Which among the following is detected by muscle spindle?

Muscle spindle primarily detect changes in the length of this muscle. They convey length information to the central nervous system sensory neurons. This information can be processed by the brain to determine the position of body pas. The responses of muscle spindles to changes in length also play an impoant role in regulating the contraction of muscles, by activating motoneurons the stretch reflex to resist muscle stretch. Golgi tendon detects muscle tension and rate of change of muscle tension. Ref: Barrett K.E., Barman S.M., Boitano S., Brooks H.L. (2012). Chapter 12. Reflex and Voluntary Control of Posture & Movement. In K.E. Barrett, S.M. Barman, S. Boitano, H.L. Brooks (Eds), Ganong's Review of Medical Physiology, 24e