THE SPECIAL SENSES 



817 



its utter loss may result from tobacco smoking, the optic nerve 

 being gradually impaired, as in the case of those who lose their 

 sight by alcohol, as described in the foregoing paragraph of 

 this Chapter, Section 109. There is a relief for this approach- 

 ing blindness if the patient will consent to wholly abstain from 

 tobacco ; and yet, " there are those who would rather smoke 

 than see," and persist in the injurious habit in spite of every 

 proper medical caution. 



115. Certain narcotic substances have an injurious influence 

 over the. sense of hearing ; among these are tobacco and coffee 

 used in excess. The opium habit is injurious to the sense of 

 sight. 



Contents of the Orbit 



THE EYE 



Lids 



Muscles 



Lachrymal 

 apparatus 



TOPICAL OUTLINE 



Eyeball. 

 Muscles. 

 Blood-vessels. 

 Nerves. 

 Fatty tissue. 



Lachrymal or tear apparatus. 

 Consist of folds of the skin. 

 Lined with a mucous membrane (the conjunc- 

 tiva) , which is also reflected over the front of 

 the ball. 



Closed by the circular orbicularis muscle. 

 . Upper lid raised by a special muscle. 



(Superior turns the eyeball up- 

 wards. 

 Inferior turns the eyeball down- 



wards. 

 External turns the eyeball 



outwards. 



Internal turns the eyeball in- 

 wards. 

 Superior turns the eyeball 



outwards and downwards. 

 Inferior turns the eyeball out- 

 wards and upwards. 

 ( Lachrymal gland in the upper and outer part 



of the orbit. 

 { Several small ducts. 



f Constant. 

 [ Secretion . . j Moistens the eyeball. 



[ Carried off by the nasal duct. 



4Recti 



2 Oblique 



115. Have alcohol and tobacco together any Influence t Other Injuries t 



