Motor System and Movement Disorders

Question 1

1a Afferents

Answer 1

• activated when extrafusal fibers are stretched

- 1a afferents do not respond to muscle shortening, they only respond to muscle stretch

Question 2

Golgi Tendon Organs

Answer 2

• are oriented in-series with muscle fibers
• 1b afferents (not as fast a 1a) that limit excessively strong contractions that may damage muscle
• fire action potentials in response to muscle contraction or passive stretch
• activate interneurons in spinal cord the INHIBIT alpha motor neurons on muscle

Question 3

Gamma motor neurons cause:

Answer 3

• intrafusal fibers to contract

- leads to stretch of spindle