Algonquin College
2.6 - Muscle Tissue
In multicellular organisms cells of similar structure and function come together to create tissues. Complex organisms have many different cell types that fulfill different structural and physiological needs of the organism. There are four basic tissue types: epithelial, connective, nervous and muscle.

Muscle tissue is unique in its function of contraction to produce movement. Contractions can be under conscious control or under direct control of the autonomic nervous system. Muscle types also vary in the strength of their contraction.

Skeletal muscle

Skeletal muscle is attached to the bones of the skeletal system and is responsible for producing voluntary movements including facial expressions and speech sounds. Skeletal muscle cells are also called muscle fibers because of their long, strand-like appearance.
  • Cell shape - Long and cylindrical
  • Number of nuclei - many (multinucleated)
  • Striations (stripes) - Yes; obvious striations
  • Function - voluntary movements including facial expression
  • Location - attached to bones of the skeletal system
  • Contractions - very fast, high force
Cardiac muscle

Cardiac muscle is only found in the heart. It is responsible for producing the movements of the heart to pump blood. Cardiac muscle contracts rhythmically to produce the heartbeat. Your cardiac muscles must work constantly for your entire lifetime!
  • Cell shape - short and branched; joined by intercalated discs
  • Number of nuclei - one
  • Striations (stripes - Yes; light striations
  • Function - involuntary movements of the heart
  • Location - heart
  • Contractions - rhythmic, high force
Smooth muscle

Smooth muscle is found lining any hollow internal spaces in the body. Its primary function is to change the size of the hollow internal space, either to push substances along or to change the pressure of fluid flow.
  • Cell shape - long, fusiform (cylinder with tapered ends)
  • Number of nuclei - one
  • Striations (stripes - No)
  • Function - involuntary contractions of hollow organs and tubes
  • Location - bladder and urinary tract, uterus, blood vessels, digestive tract, respiratory tract
  • Contractions - low force, often rhythmic