Gamma Motor Neurons and Spinal Reflexes Quiz

Motor Neurons and Reflexes

• Alpha motor neurons have cell bodies located in the anterior gray horn of the spinal cord.
• Gamma motor neurons function to regulate the sensitivity of muscle spindles, which are involved in muscle stretch reflexes.

Reflex Reactions

• Reflex reactions are characterized by rapid, unconscious responses to stimuli.
• A reflex consists of a sensory receptor, an afferent neuron, a central integrating neuron, an efferent neuron, and an effector.

Muscle Stretch Reflex

• The muscle stretch reflex involves a nerve that innervates a skeletal muscle and contains axons of both alpha and gamma motor neurons.
• The sensory neuron involved in the afferent limb of the muscle stretch reflex is a type Ia sensory neuron.
• The cell body of the sensory neuron is located in the dorsal root ganglion.
• The central process of the sensory neuron synapses with the alpha motor neuron in the ventral horn of the spinal cord.

Quadriceps Stretch Reflex

• The quadriceps stretch reflex is a specific type of muscle stretch reflex that involves the quadriceps muscle and the patellar tendon.
• The purpose of tapping the patellar tendon is to stimulate the muscle spindle receptors, which triggers the reflex.
• The receptors involved in the quadriceps stretch reflex are muscle spindle receptors and Golgi tendon organs.
• The type of fibers stretched during the quadriceps stretch reflex are intrafusal fibers.
• The type of fibers stimulated when the patellar tendon is tapped are Ia sensory fibers.
• The contraction of the quadriceps in response to the quadriceps stretch reflex is caused by the activation of alpha motor neurons.
• Tapping of a tendon elicits a stretch reflex in neurological terms.

Golgi Tendon Organs (GTOs)

• Golgi Tendon Organs (GTOs) function to regulate muscle tension and prevent muscle overload.

Reciprocal Inhibition

• In reciprocal inhibition, the inhibitory interneuron inhibits the antagonist muscle.
• The receptor located at the peripheral end of the Ia fiber in reciprocal inhibition is the muscle spindle receptor.
• The primary function of reciprocal inhibition is to coordinate muscle movements and prevent simultaneous contraction of antagonist muscles.

Autogenic Inhibition (Inverse Myotatic Reflex)

• The primary function of autogenic inhibition is to regulate muscle tone and prevent muscle overload.
• The role of the central process of sensory neurons Ib fiber in autogenic inhibition is to inhibit the alpha motor neuron.
• During reciprocal inhibition, the antagonist muscle is inhibited.

Alpha-Gamma Co-Activation

• The mechanism of alpha-gamma co-activation is the simultaneous activation of alpha and gamma motor neurons, which leads to muscle contraction and regulation of muscle tone.

Muscle Tone

• Gamma motor neurons play a crucial role in the maintenance of muscle tone.

Flexor Reflex (Withdrawal Reflex, Nociceptive Reflex)

• The flexor reflex involves type III and IV fibers and is a response to painful or noxious stimuli.

Reflex Arc

• A monosynaptic reflex is a reflex that involves only one synapse.
• The component of the reflex arc responsible for transmitting sensory information from the muscle to the spinal cord is the sensory neuron.
• Muscle spindles are embedded in muscles throughout the body.

Quadriceps Stretch Reflex

• The contraction of the quadriceps in response to the quadriceps stretch reflex leads to the extension of the knee joint.