Z disk
Definition:
The Z disk (or Z line) defines the boundaries of a muscle sarcomere. Two adjacent Z disks along the myofibril mark the boundaries of a single sarcomere. The Z disks are the attachment sites for the thin filaments. Therefore, from each Z disk, thin filaments extend to two neighboring sarcomeres. When a muscle fiber contracts, the Z disks of a sarcomere move closer together (i.e., the sarcomere also shortens).
Related glossary terms/phrases:
A bandH zoneI bandM line
Posted: Thursday, January 8, 2015
Last updated: Wednesday, March 12, 2025