The cell body (soma) of a typical motor neuron is approximately 100 microns (0.1 millimeter) in diameter. However, the overall "size" of a motor neuron is more complex than just the size of the cell body due to the extensive length of its axon, which can be up to 1 meter long.
Understanding Motor Neuron Size
It's important to differentiate between the size of the cell body and the length of the axon when considering the "size" of a motor neuron.
- Cell Body (Soma): The cell body, which houses the nucleus and other essential organelles, is relatively small, measuring around 100 microns in diameter.
- Axon: The axon is a long, slender projection that transmits signals to other neurons or muscle cells. The length of the axon can vary significantly depending on the type and location of the motor neuron. For example, motor neurons that innervate muscles in your toes can have axons that are nearly a meter long.
Analogy
Think of it like this: the cell body is like the control center of a factory, while the axon is like the delivery truck that transports the factory's products across a long distance. The factory (cell body) may be relatively small, but the delivery truck (axon) can be quite long.
Key Takeaway
While the cell body of a motor neuron is about 100 microns in diameter, the true "size" considering its function, also includes the extensive length of its axon, which can reach up to a meter.
