Muscles are bundles of parallel muscle tissue fibers. As there fibers contract (shorten in length) they pull whatever they are attached to closer together. This may move two bones closer together or make an opening more narrow. A muscle contraction occurs when a message is transmitted from the brain through the nervous system to the muscles.
Muscles under the control of the subconscious regions of the brain. The smooth muscles found in internal organs and cardiac muscles are examples of involuntary muscle tissue.
An involuntary muscle found in internal organs such as the digestive organs or blood vessels.
Muscles that a person can consciously choose to contract. The skeletal muscles of the arm and leg are examples of this type of muscle.
Connective tissue that wraps muscles. It tapers at each end of a skeletal muscle to form tendons.
Nerves that carry activity instruction from the CNS to muscles or glands out in the body; also called efferent neurons.
Another name for skeletal muscle referring to its striped appearance under the microscope.
The middle layer of the muscle. It is thick and composed of cardiac muscle. This layer produces the heart contraction.
An arm muscle named for the number of attachment points. Bi- means two and biceps have two heads attached to the bone.
A muscle named for its size and location: gluteus means rump area and maximus means large.
A muscle named for its location and the direction of its fibers: rectus means straight and abdominis means abdominal.