Written by the Fiveable Content Team • Last updated September 2025
Verified for the 2026 exam
Verified for the 2026 exam•Written by the Fiveable Content Team • Last updated September 2025
Definition
The myelin sheath is an insulating layer around nerves, including those in the brain and spinal cord. It allows electrical impulses to transmit quickly along the nerve cells.
Related terms
Schwann Cells: These are like workers who install insulation on wires. Schwann cells produce myelin in peripheral nervous system.
Nodes of Ranvier: These are gaps in myelin sheath along axon which help increase speed at which electric impulses propagate along axon - think about them as boosters or amplifiers for signal transmission.
Multiple Sclerosis (MS): This disease damages myelin sheaths around nerves in central nervous system disrupting communication between brain and body, similar to how a damaged insulation would disrupt electricity flow.