230 THE NATURE AND TREATMENT OF 



MUSCLES OF THE EYE AND EYELIDS. 



The first muscle which attracts our attention on removing 

 the palpebral integument, is the orbicularis palpebrarum ; so 

 named from the spherical or circular arrangement of its mus- 

 cular fibres. It is inserted into the orbital ])ortion of the ungis 

 and OS frontis, to the palpebral ligament, and to the skin of the 

 lids. Its use is to shut the eyelids. 



Levator palpehrce Superioris. — The action of this muscle 

 is to corrugate and draw the lid upwards ; it is located above 

 the orbit and is attached to the forehead by means of an apo- 

 neurotic expansion, and is inserted into the upper eyelid, its 

 muscular fibres being blended with those of the preceding 

 muscle. Its action is to raise the upper eyelid, in which action 

 it is aided by the levator palpebrae, internus. 



Next we find four muscles known as recti ; viz., Levator 

 oculi, depressor oculi, abductor oculi, adductor oculi ; they are 

 inserted into the cavity of the orbit, and external part of the 

 sclerotica at points equi-distant from each other. The action 

 of these four muscles are as follows : The levator raises the 

 eyeball in a superior direction ; the depressor, as its name in- 

 dicates, depresses the eyeball ; the abductor turns the eyeball 

 from the axis of the body outwards ; and the adductor rotates 

 the eyeball inwards, or towards the axis of the body. 



The three remaining muscles, making seven proper, to the 

 eye, are named, obliquus superiora et inferiora, and retractor 

 oculi. The obliquus superioria, is found in 'the upper part of 

 the inner cavity of the orbit; is attached to the margin of the 

 optic foramen ; at the inner canthus of the eye, it passes through 

 a fibro-cartilaginous pulleylike arrangement, by which means 

 the eyeball is rotated in an oblique direction upwards and out- 

 wards. 



Obliquus Superioria. — This muscle is found beneath the 

 eyeball, in the front and lower part of the orbit, it is attached 

 to the OS unguis, and to the lower and outer part of the sclero- 

 tica at its junction with the transparent part of the globe. Its 

 action is antagonistic to that of the preceding muscle. 



