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Smooth Muscle
 | Smooth muscle cells are spindle-shaped
- tapered at both ends. Depending on their location, they can be
very long and thin or fairly short and fat. They have a single
nucleus and no cross striations like the other 2 types of
muscle. |
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smooth muscle (whole mount) |
| Visceral smooth muscle is found
primarily in the walls of hollow abdominal organs such as the
intestine, urinary bladder and uterus. The cells are linked
together in large sheets of cells that contract together - no fine
movements are possible. Visceral smooth muscle does not require
external nerve stimulation for contraction, but external autonomic
nerves serve to modify contractions.
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| Multi-unit smooth muscle occurs in
small individual units - the cells are not linked into large
sheets. This type of smooth muscle requires an external nerve
supply to initiate its contractions. It is found where small fine
contractions are needed, such as the iris and ciliary body of the
eye. |
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