Muscular System

Abductor Muscles

Abduction refers to movement of a limb away from the central line of the body or of a digit away from the axis of a limb. Muscles, then, that carry out this type of movement are called "abductor muscles."

Biceps Brachii

Some muscles have more than one origin (immovable end) or insertion (movable end). The "biceps brachii" in the upper arm, for example, has two origins. This is shown in its name, "biceps," which means "two heads." It is attached to the scapula (shoulderblade) in two places and extends along the front surface of the humerus (upper arm bone). It is inserted by means of a tendon on the largest part of the radius (lower arm bone). When it contracts, the movable end is pulled toward the origin, and the arm bends at the elbow.

Adductor Longus

The adductor longus is a long, triangular muscle that runs from the pubic bone to the femur. It functions to adduct, or move the thigh inward, and assists in flexing and rotating it to the side.

Brachialis

The brachialis is a large muscle beneath the biceps brachii. It connects the shaft of the humerus (upper arm bone) to the ulna (longest) forearm bone) and is the strongest flexor of the elbow.

Brachioradalis Muscle

The brachioradalis connects the humerus (upper arm bone) to the radius (shortest lower arm bone) and aids in flexing the elbow.

Pectoral Muscles

The pectoral is a term relating to the chest. The "pectoralis major" is a large, fan-shaped muscle that covers much of the front upper chest. It begins at the breastbone (sternum) and the cartilage of the second to the sixth ribs and is attached to the collarbone (clavicle) to converge on the upper arm bone (humerus) just below the shoulder. Its main use is in moving the arm across the body. The "pectoralis minor" is a smaller, triangular muscle beneath the pectoralis major. It stems from the third to fifth ribs and converges at the shoulder blade (scapula), which it moves up and down.

Sternocleidomastoid Muscle

The sternocleidomastoid is a long muscle in the side of the neck that extends up from the thorax to the base of the skull behind the ear. When the sternocleidomastoid on one side contracts, the face is turned to the opposite side. When both muscles contract, the head is bent toward the chest. If the immovable end is fixed in position by other muscles, it can raise the sternum (breastbone) - an action which aids in forceful inhalation of a ..