It has a tubular & pulsatile heart which is found mid- dorsally in the pericardial sinus. The heart has 13 chambers. Out of them 3 are found in the thorax & 10 are situated in the abdomen.The heart is closed posterior. Anterior, the heart opens into an anterior aorta which leads into the head sinus. Each heart chamber is averted funnel-shaped and it has two lateral ostia. The blood form the pericardial sinus enters into the heart through these lateral ostia. In the heart the blood flows from behind to forwards. The first heart chamber is largest & the last heart chamber is smallest. The heart of the cockroach is neurogenic. The heart beats in cockroach are 49 per minute.
There are 13 pairs of alary muscles i.e. every segment of the thorax & abdomen has, a pair of alary muscles. The alary muscle is triangular. Its broad part is attached to the diaphragm & the pointed part to the tergum. They are also attached to the heart wall with the connective tissues. The alary muscles of the thorax are large. The alary muscles of the 10th abdominal segment.
In the cockroach, the blood circulates with the help of the alary muscles & the pulsatile heart. The contraction of the heart is called as systole & its relaxation as diastole. The duration between to heart beats is called as diastasis. As a result of the contraction alary-muscles, the blood of the perivisceral sinus enters into the pericardial sinus and finally into the heart through the lateral ostia.