NucleusOne nucleus, sometimes two, lies near the center.
StriationsCross stripes made by the lined-up sarcomeres.
Intercalated discJoins two cells end to end and passes signals between them.
BranchThe cell divides at its end to join two neighbors.
Sarcolemma (cell membrane)The cell membrane of a muscle cell.
MitochondriaThey supply the cell's energy. A cardiac muscle cell has many.
MyofibrilA rod of contractile proteins running the length of the cell.
CapillaryA tiny blood vessel beside the cell.
The disc and inside the cell 7
Fascia adherensAnchors the thin actin filaments at the end of the cell.
DesmosomeHolds the two cells together. It is tied to intermediate filaments.
Gap junctionLets the electrical signal pass from cell to cell.
T tubule (transverse tubule)A tube of the sarcolemma that runs into the cell.
Sarcoplasmic reticulumThe cell's internal store of calcium.
SarcomereOne contractile unit, from one Z disc to the next.
Z disc (Z line)The dark line at each end of a sarcomere.
How this list was compiled: Every name checked on 2026-10-01 in at least two of these, in our own words. (1) Wikipedia, Cardiac muscle, sections Cardiac muscle cells, T-tubules and Intercalated discs. (2) Wikipedia, Intercalated disc, section Structure. (3) Yale School of Medicine, Histology lab on muscle, pre-lab reading on cardiac muscle. (4) Henry Gray, Anatomy of the Human Body, 20th edition, 1918 (public domain), The Heart, on the cardiac muscular tissue. (5) Sit, Gutmann and Iskratsch, Costameres, dense plaques and podosomes, Journal of Muscle Research and Cell Motility, 2019. (6) Wikipedia, T-tubule. Licence: own work
The drawing: Drawn for this site on 2026-10-01 from plain geometry. Own original drawing; nothing is traced or copied. Licence: own work
How it works
Cardiac muscle cell diagram, labeled in two drawings: one branching cardiomyocyte joined end to end with its neighbors, and the intercalated disc close up. It doubles as a cardiomyocyte cell diagram and a heart muscle tissue diagram.
Read the full guide
The cell
A cardiac muscle cell is short and striped, with one nucleus, sometimes two, near its center. Its ends branch and join the neighboring cells at intercalated discs, so the cells form one network. Many mitochondria supply its energy, and capillaries run between the cells.
The disc and inside
An intercalated disc holds three kinds of junction. The fascia adherens anchors the actin filaments, desmosomes hold the cells together, and gap junctions pass the electrical signal on. Inside, each myofibril is a chain of sarcomeres between Z discs. T tubules carry the sarcolemma into the cell, beside the sarcoplasmic reticulum.
Questions and answers
What are the parts of a cardiac muscle cell?
A sarcolemma, one or two central nuclei, striped myofibrils made of sarcomeres, many mitochondria, T tubules and sarcoplasmic reticulum. At each end an intercalated disc joins it to the next cell.
What is an intercalated disc?
The junction that joins two cardiac muscle cells end to end. It holds three kinds of cell junction: the fascia adherens, desmosomes and gap junctions.
How is a cardiac muscle cell different from a skeletal muscle fiber?
A cardiac muscle cell is short and branched, has one or two nuclei near its center and is joined to its neighbors by intercalated discs. A skeletal muscle fiber is long, has many nuclei and has no intercalated discs.
Is a cardiomyocyte the same as a cardiac muscle cell?
Yes. Cardiomyocyte is another name for a cardiac muscle cell, the contracting cell of the heart wall.