THE EYE 



205 



transfusion of oxygen from the air. The haemorrhage may 

 descend between the superior tarsus and the conjunctiva, and 

 subsequently appear at the margin of the upper eyelid. Finally, 

 it may ascend on the outer surface of the tarsus and become 

 subcutaneous. 



Subconjunctival haemorrhage may arise from the con- 

 junctival vessels as the result of a blow on the eye, but in these 

 cases the haemorrhage begins near the cornea. 



The Lacrimal Gland lies in contact with the antero-lateral 

 part of the roof of the orbit. Its posterior portion rests on the 

 eyeball, but an- 



' Lacrimal puncta 

 Lacrimal ducts 



Lacrimal sac 



Naso-lac 



Maxillary sinu 



Plica lacrimalis 



Inferior tneatus 



FIG. 62. Diagram of the Naso-lacrimal Duct 

 and its Connections. 



teriorly it is in con- 

 tact with the superior 

 fornix of the con- 

 junctiva, and this 

 portion of the gland 

 can just be made 

 out when the upper 

 eyelid is everted. 

 Numerous small 

 ducts leave the gland 

 and open into the 

 conjunctivalsac near 

 the superior fornix. 

 The tears pass across 

 the eyeball by the 

 action of gravity, 

 aided by the periodic 

 contractions of the 



orbicularis oculi, and reach the puncta on the medial side. These 

 are small openings placed on the summits of papillae, which are 

 situated on the free margins of the lids near their medial ex- 

 tremities. They are kept in apposition with the conjunctiva by 

 the action of the inferior tarsal (tensor tarsi) muscle, which is 

 a part of the orbicularis oculi, and is supplied by the facial 

 nerve. The condition of epiphora results from the paralysis of 

 this muscle. The puncta lead into the lacrimal ducts, which at 

 first run for a short distance at right angles to the lid margins, 

 and then turn medially to enter the lacrimal sac (Fig. 62). 



The Lacrimal Sac lies behind the medial palpebral (tarsal) 

 ligament. Abscesses in the sac should be incised just below 

 the ligament, the position in which they usually point, and 



