574 THE EYE 



The meridional fibres form the outer ana greater portion of the 

 muscle. They begin just posterior to the corneal margin, taking 

 their origin from the inner surface of the solera, and radiate back- 

 ward in a meridional direction for a variable distance, to be finally 

 inserted into the fibrous bundles of the posterior half of the ciliary 

 body, the longest fibre bands passing as far back as the chorio- 

 ciliary junction, where they are attached to the anterior margin of 

 the choroid. 



The radial fibres simulate the meridional fibres 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, fibres are far less numerous 

 than the meridional. 



The circular fibres comprise numerous small non-striated muscle 

 bundles which are interspersed among the bundles of radial fibres. 

 They are disposed in a circular direction about the axial margin of 

 the ciliary body on its outer surface, and hence are in relation with 

 the inner surface of the sclero-corneal junction and the outer mar- 

 gin of the base of the iris. The circular muscle fibres are also inter- 

 spersed among the fibres of the ligamentum pectinatum, which pass 

 in a radial manner from the margin of the posterior homogeneous 

 membrane of the cornea to the base of the iris and anterior margin 

 of the ciliary body. The circular fibres are said to be deficient or 

 even absent in myopic eyes, but are exaggerated in hypermetropic 

 eyes (Iwanoff,* Fuchsf). 



The disposition of the ciliary muscle fibres is such that during 

 contraction the fibrous ciliary body and the base of the iris are 

 drawn forward, the choroid is made tense, and the suspensory liga- 

 ment of the lens is relaxed. The lens then becomes more nearly 

 spherical because of its own elasticity. 



The fibrous layer of the ciliary body consists of connective 

 tissue, and connects the fibrous portion of the choroid to the simi- 

 lar tissue of the iris. It is formed by a reticulum of fine fibres in 

 the meshes of which are numerous lamellar and a few pigmented 

 cells. Buried within the outer portion of this fibrous mass and 

 intermingling with its fibres are the fibre bundles of the ciliary 



* Strieker's Handbook, vol. iii. \ Textbook of Ophthalmology. 



