internal mammary artery

Diagram of

the course and branches of a typical intercostal nerve.

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{{Gray"s Anatomy plate}} == {{int:license-header}} == {{PD-US}} [[Category:Scalenus anterior]] [[Category:Ribs (skeleton)]] [[Category:Media missing infob

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406 Anterior

Wall of the Thorax Observe: 1. The muscles to be removed before dissection is begun: External Oblique, Rectus Abdominis, Pectoralis Major, Pectoralis Minor, Subclavius, sternal head of Sternomastoid, and Scalenus Posterior at the front; Scrratus Anterior and Latissimus Dorsi at the sides (figs. 23 & 24); Serrati Posteriores, Longissimus, and Ilio-costalis at the back (fig. 409). 2. Pulling the arm backwards and downwards forces the clavicle, padded with Subclavius, to compress the subclavian vessels against the 1st rib and thus arrest the blood flow. 3. The 11th and 12th ribs are too short to be seen from the front. 4. The 7th costal cartilages are usually the last to reach the sternum, although not uncom- monly, as here, the 8th also do so. 5. The H-shaped cut made through the perichondrium of the 3rd and 4th cartilages prior to shelling out segments of cartilage. 6. The internal thoracic vessels, crossed anteriorly by the intercostal nerves and associated with parasternal lymph nodes.

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The internal thoracic artery (previously called the internal mammary artery) supplies the anterior body wall and its associated structures from the clavicles to the umbilicus.

Gross anatomy

Origin

The internal thoracic artery arises from the first part of the subclavian artery in the base of the neck.

Course

It then passes from the neck to the thorax posterior to the subclavian vein and first rib. It has a vertical course and runs inferiorly within a few centimeters laterally of the sternum in a neurovascular plane between the transversus thoracis muscle posteriorly and the costal cartilages and internal intercostal muscles anteriorly. At the sixth-to-seventh costal cartilages the internal thoracic artery bifurcates into two terminal branches -

Along its course, the internal thoracic artery gives off perforating branches which pass superficially towards the skin. At the second-to-fourth intercostal spaces these perforating branches are larger (and become even more enlarged during pregnancy) to supply to the breasts.

The internal thoracic artery, via its superior epigastric branches anastomoses with the inferior epigastric arteries, provides an important alternate blood supply if the aorta becomes occluded between the arch of the aorta and descending aorta (see: coarctation of the aorta).

Branches

anterior intercostal arteries within each intercostal space
pericardiophrenic artery (runs with the phrenic nerve)
perforating cutaneous branches
musculophrenic artery (terminal branch)
superior epigastric artery (terminal branch)

Supply

The internal thoracic artery supplies the anterior body wall from clavicle to umbilicus including the sternum and the breasts. In addition, via the pericardiophrenic artery it supplies the mediastinum, thymus, phrenic nerves and pericardium.

Variant anatomy

Recognition of variation of origin of the internal thoracic artery is important because it is often used as a coronary artery bypass graft:

anomalous origin in 20%
- second part (uncommon; ~7%) and third part (rare; ~1%) of subclavian artery
- common origin with thyrocervical trunk
- other subclavian artery branches (e.g. subscapular or transverse cervical arteries)
terminal trifurcation (~12.5%) with an additional xiphoid branch

Siehe auch:

und weiter:

Assoziationen und Differentialdiagnosen zu Arteria mammaria interna:

transcatheter

arterial embolisation of the internal mammary artery

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