Somatic Nervous System.pptx

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: 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 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 are. damped. (reciprocal. inhibition) Key: + Excitatory synapse. – Inhibitory synapse. (a) (b)