUSCLES. 
1. MuSCLES OF THE ORBIT. 
This group includes the muscles of the eyeball proper and those of 
the eyelid, or their derivatives. The former are the dorsal, ventral, 
anterior, and posterior recti, and the dorsal and ventral oblique, to- 
gether with the m. retractor oculi and m. bursalis. Those of the eyelid 
consist of the m. depressor palpebrae inferioris and its specialized part, 
m. protrusor oculi (Bruner). 
Mm. rectus posterior (exiernus), bursalis, and retractor oculi. Not 
only in their innervation but also in their skeletal connections, these 
muscles form one group, having a more posterior origin than any of 
the other muscles of the eyeball. The bursalis (brs.) and the retractor 
oculi (rtr. oc.) arise close together within the basisphenoid bone 
(Plate 6, fig. 16), that of the bursalis being on the inner lateral surface 
of the bony cap containing the distal end of the pituitary body. The 
area of origin of the fibers of the retractor forms a median forward 
continuation of that of the bursalis; the two muscles then run rostrad 
| together into the orbit, where they separate (Plate 5, figs. 14, 15). 
| The bursalis fibers bend rather sharply dorsolaterad within the orbit 
| to be inserted on the posterior median side of the eyeball, thus offering 
a sort of loop through which passes the tendon from the nictitating 
membrane (Plate 5, fig. 14, tnd. mb. nic.). 
The retractor oculi passes directly forward across the floor of the 
orbit as a relatively slender muscle to be inserted on the median side 
of the eyeball anterior and ventral to the optic nerve (Plate 5, figs. 
13, 14). 
Somewhat anterior to the origin of these the posterior rectus arises 
from the presphenoid bone (presph.) along the median line and passes 
directly out around the posterior side of the orbit to its insertion on 
the eyeball (Plate 3, fig. 7 and Plate 5, fig. 15, rt. p.). 
Mm. recti dorsalis and ventralis. These muscles arise at the same 
cross-section level as the rectus posterior, but dorsal to it, from a 
nedian fascia between the presphenoid and a cartilaginous rod which 
sontinues forward from the inner lamellae of the basisphenoid bone 
‘Plate 5, fig. 15, rt. d., rt. v.). The one passes dorsal to the optic nerve, 
he other ventral, sind each spreads out into a broad fan-like insertion 
e the dorsal and ventral sides of eyeball respectively (Plate 5, figs. 
12, 18). 
) 
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