140 



PRACTICAL ANATOMY. 



The nerve is a branch of the frontal part of the ophthalmic, itself a branch of 

 the fifth cranial nerve. 



3. The trochlea is found on the inner wall, near the base of the orbit. 

 Around this trochlea plays the tendon of the superior oblique muscle of the 

 eyeball. (Fig. 100.) Here, too, occurs the anastomosis between the supra- 

 trochlear branch of the frontal and the infratrochlear branch of the nasal nerve. 



The nasal duct has its beginning in the internal inferior angle of the orbital 

 base. (Fig. 104.) By this duct excessive tears reach the nasal fossae. 



PALPEBRAL FISSURE 

 INNER CANTHUS 



OUTER CANTHUS 



TENDO OCULI DELAMINATES INTO SUPERIOR AND 

 INFERIOR PALPEBRAL RAMI 



Tendo oouli or internal tarsal 

 ligament 



INFERIOR TARSAL LIGAMENT 



FIG. 93. TENDO OCULI AND TARSAL CARTILAGES. 



The infraorbital nerve (Fig. 51), emerges from the orbit by the infraorbital 

 foramen just below the base of the orbit. This sends off anterior superior 

 branches to the teeth just prior to its emergence. 



The tendo oculi crosses the lachrymal sac in front (Fig. 94), giving off an 

 aponeurosis to the same. Observe the caruncula lachrymalis between the t\vo 

 diverging rami of the tendo oculi. 



The tendo oculi, or internal tarsal ligament, has its origin from the nasal 

 process of the superior maxilla. (Fig. 10.) The superior and inferior tarsal 



1 1 15J 



FIG. 94. RELATIONS OF THE EYE AND THE LACHRYMAL EXCRETORY APPARATUS. 

 I, I. Canalicirii. 2, 2. Puncta lachrymalia. 3, 3. Inner extremity of tarsal cartilage. 4, 4. Free 

 borders of lids. 5. Lachrymal sac. 6. Attachment to maxillary bone of superior tendon. 7. Bifur- 

 cation of lachrymal sac. 8, 8. Two branches. 



ligaments, of periosteal derivation (Fig. 21), are attached to the margin of the 

 base of the orbit both above and below. The external tarsal ligament is not 

 divided. 



The Angles of the Orbit. 



1 . The superior internal. This contains the anterior and posterior etJnnoidal 

 foramina. The former transmits the anterior ethmoidal artery and nasal nerve ; 

 the latter, the posterior ethmoidal artery. 



2. The superior external angle. This contains in front the lachrymal fossa 

 already described, and posteriorly the sphcnoichil fissure. This fissure transmits 



