554 



DISSECTION OF THE FACE 



Orbital or 

 external, 



attached 

 internally ; 



forms con- 

 centric 

 bundles. 



Internal or 



palpebral 



part. 



attached at 

 both ends. 



Ciliary 

 bundle. 



Relations. 



Use of inner 

 and 



outer fibres. 



Corrufjator 

 supercilli 



inserted into 

 skin: 



Muscles of 

 the mouth. 



The orbital fibres are the best marked, and are fixed only at the 

 inner side of the orbit. Above the internal tarsal ligament (which 

 is the short fibrous band at the junction between the two eyelids, 

 stretching from the palpebral fissure to the inner margin of the 

 orbit) the fibres are attached to the nasal process of the superior 

 maxillary and to the internal angular process of the frontal bone ; 

 and, below the ligament, to the orbital margin of the superior 

 maxillary bone. From this origin the fibres are directed outwards, 

 giving rise to ovals, which lie side by side, and increase in size 

 towards the outer edge of the muscle, where they project beyond 

 the margin of the orbit. Some of the peripheral fibres spread 

 upwards to the skin of the forehead, and others downwards to that 

 of the cheek. 



The palpebral fibres, paler and finer than the orbital, occupy the 

 eyelids, and are fixed at both the outer and inner sides of the orbit. 

 Internally they arise from the upper and lower margins of the internal 

 tarsal ligament : externally they end in the much smaller external 

 tar-sal ligament, by means of which they are attached to the malar 

 bone, and a few may blend with the orbital part of the muscle. 

 Close to the cilia, or eyelashes, the fibres form a small pale bundle, 

 which is sometimes called the ciliary bundle. 



The muscle is subcutaneous : and its circumference is blended 

 above with the frontalis. Beneath the upper half of the orbicularis, 

 as it lies on the margin of the orbit, is the corrugator supercilii 

 muscle with the supraorbital vessels and nerve ; and beneath the 

 lower half is a portion of the elevator of the upper lip. The outer 

 fibres are joined occasionally by slips to other contiguous muscles 

 below the orbit. 



Action. The palpebral fibres cause the lids to approach each 

 other, shutting the eye ; and in forced contraction the outer com- 

 missure is drawn inwards. In closing the eye the lids move 

 unequally the upper being much depressed, and the lower slightly 

 elevated and moved horizontally inwards. 



When the orbital fibres contract, the eyebrow is depressed, and 

 the skin over the edge of the orbit is raised around and brought 

 inwards in front of the eye, so as to protect the ball. Elevation of 

 the upper lip accompanies contraction of the outer part of the 

 orbicularis, owing to the associated action of the levator labii 

 superioris and zygomatic muscles. 



The CORRUGATOR SUPERCILII (fig. 203) is beneath the orbicularis, 

 near the inner angle of the orbit. Its fibres arise from the inner 

 part of the superciliary ridge of the frontal bone, and are directed 

 outwards between the bundles of the orbicularis to be inserted into 

 the skin above the inner half of the eyebrow. It is a short muscle, 

 and is distinguished by the closeness of its fibres. 



Action. It draws inwards and downwards the mid-part of the 

 eyebrow, wrinkling vertically the skin near the nose, and stretching 

 that outside its place of insertion. 



MUSCLES OF THE MOUTH (fig. 203). Tne muscles of the mouth 

 and lips include the elevators of the upper lip and of the angle of the 



