VAN 121: Veterinary Gross Anatomy-II (2+2)

INTERNAL THORACIC ARTERY

• This is a large vessel, which arises from the ventral face of the brachial artery opposite the first rib.
• It passes downwards and backwards within the thoracic cavity and terminates into the musculophrenic and anterior abdominal arteries.

Collateral branches

• At each intercostal space it gives off dorsal and ventral branches. The former ascends in the intercostal spaces and anastomoses with the intercostal arteries of the aorta and supply the intercostal muscles.
• The ventral branches gives off small branches to the transversus thoracis, pleura, pericardium and pass out between the costal cartilages as perforating intercostal arteries. These anastomose with the branches of the external thoracic artery and supply pectoral muscles and skin.
• In the young subject, the internal thoracic artery gives off some branches to the thymus.
• The musculophrenic or asternal artery passes along the groove between the 8th and 9th costal cartilages and then continues along the costal attachment of the diaphragm and transversus abdominis and gives off muscular branches to the intercostal muscle, transversus abdominis and diaphragm, and anastomoses with the intercostal branches of aorta.
• The anterior abdominal artery passes between the nineth costal and xiphoid cartilages, passes backwards on the deep face of the rectus abdominis and supplies this muscle and the ventral wall of the abdomen and anastomoses with the branches of the posterior abdominal artery.