Lesson: The Axon Initial Segment

The Axon Initial Segment (AIS): The Brain’s “Trigger Point” for Action

What is it?

The Axon Initial Segment (AIS) is a specialized region of a neuron located just beyond the cell body, at the very beginning of the axon.

It’s the critical “decision zone” where an action potential (nerve impulse) either happens — or doesn’t.

What Makes the AIS Unique?

• It’s packed with voltage-gated sodium channels.

• It has an extremely low threshold for activation.

• It integrates all incoming excitatory & inhibitory signals.

• If the cumulative input reaches the threshold, it fires an action potential down the axon.

Why It Matters in Kyusho & Tuite

Your strikes & manipulations don’t just hit skin or muscle — they send neural signals through sensory nerves.

These signals converge at spinal or cranial processing centers…

…which then relay those signals to motor neurons.

If those motor neurons receive conflicting or excessive signals, the AIS becomes overwhelmed, leading to:

• Uncoordinated muscle responses

• Sudden weakness or collapse

• Delayed or failed motor signals

• Even protective inhibition (the body “shuts down” to prevent damage)

Practical Application:

• In Tuite: Combining joint torque with point activation causes massive input to spinal motor neurons — overloading the AIS.

• In Kyusho: Rapid sequential strikes (e.g., GB20 ➝ ST5 ➝ LI18) flood the system, and the AIS may “choose” not to fire correctly → loss of motor control.

Kyusho & Tuite are literally science at work.

Understand the Science. Master the Art!🐼