Ch 12 - Movement ppt

A set of flashcards based on key concepts from the lecture titled 'Control of Body Movement' in Human Physiology, covering motor neurons, reflexes, and the roles of the brain regions involved in movement.

What are lower motor neurons responsible for in human physiology?

They are somatic neurons that emanate from the brainstem and spinal cord to innervate skeletal muscle, serving as the final common pathway.

What types of input do lower motor neurons receive?

Lower motor neurons receive input from local circuit neurons, nearby interneurons, upper motor neurons, basal nuclei, and the cerebellum.

What is the purpose of local circuit neurons in motor control?

They coordinate somatic reflexes and rhythmic movements of locomotion.

What components are included in a somatic reflex arc?

A sensory receptor, sensory neuron, integrating center, motor neuron, and effector.

What is a stretch reflex?

A monosynaptic reflex that causes contraction of a skeletal muscle in response to stretching of the muscle, exemplified by the patellar reflex.

What is the function of a tendon reflex?

A polysynaptic reflex that controls muscle tension by causing muscle relaxation when the tension is excessive.

Describe the flexor withdrawal reflex.

A polysynaptic reflex that occurs when a stimulus like stepping on a tack activates a nerve impulse that leads to the withdrawal of the leg.

What characterizes the crossed extensor reflex?

It is a contralateral reflex that involves contraction of muscles to extend the opposite limb in response to a painful stimulus.

What are the primary functions of upper motor neurons?

They are responsible for locomotion and maintaining rhythmic movements of limbs during walking.

What are the two main direct motor pathways?

The corticospinal pathways for voluntary control of limbs and trunk muscles, and the corticobulbar pathways for control of head muscles.

What role does the vestibular nuclei play in motor control?

It helps control posture in response to changes in balance through the vestibulospinal tract.

What is the function of the reticular formation in movement control?

It regulates posture and muscle tone during ongoing movements via the reticulospinal tract.

What does the superior colliculus promote in terms of movement?

It promotes reflexive movements of the head and trunk and saccadic eye movements.

What are the components of the basal nuclei?

They consist of masses of gray matter including the globus pallidus, putamen, caudate nucleus, subthalamic nucleus, and substantia nigra.

How do basal nuclei influence movement?

They influence movement through the initiation of movements, suppression of unwanted movements, regulation of muscle tone, and regulation of nonmotor processes.

What role does the cerebellum play in body movement?

It monitors intentions for movement and actual movement, compares command signals with sensory information, and sends out corrective feedback.

What are lower motor neurons responsible for in human physiology?

They are somatic neurons that emanate from the brainstem and spinal cord to innervate skeletal muscle, serving as the final common pathway.

What types of input do lower motor neurons receive?

Lower motor neurons receive input from local circuit neurons, nearby interneurons, upper motor neurons, basal nuclei, and the cerebellum.

What is the function of local circuit neurons in motor control?

They coordinate somatic reflexes and rhythmic movements of locomotion.

What components are included in a somatic reflex arc?

A sensory receptor, sensory neuron, integrating center, motor neuron, and effector.

What is a stretch reflex?

A monosynaptic reflex that causes contraction of a skeletal muscle in response to stretching of the muscle, exemplified by the patellar reflex.

What is the function of a tendon reflex?

A polysynaptic reflex that controls muscle tension by causing muscle relaxation when the tension is excessive.

Describe the flexor withdrawal reflex.

A polysynaptic reflex that occurs when a stimulus like stepping on a tack activates a nerve impulse that leads to the withdrawal of the leg.

What characterizes the crossed extensor reflex?

It is a contralateral reflex that involves contraction of muscles to extend the opposite limb in response to a painful stimulus.

What are the primary functions of upper motor neurons?

They are responsible for locomotion and maintaining rhythmic movements of limbs during walking.

What are the two main direct motor pathways?

The corticospinal pathways for voluntary control of limbs and trunk muscles, and the corticobulbar pathways for control of head muscles.

What role does the vestibular nuclei play in motor control?

It helps control posture in response to changes in balance through the vestibulospinal tract.

What is the function of the reticular formation in movement control?

It regulates posture and muscle tone during ongoing movements via the reticulospinal tract.

What does the superior colliculus promote in terms of movement?

It promotes reflexive movements of the head and trunk and saccadic eye movements.

What are the components of the basal nuclei?

They consist of masses of gray matter including the globus pallidus, putamen, caudate nucleus, subthalamic nucleus, and substantia nigra.

How do basal nuclei influence movement?

They influence movement through the initiation of movements, suppression of unwanted movements, regulation of muscle tone, and regulation of nonmotor processes.

What role does the cerebellum play in body movement?

It monitors intentions for movement and actual movement, compares command signals with sensory information, and sends out corrective feedback.

What is the local level of motor control coordinated by?

It is coordinated by local circuit neurons (interneurons).

What are the responsibilities of the local level of motor control?

It is responsible for somatic reflexes and rhythmic movements of locomotion.

What do somatic reflexes allow for in the body?

They allow fast, involuntary contractions of skeletal muscle and enable skeletal muscle to contract quickly in response to stimuli.

What components are included in a somatic reflex arc?

A somatic reflex arc includes a sensory receptor, sensory neuron, integrating center, motor neuron, and effector.

What is a stretch reflex?

A monosynaptic reflex that causes contraction of a skeletal muscle in response to stretching of the muscle, exemplified by the patellar reflex. It is ipsilateral.

What is the mechanism of the stretch reflex?

Stretching of a muscle activates muscle spindles, which leads to the activation of a sensory neuron that sends a signal to the spinal cord, resulting in the contraction of the muscle via a motor neuron.

What is a tendon reflex?

A polysynaptic reflex that helps control muscle tension by causing muscle relaxation when tension is excessive.

What are the sensory receptors involved in the tendon reflex?

The sensory receptors involved are Golgi tendon organs.

What happens during a tendon reflex when tension is applied?

Tension applied to the tendon stimulates the tendon organ, leading to a nerve impulse that travels to the spinal cord and causes muscle relaxation.

Describe the flexor withdrawal reflex.

A polysynaptic reflex that occurs when a stimulus like stepping on a tack activates a nerve impulse that leads to the withdrawal of the leg.

What are the characteristics of the flexor withdrawal reflex?

It is a polysynaptic reflex that is ipsilateral in nature.

What happens during the flexor withdrawal reflex when stepping on a tack?

Stepping on a tack stimulates a sensory receptor, which sends a nerve impulse that activates an interneuron, leading to the activation of the motor neuron, resulting in muscle contraction and the withdrawal of the leg.

What characterizes the crossed extensor reflex?

It is a contralateral reflex that involves contraction of muscles to extend the opposite limb in response to a painful stimulus.

What initiates the crossed extensor reflex?

Stepping on a tack (stimulus) activates a nerve impulse that leads to the activation of several interneurons.

What is the result of the crossed extensor reflex when stepping on a tack with one leg?

Flexion of the leg stepping on a tack and extension of the opposite leg.

What type of reflex is the crossed extensor reflex?

It is a polysynaptic reflex.

How does the crossed extensor reflex contribute to balance?

By extending the opposite limb, it helps maintain balance while the affected leg is withdrawn.

What are upper motor neurons responsible for in terms of movement?

They are responsible for locomotion and maintaining rhythmic movements of limbs while walking.

What does the primary motor cortex control?

It controls the execution of voluntary movements and gives rise to direct motor pathways.

What is the function of the premotor cortex?

It creates a motor plan and stores information about learned motor activities.

What are direct motor pathways responsible for?

They provide input to lower motor neurons via axons derived from the cerebral cortex.

What are the two main types of direct motor pathways?

The corticospinal pathways and the corticobulbar pathways.

What is the function of the corticospinal pathways?

They control voluntary movement of skeletal muscles of the limbs and trunk.

What is the function of the corticobulbar pathways?

They control voluntary movement of skeletal muscles of the head.

How many pairs of cranial nerves do lower motor neurons exit in the corticobulbar pathways?

They exit 9 pairs of cranial nerves.

Name some cranial nerves associated with the corticobulbar pathways.

Oculomotor (III), trochlear (IV), trigeminal (V), abducens (VI), facial (VII), glossopharyngeal (IX), vagus (X), accessory (IX), and hypoglossal (XII).

What are the four major motor centers located in the brain stem?

The four major motor centers are the vestibular nuclei, reticular formation, superior colliculus, and red nucleus.

What is the function of the vestibular nuclei?

They are involved in balance and eye movements.

What role does the reticular formation play in motor control?

It helps regulate alertness and posture through its connections with the spinal cord.

What is the superior colliculus responsible for?

It is involved in coordinating eye movements and visual reflexes.

What is the red nucleus associated with in terms of movement?

It is involved in motor coordination and the control of limb movements.

What do indirect motor pathways regulate?

Indirect motor pathways regulate posture, balance, muscle tone, and reflexive movements of the head and trunk.

What are some components of indirect motor pathways?

Components include the vestibular nucleus, red nucleus, reticular formation, and upper motor neurons.

What is the role of motor centers in indirect motor pathways?

Motor centers give rise to the indirect motor pathways which initiate involuntary movements.

What type of movements do indirect motor pathways initiate?

They initiate involuntary movements.

Which tracts are part of the indirect motor pathways?

The reticulospinal tract and vestibulospinal tract are part of the indirect motor pathways.

What is the function of the vestibular nuclei?

They help control posture in response to changes in balance through the vestibulospinal tract.

What are postural reflexes associated with the vestibular nuclei?

Postural reflexes arise from input from the eyes, vestibular apparatus, and proprioceptors.

What tract is associated with the vestibular nuclei?

The vestibulospinal tract.

From where do postural reflexes come?

They come from three places: eyes, vestibular apparatus, and proprioceptors.

What is the function of the reticulospinal tract?

It helps regulate posture and muscle tone during ongoing movements.

What are the outputs of the reticular formation?

Output includes the medial reticulospinal tract and lateral reticulospinal tract.

What does the superior colliculus promote?

It promotes reflexive movements of the head and trunk and saccadic eye movements.

What is the tectospinal tract associated with?

It is associated with reflexive movements of the head and trunk.

What are Saccades in relation to the superior colliculus?

Saccades are quick, simultaneous movements of both eyes in the same direction.

What are gaze centers?

They are the areas in the brain, including the superior colliculus, that control eye movements.

What is the function of the red nucleus?

It helps control voluntary movements of the upper limbs through the rubrospinal tract.

What are the components of the basal nuclei?

The basal nuclei consist of masses of gray matter including the globus pallidus, putamen, caudate nucleus, subthalamic nucleus, and substantia nigra.

What tract is associated with the red nucleus?

The rubrospinal tract is associated with the red nucleus.

What is the primary role of the basal nuclei in movement control?

They help initiate movements, suppress unwanted movements, regulate muscle tone, and influence nonmotor processes.

How do basal nuclei influence movement?

They influence movement in several ways: initiation of movements, suppression of unwanted movements, regulation of muscle tone, and regulation of nonmotor processes.

What is the role of the cerebellum in movement?

The cerebellum monitors intentions for movement, monitors actual movement, compares command signals with sensory information, and sends out corrective feedback.