THE OCULOMOTOR MUSCLES 37 



functions is to bar conjunctival infections from the orbit where they 

 might do great damage to the eye and the brain. 



Becoming tendinous on passing through Tenon's capsule, the inser- 

 tions of the muscles fuse with the tissue of the sclera. Since the fascial 

 sheaths of the muscles are continuous with Tenon's capsule, it is possible 

 to dissect a diseased eye out of the capsule, and by sewing a ball into 

 the latter, provide a stump for an artificial eye which will move in har- 

 mony with the good eye of the other side. 



Fig. 16 — Oculomotor muscles of man, as seen from above in a dissected head. 



On the left, a portion of the superior oblique has been cut away to reveal the inferior 

 oblique; on the right, the superior rectus has been removed to permit a view of the inferior 

 rectus. Modified from Adler. 



io- inferior oblique; ir- inferior rectus; /r- lateral (external) reaus; mr- medial (internal) 

 rectus; n- optic nerve; p- pulley through which tendon of superior oblique passes; so- tendin- 

 ous portion of superior oblique; sr- superior rectus. 



Two Other muscles (Figs. 16 and 17) meet the superior and inferior 

 surfaces of the eyeball obliquely from the nasal side of the anterior part 

 of the orbit, where one of them, the 'inferior oblique' muscle, is attached. 

 The other, 'superior oblique', has however greatly lengthened phylogen- 

 etically and its origin has moved back toward that of the recti. Its side- 

 wise attack upon the eyeball was preserved throughout the backward 

 migration of its origin by the development of a tough ring or pulley, 

 through which it passes. The pulley formed at the old sub-mammalian 

 site of attachment of the muscle on the anterior nasal orbital wall. As 

 an anomaly, the muscle may atavistically end here, or a normal superior 



