Control Of Body Movement

Question 1

Neural Reflex - Efferent Divisions (2)

Answer 1

Somatic or autonomic

Question 2

Neural Reflexes - CNS Location for Info Processing (2)

Answer 2

Cranial or Spinal

Question 3

Neural Reflexes - Time at which reflex develops in life (2)

Answer 3

Innate or Learned

Question 4

Neural Reflexes - Number of neurons in loop (2)

Answer 4

Monosynaptic or polysynaptic

Question 5

Skeletal Muscle Reflexes - Input

Answer 5

Proprioceptors

• joint movement
• muscle tension & length

Question 6

Skeletal Muscle Reflexes - CNS Job

Answer 6

To determine if Muscle should contract or relax

Question 7

Skeletal Muscle - Output

Answer 7

Based on CNS decision

• somatic motor neuron = ONLY contraction
• NO inhibitory neurons that synapse on skeletal Muscle
• can only inhibit contraction at interneurons in IC

Question 8

Skeletal Muscle Reflex Pathway

Answer 8

Stimulus=Joints, muscle tension, & muscle length
Sensor=Proprioreceptors
Input=Sensory Neuron
IC=CNS (need interneurons to block signal and stop contraction)
Output=Efferent Neurons (somatic motor)
Target=Skeletal Muscle
Response=Cellular (synapses fire on muscle fibers and they contract)
Systemic=muscle contracts

Question 9

Proprioceptors (3 types)

Answer 9

1. The Muscle spindle
2. The golgi tendon organ
3. Joint receptors

Question 10

The Muscle spindle

Answer 10

Proprioceptor that detects muscle length

Question 11

The golgi tendon organ function

Answer 11

Proprioceptor that detects muscle tension

Question 12

Joint receptors

Answer 12

Proprioceptor that detects changes in the bone position

Question 13

Stretch Receptors

Answer 13

Signal the brain about muscle length

Question 14

Intrafusal fibers

Answer 14

Where the Muscle spindle is; gamma motor neurons

Question 15

Extrafusal Fibers

Answer 15

Normal contractile muscle fibers; alpha motor neurons

Question 16

Muscle tone

Answer 16

Tonic activity

Question 17

Alpha-gamma coactivation

Answer 17

Keeps the spindle stretched when the Muscle contracts

Question 18

The Stretch Reflex

Answer 18

Stimulus=muscle stretches/lengthens
Sensor=Proprioceptors in Muscle spindle
Input=increased afferenr signals to spinal cord through sensory neuron
IC=spinal cord
Output=increased efferent output through alpha motor neurons
Target=muscle fibers
Response=Muscle contracts
Negative feedback pathway=firing rate of afferent sensory neuron decreases

Question 19

The golgi tendon organ

Answer 19

• The junction of Muscle fibers and tendons

- afferent input from golgi tendon excites inhibitory interneurons (which reduce/end muscle contraction)

Question 20

Pathway

Answer 20

Stimulus=tension on tendon activates sensory neuron
Sensor=proprioceptors
Input=sensory neuron -> dorsal root ganglia
IC=spinal cord
- sensory neuron stimulates interneuron
- interneuron inhibits motoneuron
*since signal is blocked by inhibitory interneurons, no output, no target, or cell response. STOPS AT IC (negative feedback)

Question 21

Joint receptors

Answer 21

• found in joint capsules and ligaments around joints
• respond to joint movement velocity, joint position, inflammation, & pain.
• works with vestibular apparatus to help w balance and movement

Question 22

3 types of movement

Answer 22

• Reflex
• Voluntary
• Rhythmic

Question 23

Reflex movement

Answer 23

• Least complex; integrated mainly in spinal cord
  Ex: knee jerk, cough
• Postural Reflexes

Question 24

Postural Reflexes

Answer 24

Maintain body position as we stand/move; brain stem integration

Question 25

Voluntary movement

Answer 25

-most complex; integrated in cerebral cortex | Ex: playing piano

Question 26

Rhythmic movement

Answer 26

- intermediate complexity; integration in spinal cord and cerebral cortex - Central Pattern Generators (CRG's) - > interneurons: take over so you don't have to think about moving anymore Ex: walking, running

Question 27

3 factors that influence movement

Answer 27

- the number of spinal cord segments needed - the use of upper or lower motor neurons - section of the CNS controlling movement (IC location)

Question 28

Number of spinal cord segments - segmental

Answer 28

- The Reflex only passes through a small portion of the spinal cord Ex: quadriceps stretch Reflex "knee jerk Reflex"

Question 29

Number of spinal cord segments - intersegmental

Answer 29

- the reflex passes through many segments of the spinal cord or brain Ex: vestibulospinal Reflexes for balance and posture

Question 30

Segmental "simpler Reflex"

Answer 30

Stimulus=instrument pressure Sensor=mechanoreceptors -joint receptors -golgi tendon organ -Muscle spindle Input=sensory neuron IC=spinal cord Output=somatic motor neuron (SMN) sends signal to quads -SMN signal blocked by inhibitory neurons so hamstring relaxes (no signal) Target=muscle fibers Response=muscle contraction or relaxation

Question 31

Flexion Reflexes (crossed extensor Reflex)

Answer 31

Stimulus=stepping on a pin Sensor=nociceptor Input=sensory neuron IC=spinal cord & brain (vestibular balance) Output= alpha motor neurons Target=muscle fibers Response= -painful leg=extensors inhibited, flexors contract; moving foot away from painful stimulus -opposite leg=extenders contract as weight shifts to leg, flecked inhibited

Question 32

Lower Motor Neuron

Answer 32

"Alpha Neuron" | - Cell body in CNS and axon synapses on skeletal Muscle fibers

Question 33

Upper Motor Neurons

Answer 33

- Lie entirely within CNS (interneurons) - Control lower motor neurons (Voluntary and Rhythmic)

Question 34

White Matter

Answer 34

Myelinated axons | - Bundles of axons knows as tracts

Question 35

Ascending tract

Answer 35

Carry sensory info to the brain Ex: dorsal, external lateral

Question 36

Descending Tract

Answer 36

Carry efferent (motor) signals from brain to spinal cord Ex: central, interior lateral

Question 37

Medial Tract

Answer 37

``` - Controls axial & proximal muscles • tectospinal tract • vestibulospinal Tract • reticulospinal tract - Originate in brain stem ```

Question 38

Tectospinal Tract

Answer 38

- head orientation to environmental stimuli Ex: someone slams a door during an exam & everyone looks up

Question 39

Vestibulospinal Tract

Answer 39

- Muscle control against gravity Ex: balancing

Question 40

Reticulospinal Tract

Answer 40

- Controls muscle tone in axial and proximal muscles Ex: muscle tone; muscle spindle

Question 41

Lateral Tract

Answer 41

- Controls distal muscles | Ex: rubrospinal tract

Question 42

Rubrospinal Tract

Answer 42

- Voluntary muscle control - implicated in control of skilled, repetitive movement - more developed in humans than animals

Question 43

Corticospinal Tract

Answer 43

- Controls most skilled voluntary muscle movements | - Connexts motor cortex in parietal lobe of the brain with lower motor neurons