Question

Describe the structure of the heart of rabbit. Draw a neat, labelled diagram of L.S. of heart.

Answer 1

The heart of the rabbit is four-chambered. There are two atria (auricles) and two ventricles. The ventricular chambers are larger than the auricles. The auricles are thin walled compared to the ventricles. The right auricle and left auricle are separated by the interauricular septum. The aperture in the right ventricle is known as sinu-auricular aperture. This aperture is guarded by valves. The pulmonary vein opens in the left auricle through an oblique aperture. The two auricles are separated from the ventricles by auriculo-ventricular septum. The right and left auricle open into the ventricle through auriculo-ventricular aperture. The auriculo-ventricular aperture is guarded by auriculo ventricular valve. This valve has four flaps. Chordae tendinae are attached to the margin of the four flaps of this valve. Chordate tendinae are thread like chords which are attached to the muscular wall of the ventricle at their other ends.

Truncus arteriousus arises from the anterior and ventral part of the ventricle. This part runs obliquely on the ventral surface of the right auricle. There are three semilunar valves at the proximal end in the truncus arteriosus. The basal, broad and thick-walled portion of the truncus arteriosus is known as conus arteriosus. The anterior, thin walled and narrow portion of the truncus arteriosus is known as the ventral aorta. There is a spinal valve in the conus arteriosus. This valve divides the lumen of conus arteriosus into a left cavum pulmocutaneum and right cavum aorticum. The blood entering the cavum pulmocataeum enters through pulmocutaneous arches. The ventral aorta divides into two lateral aortae. Each lateral aorta is divided into two arches, carotid arch and systemic arch.