Ch. 4 Anatomy & Physiology of the Muscular System

extensor carpi

A muscle named for its action, extension.

flexor carpi

A muscle named for its action, flexion.

rectus abdominis

A muscle named for its location and the direction of its fibers: rectus means straight and abdominis means abdominal.

gluteus maximus

A muscle named for its size and location: gluteus means rump area and maximus means large.

external oblique

A muscle named for the direction of its fibers, on an oblique angle.

skeletal muscle

A voluntary muscle that is attached to bones by a tendon.

biceps

An arm muscle named for the number of attachment points. Bi- means two and biceps have two heads attached to the bone.

smooth muscle

An involuntary muscle found in internal organs such as the digestive organs or blood vessels.

striated muscle

Another name for skeletal muscle referring to its striped appearance under the microscope.

fascia

Connective tissue that wraps muscles. It tapers at each end of a skeletal muscle to form tendons.

sternocleidomastoid

Muscle named for its attachments, the sternum, clavicle, and mastoid process.

muscles

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.

voluntary muscles

Muscles that a person can consciously choose to contract. The skeletal muscles of the arm and leg are examples of this type of muscle.

involuntary 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.

motor neurons

Nerves that carry activity instruction from the CNS to muscles or glands out in the body; also called efferent neurons.

antagonistic pairs

Pair of muscles arranged around a joint that produce opposite actions.

origin

The attachment of a skeletal muscle to the less movable bone in the joint.

insertion

The attachment of a skeletal muscle to the more movable bone in the joint.

muscle tissue fibers

The bundles of muscle tissue that form a muscle.

cardiac muscle

The involuntary muscle found in the heart.

myocardium

The middle layer of the muscle. It is thick and composed of cardiac muscle. This layer produces the heart contraction.

visceral muscle

The muscle found in the walls of internal organs such as the stomach.

myoneural junction

The point at which a nerve contacts a muscle fiber.

tendon

The strong connective tissue cords that attach skeletal muscles to bones.

action

The type of movement a muscle produces.