An<unk>  is an undulating double membrane separating adjacent cells in cardiac muscle fibers.<unk> s support synchronized contraction of cardiac tissue.  They can easily be visualized by a longitudinal section of the tissue.
Three types of membrane junctions exist within an<unk> —fascia adherens, macula adherens, and gap junctions.
Fascia adherens are anchoring sites for actin, and connects to the closest sarcomere.
Macula adherens stop separation during contraction by binding intermediate filaments joining the cells together also called a desmosome.
Gap junctions allow action potentials to spread between cardiac cells by permitting the passage of ions between cells, producing depolarization of the heart muscle.
When observing cardiac tissue through a microscope,<unk> s are an<unk> entifying feature of cardiac muscle.
Intercalated disc
Spinous process
Intervertebral foramina
Tendinous intersection
Ischial spine
Plexus
Costovertebral angle
Lamina of the vertebral arch