[Verse 1]
Rubber hammer taps the tendon, just below the cap,
Stretch receptor in the spindle fires a single snap,
One line straight to the spinal cord, no detour, no delay,
Quadriceps kicks forward in a blink-and-miss-it way,
One synapse, that's the whole story, nothing in between,
Sensory neuron shakes hands with motor — cleanest link you've seen.
[Chorus]
One sense, one jump, one kick — that's the monosynaptic trick,
Knee bone talking straight to muscle, fast and slick,
Hammer tap, spindle stretch, leg obeys the call,
Simplest circuit in the body, shortest hallway of them all.
[Verse 2]
That same sensory neuron's got a second wire to pull,
Whispers to an interneuron, quiet, calm and full,
Hamstring on the backside gets a hush-now, stand-down cue,
Quadriceps leaps forward while the hamstring lets it through,
Call it reciprocal inhibition, partners in the dance,
One side fires, the other quiets — nothing left to chance.
[Chorus]
One sense, one jump, one kick — that's the monosynaptic trick,
Excite the puller, calm the pusher, that's the clever trick,
Hammer tap, spindle stretch, leg obeys the call,
Reflexes keep their balance so you never trip and fall.
[Verse 3]
Step upon a tack and the story grows a lot more wide,
Pain shoots up through many stops — the withdrawal is your guide,
Interneurons pass the news through branching, chattering trees,
Polysynaptic pathways bend with every new degree,
That foot pulls back while on the other, something strange occurs,
The crossed extensor locks the knee so standing weight transfers.
[Verse 4]
Sherrington watched a dog's hind leg and counted every spark,
Found that signals pile up high or cancel in the dark,
Summation stacks the whispers till a neuron starts to shout,
Inhibition hushes others till their voice is counted out,
Every pathway, every nerve, however it began,
Funnels down to one last gate — that's Sherrington's master plan.
[Bridge]
Sensor feels it, cord decides, muscle makes the move,
Three parts spinning like a wheel that's got something to prove,
Input, middleman, output — circuit closed and done,
Oldest loop the nervous system ever spun.
[Chorus]
One sense, one jump, one kick — that's the monosynaptic trick,
Many synapse, many stops — the withdrawal's thick,
Hammer tap or burning foot, the nerves still make the call,
Final common path's the motor neuron, ruling over all.
[Outro]
Tap the knee, pull the foot, feel the body's oldest rule,
Reflex arc, the tiny engine built before the school,
One synapse or a dozen, the message still gets through,
Final... common... path — the motor neuron carries it to you.