Somatic Nervous System

1. Somatic Nervous System

2. Somatic Nervous System
The somatic system is the part of the peripheral nervous system that is responsible
for carrying motor and sensory information both to and from the central nervous
system. This system is made up of nerves that connect to the skin, sensory organs,
and all skeletal muscles. The system is responsible for nearly all voluntary muscle
movements as well as for processing sensory information that arrives via external
stimuli including hearing, touch, and sight. The somatic system is responsible for
transmitting sensory information as well as for voluntary movement. This system
contains two major types of neurons:
1. Sensory neurons (or afferent neurons) that carry information from the nerves to
the central nervous system. It is these sensory neurons that allow us to take in
sensory information and send it to the brain and spinal cord.

3. Somatic Nervous System
2. Motor neurons (or efferent
neurons) that carry information
from the brain and spinal cord to
muscle fibers throughout the
body. These motor neurons
allow us to take physical action
in response to stimuli in the
environment.

4. Somatic Nervous System
The stretch reflex. Interneuron. Cell body of. sensory
neuron. 1. Afferent impulses. from stretch. receptor
to. spinal cord. Motor neuron. serving quadriceps.
2. Efferent. impulses to. alpha (a) motor. neurons
cause. contraction. of the stretched. muscle that.
resists/reverses. the stretch. Motor neuron. serving
antagonist. muscle group. (hamstrings) – Initial.
stimulus: muscle. stretch. Spinal cord. (L2–L4)
Muscle. spindle. Patella. Quadriceps. (extensors)
Muscle. spindle. Patellar. ligament. Hamstrings.
(flexors) 3. Efferent impulses. to antagonist. muscles