64 THE EYE. 
How are muscle fibres distributed to the eyelid? 
Between the skin and tarsus are bundles of striated muscle (musculus 
orbicularis palpebrarum). Between the tarsus and conjunctival mu- 
cous membrane is a layer of smooth muscle cells. 
What are the Meibomian glands ? 
They consist of vesicular alveoli, lined with cylindrical cells, and 
are arranged along and open into excretory ducts lined with laminated 
epithelium. They open upon the free edge of the lid. 
Describe the accessory tear glands ? 
They are small, racemose glands opening on the surface of the 
eyeball near the line of the reflection of the conjunctiva. 
EYEBALL, 
Of what is the outer wall of the eyeball composed ? 
Of a dense, connective-tissue layer called the sclera or sclerotic. It 
is transparent at the outer segment of the eyeball and is here called the 
cornea. The point of union of the two portions is called the sclero- 
corneal junction. 
What is the layer within the sclerotic ?' 
It isa delicate vascular coat called the choroid. At the sclero- 
corneal junction this layer is thrown into numerous longitudinal folds 
called the ciliary processes. Extending from the ciliary processes 
is a perforated vascular curtain composed of connective tissue and 
muscular fibres called the cris. It is suspended behind the cornea 
and connected peripherally near the sclero-corneal junction with a 
connective-tissue structure called the ligamentum pectinatum. 
Descrite the ciliary muscle. 
It is a flattened ring of smooth muscle fibre, passing backward from 
the ligamentum pectinatum, between the ciliary processes and sclerotic, 
to be attached posteriorly to the choroid. 
What is the ciliary body ? 
The ciliary processes and muscle together form it. 
What is the retina ? 
It is the innermost layer of the wall of the eyeball, and, beginning 
at the entrance of the optic nerve, spreads out over the choroid. The 
nerve elements extend about two-thirds of the way forward from the 
back of the eye and cease in a wavy line (the ora serrata). Certain 
cellular elements continue over the ciliary processes and are called 
pars ciliaris retine. 
