The panniculus carnosus is a part of the subcutaneous tissues in vertebrates.
It is a layer of striated muscle deep to the panniculus adiposus.
Some of the muscles of facial expression in the head are part of the panniculus carnosus.
In other parts of the body, the layer is vestigial, and may be absent or may exist only as microscopic, disconnected fibers.
For example, the panniculus carnosus in the echidna covers almost its entire body, enabling it to change its shape to a certain degree, most characteristically by rolling into a ball and presenting its spines to a potential predator.