The internal thoracic artery (ITA), also known as the internal mammary artery, is an

artery An artery () is a blood vessel in humans and most other animals that takes oxygenated blood away from the heart in the systemic circulation to one or more parts of the body. Exceptions that carry deoxygenated blood are the pulmonary arteries in ...

that supplies the anterior

chest wall The thoracic wall or chest wall is the boundary of the thoracic cavity. Structure The bony skeletal part of the thoracic wall is the rib cage, and the rest is made up of muscle, skin, and fasciae. The chest wall has 10 layers, namely (from ...

and the

breasts The breasts are two prominences located on the upper ventral region of the torso among humans and other primates. Both sexes develop breasts from the same embryology, embryological tissues. The relative size and development of the breasts is ...

. It is a paired artery, with one running along each side of the

sternum The sternum (: sternums or sterna) or breastbone is a long flat bone located in the central part of the chest. It connects to the ribs via cartilage and forms the front of the rib cage, thus helping to protect the heart, lungs, and major bl ...

, to continue after its bifurcation as the superior epigastric and musculophrenic arteries.

Structure

The internal thoracic artery arises from the anterior surface of the subclavian artery near its origin. It has a width of between 1-2 mm. It travels downward on the inside of the

rib cage The rib cage or thoracic cage is an endoskeletal enclosure in the thorax of most vertebrates that comprises the ribs, vertebral column and sternum, which protect the vital organs of the thoracic cavity, such as the heart, lungs and great ve ...

, approximately 1 cm from the sides of the

, and thus medial to the

nipple The nipple is a raised region of tissue on the surface of the breast from which, in lactating females, breast milk, milk from the mammary gland leaves the body through the lactiferous ducts to Breastfeeding, nurse an infant. The milk can flow th ...

. It is accompanied by the internal thoracic vein. It runs deep to the

abdominal external oblique muscle The abdominal external oblique muscle (also external oblique muscle or exterior oblique) is the largest and outermost of the three flat Abdomen#Muscles, abdominal muscles of the lateral anterior abdomen. Structure The external oblique is situat ...

, but superficial to the

vagus nerve The vagus nerve, also known as the tenth cranial nerve (CN X), plays a crucial role in the autonomic nervous system, which is responsible for regulating involuntary functions within the human body. This nerve carries both sensory and motor fibe ...

. In adults, the internal thoracic artery lies closest to the

at the first

intercostal space The intercostal space (ICS) is the anatomic space between two ribs (Lat. costa). Since there are 12 ribs on each side, there are 11 intercostal spaces, each numbered for the rib superior to it. Structures in intercostal space * several kind ...

. The gap between the artery and lateral border of the sternum increases when going downwards, up to 1.1 cm to 1.3 cm at the sixth intercostal space. In children, the gap ranges from 0.5 cm to 1.0 cm.

Branches

* Mediastinal branches * Thymic branches * Pericardiacophrenic arterytravels with the

phrenic nerve The phrenic nerve is a mixed nerve that originates from the C3–C5 spinal nerves in the neck. The nerve is important for breathing because it provides exclusive motor control of the diaphragm, the primary muscle of respiration. In humans, t ...

* Sternal branches * Perforating branches * Twelve anterior intercostal branches, two to each of the top six

s. In a given space, the upper branch travels laterally along the bottom of the rib until it

anastomoses An anastomosis (, : anastomoses) is a connection or opening between two things (especially cavities or passages) that are normally diverging or branching, such as between blood vessels, leaf#Veins, leaf veins, or streams. Such a connection may be ...

with its corresponding posterior intercostal artery. The lower branch of the space anastomoses with a collateral branch of the posterior intercostal artery. After passing the sixth intercostal space, the internal thoracic artery splits into the following two terminal branches: * Musculophrenic arteryroughly follows the costal margin and it again gives branch for 7,8,9 ribs *

Superior epigastric artery In human anatomy, the superior epigastric artery is a terminal branch of the internal thoracic artery that provides arterial supply to the abdominal wall, and upper rectus abdominis muscle. It enters the rectus sheath to descend upon the inner ...

continues the course of the internal thoracic artery, travelling downward into the abdominal wall and to the content of rectus sheath

Function

The internal thoracic artery supplies the chest wall and the

breast The breasts are two prominences located on the upper ventral region of the torso among humans and other primates. Both sexes develop breasts from the same embryology, embryological tissues. The relative size and development of the breasts is ...

Clinical significance

Use in bypass grafts

The internal thoracic artery is the cardiac surgeon's

blood vessel Blood vessels are the tubular structures of a circulatory system that transport blood throughout many Animal, animals’ bodies. Blood vessels transport blood cells, nutrients, and oxygen to most of the Tissue (biology), tissues of a Body (bi ...

of choice for coronary artery bypass grafting. The left ITA has a superior long-term patency to saphenous vein grafts and other arterial grafts (e.g.

radial artery In human anatomy, the radial artery is the main artery of the lateral aspect of the forearm. Structure The radial artery arises from the bifurcation of the brachial artery in the antecubital fossa. It runs distally on the anterior part of the ...

, gastroepiploic artery) when grafted to the left anterior descending coronary artery, generally the most important vessel, clinically, to revascularize. Plastic surgeons may use either the left or right internal thoracic arteries for autologous free flap reconstruction of the breast after

mastectomy Mastectomy is the medical term for the surgical removal of one or both breasts, partially or completely. A mastectomy is usually carried out to treat breast cancer. In some cases, women believed to be at high risk of breast cancer choose to have ...

. Usually, a microvascular

anastomosis An anastomosis (, : anastomoses) is a connection or opening between two things (especially cavities or passages) that are normally diverging or branching, such as between blood vessels, leaf veins, or streams. Such a connection may be normal (su ...

is performed at the second intercostal space to the artery on which the free flap is based.

Additional images

File:Grant 1962 407.png, Anterior thoracic wall, from behind File:Grant 1962 405.png, Diagram of an intercostal space

References

External links

Figures of ITA grafts

Figure of heart with two saphenous vein grafts (SVGs) and a LITA graft
- texheartsurgeons.com
Drawing of the heart with a SVG to the right coronary artery (RCA) and a LITA graft to the LAD
- D'Arcy Studios
Drawing of the heart with a SVG to the RCA and a LITA graft to the LAD
- Mayo Clinic {{Authority control Arteries of the thorax