THE PROTECTIVE ORGANS OF THE EYE. 



471 



3. Besides the tarsus (fibrocartilage) the middle layer of the eye- 

 lid contains : (i) The musculus orbicularis oculi, which lies beneath 



Fig. 364. Vertical section of the upper eyelid of man; X 14: at, arterial arcus tar- 

 seus; c, cilia; dgt, excretory duct of Meibomian gland ; glc, ciliary gland (Moll) ; McK, 

 ciliary muscle of Riolani ; Mop, m. orbicularis palpebrarum ; Mt, nonstriated muscle-fibers 

 of the tarsal muscle and tendon of the levator palpebrae superioris ; nlc, lymph-node of 

 the conjunctiva palpebrae ; T, tarsus (Sobotta, "Atlas and Epitome of Histology."). 



the subcutaneous tissue. At the margin of the lid this structure 

 gives off the musculus ciliaris Riolani, which is composed of two 



