Musculoskeletal / VISUAL EXPLAINER
How Do Muscles Adjust How Hard They Pull?
Muscle force can be adjusted by recruiting more motor units and changing their discharge frequency. A motor unit is one motor neuron and the fibers it supplies, not a fascicle; stronger force is not encoded by taller nerve impulses.
READ THE IMAGE
What the illustration shows
Navy and gold educational poster with a clearly labeled motor-unit schematic. Six separated striated muscle fibers alternate gold A and teal B. One gold axon branches from the left only to the three A fibers; a separate teal axon from the right supplies only the three B fibers. Recruitment panels show identical intermingled A/B maps, first with A active and B muted, then both active. Firing-rate panels compare sparse and closely spaced impulses without increasing impulse height. Text defines a motor unit as one motor neuron and its fibers, and distinguishes recruitment from firing rate. Gold AllHumanBody.com branding appears below.
How to interpret this poster
- Isolated fibers and opposite-side axon entry are a schematic, not an exact whole-muscle map or normal endplate-location diagram.
- No measured frequencies, force curve or claim that every force task shortens muscle.
- AI-assisted educational illustration; not physician certification, microscopy, a diagnosis or individualized medical advice.
- Fine annotations need enlargement; the full description provides an accessible text alternative.
- Display the full uncropped illustration; do not trim titles, legends or boundary annotations.
AI-assisted educational illustration, adapted into web-sized images without changing its composition. This is general education, not an individual diagnosis or treatment recommendation.
EVIDENCE / CONTEXT
Sources and what they support
- Anatomy and Physiology 2e: 10.4 Nervous System Control of Muscle Tension ↗
Motor-unit recruitment and stimulation-frequency effects on tension.