Neurophysiology: Which receptor starts this?

Stretch-reflex recall: increased muscle length activates a muscle spindle. Its afferent has a direct excitatory spinal connection to motor neurons supplying the same muscle. The visual isolates this branch; antagonist inhibition and other circuitry are not drawn. This 36-second silent lesson teaches the mechanism, not how to examine or diagnose a person. Silent caption-led lesson; no narration or music. Original AI-assisted diagrams; AI source review 16 October 2026, not clinician certification. Sources: https://openstax.org/books/anatomy-and-physiology-2e/pages/12-1-basic-structure-and-function-of-the-nervous-system https://openstax.org/books/anatomy-and-physiology-2e/pages/14-3-motor-responses Create a review prompt: https://meyshan.com/app/recall?utm_source=meyshantube&utm_medium=video&utm_campaign=student_daily_202610&utm_content=d08_c Transcript: on-screen text from this silent video; no spoken narration.