The Achilles tendons are thick and powerful bands of fibrous tissue. They connect your calf muscles to your heel bones. The tendons help you walk, run and jump. And that means they are under a lot of stress, making injuries to the Achilles tendons common.

This arthritis affects a joint at the top of your shoulder. It's where the shoulder blade's bony protrusion (called the "acromion") meets the clavicle. This joint acts as a pivot point when you raise your arm above your head.

"The brain is the control center of the human body. It forms your thoughts and preserves your memories. It regulates your body's actions, from the movements you choose to perform to the functions you don't even consciously think about. Let's take a closer look at the anatomy and the function of the brain. "

Your hands are complex and versatile. They're strong and nimble, and can do very delicate movements. Let's look at the main structures of your hands so we can see how they do all the things they do.

The hip joint is one of the largest weight-bearing joints in the body. This ball-and-socket joint allows the leg to move and rotate while keeping the body stable and balanced. Let's take a closer look at the main parts of the hip joint's anatomy.

The knee is the body's largest joint. It's the place where three bones meet: the tibia, the femur and the patella. The knee is a "hinge" joint. It allows the leg to bend in one direction only. Let's take a closer look at the main parts of the knee's anatomy.

The shoulder is a complex structure made of three separate joints. They work together to give the shoulder a tremendous range of motion. Let's take a closer look at the main parts of the shoulder's anatomy.

The spinal column is the body's main support structure. Its thirty-three bones, called vertebrae, are divided into five regions: cervical, thoracic, lumbar, sacral and coccygeal.

Ligaments are fibrous, elastic bands of tissue that connect and stabilize the bones. An ankle sprain is a common, painful injury that occurs when one or more of the ankle ligaments is stretched beyond the normal range of motion. Sprains can occur as a result of sudden twisting, turning or rolling movements.

The anterior cruciate ligament, commonly called the ACL, is a thick, elastic band of tissue that runs from the bottom of the femur to the top of the tibia. It helps stabilize the knee joint. The ACL can become stretched or torn when the knee is twisted or hyperextended. For reasons that are not fully understood, ACL injuries are much more common in women than in men.

This injury is a tearing of the ACL ligament in the knee joint. The ACL ligament is one of the bands of tissue that connects the femur to the tibia. An ACL tear can be painful. It can cause the knee to become unstable.

If your heart beats too fast, too slow, or irregularly, you have an arrhythmia. It's a problem with the rhythm of your heart. For many people, an arrhythmia is harmless. But for some, it can be life-threatening.

This disease is a buildup of a sticky, fatty substance called "plaque" on the inner walls of your arteries. Plaque buildup limits the flow of blood. This can lead to serious health problems.

This is a weakening and collapse of the bone in the head of your femur. That's the ball that fits in the socket of your hip. As this bone gradually dies and breaks apart, you can develop painful arthritis in your hip.

This condition occurs when a bone's normal blood supply is disrupted. The affected bone cells die and the dead bone weakens. The bone may begin to fracture and collapse, leading to arthritis.

Tendons are strong bands of tissue that connect muscle to bone. With this injury, one of the tendons anchoring your biceps muscle is torn. It may be torn partially or completely. Because the biceps is attached with two separate tendons, you may find that you can still use your biceps muscle even if one tendon is completely torn.

This is a problem with a tendon in your shoulder. Most often, it's the "long head of biceps" tendon. It travels from the front of your upper arm to the top of your shoulder socket. With this condition, the tendon becomes painfully inflamed or irritated.

This is a problem with a tendon in your elbow. It's called the "distal biceps tendon." It connects the biceps muscle of your upper arm to the radius bone at the elbow. With this condition, the tendon becomes painfully inflamed or irritated.

This condition is a bulge that forms in the wall of a weakened artery in the brain. This bulge can leak or rupture, causing a stroke. An aneurysm can be life-threatening.

These are warm or painful sensations caused by an injury to the brachial plexus. This is a network of nerves that passes through your shoulder. They travel down your arm and to your hand.

This is an irritation or swelling of the trochanteric bursa. This small, fluid-filled sac is found on the outer side of the femur. It acts as a cushion for the iliotibial band, a thick tendon in your leg.

This condition is an abnormally high arch of the foot that results in an excessive amount of body weight being directed to the ball and heel of the foot. Cavus foot can be congenital or acquired, may develop at any age, and can affect one or both feet.

This condition is an irritation or compression of one or more nerve roots in the cervical spine. Because these nerves travel to the shoulders, arms and hands, an injury in the cervical spine can cause symptoms in these areas. Cervical radiculopathy may result from a variety of problems with the bones and tissues of the cervical spinal column.

This is a pain on the outer side of your ankle. It's a lasting pain that you may feel all the time. It can make it hard for you to walk and run, and it can increase the possibility of ankle sprains.

This condition is an inflammation of the tip of the tailbone, called the coccyx. It causes pain and tenderness between the buttocks.

This is a type of chronic, long-lasting, pain. In most cases, it develops in an arm or a leg that you have previously injured. With CRPS, you may have unexplained pain that won't go away. It may be severe, and it may spread.

This is a collapse of vertebral bone. It can affect one or more vertebrae. Compression fractures typically develop in your mid or lower back. This can change the shape of your spine.

This is a serious brain injury. It happens when your brain bumps back and forth violently inside your skull. A concussion can affect the way your brain functions. It can cause permanent problems.

Coronary arteries are the blood vessels that feed your heart muscle. If the arteries harden and narrow, your heart muscle can't get the blood it needs to work well. Coronary heart disease can lead to a heart attack. It is the leading cause of death for men and women in the United States.

This condition, also called "ulnar nerve entrapment," happens to the ulnar nerve in your elbow. This nerve travels along the inner side of your elbow and down to your hand. It's the nerve that makes the jolt you feel when you bump your "funny bone." With this condition, your ulnar nerve is compressed, stretched or irritated.

This condition is a blood clot that forms in a vein deep inside the body. This type of clot most commonly develops in the legs. This condition is dangerous, because the clot can break free and travel through the bloodstream to the lungs.

This condition is a weakening of one or more vertebral discs, which normally act as a cushion between the vertebrae. This condition can develop as a natural part of the aging process, but it may also result from injury to the back.

This is a swelling of a fluid-filled sac in the back of your elbow. This sac is called the "olecranon bursa." You have similar sacs near other large joints throughout your body. They act as cushions between your bones and your soft tissues. Normally they have a small amount of fluid inside them. But sometimes they can swell. That is called "bursitis."

This condition is a deterioration of the facet joints, which help stabilize the spine and limit excessive motion. The facet joints are lined with cartilage and are surrounded by a lubricating capsule that enables the vertebrae to bend and twist.

This is stiffening of your shoulder. It happens over time, and you may not know what caused it. With a frozen shoulder, it can be hard for you to be as active as you like.

If you have pain in your shoulder, you may have a torn labrum. That's the thick band of tissue that goes around your shoulder socket. It helps make the socket deeper. It cushions the bone of your upper arm and keeps it from slipping.

Growth plates are places where new bone tissue forms. They are found near the ends of the long bones in growing children. Growth plates are weaker than the surrounding bone. That makes them easier to injure.

This is a blockage in one of your coronary arteries. They're the vessels carrying blood to your heart's tissue. A heart attack can strike suddenly, often without any warning.

Fast action during a heart attack can be the difference between life and death. Fortunately, most heart attacks start slowly. Many begin with telltale warning signs. If you know how to spot these signs, and if you act quickly, you can get the help you need before it's too late.

Many people don't realize that women and men often experience heart attack differently. We tend to think of a heart attack as a dramatic, chest-clutching event. But for many women, the signs are more subtle. Some women may mistake them for symptoms of heartburn, the flu, or aging. This can be dangerous.

Between the vertebrae of your spine are soft discs. They let your spine twist and bend. They absorb shocks. But if damaged, the disc's soft center can push through the disc wall. That's a herniated disc. This bulge presses against nerves in your spine.

This condition is a rupture of one of the vertebral discs in your neck. A herniated disc can allow disc material to press harmfully against the spinal nerves.

This condition is a sprain of one or more of the ligaments that hold the tibia and fibula together at the ankle. This joint, called the ankle syndesmosis, is made up of ligaments on the front and rear of the ankle, and in the space between the tibia and fibula.

When your heart beats, it pushes blood through your arteries. This creates pressure against the artery walls. If this pressure is too high, you have high blood pressure. It's a common disease. But if you don't manage it properly, it can cause health problems.

This is a shoulder injury. It's a compression fracture that creates a dent in the head of the humerus. That's the ball of the arm bone that fits into your shoulder socket. The dent interferes with the motion of your shoulder.

With this injury, the head of your femur (which is shaped like a ball) slips out of your hip socket. It may slip forward or backward out of position. This can damage structures around the joint.

A broken hip is serious and disabling. With a broken hip, you may not be able to care for yourself. Sometimes, complications from a hip fracture can lead to death. Avoid a broken hip with these basic safety measures.

This happens when you extend your elbow back farther than it's supposed to go. That damages the bones and soft tissues in your joint. Hyperextension can dislocate or even fracture your elbow.

This is a problem on the outer side of your thigh. It's an inflammation of the iliotibial band. That's a thick band of tissue that spans from your hip to your shinbone. When this band becomes in inflamed, it can hurt.

This is a type of arthritis that can affect people of all ages. It's not the same as the most common form of arthritis, called "osteoarthritis." That type commonly comes from wear and tear. Inflammatory arthritis can develop without any wear and tear at all.

This condition is a deformity of the spine. With it, your vertebrae change from a cylindrical shape to a wedge shape. Your spine may begin to curve forward. Eventually, this gives your upper back a rounded appearance.

This condition, commonly called tennis elbow, is an inflammation of the tendons that connect the muscles of the forearm to the elbow. The pain is primarily felt at the lateral epicondyle, the bony bump on the outer side of the elbow.

Your brain is divided into left and right halves, called "hemispheres." They specialize in different things. Because of this, a stroke on the left side of your brain can be very different from a stroke on the brain's right side. Let's look at some symptoms of a left brain stroke.

"This condition is an irritation or compression of one or more nerve roots in the lumbar spine. Because these nerves travel to the hips, buttocks, legs and feet, an injury in the lumbar spine can cause symptoms in these areas. Sciatica may result from a variety of problems with the bones and tissues of the lumbar spinal column. "

This is an injury of a growth plate on the elbow's inner side. Growth plates are places where new bone tissue forms. They are found near the ends of the long bones of growing children. But growth plates are weaker than the surrounding bone. That makes them easier to injure.

This condition, commonly called golfer's elbow, is an inflammation of the tendons that connect the muscles of the forearm to the elbow. The pain is primarily felt at the medial epicondyle, the bony bump on the inner side of the elbow.

You can have a stroke that lasts for only a few minutes and then seems to go away. We call that a "mini-stroke." It happens when part of your brain's blood supply is blocked for a short time. But even if your symptoms disappear, a mini-stroke is a dangerous event. You need to seek help right away.

Some of the muscles in your shoulder have opposing roles. When you move your arm, certain muscles contract while their opposing muscles relax. But when a muscle becomes much stronger than its opposing muscle, your shoulder can become unstable. You may have trouble moving it normally. We call this a "muscle imbalance."

The hip is where the femur meets the pelvis. Several strong muscles are found here. They handle high loads of stress. They may suffer from overstretching and tearing. This is called a muscle "strain." It's a common injury among athletes who play sports that require sudden starts and stops.

Your thigh has groups of powerful muscles. The quadriceps, the adductors and the hamstring muscles handle high loads of stress. They may suffer from overstretching and tearing. This is called a muscle "strain." It is a common injury among athletes who play sports that require sudden starts and stops.

This common injury is a stretching or tearing of the trapezius. This large muscle group spans the upper back, shoulders and neck. These muscles are commonly called the "trap" muscles.

This is a problem that affects your spinal cord. It happens when something presses harmfully against it. Your spinal cord is the main nerve pathway between your brain and your body. Pressure on it can cause problems throughout your body.

This type of arthritis, also called "degenerative joint disease," is a breakdown of the cartilage in your hip joint. As this protective cartilage wears away, bone rubs against bone. Bony growths called "bone spurs" may form in the joint. Pain from osteoarthritis can keep you from being as active as you like.

Knee pain may keep you from being as active as you like. And it may come from a gradual breakdown of your knee's cartilage. That's a protective tissue on the ends of your bones. In a healthy knee, the bones glide smoothly against each other. But in a knee with osteoarthritis, cartilage begins to wear away. Bone rubs against bone. Bony bumps we call "bone spurs" may form.

Osteoarthritis, also called degenerative arthritis, is a gradual breakdown of cartilage in the joints. Cartilage is a tough, flexible connective tissue that protects the ends of bones in the joints. Osteoarthritis of the shoulder can severely impact a person's lifestyle.

If you have back or neck pain that doesn't go away, you may have osteoarthritis of the spine. Osteoarthritis is the most common form of arthritis. For many of us, it develops slowly as we age. And it can keep you from being as active as you like.

This is a disorder that most often affects young athletes. It happens when part of a bone in the elbow loses its blood supply. It weakens, and so does the cartilage that covers it. Bone and cartilage may break off and drift around in the elbow. That can cause the joint to catch and lock up.

If you have an infection in a bone, you have osteomyelitis. It's a serious condition that can cause part of your bone to die. And, the infection can spread to other parts of your body.

As you get older, your bones may get weaker. This is called "osteoporosis." Weak bones are more likely to break. Osteoporosis can be a problem for anyone, but it is more common in women.

If you are an athlete, or if you work with your arms and hands, your elbows may be at risk for an overuse injury. This is an injury caused by repetitive motions. This type of injury can be a problem for people who play sports such as tennis or baseball. Children also have a higher risk, because their bones are still growing.

Staying fit is a challenge for many people. Carrying too much body fat is bad for your health. Being "overweight" means you weigh more than what we consider normal for your body type. If you keep gaining weight, you may become "obese." Let's take a few minutes to learn about weight and your health.

This is a pain you feel just below your patella (the bone we commonly call the "kneecap"). It's an injury to your patellar tendon, which connects the bottom of the kneecap to the shinbone.

This is a tear of a large tendon in the front of your knee. We call it the "patellar tendon." It connects the bottom of the kneecap to the top of the shinbone. It helps you straighten your leg. You can have a tear that doesn't go all the way through the tendon, or you can tear the tendon completely. A complete tear is a disabling injury.

This is a problem with the alignment of the patella (the bone at the front of the knee, commonly called the "kneecap"). With this disorder, the patella shifts out of its normal track as you bend or extend your knee.

This is a pain you feel in the front of your knee. It involves the patella. That's the bone we commonly call the "kneecap." The patella slides up and down in a groove on your femur as you bend and extend your knee. If you have this syndrome, you may have injured the soft tissues that support and cushion your kneecap. Or, you may have some damage to the cartilage on the underside of the kneecap.

This condition is an inflammation of one or both peroneal tendons, which travel down the lower leg, behind the lateral malleolus and along the outer side of the ankle.

Plantar fasciitis is an irritation of the plantar fascia. This thick band of connective tissue travels across the bottom of the foot between the toes and the heel. It supports the foot's natural arch. It stretches and becomes taut whenever the foot bears weight.

This is a set of symptoms that you may have after a concussion. That's when your head is hit so hard your brain is injured. You can have a concussion even if you don't lose consciousness.

Strong bands of tissue called "ligaments" help stabilize the bones that form the knee joint. One of these ligaments is called the "PCL." It helps connect the femur to the tibia. If you stretch or tear a PCl, your knee may become unstable.

This is a problem with a tendon supporting the foot's arch. We call it the posterior tibial tendon. It connects the calf muscle to the bones on the inner side of the foot. With posterior tibial tendon dysfunction, the tendon becomes inflamed or torn. Your arch becomes unstable, and it may collapse.

This condition, also called "failed back surgery syndrome," is a type of chronic pain. It can develop in some people after spine surgery.

This condition is an inflammation of the prepatellar bursa, a fluid-filled sac that covers the front of the kneecap. Prepatellar bursitis results in pain and swelling at the front of the knee.

This condition is a tear of the tendon that connects the patella to the quadriceps muscles of the thigh. The quadriceps muscle is used to straighten the leg from the bent position. A complete rupture of the quadriceps tendon is a disabling injury.

This condition involves the radial nerve in your elbow. The radial nerve passes down your arm to your hand. Its branches travel into your thumb, forefinger and middle finger. With this condition, your radial nerve is compressed, stretched or irritated.

Rheumatoid arthritis, a condition that can attack joints throughout the body, commonly affects both feet and both ankles at the same time. It can cause the joints to become swollen and possibly deformed, causing disability.

Rheumatoid arthritis is a disease of the immune system. This is the system that protects you from infection. RA may cause pain and stiffness in your shoulder where the humerus (the bone of the upper arm) meets the shoulder socket. It can also affect the joint where your clavicle meets your scapula.

Rheumatoid arthritis (we call it "RA") is a chronic disease. It affects joints throughout your body. It commonly starts in your hands or feet. For many people, it causes problems in the feet and ankles.

Your brain is divided into left and right halves, called "hemispheres." They specialize in different things. Because of this, a stroke on the right side of your brain can be very different from a stroke on the brain's left side. Let's look at some symptoms of a right brain stroke.

The rotator cuff muscles and tendons hold your upper arm bone in your shoulder socket. A hard fall, repetitive arm motions or problems with the structure of your shoulder can injure the rotator cuff.

The rotator cuff is a group of muscles and tendons in each shoulder. It holds your upper arm bone in your shoulder socket. It keeps your arm stable while allowing it to lift and rotate. Too much stress on the rotator cuff can cause a tear. This can be a painful injury.

This condition is an abnormal curvature of the spine. It most often develops in early childhood, just before a child reaches puberty.

This is an infection in the knee joint. It causes your knee to become painfully inflamed. Without proper treatment, it can become a chronic problem. It can permanently damage your knee.

This is pain you feel in the front of one or both of your lower legs. It can be a problem for runners, dancers, gymnasts and other active people.

The shoulder is a ball-and-socket joint. The ball of your upper arm bone fits into a socket in your shoulder blade. If the ball slips out, your shoulder has "dislocated."

This is a painful pinching of soft tissues in your shoulder. It happens when these tissues rub and press against a part of your shoulder blade called the "acromion." This can irritate your rotator cuff tendons, and also a soft sac called the "subacromial bursa."

This is a looseness of the shoulder joint. With it, your arm slides around too much in the socket. It may slip out of the socket easily. Instability can happen because the ligaments that hold your shoulder together aren't tight enough. Or, the cartilage around your shoulder socket may be damaged.

This is an injury of the acromioclavicular joint (commonly called the "AC" joint). This is the joint where the clavicle meets the scapula. A shoulder separation is a stretching or a tearing of the ligaments that support these bones. This allows the bones to move out of position.

This is a shoulder injury. It's a tear of the labrum. That's a ring of cartilage that surrounds the shoulder socket and helps hold the head of the humerus in place. This type of tear happens where the biceps tendon attaches to the labrum.

This is a snapping or a popping sensation in your hip. It may happen when you stand up, when you walk, or when you move your leg a certain way.

This is a problem that involves the scapula. That's the bone we call the ""shoulder blade."" With this condition, you have a shoulder blade that catches when you lift or move your arm. You may find this only slightly irritating, or it may be very painful. 

Your spinal nerves travel through your spinal canal and exit through openings we call "foramen." If any of these spaces are too narrow, your nerves become compressed. We say you have "spinal stenosis." It's a problem that most often happens in the neck and lower back.

This problem affects the spinal nerves in your neck. It's a narrowing of the spinal canal. That's the space your spinal nerves travel through. In a healthy spine, the spinal canal protects these nerves. It keeps them free from injury. But with spinal stenosis, the spinal canal is too narrow, and your nerves get compressed.

This condition affects the thoracic spine between the neck and the lower back. It is a narrowing of the spinal canal that results from degeneration of bones in the spine, disc herniation, or thickening of the tissues that surround the spinal cord.

This condition occurs when a lumbar vertebra slips out of place. It slides forward, distorting the shape of your spine. This may compress the nerves in the spinal canal. The nerves that exit the foramen (open spaces on the sides of your vertebrae) may also be compressed. These compressed nerves can cause pain and other problems.

This condition is a degeneration of the spine that can affect the spine at any level, resulting in pain and discomfort that can grow worse over time.

Fast action during a stroke can be the difference between life and death. Fortunately, there are many stroke warning signs. To help you remember the signs and how to respond, just use the word "FAST." That's F-A-S-T.

This is a slow down or blockage of the blood that normally flows to part of your brain. When it happens, your brain cells don't get the oxygen and nutrients they need. Within minutes, they begin to die.

During a stroke, fast action is key. Getting help quickly can be the difference between life and death. Fortunately, there are many warning signs that show you a stroke is happening. So get help immediately if you notice any of the following symptoms.

This is a label given to a group of disorders. In these disorders, nerves or blood vessels are compressed in the space between your collarbone and the underlying rib. This space is called the "thoracic outlet."

Throwing overhand again and again puts a lot of stress on your elbow. It can lead to injury. Young athletes, in particular, are at risk. Some play sports all year without learning how to throw properly. And, their bones are still growing. Let's look at how the elbow can be damaged.

If you hear an annoying buzzing or ringing sound in one or both ears, you have tinnitus. It can bother you a lot. Tinnitus is a problem with your auditory system. That's the system that lets you hear. The problem may be in the ear. It may be in the nerve that connects your ear to your brain. Or, it may be in the part of your brain that makes sense of sound signals. Usually, tinnitus is not a sign that you have a serious issue.

This is an inflammation of a tendon at the back of your elbow. It's called the "triceps" tendon. It anchors your upper arm's triceps muscle to the ulna (one of the bones of your forearm).

Like other joints, the elbow is held together by strong bands of tissue called "ligaments." On the elbow's inner side is the ulnar collateral ligament complex. We call it the "UCL." It's made of three bands that connect the humerus (the upper arm bone) to the lower arm's ulna. The UCL is the elbow ligament most often injured by baseball pitchers and by other athletes who play throwing sports.

If you feel like you're spinning for no reason, you have vertigo. This dizziness can be a nuisance, but it's usually not a sign of anything serious. It can interrupt your day. And it can put you at risk for falling.

Lower back pain is a common problem that severely impacts the quality of your life. It can limit your ability to be active. It can cause you to miss work. Many different causes may lead to pain in your lower back.

Neck pain is a common problem that severely impacts the quality of your life. It can limit your ability to be active. It can cause you to miss work. Many different causes may lead to pain in your neck.

This is a common neck injury. It happens when your neck jerks back and forth quickly and violently. Your spine bends past its normal range of motion. This can injure the vertebrae of your cervical spine. It can damage the supporting ligaments and muscles in your neck.