98 THE MUSCLES. 
inserted into the whole extent of the upper eyelid, especially 
near the caudal angle. Here the fibres unite with those of the 
orbicularis oculi (c). 
This muscle is continuous caudad with the intermedius 
scutulorum (a), craniad with the orbicularis oculi (c); laterad 
with the corrugator supercilii lateralis (7). Toward the medial 
side the fibres lose themselves in a tendinous sheet that joins 
the galea aponeurotica. 
Relations.—Outer surface with the integument. Inner sur- 
face with the frontoscutularis and the skull. 
Action.—Raises the upper eyelid. 
M. orbicularis oculi (Fig. 63, c; Fig. 64, s).—This con- 
sists of two thin bands of muscle-fibres which lie one in either 
eyelid parallel to its border and unite at the angle of the eye. 
Origin by short tendon-fibres from a tubercle on the surface 
of the frontal process of the maxillary bone just dorsad of the 
orbital end of the lachrymal canal and between the two parts 
of the quadratus labii superioris (Fig. 63, # and 9). 
The muscle splits into.two parts which pass into the two 
eyelids. At the outer angle of the eye the two bands unite 
by the intervention of tendon-fibres between the muscle-fibre 
bundles of the two. 
Relations. —Outer surface with the integument. Inner sur- 
face with the inner membrane of the eyelid. 
Action. —Closes the eye. 
M. corrugator supercilii lateralis (Fig. 63, d; Fig. 64, &). 
—tThis consists of a number of scattered fibres which arise from 
among the fibres of the frontoscutularis, and from the tendon 
lying just craniad of the external opening of the ear, to which 
are united also parts of the zygomaticus (Fig. 64, @) and sub- 
mentalis (Fig. 64, ¢). The fibres pass craniad, converging so 
as to form a narrow band which is inserted at the caudolateral 
angle of the eye, where it unites with the orbicularis oculi 
(Fig. 64, s). This muscle is continuous on the medial side 
with the corrugator supercilii medialis (Fig. 64, 7) and the 
frontoauricularis, on the lateral side with the platysma. 
Relations.—-Outer surface with the integument. Inner sur- 
face with the frontal bone and the frontoscutularis. 
