144 



PR A CT1CAL ANA TO MY. 



The external rectus muscle lies to the outer side of the optic nerve. It is 

 attended by the lachrymal nerve, a branch of the ophthalmic nerve, and the 

 lachrymal artery, a branch of the ophthalmic artery. You will dissect the 

 three together and associate them in your memory. The lachrymal structures 

 are on their way to the lachrymal gland. Turn the external rectus muscle 



Tendon of superior oblique 



Internal reotua 



Inferior oblique muscle 



Levator palpebrse super- 



ioris, out 

 Superior rectus 



External rectua 



Inferior rectus 



KIG. 99. LEFT EYEBALL SEKN IN ITS NOKMAL POSITION IN THE ORBIT, WITH VIEW OF TIN 

 OCULAR MUSCLES. (After Merkel, modified.) 



FIG. too. MUSCLES OF THE EYF;. TENDON OR LIGAMENT OF ZINN. 



I. Tendon of Zinn. 2. External rectus divided. 3. Internal rectus. 4. Inferior rectus. 5. Superior 

 rectus. 6. Superior oblique. 7. Pulley for superior oblique. 8. Inferior oblique. 9. Levator 

 palpebne superioris. 10, 10. Its anterior expansion. II. Optic nerve. 



outward, and on its inner surface you will see the fine filaments of the sixth 

 cranial nerve the abducens. 



The Superior Oblique Muscle and the Fourth Nerve (Fig. 97). These 

 lonn a group by themselves. You will trace the tendon of this muscle around 

 the trochlea, where it turns at a right angle and passes outward under the 



