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 type of sleep apnea is obstructive sleep apnea. In this condition, the airway collapses or becomes blocked during sleep. This causes shallow breathing or breathing pauses. When you try to breathe, any air that squeezes past the blockage can cause loud snoring.