Magnetic resonance imaging (MRI) uses a magnetic field and radio waves to create cross-sectional images of your head and body. Your doctor uses these detailed, clear images to identify and diagnose many conditions. It is particularly ...

Depression is a serious mood disorder. It touches every part of your life and is caused by a chemical imbalance in your brain. Treatment involves medicine and counseling.

Major depression goes beyond the day's normal ups and downs. It involves a teen's body, mood, and thoughts. It can affect and disrupt eating, sleeping, or thinking patterns.

Malaria is caused by a parasite. It is passed to humans by the bite of an infected Anopheles mosquito.

Breast cancer happens when certain cells in the breast become cancerous and form a tumor. Men can have the same types of breast cancer as women. Seventy percent of male breast cancers are a type called ductal carcinoma. Breast cancer in ...

Male infertility means that a man has a problem with his reproductive system. It means he can't start a pregnancy with a female partner. Read on to learn about causes, diagnosis, and treatment.

The mesothelium is a tissue that covers and protects the outer surface of some organs. Malignant mesothelioma is a rare kind of cancer that starts in the mesothelium. Learn more about symptoms, diagnosis, and treatments.

Mallory-Weiss syndrome is a condition in which the inner lining of the esophagus tears at or near where it connects to the stomach.

Your esophagus is the tube that carries food from your throat to your stomach. It plays a vital role in digestion. Sometimes, violent coughing or vomiting can tear the tissue of your lower esophagus and it can start to bleed. The ...

Malocclusion is when a child’s teeth become crooked or crowded. The child may also have a problem with their bite. That means the teeth of the upper jaw don’t meet normally with the teeth of the lower jaw when the jaw is closed.

Marfan syndrome is an inherited disorder of the connective tissue that causes abnormalities in the eyes, bone, heart and blood vessels.

Marfan syndrome is a genetic disorder that affects the body's connective tissue. Connective tissue holds the body's cells, organs, and other tissue together. Connective tissue is also important in growth and development.

Detailed information on breastfeeding and mastitis

Mastoiditis is a complication of a middle ear infeciton. Read on to learn more about symptoms, diagnosis, and treatment.

McArdle disease is a rare muscle disorder. In McArdle disease, the muscle cells can’t effectively store energy in the

Measles (rubeola) is a respiratory illness caused by a virus. It causes a red, blotchy rash. It’s a very contagious illness.

Meckel diverticulum is a small pouch in the wall of the intestine. It’s near where the small and large intestines meet. This condition is the most common birth defect of the digestive system. It happens to about 1 in 50 babies.

Meconium aspiration happens when a newborn breathes in a mixture of meconium and amniotic fluid. Amniotic fluid is the liquid that surrounds the baby in the womb. Meconium is the baby's first stool, or poop, which is sticky, thick, and ...

The menisci are crescent-shaped bands of thick, rubbery cartilage attached to the shinbone. They act as shock absorbers and stabilize the knee. Meniscus tears can vary widely in size and severity. Some, but not all, require surgical repair.

The medial collateral ligament's main function is to prevent the leg from extending too far inward, but it also helps keep the knee stable and allows it to rotate. Injuries to the medial collateral ligament most often happen when the ...

Other activities that can cause this condition include carrying a heavy suitcase, chopping wood, and using a chainsaw.

The mediastinum is the area that separates the lungs. It is surrounded by the breastbone in front and the spine in back, with the lungs on either side. It encompasses the heart, aorta, esophagus, thymus (a gland in the back of the neck) ...

A medicine rash is the body's reaction to a certain medicine. Learn more about symptoms, diagnosis, and treatments.

Medicine rashes are the body’s reaction to a certain medicine. The type of rash that occurs depends on the type of medicine that is causing it. Rashes can range from mild to severe.

Medulloblastoma is a type of brain cancer. It most often affects children, but it can also happen in adults. These tumors often grow in the cerebellum, the part of the brain that controls balance and coordination.

Anemia is a problem in which there are not enough red blood cells or hemoglobin. Hemoglobin is the part of red blood cells that carries oxygen throughout the body. In megaloblastic anemia, the bone marrow, where the cells are formed, ...

Megaureter is a ureter that is much wider than normal. A megaureter may not drain urine normally. This can lead to infections and kidney damage.

Skin cancer is the most common of all cancers. Between 40 to 50% of all cancer cases diagnosed every year are skin cancer. There are two main types of skin cancer: malignant melanoma and nonmelanoma skin cancer. Melanomas account for ...

Melanoma is a type of skin cancer. Here are answers to some frequently asked questions about melanoma.

Mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes (MELAS) is an extremely rare genetic condition that begins in childhood. The disorder affects many areas of the body, especially the brain and nervous system ...