The Structure & Function of Cardiac Myocytes

Written by michael paul maupin | 13/05/2017
The Structure & Function of Cardiac Myocytes
The structure of a cardiac myocyte looks a bit like a California roll in appearance. (sushi image by Maryna Girard from

Cardiac myocytes are a kind of highly specialised muscle cell. Myocytes are not exclusive to cardiac tissue. Other bodily tissues contain myocytes, such as the skeletal muscles of the arms and legs and the smooth muscles that line the structures of the cardiovascular system. Through a functional process known as automaticity, cardiac myocytes enable the heart muscle to generate electrical impulses. Structurally speaking, cardiac myocytes arguably resemble a sushi-style California roll.

The Outside Structure of Cardiac Myocytes

Cardiac myocytes are barrel shaped. A basement membrane wrap the internal cell structures. At the level of the internal transverse tubules, fibrillar collagen sprouts from the basement membrane.

Sarcolemmic Layer

Beneath the external basement membrane is a sub-layered structure that surrounds the innermost components of the cardiac myocyte. This sub-layer is known as the sarcolemmic layer.


Multiple mitochondrial structures are present within the cell body. Mitochondria have a latitudinal orientation when studying the myocyte in a latitudinal view.

Contractile Apparatus

The contractile apparatus structures can be described as both short and stumpy. The apparatuses present in a stacked pattern. These apparatuses have a latitudinal orientation when examining the myocyte in a latitudinal view.

Sarcoplasmic Reticulum

A webbed matrix of sarcoplasmic reticuli form around the contractile apparatuses in close proximity to the mitochondria.

Transverse Tubules

When examining the cardiac myocyte in a longitudinal view, the transverse tubules, or T-tubules, present longitudinally from the mitochondria, contractile apparatuses, and sarcoplasmic reticuli. The T-tubules are situated between the contractile apparatuses, lending to the stacked appearance of this component.

Cell Nucleus

Cardiac myocytes are multinuclear, meaning the cell bodies have more than one nuclei.

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