The Left Ventricle

• • The left ventricle has the thickest wall of any heart chamber. Its extra thick myocardium enables the left ventricle to develop enough pressure to force blood around the entire systemic circuit.
• Wall of left ventricle about three times thicker than wall of right ventricle
• Contractions of the left ventricle must produce enough pressure to push the blood through the entire systemic circuit
• Contractions of the right ventricle must produce enough pressure to push the blood through the lungs and back to the heart
• Internal organization of left ventricle resembles right ventricle, but...

  • its trabeculae carneae are more prominent than they are in right ventricle
  • no moderator band
  • since the left AV valve has two cusps, there are two large papillary muscles rather than three
• Blood leaving the left ventricle passes through the aortic valve into the ascending aorta
• Aortic sinuses are sacs that prevent the individual cusps from sticking to the wall of the aorta when the valve opens
• The right and left coronary arteries deliver blood to the myocardium which originate at the aortic sinuses
• From the ascending aorta, blood flows into the aortic arch and then into the descending aorta
• The pulmonary trunk is attached to the aortic arch by the ligamentum arteriosum, a fibrous band of connective tissue that is left over from an important fetal blood vessel