DISSECTION OF THE HEAD AND NECK. 



209 



number of ducts which open on the ocular surface of the upper eyelid, 

 close to the temporal canthus. The gland is to bie removed. 



The Levator Palpebr^: Supbriokis is described at page 175. 



The Mbmbrana Nictitans and its connection with the adipose tissue 

 of the cavity are described at page 173. 



Fig. 22. 



Muscles of the Eyeball, 



1 1 Sunerior oblique ; 2. Fibrous loop for the same ; 3. Superior rectus ; 4. Internal rectus ; 



5. External rectus; 6. Inferior rectus ; 7, 7, 7. FascicuU of the retractor ; 8. Cut origin of the levator 



of the upper eyelid ; 9. Nerve to inferior oblique. 



Muscles of the Ui/ehall.— These are seven in number, viz., four recti, 

 one retractor, and two oblique. (A third oblique muscle was described 

 by the late Professor Strangeways, of the Dick Veterinary College, but 

 its presence is, to say the least, not constant.) 



mrections.— The muscles are to be defined by detaching the eyelids 

 and conjunctiva from the front of the eye, and removing the levator 

 palpebras and the loose fat which forms a packing material between the 

 muscles. Special care must be taken not to injure the fibrous arch for 

 the tendon of the superior oblique at the inner side of the orbit. 



The Kboti. There are four of these, distinguished as the superior 

 rectus the inferior rectus, the external rectus, and the internal rectus. 

 They 'are placed one above, one below, and one on either side of, the eye. 

 They have all a flat riband-like form, and are terminated anteriorly by 

 aponeurotic tendons. They all take origin around the optic foramen, 

 and each becomes inserted into the forepart of the sclerotic. 



The Ebtractor Oculi is placed within the recti, and around the 



