Compendium Review topic TWO Unit 3

Movement- Musle and Bone-

Muscle Structure and Function-

Muscle tissue can be one of several types in the body: smooth, cardiac, or skeletal. For our purposes we are concerned with skeletal muscle, which makes up the bulk of the body's muscle and is the tissue we use for physical activity.
The muscle that you can see is composed of subunits called fascicles. Fascicles are bundles of individual muscle fibers. Each fiber is one elongated cell that may extend for the length of the muscle. Each muscle fiber cell has several nucleii (unlike most cells, which have only one), and is segmented into distinct sectional bands. Within each muscle cell are numerous myofibrils, which also extend for the length of the muscle cell. Sarcomeres are the basic contractile subunit of myofibrils.

A whole skeletal muscle is considered an organ of the muscular system. Each organ or muscle consists of skeletal muscle tissue, connective tissue, nerve tissue, and blood or vascular tissue.
Skeletal muscles vary considerably in size, shape, and arrangement of fibers. They range from extremely tiny strands such as the stapedium muscle of the middle ear to large masses such as the muscles of the thigh. Some skeletal muscles are broad in shape and some narrow. In some muscles the fibers are parallel to the long axis of the muscle, in some they converge to a narrow attachment, and in some they are oblique.

Movement across the joints-

Most joints in the body are freely movable joints. The joint consists of the joint capsule, articular cartilage, synovial membrane, and synovial cavity. There are six classifications of freely movable joints: ball-in-socket, condyloid, gliding, hinge, pivot, and saddle joints. These joints have much more complex structures than the immovable and slightly movable joints. The ends of the bones in this type of joint are covered with a smooth layer of cartilage. The whole joint is enclosed in a watertight sac or membrane containing a small amount of lubricating fluid. This lubrication enables the joint to work with little friction. Ligaments reach across the joints from one bone to another and keep the bone stable. When ligaments are torn, we call the injury a sprain; when bones are out of place, we refer to this as a dislocation; and when bones are chipped or broken, the injury is called a fracture.

TYPES OF JOINT MOVEMENTS

Joint movements are generally divided into four types: gliding, angular, rotation, and circumduction. Gliding Gliding is the simplest type of motion. It is one surface moving over another without any rotary or angular motion. This motion exists between two adjacent surfaces. Angular Angular motion decreases or increases the angle between two adjoining bones. The more common types of angular motion are as follows:

· Flexion—bending the arm or leg.

· Extension—straightening or unbending, as in straightening the forearm, leg, or fingers. · Abduction—moving an extremity away from the body.

· Adduction—bringing an extremity toward the body. Rotation Rotation is a movement in which the bone moves around a central point without being displaced, such as turning the head from side to side.

Bones-

Bones are rigid organs that form part of the endoskeleton of vertebrates. Bones function to move, support, and protect the body, produce red and white blood cells and store minerals. Bones come in a variety of shapes and have a complex internal and external structure, allowing them to be lightweight yet strong and hard, while fulfilling their many other functions. One of the types of tissues that makes up bones is the mineralized osseous tissue, also called bone tissue, that gives bones their rigidity and honeycomb-like three-dimensional internal structure. Other tissue types found in bones include marrow, the periosteum, nerves, blood vessels and cartilage.