Final answer:
The internal thoracic artery divides into the Muscular Phrenic Artery and Superior Epigastric Artery at the 8th costal cartilage, supplying blood to the anterior chest wall, breasts, diaphragm, and anterior part of the abdominal wall.
Step-by-step explanation:
The artery that branches into the Muscular Phrenic Artery and Superior Epigastric Artery at the 8th costal cartilage is the internal thoracic artery (also known as internal mammary artery).
The internal thoracic artery is a major branch of the subclavian artery, and as it descends, it supplies the anterior chest wall and the breasts. The internal thoracic artery finally divides into the superior epigastric artery, which supplies the anterior part of the abdominal wall, and the musculophrenic artery, which supplies the diaphragm and intercostal muscles.
Understanding the vascular anatomy of the thorax and abdomen is important for surgical procedures and diagnosing health conditions related to blood supply. The thoracic aorta and the internal thoracic artery are pivotal in distributing blood to the thoracic and upper abdominal regions, respectively.