Editing Anatomy (section)

===Muscle tissue===
[[File:Skeletal muscle - cross section, nerve bundle.jpg|right|thumb|Cross section through [[skeletal muscle]] and a small [[nerve]] at high magnification ([[H&E stain]])]]
[[Muscle cells]] (myocytes) form the active contractile tissue of the body. [[Muscle tissue]] functions to produce force and cause motion, either locomotion or movement within internal organs. Muscle is formed of contractile [[Myofibril|filaments]] and is separated into three main types; [[smooth muscle]], [[skeletal muscle]] and [[cardiac muscle]]. Smooth muscle has no [[Striated muscle tissue|striations]] when examined microscopically. It contracts slowly but maintains contractibility over a wide range of stretch lengths. It is found in such organs as [[sea anemone]] tentacles and the body wall of [[sea cucumber]]s. Skeletal muscle contracts rapidly but has a limited range of extension. It is found in the movement of appendages and jaws. Obliquely striated muscle is intermediate between the other two. The filaments are staggered and this is the type of muscle found in [[earthworm]]s that can extend slowly or make rapid contractions.<ref name=Ruppert103>{{cite book |title=Invertebrate Zoology, 7th edition |last1=Ruppert |first1=Edward E. |last2=Fox |first2=Richard, S. |last3=Barnes |first3=Robert D. |year=2004 |publisher=Cengage Learning |isbn=978-81-315-0104-7 |page=103 }}</ref> In higher animals striated muscles occur in bundles attached to bone to provide movement and are often arranged in antagonistic sets. Smooth muscle is found in the walls of the [[uterus]], [[bladder]], [[intestines]], [[stomach]], [[oesophagus]], [[respiratory airways]], and [[blood vessel]]s. [[Cardiac muscle]] is found only in the [[heart]], allowing it to contract and pump blood round the body.