Set #1 (Lecture 17 + Textbook PGs 196-206 Study Guide)

What does the motor system refer to?

Movement and the ability to move muscles and the body.

Why is movement considered a basic behavior?

Movement allows organisms to interact with the environment.

What did papers from the 1950s and 1960s argue about the evolution of the body?

The body evolved primarily for movement.

Why is movement important for survival?

Movement helps organisms find food and avoid becoming prey.

About how many muscles are in the human body?

About 640 muscles.

Why are many muscles concentrated in the face?

Small facial muscles allow talking, facial expressions, eye movements, and other small movements.

What three muscle types can be identified microscopically?

Smooth, cardiac, and striated or skeletal muscle.

What is smooth muscle?

Muscle that lines internal organs.

What example of smooth muscle is given?

Muscle lining the small intestine.

What is cardiac muscle?

Muscle that makes up the heart.

What characteristics does cardiac muscle have?

Characteristics of both smooth and striated muscle.

What is another name for striated muscle?

Skeletal muscle.

What is skeletal muscle?

Muscle connected to bones that allows movement of the body and limbs.

Which muscle type receives the most attention in the movement material?

Skeletal muscle.

What is a flexor?

A muscle that closes a joint.

What is an extensor?

A muscle that opens a joint.

How do flexors and extensors work around a joint?

Flexors and extensors work as opposing pairs to move a joint back and forth.

Which muscle acts as a flexor at the elbow?

The biceps.

Which muscle acts as an extensor at the elbow?

The triceps.

What do flexors and extensors allow a joint to have?

A full range of motion.

Are muscles directly attached to bones?

No. Muscles attach to tendons, and tendons attach to bones.

What is a tendon?

A structure that connects a muscle to a bone.

What is flexion?

Movement that bends a joint and decreases the angle between body parts.

What is extension?

Movement that straightens a joint and increases the angle between body parts.

What are antagonistic muscles?

Muscles that produce opposite actions.

How are the biceps and triceps antagonistic muscles?

The biceps flex the arm while the triceps extend the arm.

Where is white matter located in the spinal cord?

On the outside of the spinal cord.

Where is gray matter located in the spinal cord?

On the inside of the spinal cord.

What type of information enters the dorsal side of the spinal cord?

Sensory information.

What type of information leaves the ventral side of the spinal cord?

Motor information.

What is the dorsal root?

The spinal nerve root that carries sensory information into the spinal cord.

What type of information does the dorsal root carry?

Afferent sensory information.

What does afferent information mean?

Sensory information traveling toward the central nervous system.

What is the ventral root?

The spinal nerve root that carries motor information away from the spinal cord.

What type of information does the ventral root carry?

Efferent motor information.

What does efferent information mean?

Motor information traveling away from the central nervous system toward muscles.

What are dorsal root ganglia associated with?

Sensory information entering the spinal cord.

What does the ventral horn contain?

Cell bodies of motor neurons.

What is another name for the dorsal horn?

The posterior horn.

What is another name for the ventral horn?

The anterior horn.

What can sensory information do after entering the spinal cord?

Sensory information can travel toward the brain or participate in local reflex circuits.

What are slow-twitch muscle fibers specialized for?

Endurance.

What are fast-twitch muscle fibers specialized for?

Short bursts of high energy.

What food comparison is used for slow-twitch and fast-twitch fibers?

Dark meat and white meat in chicken.

What influences the amount of slow-twitch and fast-twitch fibers?

Both genetic predisposition and experience or practice.

What type of muscle fibers may be common in a naturally fast sprinter?

Fast-twitch fibers.

What type of muscle fibers may be common in a long-distance runner?

Slow-twitch fibers.

Can training influence slow-twitch and fast-twitch characteristics?

Yes. Experience and practice can influence muscle-fiber characteristics.

What is a neuromuscular junction?

The synapse between a motor neuron and a muscle.

What neurotransmitter is used at the neuromuscular junction?

Acetylcholine.

What abbreviation is used for acetylcholine?

ACh.

Why is the neuromuscular junction called a cholinergic synapse?

The neuromuscular junction uses acetylcholine.

What is a cholinergic synapse?

A synapse that uses acetylcholine as the neurotransmitter.

What must happen before a skeletal muscle can contract?

A motor neuron must activate the muscle at the neuromuscular junction.

What does a motor neuron release onto a muscle?

Acetylcholine.

What happens after acetylcholine binds to receptors on a muscle?

The muscle fiber becomes activated and contracts.

What happens to a muscle when the muscle contracts?

The muscle shortens.

What does muscle shortening do?

Muscle shortening pulls on the structures attached to the muscle.

What are lower motor neurons?

Motor neurons with cell bodies in the ventral horn whose axons contact muscles.

What is the final common pathway?

The lower motor neuron system that provides the final route for activating muscles.

Why are lower motor neurons called the final common pathway?

Muscles cannot contract without activation from lower motor neurons.

What happens to the axon of a lower motor neuron?

The axon leaves the spinal cord, travels through a nerve, and contacts a muscle.

What are upper motor neurons?

Motor neurons higher in the motor system that synapse on lower motor neurons.

What do upper motor neurons synapse on?

Lower motor neurons.

What do lower motor neurons synapse on?

Muscles.

How can the final common pathway be compared with a funnel?

Many motor signals eventually funnel into lower motor neurons before muscles can move.

What determines whether a muscle ultimately receives a motor signal?

Whether the appropriate lower motor neuron fires.

What disease is associated with the upper motor neuron system in the course lecture?

Parkinson's disease.

What disease is associated with the lower motor neuron side of the system in the course lecture?

Myasthenia gravis.

What is proprioception?

The ability to know where the body and individual body parts are in space.

What vestibular structures provide information during movement?

The semicircular canals.

What vestibular structures provide information about gravity?

The utricle and saccule.

What two muscular receptors provide proprioceptive feedback?

Muscle spindles and Golgi tendon organs.

What is a muscle spindle?

A specialized structure inside a muscle that detects muscle stretch.

What happens to a muscle spindle when the surrounding muscle stretches?

The muscle spindle stretches along with the muscle.

Where does muscle-spindle sensory information travel?

Toward the spinal cord through the dorsal root.

What can happen to muscle-spindle information after reaching the spinal cord?

The information can reach the brain or participate in local reflexes.

When is a muscle spindle relatively quiet?

When the muscle is not being stretched.

What is a Golgi tendon organ?

A receptor in a tendon that detects stress or stretching of the tendon.

What happens when a Golgi tendon organ is physically stretched?

Ion channels open and an action potential is generated.

Where does Golgi tendon organ information enter the spinal cord?

The dorsal horn.

What is the main difference between muscle spindles and Golgi tendon organs in the lecture?

Muscle spindles detect muscle stretch, while Golgi tendon organs detect tendon stretch or stress.

Why can muscle spindles and Golgi tendon organs provide information at the same time?

Muscle and tendon stretching commonly occur together during movement.

Which muscles contain more muscle spindles and Golgi tendon organs?

Muscles requiring fine, precise control.

Why do muscles involved in fine control have more sensory receptors?

Fine control requires precise information about muscle position and state.

What example demonstrates a movement requiring many proprioceptive receptors?

Threading a needle with the fingers.

Why does the back have fewer muscle spindles and Golgi tendon organs than the fingers?

Back muscles require less precise control.

What is a tract?

A bundle of axons running together in the central nervous system.

What does the first part of a motor tract name usually identify?

Where the pathway begins.

What does the second part of a motor tract name usually identify?

Where the pathway ends.

What does corticospinal mean?

The pathway begins in the cerebral cortex and travels to the spinal cord.

What is another name for the corticospinal tract?

The pyramidal tract.

Where does the corticospinal tract begin?

The cerebral cortex, especially the primary motor cortex.

What is the central sulcus?

The groove separating the frontal and parietal lobes.

What is a sulcus or fissure?

A groove separating areas of the cerebral cortex.

What is a gyrus?

A raised portion or bump of cerebral cortex.

What is the postcentral gyrus?

The gyrus behind the central sulcus containing primary somatosensory cortex.

Which lobe contains the primary somatosensory cortex?

The parietal lobe.

What is the precentral gyrus?

The gyrus in front of the central sulcus containing primary motor cortex.

Which lobe contains the primary motor cortex?

The frontal lobe.