nerves

Question 1

the pns

Answer 1

The Peripheral Nervous System (PNS) includes:

Nerves → bundles of axons that carry signals to and from the CNS

Ganglia → clusters of neuron cell bodies located outside the CNS

🔁 How it works:
A sensory neuron in the PNS has its cell body in a ganglion (like the dorsal root ganglion).

Its axon travels into the spinal cord to deliver the signal to the CNS.

The CNS then processes it and may send a motor response back out through the PNS.

Answer 2

A nerve is a bundle of neuron fibers (axons) found outside the central nervous system (CNS) — so it’s part of the peripheral nervous system (PNS).

Think of a nerve like a cable made up of many wires, and each wire is an axon from a neuron.

🧵 Connective Tissue Layers of a Nerve (like wrapping around wires):
Endoneurium

Wraps each individual axon (fiber)

Like the plastic coating around a single wire

Perineurium

Wraps a bundle of axons (called a fascicle)

Like wrapping a few wires together in a smaller cable

Epineurium

Wraps the entire nerve (all fascicles together)

Like the thick outer layer of a big electrical cord

Nerves are NOT found in the CNS —
In the CNS, we use the word tracts, not nerves.
→ Nerves = PNS
→ Tracts = CNS

Bundles of axons are called nerves in the PNS and tracts in the CNS.
They’re basically the same thing, just named differently based on where they are.

Question 3

mixed chords

Answer 3

It contains both:

Sensory (afferent) fibers → bring signals into the CNS

Motor (efferent) fibers → carry signals out of the CNS

🧠 Example: Spinal Nerves
All spinal nerves are mixed nerves

That’s why they can:

Feel (like pain, pressure, heat)

Move (like muscles contracting)