Final answer:
The left circumflex artery and the left marginal artery are branches of the left coronary artery, which supplies blood to the left side of the heart.
Step-by-step explanation:
The left circumflex artery and the left marginal artery both branch off of the left coronary artery. The left coronary artery distributes blood to the left side of the heart, including the left atrium and ventricle, and the interventricular septum. The circumflex artery specifically follows the coronary sulcus to the left and may eventually connect with small branches of the right coronary artery. Additionally, the left coronary artery gives rise to the anterior interventricular artery, also known as the left anterior descending artery (LAD), which travels around the pulmonary trunk and is responsible for supplying blood to a significant portion of the heart muscle through its branches and anastomoses.