A muscle strain is an injury to one of your muscles that causes it to tear. They’re one of the most common injuries, especially among athletes. Strains are classified with three grades to indicate how severe they are. Most people can recover by resting their muscle and using at-home treatments like ice and over-the-counter medicine. If you’re feeling pain for …

Mumps is a contagious disease caused by the mumps virus, which belongs to a group of viruses known as paramyxoviruses. The illness starts with mild symptoms such as headache, fever and fatigue. But then it typically leads to severe swelling in certain salivary glands (parotitis) that causes puffy cheeks and a tender, swollen jaw. Mumps used to be a very …

Multiple system atrophy (MSA) is a rare neurological disease that causes certain brain areas to deteriorate. Over time, this disrupts abilities and functions handled by those brain areas. This disease is ultimately fatal. MSA is a new term that combines features of three older condition names. Those conditions are: Shy-Drager syndrome. Sporadic olivopontocerebellar atrophy. Striatonigral degeneration. Experts introduced the name multiple …

Multiple sclerosis (MS) is an autoimmune condition that affects your brain and spinal cord (central nervous system). With MS, your immune system mistakenly attacks myelin cells. These are the protective covers (sheaths) that surround brain and spinal cord nerves. Myelin sheath damage interrupts messages (signals) that your nerves send throughout your body to perform functions like vision, sensation and movement. Myelin damage can occur in your brain, …

Moyamoya disease is a type of cerebrovascular disease — a condition that affects the blood vessels in your brain. In moyamoya disease, at least one of your carotid arteries — and sometimes both — narrow or close. It also affects your front and/or middle cerebral arteries. These key arteries deliver blood and oxygen to the front two-thirds of your brain. When these blood vessels narrow, it blocks blood flow …

Movement disorders are a group of neurological conditions that cause abnormal movements. They could be increased movement (like spasms, jerking or shaking) and/or decreased or slow movement. They can affect actions you choose to make (voluntary) or cause uncontrolled (involuntary) movements. Every body movement you make, from lifting your leg to moving your jaw and tongue to talk, involves complex …

Mosquito bites are small, raised bumps on the skin resulting from a female mosquito feeding on human blood. Mosquitoes are small, flying insects. They have six legs and long mouthparts — used to feed on blood and nectar. Only female mosquitoes feed off of blood. Three different types of mosquitoes exist in various parts of the world: Aedes, Culex and …

A Morton’s neuroma is inflammation on a nerve in your foot. More specifically, it’s an enlargement in the interdigital nerves between the metatarsal bones that connect your foot to your third and fourth toes (your middle toes closest to your pinkie toe). Some healthcare providers refer to Morton’s neuromas as intermetatarsal neuromas or interdigital neuromas. If you have a Morton’s neuroma, the …

Morning sickness is nausea and vomiting during pregnancy. It’s a common condition affecting up to 70% of pregnant people in the first trimester of pregnancy (the first three months). Despite its name, “morning” sickness can happen at any time of the day. There are various at-home treatments for morning sickness, including diet and lifestyle changes. Some obstetricians recommend over-the-counter (OTC) medications for nausea. …

A mood disorder is a mental health condition that primarily affects your emotional state. It’s a disorder in which you experience long periods of extreme happiness, extreme sadness or both. Certain mood disorders involve other persistent emotions, such as anger and irritability. It’s normal for your mood to change, depending on the situation. However, for a mood disorder diagnosis, symptoms …