There are various degrees of this, and various combinations with defect of the anterior abdominal wall, the highest degree being a complete cleft of thorax and abdomen. In these extensive clefts the organs are generally extruded, but even when there is a limited cleft of the sternum, the heart is liable to lie outside the chest. In this ectopia cordis the heart generally lies in the middle line, communicating with the inside of the chest by a narrow peduncle composed of the great vessels. The heart itself is usually malformed. Sometimes the heart lies at the root of the neck, the manubrium being cleft. Sometimes ectopia cordis occurs without any cleft in the sternum, in which case the heart lies in the neck or in the epigastrium, in the latter case projecting through an aperture in the diaphragm. These facts indicate a displacement by pressure from behind, and probably the whole phenomena are due to dropsy of the pleural cavity at an early period.