DISSECTIOA' OF THE EYE. 89 



1. The External Rectus Muscle lies on the outer 

 surface of the eyeball ; it arises from the bony portion 

 of the orbit round the optic foramen, and is inserted 

 by a flat tendon into the outer surface of the eyeball 

 beneath the conjunctiva. 



2. The Inferior Rectus Muscle lies alona: the lower 

 surface of the eyeball, and has the same general inser- 

 tion and origin as the internal rectus, arising also 

 from the bone round the optic foramen where the op- 

 tic nerve enters the orbit. Its fibres do not lie exactly 

 along the vertical meridian of the eyeball, so that its 

 contraction will not rotate the eyeball directly down- 

 ward. 



3. The Superior Rectus Muscle lies along the upper 

 surface of the eyeball ; it arises also from the bone 

 round the optic foramen, and is inserted into the eye- 

 ball on its upper surface. Owing to the direction of 

 its fibres its pull will not rotate the eyeball directly up- 

 wards. Along the inner edge of this muscle a muscular 

 slip may be seen, passing to the inner and upper angle 

 of the orbit ; this slip forms part of the levator palpe- 

 brse superioris, not one of the muscles of the eyeball. 



4. The Internal Rectus Muscle lies along the inner 

 side of the eyeball. It arises from the bone round 

 the optic foramen, and passes forward to be inserted 

 into the inner aspect of the eyeball. 



5. The Inferior Oblique Muscle will be found along 

 the lower and outer side of the front of the eyeball. 

 Its fibres arise from the front portion of the floor of 

 the orbit, from the orbital portion of the maxillary 

 bone, and passing outward obliquely round the eye- 

 ball are inserted over the tendon of the external rectus 

 muscle. 



6. The Superior Oblique Muscle. The muscular 



