32 CLASSIFICATION OF TISSUES. 
Into what two general classes are muscle fibres divided ? 
Voluntary or striated muscle, controlled by the will. Involuntary 
or smooth muscles, over which the will has no control whatever. 
What is the arrangement of voluntary muscle tissue ? 
The muscle fibres are collected into bundles or fasciculi, which 
fasciculi converge toward the tendinous attachment of the muscle and 
taken together make up the organ called a muscle. 
How are the fasciculi held together ? 
By investing areolar tissue. That surrounding the whole muscle 
being termed the epimysium; that surrounding the fasciculi, the 
perimysium, while that extending between but not completely covering 
the muscle fibres is called the endomysium. 
Describe muscle fasciculi. 
They are bundles composed of muscle fibres. They are of a 
prismatic figure giving an angular outline on section. The texture of 
the muscles being coarse or fine as the fasciculi are large or small. 
What is the appearance of muscular fibres ? 
They are usually cylindrical, sometimes prismatic, and are usually 
not more than one and a half inches in Jength. 
Of what elements are voluntary muscle fibres composed ? 
The bulk of the fibre is made up of contractile substance upon which 
lie several nuclei. The whole is enclosed in a delicate membrane called 
the sarcolemma. 
What is the microscopical appearance of muscle substance ? 
It is crossed transversely by light and dark bands, hence its name of 
striated muscle. 
With high magnifying powers single fine lines may be seen crossing 
these bands. That crossing the light band being called Krause’s line, 
and that crossing the dark band, Hensen’s line. 
What are sarcous elements ? 
By treating a muscle cell with certain chemicals it can be made to 
separate into plates at each one of the lines called Krause’s lines. 
These plates may be still further separated in a direction parallel with 
the long axis of the muscle fibre, into tiny prismatic structures, called 
sarcous elements. 
What is the appearance of the muscle nuclei ? 
They are oval, have nucleoli, and are arranged with their long axis 
parallel to the long axis of the muscle cell, 
