THE FACE. 9 



bearing is lost, as in facial paralysis or by a cicatrix near 

 the lid, the tears overflow the cheek. The length of the 

 lachrymal canals is from three to four lines. The lower is a 

 little shorter and wider than the upper. As each makes a 

 little angle in its course, about a line from its orifice, the lid 

 should be drawn outwards to straighten the canal when we 

 introduce a probe. 



1 6. Lachrymal sac. To find the lachrymal sac, draw 

 outwards the eyelids to tighten the tendo oculi, which crosses 

 the sac a little above its middle. A knife introduced just 

 below the tendon close to the edge of the orbit would enter 

 the sac. The angular artery and vein would be on the inner 

 side of the incision. A probe directed in a line with the inner 

 edge of the orbit, z>. downwards, outwards, and backwards, 

 would pass down the nasal duct, and appear in the inferior 

 meatus of the nose. 



The tendo oculi serves many purposes besides giving 

 attachment to the cartilages and muscles of the lids. One 

 purpose is said to be to pump the tears into the lachrymal 

 sac. Place a finger on the tendon, and feel that it tightens 

 every time the lids are closed. The tendon, being intimately 

 connected to the sac, draws, as it tightens, the sac wall out- 

 wards and forwards, and in this way it may pump along the 

 lachrymal canals any fluid collected at the angle of the eye. 



17. Nasal duct. The nasal duct is from six to eight 

 lines long, and narrowest in the middle of its course. Its 

 termination in the inferior meatus lies under the inferior 

 spongy bone, about a quarter of an inch behind the bony 

 edge of the nostril. The appearance of the orifice in the dry 

 bone conveys no idea of its size and shape in life ; for it is 

 diminished by a valve-like fold of mucous membrane, so that 

 it becomes, in most cases, a mere slit, not exceeding a line in 

 diameter. 



The facility with which instruments can be introduced 

 into the nasal opening of the duct depends upon its position 

 as well as its size. This position varies in different instances. 

 Sometimes it opens directly into the roof of the inferior meatus, 

 in which case the hole is large and round, so that tears readily 



