Subclavian Artery – Thoracic Vessels

00:00 Now, let’s take a look at the subclavian artery. And again, we’ll have a right subclavian; we’ll have a left subclavian. It’s going to issue some branches that help to supply the thorax. Those branches are the internal thoracic, also known as the internal mammary artery.

00:20 And there are two trunks that will issue from each of the subclavian arteries. We have a costocervical trunk and we have a thyrocervical trunk. Any time you hear the word “trunk” being utilized with the circulation, it is in reference to an arterial structure, so we never have to designate it as being an artery.

00:42 This slide captures the internal thoracic artery. There’s an internal thoracic artery that’ll issue from the right subclavian and there’s a left internal thoracic artery that’s going to issue from your left subclavian. If we take a look at the illustration, here is the right internal thoracic artery, also known as the internal mammary artery. It is traveling along the lateral border or margin of the sternum. The left internal thoracic artery or mammary artery is doing the same on the left margin of the sternum. There are several branches that will issue from the internal thoracic, but its two terminal branches are occurring right here, where we have the musculophrenic and then, the one that courses more vertically and medial to the musculophrenic will be the superior epigastric artery. The internal thoracic artery will help supply the anterior intercostal spaces with anterior intercostal arteries. The branches that come off the internal thoracic will help supply the first six intercostal spaces anteriorly. And then the musculophrenic that comes off the internal thoracic will help supply anterior intercostal arteries to intercostal spaces 7, 8 and 9. We do not have anterior intercostal spaces that would correspond to space 10 and 11. Those are fed solely by the posterior intercostal arteries. In addition, there is a pericardiacophrenic artery that will help supply the phrenic nerve, the pericardium, pleura. Also help to supply the diaphragm. The superior epigastric artery will assist in the arterial supply of the anterior abdominal region.

02:43 The costocervical trunk, the branch that we’re interested in as it relates to the thoracic region, is the supreme or highest intercostal artery. Here, we can see the costocervical trunk coming off the subclavian on the right side. There would also be one on the left.

03:07 It will then issue the supreme or highest intercostal artery and then this will branch and supply the first two intercostal spaces. And the branches of the supreme intercostal artery that do that are referred to as the first two posterior intercostal arteries.

03:27 By traveling within the first two intercostal spaces, back structures are supplied. The serratus anterior muscle receives partial distribution from this vascular system. The pectoral muscles anteriorly receive some arterial supply and then the breast region will also receive some of its arterial distribution through this branching pattern.

03:54 The thyrocervical trunk is the last arterial component to take a look at as it relates to the subclavian artery. We see the left thyrocervical trunk here. The right thyrocervical trunk is seen here and it has several branches. But, the branches that we’re interested in as it relates to thoracic structures will be the esophageal branches that we see from the inferior thyroid. Right here: There’s the esophageal branch on the right one. Here’s the inferior thyroid from the thyrocervical trunk on the left giving rise to its esophageal branch. So, these esophageal branches will supply the first part of the esophagus and that is the cervical esophagus.