OCULAR GROUP. 169 



the same time, by means of its osseous attachment, the integument and 

 lids inwards towards the nose. The corrugatores superciliorum draw 

 the eyebrows downwards and inwards, and produce the vertical 

 wrinkles of the forehead. The tensor tarsi, or lachrymal muscle, 

 draws the extremities of the lachrymal canals inwards, so as to place 

 the puncta in the best position for receiving the tears. It serves also 

 to keep the lids in relation with the surface of the eye, and compresses 

 the lachrymal sac. Dr. Homer is acquainted with two persons who 

 have the voluntary power of drawing the lids inwards by these 

 muscles so as to bury the puncta in the angle of the eye. 



3. Ocular group. Levator palpebrae, 

 Rectus superior, 

 Rectus inferior, 

 Rectus internus, 

 Rectus externus, 

 Obliquus superior, 

 Obliquus inferior. 



Dissection. To open the orbit (the calvarium and brain having 

 been removed) the frontal bone must be sawn through at the inner 

 extremity of the orbital ridge ; and, externally, at its outer extremity. 

 The roof of the orbit may then be comminuted by a few light blows 

 with the hammer ; a process easily accomplished, on account of the 



Fig. 83.* 



* The muscles of the eyeball ; the view is taken from the outer side of the 

 right orbit. 1. A small fragment of the sphenoid bone around the entrance 

 of the optic nerve into the orbit. 2. The optic nerve. 3. The globe of the 

 eye. 4. The levator palpebrse muscle. 5. The superior oblique muscle. 6. 

 Its cartilaginous pulley. 7- Its reflected tendon. 8. The inferior oblique 

 muscle, the small square knob at its commencement is a piece of its bony 

 origin broken off. 9- The superior rectus. 10. The internal rectus almost 

 concealed by the optic nerve. 11. Part of the external rectus, shewing its 

 two heads of origin. 12. The extremity of the external rectus at its insertion ; 

 the intermediate portion of the muscle having been removed. 13. The inferior 

 rectus. 14. The tunica albuginea, formed by the expansion of the tendons of 

 the four recti. 



