Smooth muscle

involuntary non-striated muscle

Smooth muscle is muscle inside the body and not attached to bones. It is not under conscious control. Its function is to help the inner workings of the body.[1]

Three distinct types of muscle (L to R): Smooth (non-striated) muscle in internal organs, cardiac or heart muscle, and skeletal muscle.

There are three distinct types of muscle: skeletal muscle, cardiac or heart muscle, and smooth muscle. Muscles provide strength, balance, posture, movement, and heat for the body to keep warm.[2]

Smooth muscle is found in the walls of blood vessels, vessels of the lymphatic system, the urinary bladder, uterus, male and female reproductive tracts, gastrointestinal tract, respiratory tract, most ducts, and a number of other places such as the iris.

The smooth muscle looks different from the skeletal muscle, and works differently. It can squeeze slowly, and move in waves along a duct. Most types of smooth muscle squeeze gently for a long time, and use little energy. Some smooth muscle squeezes quickly and relaxes in phases.



  1. Stephen M. Schwartz & Robert P. Mecham (eds) 1995. The vascular smooth muscle cell: molecular and biological responses to the extracellular matrix. Academic Press. ISBN 0-12-632310-0
  2. Mescher AL, Junqueira LC (2013-02-22). Junqueira's basic histology : text and atlas (Thirteenth ed.). New York. ISBN 9780071807203. OCLC 854567882.{{cite book}}: CS1 maint: location missing publisher (link)