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Male and female pelvis

Except for the pelvis, most of the bones in the female skeleton are the same shape as the bones in the male skeleton but are usually a little smaller. The female pelvis is usually broader than the male pelvis and has a larger space in the middle, to accommodate the head of a baby as it passes through the pelvis during childbirth.

Joint Movements

The finger joints are typical hinge joints and move primarily in one plane—backward and forward. Elbow joints move in the same way. A ball-and-socket joint such as the shoulder or hip allows movement in two planes—backward and forward and sideways. A ball-and-socket joint also allows the limb to rotate. Most actions of the arms and legs involve a combination of these movements.

Different types of joints

Some joints (such as the fibrous sutures that join the bones of the skull in adults) weld the bones into one rigid structure and allow no movement. Other joints provide limited movement. Each vertebra can move only slightly but, over the whole spine, the vertebrae allow considerable flexibility. Joints such as the shoulders and hips provide a wide range of movement.

Each joint is a complicated structure held together on the outside by fibrous bands called ligaments. Under each ligament is a capsule made of fibrous tissue surrounding the joint. The capsule is lined on the inside by a slippery, fluid-filled membrane called the synovial membrane; the synovial fluid lubricates the joint. Where the bone ends meet, the surfaces are covered by a tough, rubbery tissue called cartilage. Cartilage acts as a shock absorber, or cushion, between the bones, allowing them to move against each other smoothly.

Sports Injuries

Exercise involves the risk of injury, but the health benefits of exercise far outweigh the risks. Anyone who exercises vigorously has an increased risk of injuring his or her muscles, ligaments (tough elastic bands of tissue that hold bones together), bones, and joints. Sports injuries frequently occur in athletes at the beginning of a sports season and in people who are new to a sport or who start an exercise or activity after a long period of inactivity. Exercising without warming up first can also contribute to injuries.

Taking precautions such as stretching before exercising can help you avoid injury. If you are injured, stop the activity right away to determine the extent of the injury. If you’re not sure how serious your injury is, or if you are disoriented, even for only a few seconds, stop the exercise or sport immediately and see a doctor as soon as possible. Many injuries require no treatment other than rest. You may need physical therapy to treat damaged tissues and to strengthen affected muscles. If the injury is severe, you may need surgery. If an injury recurs, you may have permanently damaged a ligament or bone and may have to give up the sport or activity or risk developing a chronic condition such as osteoarthritis (see page 996). To help prevent an injury from worsening or becoming permanent, get an accurate evaluation of the damage from a doctor. He or she will probably order X-rays, a CT scan (see page 112), MRI (see page 113), ultrasound (see page 111), or arthroscopy (see page 1001) to determine the extent of the injury.

The RICE Routine

If you have a minor muscle or ligament injury such as a strain or sprain, RICE—which stands for rest, ice, compression, and elevation—is usually the best way to treat it. Performing the RICE routine will help relieve any pain or swelling and enable you to recover more quickly.

Rest

Rest the injured area and avoid moving it or putting any unnecessary weight or pressure on it. Use a sling to rest an injured shoulder or arm, and crutches to take weight off an injured leg. Rest reduces bleeding from damaged blood vessels, minimizes the risk of more damage, and enables tissues to heal.

Ice

Apply an ice pack to the injured area as soon as possible. Apply the ice every hour you’re awake for 20 minutes for the first 24 to 48 hours