amnion. the innermost fetal membrane, which forms a sac filled with amniotic fluid that surrounds the embryo and later the fetus; as it enlarges it gradually obliterates the chorionic cavity and enfolds the umbilical cord. Called also bag of waters.
cluster breathing. cluster breathing. a breathing pattern in which a closely grouped series of respirations is followed by apnea. The activity is associated with a lesion in the lower pontine region of the brainstem. See also Biot's respiration, Cheyne-Stokes respiration.
The most common sleep breathing disorder is Obstructive Sleep Apnea (OSA), which is caused when the upper throat muscles relax too much during sleep, cutting off or restricting the airway. (1-4) These episodes, which also cause the oxygen level in the blood to drop, last from 10 seconds to a minute or longer.