Spinal Control Of Movement

Question 1

Two types of striated muscle

Answer 1

Cardiac

Skeletal muscle (run voluntary somatic motor system)

Question 2

What happens when a muscle contracts

Answer 2

Either flexes or extends a joint

Question 3

In skeletal muscles, flexors can either be…

Answer 3

Synergist

Antagonist (have extendors)

Question 4

Nerve fibers split into two branches, which are called____before attaching to the spinal cord

Answer 4

Roots

Question 5

Motor neurons in the _____ of the spinal cord innervate skeletal muscle fibers

Answer 5

Ventral horn

Question 6

In the spinal cord, which parts are larger and why

Answer 6

Cervical (C3-T1) and Lumbar (L1-S-3) enlargements innervate the arms and legs, respectively

Question 7

What is a motor unit

Answer 7

One alpha motor neuron and all the fibers it innervates

Question 8

Alpha Motor Neurons can have 3 inputs which are______

Answer 8

1. ) Input from Upper Motor Neurons in Cortex
2. ) Input from Muscle Spindles
3. ) Input from Spinal Interneurons (central pattern generators CPG’s both + and -)

Question 9

What is the purpose of the Proprioceptive Feedback Muscle Spindles

Answer 9

Affects the degree of movement accuracy

Critical source of sensory feedback for standing balance

Question 10

How is the organization of the eye and spinal cord similar

Answer 10

Like the retinotopic map in the eye, the spinal cord also maps the outside world

Question 11

What neurotransmitter is released to help muscles contract

Answer 11

ACh

Question 12

Where is ACh released

Answer 12

motor neuron on the end plate of the muscle.

Question 13

How do muscle fibers contract

Answer 13

Ca2+ binds to troponin and makes the Actin and Myosin filaments slide and contract the muscle

Question 14

What are the three types of motor units

Answer 14

Slow

Fast (fatigue-able)

Fast (fatigue resistant)

Question 15

Activation of slow motor unit

Answer 15

10-20 Hz

Question 16

Respiration type of slow motor unit

Answer 16

Aerobic

Question 17

Example of slow motor unit

Answer 17

Soleus

Question 18

Example of fast fatiguable muscle

Answer 18

Gastrocnemius

Question 19

Example of fast fatigue resistant muscle

Answer 19

Quadriceps

Question 20

Activation frequency of fast fatiguable muscle

Answer 20

30-60Hz

Question 21

Activation frequency of fast fatigue resistant motor unit

Answer 21

30-60hz

Question 22

Respiration type of fast fatigueable motor unit

Answer 22

Anerobic

Question 23

Respiration type of fast non fatiguable muscle

Answer 23

Mixed

Question 24

Eccles showed that….

Answer 24

Innervation can change the properties of muscles (but not vice versa)

crossing the fibers makes muscles change; Lomo believes changing firing frequency (e.g. 10-20 Hz to 30- 60 Hz) can do it!

Question 25

Myasthenia Gravis

Answer 25

an Autoimmune disease that interferes with the normal workings of ACh receptors – Characteristic eye and mouth drooping

Question 26

Bell’s palsy

Answer 26

occurs when the 7th cranial nerve becomes swollen within the bony canal that it passes through. The cause for this is generally unknown but research has linked it to viral infections like herpes simplex, sarcoidosis, HIV and herpes zoster.

Question 27

Lou Gehrig’s Disease or Amyotrophic Lateral Sclerosis

Answer 27

the progressive degeneration of Alpha motor neurons (possibly related to Glu excitotoxicity)

Question 28

Monosynaptic Myotatic Stretch Reflex

Answer 28

Sudden stretch of a muscle leads to Muscle Spindle Discharge of 1a afferent neurons... Alpha motor Neurons respond with contraction

Question 29

Golgi Tendon Organ Circuit

Answer 29

1b neurons INHIBIT the Alpha Motor Neurons of the same muscle proprioceptive sensory receptor organ that senses changes in muscle tension. It protects against excessive muscle force.

Question 30

Reciprocal Inhibition of Flexors and Extensors

Answer 30

Spinal Interneurons mediate the Contraction and Inhibition of Flexors vs. Extensors (and vice versa)

Question 31

Crossed-Extensor Reflex

Answer 31

Spinal Interneurons mediate the contralateral Extension of limbs – the basis for Central Pattern Generators reflex in which the contralateral limb compensates for loss of support when the ipsilateral limb withdraws from painful stimulus in a withdrawal reflex.

Question 32

Central Pattern Generators

Answer 32

Insimpleranimals(e.g.Crayfishandeels),spinal pattern generators control complex movement.

Question 33

1b affrent neurons

Answer 33

This interneuron makes an inhibitory synapse onto the alpha motor neuron that innervates the same muscle that caused the Ib afferent to fire.

Question 34

When tension is applied to a muscle, the _______ that innervate the Golgi tendon organ are activated.

Answer 34

Group Ib fibers