The Tongue

Muscle Pics

Joints

A joint is a connection in two or more bones. There are four main different kinds of joints: hinge joints, fixed joints, pivot joints, and ball-and-socket joints. Hinge joints, such as the knee, allow a forward and backward swinging movement, like a door on hinges. Fixed joints, like the bones between the skull, allow no movement. Pivot joints give a rotating motion, like the pivoting movement of the neck joints. Ball-and-socket joints allow the most free movement. They are made of the rounded end of one bone and the hollow end of another. They allow side to side movement and rotating movement. some examples are the hips and shoulder. Some joints, however, are allowed more movement by the way they are arranged. All joints are protected from wearing away by cartilage. Cartilage also allows smooth movement of joints. All of these parts work together to create a movement and a smooth one.

Smooth Muscles

Smooth muscles (also called involuntary muscles) are found in the walls of the stomach, intestines, blood vessels, and bladder. They move in a slow, automatic movement, always followed by contraction, then relaxation. Smooth muscles are stimulated by a special set of nerves ,belonging to the autonomic nervous system, and and by certain body chemicals. smooth muscles are usually in sheets or layers, with one layer on top of the other. They are controlled by your brain and do things without you even thinking about it. Smooth muscle fibers are smaller than skeletal muscle fibers. They have only one nucleus, unlike the skeletal muscles. Smooth muscles work together with your brain to help your body function.

Skeletal Muscles

Skeletal muscles hold the skeleton together and give the body its shape. They help the body move. Each skeletal muscle is composed with thousands of cylindrical muscle fibers. Each muscle fiber skeletal muscle fiber has many elements called nuclei. Skeletal muscles are voluntary muscles, which means you control what they do. The skeletal muscles work together with your bones to give your body strength and power. Skeletal muscles usually attach to a bone, then to a joint, and then to another bone. Skeletal muscles are held to your bones with tendons. These muscles work together to help your body move.