magnetic field therapy - using an alternating magnetic field to generate an electric current inside the tissues, resulting in changes to blood flow.

magnetic resonance imaging (MRI) - a non-invasive procedure that produces two-dimensional view of an internal organ or structure, especially the brain and spinal cord.

malabsorption syndromes - conditions that happen when the small intestine cannot absorb nutrients from foods.

malignant tumor - a mass of cancer cells that may invade surrounding tissues or spread to distant areas of the body.

mallet finger - common condition due to the rupture of the long extensor tendon of the finger.

malocclusion - an orthodontic problem that means "bad bite," including crowded, missing, or crooked teeth, extra teeth, or a misaligned jaw.

mammogram - a low-dose x-ray of the breast.

manometry - tests that measure muscle pressure and movements in the gastrointestinal (GI) tract.

massage - mechanical form of therapy in which the soft tissues are made more pliable with different techniques, promoting increased blood flow and subsequent healing.

mast cells - cells, which synthesize and store histamines, found in most body tissues, particularly just below the epithelial surfaces, serous cavities and around blood vessels.

mastitis - infection of the milk ducts in the breast.

mastoid - back portion of the temporal bone behind the ear.   

mastoid surgery - surgical procedure to remove an infection from the mastoid bone.

mean blood pressure - average blood pressure, taking account of the rise and fall that occurs with each heartbeat. It is often estimated by multiplying the diastolic pressure by two, adding the systolic pressure, and then dividing this sum by three.

median nerve - large nerve, comprising segments from the cervical spine, that is involved in neural function of the upper limb; commonly entrapped in the carpal tunnel of the wrist, to create carpal tunnel syndrome.

melanocytes - cells in the skin that produce and contain the pigment called melanin.

melena - blood in the stool.

meniscus - a part of the cartilage in the knees and other joints.  

micrographia - a change in handwriting with the script becoming smaller and more cramped.

middle ear - part of the ear that includes the eardrum and three tiny bones of the middle ear, ending at the round window that leads to the inner ear.

minimally invasive surgery - any technique involved in surgery that does not require a large incision. (See also endoscopy, abdominoscopy, or laparoscopy.)

miosis - constriction of the pupil.

misarticulation - inaccurately produced speech sound (phoneme) or sounds.

miscarriage - spontaneous termination of a pregnancy before the fetus has developed enough to survive outside the uterus.

mitral valve - the valve that controls blood flow between the left atrium and left ventricle in the heart.

modified radical mastectomy - the removal of the breast, some lymph nodes in the armpit, and sometimes part of the chest wall muscles.

motility - movement of food through the digestive tract.

motion sickness - dizziness, sweating, nausea, vomiting, and generalized discomfort experienced when an individual is in motion.

motor speech disorders - group of disorders caused by the inability to accurately produce speech sounds (phonemes).

moxibustion - the burning of herbal leaves on or near the body.

mucosal lining - lining of gastrointestinal (GI) tract organs that makes mucus.

mucosal protective drugs - medicines that protect the stomach lining from acid.

mucous colitis - see irritable bowel syndrome (IBS).

mucus - clear liquid made by the intestines that coats and protects tissues in the gastrointestinal tract.

multifidus - deep lumbar spine muscle that stabilizes the lumbar spine.

murmur - a blowing or rasping sound heard while listening to the heart; may or may not indicate problems within the heart or circulatory system.    

musculoskeletal system - the complex system that includes the bones, joints, ligaments, tendons, muscles, and nerves.

mycoplasma - very common sexually transmitted disease or urinary tract infection caused by a bacteria-like organism in the urethra and reproductive system.

mydriasis - dilation of the pupil.

myelogram - a specific x-ray study that uses an injection of a dye or contrast material into the spinal canal to allow careful evaluation of the spinal canal and nerve roots.

myocardial infarction (Also called heart attack.) - occurs when one of more regions of the heart muscle experience a severe or prolonged decrease in oxygen supply caused by a blocked blood flow to the heart muscle.

myocardial ischemia - insufficient blood flow to part of the heart.

myocardium - the muscle wall of the heart.

myoclonus - jerking, involuntary movements of the arms and legs; may occur normally during sleep.  

myofascial pain - the most common form of temporomandibular disorder; discomfort or pain in the muscles that control jaw function and the neck and shoulder muscles.

myomectomy - surgical procedure done to remove fibroids from the uterus while leaving the uterus intact.

myopia - nearsightedness.