EYEBROWS EYELIDS. 453 



APPENDAGES OF THE EYE. 



The Appendages of the Eye (tutamina oculi) are, the eyebrows, eye 

 lids, eyelashes, conjunctiva, caruncula lachrymalis, and the lachrymal ap- 

 paratus. 



The Eyebrows (supercilia) are two projecting arches of integument 

 covered with short thick hairs, which form the upper boundary of the 

 orbits. They are connected beneath with the orbiculares, occipito-fron- 

 tales, and corrugatores superciliorum muscles ; their use is to shade the 

 eyes from too vivid a light, or protect them from particles of dust and 

 moisture floating over the forehead. 



The Eyelids (palpebrce) are two valvular Fig. 203.* 



layers placed in front of the eye, serving to 

 defend it from injury by their closure. When 

 drawn open, they leave between them an ellip- 

 tical space, the angles of which are called 

 canthi. The outer canthus is formed by the 

 meeting of the two lids at an acute angle. 

 The inner canthus is prolonged for a short 

 distance inwards towards the nose, and a 

 triangular space is left between the lids in this 

 situation, which is called the lacus lachrymalis. 

 At the commencement of the lacus lachrymalis 

 upon each of the two lids is a small angular 

 projection, the lachrymal papilla or tubercle ; and at the apex of each 

 apilla a small orifice (punctum lachrymale), the commencement of the 

 achrymal canal. 



The eyelids have, entering into their structure, integument, orbicularis 

 muscle, tarsal cartilages, Meibomian glands, and conjunctiva. 



The tegumentary areolar tissue of the eyelids is remarkable for its loose- 

 ness and for the absence of adipose substance ; it is particularly liable to 

 serous infiltration. The fibres of the orbicularis muscle covering the eye- 

 lids, are extremely thin and pale. 



The Tarsal cartilages are two thin lamella? of fibro-cartilage about an 

 inch in length, which give form and support to the eyelids. The superior 

 is of a semilunar form, about one-third of an inch in breadth at its middle, 

 and tapering to each extremity. Its lower border is broad and flat, its 

 upper is thin, and gives attachment to the levator palpebra? and to the 

 fibrous membrane of the lids. 



The Inferior Jib ro-cartilage is an elliptical band, narrower than the su- 

 perior, and situated in the substance of the lower lid. Its upper border 

 is flat, and corresponds with the flat edge of the upper cartilage. The 

 lower is held in its place by the fibrous membrane. Near the inner can- 

 thus the tarsal cartilages terminate, at the commencement of the lacus lach 



* The appendages of the eye. 1. The superior tarsal cartilage. 2. The lower border 

 of the cartilage on which are seen the openings of the Meibomian glands. 3. The infe 

 rior tarsal cartilage ; along the upper border of this cartilage the openings of the Meibo- 

 mian glands are likewise seen. 4. The lachrymal gland ; its superior or orbital portion. 

 5. Its inferior or palpebral portion. 6. The lachrymal -ducts. 7. The plica semilunaris, 

 8. The caruncula lachrymalis. 9. The puncta lachrymalia of the lachrymal canals 

 10. The superior lachrymal canal. 11. The inferior lachrymal canal. 12. The lachry 

 m:l sac. 14. The dilatation of the nasal duct, where it opens into the inferior meatm 

 of the nose. 15. The nasal duct. 



