Learn about the relationships between agonist and antagonist muscle pairs and how they work together to maintain balance, posture, and smooth movement.
The brain is the body’s command center, sending signals through the spinal cord to coordinate every movement. To keep actions smooth rather than clumsy, muscles work in pairs: when one (the agonist) contracts, its partner (the antagonist) relaxes. In this experiment, you’ll uncover how this push–pull system produces graceful motion.
Materials:
Setup:
Procedure:
Analyze your traces to see how agonist and antagonist spikes alternate. During waving, does one muscle stay mostly silent while the other fires? During push-ups, does the agonist switch roles? Discuss how reciprocal inhibition and co-contraction maintain smooth, controlled movement.
Draw the pathway from your motor cortex through your spinal cord to your biceps and triceps, and label where each channel recorded. For each phase of the push-up, mark which muscle your recording says got the “go” signal.
MS-LS1-3 Use argument supported by evidence for how the body is a system of interacting subsystems composed of groups of cells.
Nervous commands coordinate two muscle subsystems as a pair.
HS-LS1-2 Develop and use a model to illustrate the hierarchical organization of interacting systems that provide specific functions within multicellular organisms.
Draw the pathway from motor cortex through spinal cord to biceps and triceps, and mark which muscle gets the "go" in each phase.
1 Asking Questions and Defining Problems
Hypothesize which muscle is the agonist and which the antagonist before recording.
2 Developing and Using Models
Draw the pathway to biceps and triceps, label both channels, and mark which muscle gets the "go" in each push-up phase.
3 Planning and Carrying Out Investigations
Record biceps and triceps together while waving and doing push-ups.
4 Analyzing and Interpreting Data
Read the two traces to see which muscle fires and which stays quiet at each point.
6 Constructing Explanations and Designing Solutions
Explain stray antagonist spikes and how reciprocal inhibition and co-contraction keep movement smooth.
Structure and Function
Muscles work in pairs: flexors and extensors.
Patterns
Agonist and antagonist spikes alternate.
Systems and System Models
Brain, spinal cord and a muscle pair form a push–pull system.
LS1.A Structure and Function
Flexor and extensor muscles are built to pull a joint in opposite directions.
LS1.D Information Processing
Motor commands keep one muscle firing while its partner relaxes.
Backyard Brains mapping using the book's method. Not in the book.
