VOL. LXXXIV.] PHILOSOPHICAL TRANSACTIONS. 4O9 



traction, and yet the eye be capable of adapting itself to the different distances 

 of objects. For a more full refutation of these opinions, see Haller's large 

 work. 



On the Situation, Structure, and Action of the External Muscles*. 



On carefully removing the eyelids, with their muscles, we are presented with 

 the muscles of the eye itself, which are 6 in number; 4 called recti, or straight; 

 and 2 oblique; so named from their direction, (see fig. 7.) a a a a, the ten- 

 dons of the recti muscles, where they are inserted into the sclerotic coat, at the 

 anterior part of the eye. b, the superior oblique, or trochlearis, as sometimes 

 called, from its passing through the loop or pulley connected to the lower angle 

 of the orbiter notch in the os frontis; it passes under the superior rectus muscle, 

 and backwards to the posterior part of the eye, where it is inserted by a broad 

 flat tendon into the sclerotic coat, c, the inferior oblique, arising tendinous from 

 the edge of the orbiter process of the superior maxillary bone, passes strong and 

 fleshy over the inferior rectus, and backwards under the abductor to the posterior 

 part of the eye, where it is also inserted by a broad flat tendon into the sclerotic 

 coat. DDD, the fat in which the eye is lodged. In fig. 8, we have removed 

 the bones forming the external side of the orbit, with a portion of the fat, by 

 which we have a distinct view of the abductor, abc, 3 of the recti muscles, 

 arising from the back part of the orbit, passing strong, broad, and fleshy over 

 the ball of the eye, and inserted by flat, broad tendons into the sclerotic coat, at 

 its anterior part, d, the tendon of the superior oblique muscle, e, the inferior 

 oblique, fig. Q. a, the abductor of the eye. b, the fleshy belly of the supe- 

 rior oblique, arising strong, tendinous, and fleshy from the back part of the orbit. 

 c, the optic nerve, d and e, the recti muscles. 



The use ascribed to these different muscles, is that of changing the direction 

 of the eye, to turn it upwards, downwards, laterally, or in any of the interme- 

 diate directions, accommodated either to the different situation of objects, or to 

 express the different passions of the mind, for which they are peculiarly adapted. 

 But is it inconsistent with the general laws of nature, or even with the animal 

 economy, that from their combination they should have a different action, and 

 thus an additional use? To illustrate this we need only witness the action of al- 

 most any set of muscles in the body; for example, in lifting a weight, the com- 

 bined action of the muscles of the arm, shoulder, and chest, is different from 

 the individual action of either set, or of any individual muscle; or an instance 

 nearer our purpose may be adduced, viz. the actions of the muscles of the chest 



• For the accuracy of the representation I have annexed (In figs. 7, S, 9.) I can vouch, having 

 been at much pains in the dissection ; from which I had the painting taken by a most accurate hand, 

 Mr. S. Edwards, a gentleman well known tor his abilities in the plates of that admirable work, the 

 Flora Londinensis. — Orig. ^ 



VOL. XVII. 3 G 



