n. the membrane surrounding the heart, consisting of two portions. The outer fibrous pericardium completely encloses the heart and is attached to the large blood vessels emerging from the heart. The internal serous pericardium is a closed sac of serous membrane: the inner visceral portion (epicardium) is closely attached to the muscular heart wall and the outer parietal portion lines the fibrous pericardium. Within the sac is a very small amount of fluid, which prevents friction as the two surfaces slide over one another as the heart beats. —pericardialadj.
Subjects: Medicine and Health.