Module 4: Section 5

Question 1

Proprioception

Answer 1

Awareness of your body in the environment

Question 2

What do muscle spindles do?

Answer 2

Monitor changes in muscle length and play a role in stretch reflexes

Question 3

What are intrafusal fibres?

Answer 3

• Specialized muscle fibres that make up the muscle spindle and detect stretch
• They have contractile ends but a non-contractile middle region that contains sensory receptors

Question 4

How do extrafusal and intrafusal fibres differ?

Answer 4

• Extrafusal fibres are innervated by alpha motor neurons and cause muscle contraction
• Intrafusal fibres (in muscle spindles) are innervated by gamma motor neurons and send information about muscle stretch to the CNS

Question 5

Golgi tendon organs

Answer 5

• They respond to changes in muscle tension
• They are receptors found at the junction of tendons and muscle fibres and respond to both stretch and contraction of the muscle

Question 6

What do Golgi tendon organs detect and how do they work?

Answer 6

• When extrafusal fibres contract, they pull on tendons, activating afferent fibres in the Golgi tendon organs
• The stronger the tension, the faster the firing rate
• Information is sent to the brain for processing

Question 7

Afferent neurons

Answer 7

• Occur at level of spinal cord and are involved in spinal reflexes
• Essential for maintaining posture and protective movements such as the withdrawal reflex

Question 8

Primary motor cortex

Answer 8

• Contains pyramidal cells whose fibres form the corticospinal motor system
• Corticospinal motor system sends signals to motor neurons in the spinal cord to control fine voluntary movements, especially of the hands and fingers

Question 9

Brain Stem

Answer 9

• Is the multineuronal motor system as its influenced by motor regions of the cortex, cerebellum and basal nuclei
• System regulates overall body posture and involuntary movements of the larger muscle groups