Skeletal muscle is supplied by somatic nerves. The nerve to a skeletal muscle is a mixed nerve containing 60% motor and 40% sensory fibers

1. MUSCLES

2. Content
Nerve supply of skeletal muscle
Nerve supply of smooth muscle

3. NERVE SUPPLY OF SKELETAL MUSCLE
The nerve supplying a muscle is called motor
nerve.
 In fact it is a mixed nerve and consists of the
following types of fibres.
Motor Fibers 60 %
Sensory Fibers 40%

5. .Motor fibres (60%) comprise:
 (a) Large myelinated alpha efferents which supply
extrafusal muscle fibres
 (b) Smaller myelinated gamma efferents which supply
intrafusal fibres of the muscle spindles which refine and
control muscle contraction.
 (c) The fine non-myelinated autonomic efferents which
supply smooth muscle fibres of the blood vessels.

7.  .Sensory fibres (40%) comprise:
 Myelinated fibres distributed to muscle spindles for
proprioception, also to tendons.
Muscle spindles are spindle-shaped sensory end
organs of the skeletal muscle.
Each spindle contains 6-14 intrafusal muscle fibres
Muscles
which are of two types, the larger nuclear bag
fibres, and the smaller nuclear chain fibres

9. NERVE SUPLY TO SPINDLE
The spindle is innervated by both the
sensory and motor nerves. The sensory
endings are of two types, the primary
sensory endings (annulospiral endings)
around the central nuclear region of the
intrafusal fibres, and the secondary sensory
endings (flower spray endings) beyond the
nuclear region on either side of these fibres.

10. Motor point
It is the site where the motor nerve enters
the muscle. It may be one or more than
one. Electrical stimulation at the motor
point is more effective

11. Motor unit (myone)
It is defined as a single alpha motor neuron together with the
muscle fibres supplied by it. The size of motor unit depends
upon the precision of muscle control.
Small motor units (5-10 muscle fibres) are found in muscles of
fine movements (extraocular muscles).
Large motor units (100-2000 muscle fibres) are found in
muscles of gross movements (proximal limb muscles).

12. Composite/hybrid muscle:
 Muscle supplied by two different motor nerves
with different root values is called a composite or
hybrid muscle,
e.g. adductor magnus, flexor digitorum profundus
and pectoralis major.

14. Nerve Supply of Smooth Muscle
 According to nerve supply the smooth muscles are classified into:
 Single-unit type:
 Seen in intestines. The nerve impulse reaches one muscle cell, is
transmitted to other cells by the mechanical pull through the fused
cell membrane. The nerve supply is sparse.
 Multi-unit type:
 Seen in the muscles of the ductus deferens. Each muscle cell receives
a separate nerve fibre. The contraction is simultaneous. The nerve
supply is rich

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