88 
MAMMALIAN ANATOMY 
chip away the roof of this fossa by means of bone forceps, and 
thus disclose the eyeball and its surroundings in situ. Keeping 
each nerve intact, remove bit by bit the packing of areolar tissue 
and fat until finally the various muscles and their innervation are 
correctly and conclusively demonstrated, and their identification 
made certain by reference to the accompanying tabulation. 
Record this dissection of the eyeball surroundings and innervation 
by a series of drawings. 
Early in this dissection, the large lacrimal (tear) gland will 
be noted between the eyeball and the outer dorsal region of the rim 
of the orbit. Incidentally, also, note the course of the superior 
and inferior ophthalmic branches of the trigeminal nerve, as they 
cross the medial and lateral regions of the orbit respectively, 
each giving off small branches to supply local regions. Skillful 
dissection will disclose, also, the ciliary ganglion (sympathetic) 
located lateral to the optic nerve. Note connections between 
this ganglion and the oculomotor nerve, and trace numerous small 
nerves from the ganglion to the eyeball. As the dissection 
continues, after the trochlear, abducent, and superior branch of 
the oculomotor nerve have been traced to the muscles which they 
innervate, and the relationships thus worked out have been 
recorded, these muscles, together with the optic nerve, may 
be severed a short distance from their insertion into the eyeball, 
and the eyeball thus in part set free may then be turned forward 
thus giving access to the muscles which are more deeply located 
and are innervated by the inferior branch of the oculomotor. 
Retain all of the nerve and muscle connections which are worked 
out so that after the dissection is completed, all of the relation¬ 
ships may be clearly demonstrated. 
The Eyeball (if possible fresh material should be used).—Note 
that in removing the eyeball the thin layer of skin, the 
conjunctiva, which covers the front, or exposed surface, of the eye¬ 
ball, has been cut leaving intact, probably, the thin, cartilage- 
supported, semilunar fold (third eyelid or nictitating membrane) 
which crosses obliquely the medial region of the eyeball and has 
connected with it a firm mass, the Harderian gland. These 
structures may be used, together with the lacrimal gland and the 
openings of its ductules under the lateral region of the upper 
