638 THE EYE 



crystals giving to these eyes an iridescent sheen, and is known as the 

 tapetum cellulosum. 



THE CILIARY BODY 



The ciliary body (corpus ciliare} represents the thickened anterior 

 border of the choroid coat. It is, therefore, of annular shape and occu- 

 pies a zone whose posterior border blends with the choroid at a 

 point opposite the ora serrata of the retina, and whose anterior 

 margin is continued into the iris opposite the sclerocorneal junction. 

 It may be said to consist of three structures arranged in layers of vary- 

 ing thickness: 1, the ciliary muscle; 2, the fibrous layer with its ciliary 

 processes; and 3, that portion of the pigmented epithelium of the retina 

 which constitutes the pars ciliaris reiince or ciliary epithelium, and 

 covers the inner surface of the ciliary body. The suspensory ligament of 

 the crystalline lens is attached to the inner surface of the retinal epithe- 

 'lium of the ciliary processes and grooves. 



The ciliary muscle consists of an annular mass of non-striated fibers 

 which arise from the inner surface of the sclera near the sclerocorneal 

 junction, and are inserted into the entire breadth of the fibrous mass 

 of the ciliary body as far back as the anterior margin of the choroid. 

 The muscle fibers are divisible into three sets, according to the direction 

 of their long axis; these are the meridional, the radial, and the 

 circular. 



The meridional fibers form the outer and greater portion of the mus- 

 cle. They begin, just posterior to the corneal margin, taking their 

 origin from the inner surface of the sclera, and radiate backward in a 

 meridional direction for a variable distance, to be finally inserted into 

 the fibrous bundles of the posterior half of the ciliary body (ciliary ring), 

 the longest fiber bands passing as far back as the choriociliary junction, 

 where they are attached to the anterior margin of the choroid. 



The radial fibers simulate the meridional fibers in that they radiate 

 from the corneal margin. They pursue, however, a shorter course. 

 From their origin they pass backward with a sharp inward curve to 

 assume a direction which approaches that of the radii of the ocular globe 

 (hence their name) ; they are inserted into the anterior half of the fibrous 

 layer of the ciliary body. Their radial disposition becomes progressively 

 more apparent toward the axial margin of the ciliary body. These 

 fibers are far less numerous than the meridional. 



The circular fibers comprise numerous small non-striated muscle 

 bundles which are interspersed among the bundles of radial fibers. 



