... Deep in the back of the abdomen, oneither side of the lumbar spine, lie the psoas muscles.They flex the hips. An abscess can develop in one of these muscles, usually when it spreads from the appen-dix, ... types of abscessesListed below are some of the more common andimportant abscesses.• Carbuncles and other boils. Skin oil glands (sebaceousglands) on the back or the back of the neck are the ... chambers of the heart. These factors greatly increase the risk of stroke,which can occur if a blood clot from the heart enters the circulatory system, goes to the brain, and blocks one of its...