Muscular System

Types of Muscles Skeletal Control voluntary movements of the skeleton and body Striated Smooth Control the involuntary movements of the digestive and vascular system Not striated Cardiac Control the involuntary muscles of your heart Striated

Types of Muscles Skeletal Smooth Cardiac

Skeletal Muscles

Skeletal muscles are made up of many muscle fibers Those fibers are made up of many myofibrils Those myofibrils are made up of actin and myosin, which work together to contract and relax the muscle

Relaxed Muscle

Actin and Myosin During muscle contraction the little sticky heads on myosin filaments bind to the actin. When ATP (energy from cellular respiration) is added the myosin changes shape bending towards the middle and pulling the actin fibers with it. This makes the muscle fiber shorten or contract.

Actin and Myosin

Tendons and Ligaments The reason we move when our muscle contract is because they are attached to bones by tendons This typically happens at joints. Joints are where one bone meets another and movement can occur. Ligaments attach bone to bone, to restrict and help control our movements

Joints Joints are where one bone attaches to another bone Most joints have cartilage between them to prevent bone to bone contact and damage. There are five different types of joints, four of which allow movement The different joints are classified by the type of movement they allow

Immovable Joint These are also referred to as fixed joints because they allow no movement These can be found in your skull and pelvis where the different bones fuse together.

Ball-and-Socket Joint Joint formed by a ball at the end of one bone that fits into a cavity in the end of another bone. This allows free movement in almost every direction Examples of these would be your shoulders and hips.

Hinge Joint Hinge joints allow back and forth movement in one direction, and a little movement in the other direction The bones are held in place by tough ligaments that allow more limited movement than the ball-and socket joint. Examples can be found in the elbow, knee, and knuckles of the fingers.

Pivot Joint Pivot joints allow rotation around one point. The bone can twist back and forth allowing a twisting or rotating movement Examples can be found in the radius in the forearm and in the neck, which allows us to turn our heads from side to side.

Saddle Joint A saddle joint is formed when the end of one bone is the mirror image of its adjoining bone creating a saddle shape. The two bones meet to form an X, the saddles cradle each other. This allows a wide range of movement, or rocking movement in either direction An example would be your thumbs.