Muscular System
Name of Muscles
Frontalis-is a muscle that covers parts of the forehead of the skull. It performs the action of raising eyebrows.
Temporalis-is a broad, fan-shaped muscle on each side of the head that fills the temporal fossa. It performs the action of closing the jaw.
Orbicularis Oculi-circular-shaped muscle. It performs the actions of closing the eye and winking.
Orbicularis Oris-is a complex of muscles in the lips that encircles the mouth. It performs the action of closing the lips.
Zygomaticus-is a muscle of facial expression. It performs the actions of raising the corners of the mouth and smiling.
Masseter-one of the two muscles that close the jaw. It performs the action of closing the jaw.
Buccinator-a flat, thin muscle in the wall of the cheek. It performs the action of sucking in your cheek.
Sternocleidomastoid-one of the most superficial cervical muscle. It performs the following actions:Laterally flexing neck, Rotating the head to opposite side, and Flexing neck forward.
Platysma-superficial muscles of the front of the neck.The actions of the platysma muscle include pulling down the mandible, which opens the mouth, and pulling the corners of the lips out to the side and down, which forms a frown.
Pectoralis Major-it flexes, adducts, and rotates the shoulder medially. It performs the action of raising the arm forward.
Trapezuis-extends or straightens and hyperextends the neck. It performs the action of shrugging the shoulder.
Rectus Abdominis-the abdominal muscle that flexes the vertebral column(superficial). Action:Flexion of the trunk.
External Obliques-laterally flexes and rotates vertebral column(superficial). Action:Helps rotate the trunk.
Latissimus Dorsi-the largest muscle in the upper body. Actions:Extends, Adducts, and Medially rotates the shoulder.
Erector Spinae-a group of muscles and tendons which run move or less the length of the spine on the left and the right. Actions:Straightening the back and provides for side-to-side rotation.
3 Types of Muscle Tissues
Skeletal Muscle-are the longest muscles, has obvious stripes(striations), Voluntary muscle, tires easily, remarkably adaptable.
Cardiac Muscle-has striations as well, Non-Voluntary.
Smooth Muscle-consists of elongated cells, has no striations, forces fluids and other substances through internal body channels.
Body Movement Terminology
Supination-palm is upward.
Pronation-palm is downward.
Abduction-moving parts away from the midline.
Extension-straighten or increase angle at a joint.
Flexion-bending a joint, decreasing the angle.
Plantar Flexion-bending foot downward or pointing toes down.
Eversion-moving foot outward.
Inversion-moving foot inward.
Dorsiflexion-flexing foot at the angle or toes off the ground.
Adduction-moving parts toward the midline.
Hyperextension-moving parts beyond the 180 degrees.
Circumduction-one end stays same position and the other end moves in circular motion.
Opposition-movement of thumb to touch the tip of the other fingers of the same hand.
Rotation-spinning on an imaginary axis.
Organizational Levels of the Skeletal Muscle
Muscle-a muscle consists of hundreds to thousands of muscle cells, plus connective tissue wrappings, blood vessels, and nerve fibers.
Fascicle-a discrete bundle of muscle cells, segregated from the rest of the muscle by a connective tissue sheath.
Muscle Fiber-an elongated multinucleate cell; it has a banded(striated) appearance.
Myofibril-rod-like contractile elements that occupy most of the muscle cell volume. Composed of sarcomeres arranged end to end.
Sarcomere-the contractile unit, composed of myofilaments made up of contractile proteins.
Physiology of Muscle Contraction
Sliding Filament Theory-during contractions, thin filaments slide past the thick ones so that the actin and myosin filaments overlap to a greater degree.