What is the Thoracic Artery?

The thoracic artery is also known as the internal mammary artery. It supplies the breasts and the anterior chest wall. There are two internal arteries, the right and left artery, which are situated anterior to the chest wall on either side of the sternum.

Origin of the thoracic artery – It arises from the first part of the subclavian artery.

How is the Blood Supplied to the Thoracic Wall?

The internal thoracic artery arises from the subclavian artery and supplies the breast, the anterior thoracic wall. The rest arises from the axial artery. The branch of the internal thoracic artery, pericardiophrenic artery, supplies the fibrous membrane which encloses the heart. The anterior intercostal arteries supply the ribs and intercostal muscles. Many arteries branch from the axillary artery. The shoulder and the pectoral region are supplied by the thoracoacromial trunk. The lateral thoracic wall gets blood from the lateral thoracic artery. The scapula, posterior thoracic wall and the latissimus dorsi muscles are obtaining the blood from the subscapular artery.

The Course of the Thoracic Artery

The internal thoracic artery descends posterior to the medial end of the clavicle and upper six costal cartilages around one centimeter away from the lateral margin of the sternum. It ends in the sixth intercostal space by dividing into superior epigastric and muscular phrenic arteries.

The Relation of the Thoracic Artery

Anteriorly, from top to bottom the thoracic artery is related to the medial end of the clavicle, internal jugular vein, brachiocephalic vein, phrenic vein, pectoralis major, external intercostal membranes, the six upper costal cartilages, internal intercostal muscles and upper six intercostal nerves.

Posteriorly, above the second costal cartilage, it is related to the endothoracic fascia and pleura. Below the second costal cartilage, intervene between the artery and the endothoracic fascia and pleura.

The internal mammary artery is accompanied by veins that unite at the level of the third costal cartilage to form the internal thoracic vein that runs upward along the medial side of the artery.

Branches of the Thoracic Artery 

The pericardiophrenic artery starts from the root of the neck over the first costal cartilage and it plunges along with the phrenic nerve until the diaphragm. It supplies the pericardium and pleura.

Mediastinal branches- They are small blood vessel which supplies the lymph glands, connective tissues and thymus, in front of the pericardium.

Anterior intercostal arteries- They are present in a pair for each of the upper six costal spaces.

Perforating branches- They accompany the anterior cutaneous branches of the intercostal nerve. In females, the perforating branches of the 2nd, 3rd, and 4th intercostal spaces are larger.

Superior epigastric artery- It supplies to the anterior abdominal wall. It runs downwards behind the 7thcostal cartilage between the sternum and the first costal slits of the diaphragm.

Musculophrenic artery- This runs downwards and laterals, behind the 7th, 8th and 9thcostal cartilages and gives two anterior intercostal arteries to each of those intercostal spaces.

Abdominal Arteries

10 major arterial branches arise from the abdominal aorta.

  • The lower surface of the diaphragm is supplied by the paired inferior phrenic arteries to the adrenal gland.
  • The celiac trunk branches into the left gastric artery, large common hepatic artery and splenic arteries which helps in supplying the upper abdominal organs.
  • The superior mesenteric artery supplies the intestines.
  • A paired middle suprarenal artery is adjacent to the superior mesenteric artery that supplies the adrenal gland.
  • The paired renal arteries supply to the kidney. The long narrow pairs of gonadal arteries descend to the female pelvic cavity, they are called the ovarian arteries, and in males, they are called the testicular arteries.
  • The large intestine is supplied by the inferior mesenteric artery.
  • The four pairs of lumbar arteries supply the abdomen’s posterior wall.
  • Lastly, the paired common iliac arteries arise at the abdominal aorta branches. It supplies to the pelvic organs, lower abdominal wall and limbs.

The celiac trunk provides blood to abdominal organs with 3 subdivisions that are branched from them. Those are the common hepatic, left gastric and lymphatic tissue artery. The common hepatic artery includes 2 primary branches. The proper hepatic artery is continued from the common hepatic which supplies the liver and gallbladder. The spleen artery which arises from the celiac trunk dispenses blood to the spleen. The circulation for the mesenteric arteries is provided by the inferior and superior mesenteric arteries. The small intestine, large intestine and other organs are supplied by the four mesenteric arteries: the pancreatic duodenal artery, intestinal artery, ileocolic artery and middle colic artery. The distal large intestine comprising the rectum is supplied by the three branches of the inferior mesenteric artery: the left colic artery, sigmoid arteries and superior rectal artery.

Context and Applications  

This topic is significant in the professional exams for both undergraduate and graduate courses, especially for;

  • Bachelors in Zoology
  • Masters in Biochemistry
  • Masters in Zoology
  • Masters in Anatomy and physiology
  • Abdominal aorta
  • Internal mammary glands
  • Abdominal veins
  • Thoracic arteries

Practice Problems

What does the left gastric artery provide?

It provides blood to the esophagus and the stomach. Then it becomes the right gastric artery and then supplies the duodenum and the stomach.

What is a mesenteric gland?

The mesentery is a gland that keeps the organs in position; it is in the form of a layer that helps in attaching the organs, i.e., the intestinal wall to the abdominal wall. In mesentery, mesenteric lymphadenitis is an inflammation of the lymph nodes. Lymphadenitis is a condition where the lymph nodes are distended up.

What are intercostal arteries?

These are a bunch of arteries that supply the space or area between the ribs and that space known as the intercostal space. They are placed in two places: one in between pleurae and intercostalesinterni. Other, in between the intercostalesinterni and innermost intercostal muscle.

What is an epigastric artery?

The epigastric artery is the blood vessel that carries the oxygenated blood to the abdominal wall and the upper abdominis rectus muscle.

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