Each fiber is inclosed in a thin homogeneous elastic membrane
called the sarcolemma. The material inside the fiber is striated.
It is supposed to be of a semi-viscous consistency. This material
is the muscle plasma. The muscle plasma is made up of fibrils
which run the whole length of the intervening sarcoplasm. The
fibrils seem to be made up of alternating dim and light discs.

Neural Endings in Muscles. --The peripheral motor and sen-
sory neurones end in the muscles. We have already spoken of the

FIG. 47. --Ending of motor nerves in striped muscle. The axones pierce the perimysium,
lose their medullary sheath and end in a plate-like formation on the individual muscle
fibers. ( Piersol Anatomy.)

sensory endings in muscles on page 59. The axones of the motor
nerves upon reaching the muscle lose their medullary sheath and
break up into numerous fine fibrils. These fibrils spread out in
plate form (motor end plates) and pass to each muscle fiber. Fig.
47 shows the ending in striped muscle fibers of axones of efferent
neurones.

In addition to the afferent and efferent supply coming from
the central nervous system, the muscles receive sympathetic
fibers, i.e., the axones of post-ganglionic neurones end in the

-161-