. Human physiology. ts, it turns the eyeball ob-liquely outwards and inferior oblique muscle springsfrom the lower and front portion ofthe orbit, and passes obliquely back-wards and outwards. By its con-traction the front of the eyeball isturned upwards and outwards. The front of the eyeball is kept clean and moist by a saline Figs_ xg6 and „g7 The Muscles of fluid which is secreted continu- the Bight Orbit. OUSly by the lachrymal gland tj sphenoid bone: 1, muscle which rakes the(Lat. lachryma, a tear). This upper lid; 2, pulley and tendon of the superior gland is about the size
. Human physiology. ts, it turns the eyeball ob-liquely outwards and inferior oblique muscle springsfrom the lower and front portion ofthe orbit, and passes obliquely back-wards and outwards. By its con-traction the front of the eyeball isturned upwards and outwards. The front of the eyeball is kept clean and moist by a saline Figs_ xg6 and „g7 The Muscles of fluid which is secreted continu- the Bight Orbit. OUSly by the lachrymal gland tj sphenoid bone: 1, muscle which rakes the(Lat. lachryma, a tear). This upper lid; 2, pulley and tendon of the superior gland is about the size of a smallalmond, and is situated in theupper and outer portion of theorbit. It is very similar to the salivary glands in structure. It is pro-vided with several small ducts by which the lachrymal fluid is con-ducted to the upper surface of the eyeball. The fluid gradually movesover the surface of the ball, assisted by every motion of the eyelid,till it reaches the inner angle formed by the eyelids, having carried. oblique ; 3, tendon of the superior rectus ;4, external rectus—partly removed in ; 5, inferior oblique muscle ; 6, inferiorrectus ; 7, internal rectus ; 8, optic nerve. 204 ELEMENTARY PHYSIOLOGY with it any particles of dust which may have adhered to the lachrymal fluid now enters the nasal or lachrymal duct bymeans of two small lachrymal canals, and is then conveyed intothe nose. When there is a redundant secretion of the lachrymal fluid, suchas may arise from irritation of the conjunctiva by powerful vapours&c, or from some strong mental emotion, the nasal duct cannot
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