Khmara Т. V., Okrim I. I.

AGE AND INDIVIDUAL ANATOMICAL VARIABILITY OF THE INTERNAL THORACIC ARTERY IN HUMAN FETUSES

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About the author:	Khmara Т. V., Okrim I. I.
Heading	EXPERIMENTAL MEDICINE
Type of article	Scentific article
Annotation	The internal thoracic artery (ITA) plays a significant role in the blood supply of the anterior wall of the thoracic and abdominal cavities, of the thymus, the diaphragm and the pericardium. To perform surgical interventions, the surgeon has to know clearly the variant anatomy of the branches of the ITA at different stages of human ontogenesis. The development of modern medicine, which makes it possible to regard the fetus as a patient, poses new challenges and questions to the morphologists. The purpose of the study. To learn the anatomical variability of the ITA and the variants of its branching in human fetuses aged 4-6 months. Materials and methods. The macroscopic study involved 31 specimens of human fetuses with 81.0-230.0 mm of crown-rump length (CRL) without external signs of anatomical abnormalities or those in the development of the chest skeleton by the method of injection of vessels, macroscopy, anatomical preparation and morphometry . Results and discussion. Topographically, ITA in the fetuses can be divided into 3 parts: 1) superior – supracostal; 2) medium – costal; 3) inferior – abdominal. The supracostal part of the ITA is located more cephalad of the first rib and gives small branches to the soft tissues of the neck and in rare cases, the pericardiacophrenic artery. The costal part of the ITA is located on the posterior surface of the anterior thoracic wall, giving lateral, medial, dorsal and ventral branches. The lateral and medial branches of ITA have a segmental placement. The following variants of the topography of the lateral (anterior intercostal) branches of the ITA in the intercostal space have been found: 1) two anterior intercostal branches arise independently from the ITA: upper and lower ones, with the lower branch extending along the upper edge of the lower rib, and the upper branch extends along the lower edge above the rib; 2) The ITA gives one arterial vessel in the intercostal space. It divides into the upper and lower branches; 3) the upper and lower anterior intercostal branches pass a small distance from the place of origin from the ITA and merge into one trunk, with the upper branch crossing the rib almost at a right angle and entering the lower branch; 4) the anterior intercostal branch first passes along the upper edge of the costal cartilage, then forms a pronounced bend, crosses the rib and runs along its lower edge. The lateral group of branches of the ITA also includes the lateral costal branch, which was found on 3 specimens. Medial (sternal) branches arise throughout the costal part of the ITA. In 6 cases, the sternal branches arising from the superior epigastric artery headed to the area of the xiphoid process. The sternal branches of the ITA are involved in the formation of the arterial net in the sternum area and connect the right and left ITA. The ventral group of the branches of the ITA includes perforatory branches, which arise, mainly, from the trunk of the ITA, more rarely, from its lateral and median branches. The dorsal branches of the ITA include: mediastinal, bronchial, tracheal branches, those of the thymus and the pericardiacophrenic artery. The topography of the anterior group of the ITA branches is asymmetric, which is due to the variants of the origin, course, branching of individual arteries, and it is usually one-sided. In particular, on 5 specimens of fetuses the left pericardiacophrenic artery had a low beginning within II-V ribs, and in a fetus with 205.0 mm of CRL the left pericardiacophrenic artery arose from the left ITA at the level of the III rib, then headed to the caudal-medial direction and at the VI rib level the distal end of the pericardiacophrenic artery entered the trunk of the ITA, forming a closed circle. Branches of the thymus arise from the ITA mainly below the pericardiacophrenic artery. In 2 cases, the beginning of the above branches and the pericardiacophrenic artery was found to have a common trunk, in 3 fetuse – from the pericardiacophrenic artery and in 2 fetuses – from the anterior intercostal branches. Branching of the costal part of the ITA into the upper epigastric artery and the musculophrenic artery, usually of the same diameter, occurs at the level the VI rib, at an angle 45-65 °, and on the left – 60-80 °. Conclusions. 1. The fetuses aged 4-6 months were found to have anatomical variability of the vessels of the ventral wall of the trunk which is manifested by variants of the topography of the internal thoracic artery. Topographically the internal thoracic artery can be divided into the supracostal, costal and abdominal parts. The costal part of the internal thoracic artery gives the lateral, medial, dorsal and ventral branches that are distinguished by the variability of its topography and branching. 2. The ITA in the experimental fetuses arises from the subclavian artery more laterally (63%), at the level (32%) or more medially (5%) of the vertebral artery. In 52% of cases the ITA was found to arise asymmetrically. The length of the right ITA slightly exceeds the length of the left artery of the same name. 3. The variants of the branching of the anterior intercostal branches in the intercostal spaces which were founf in human fetuses, the presence of the lateral costal branch, the forms of the anatomical variability of the thoracic and perforatory branches, and the pericardiacophrenic artery, in particular the low beginning of the pericardiacophrenic artery, or the formation of a closed circle between the pericardiacophrenic and the internal thoracic arteries, should be taken into account by fetal and neonatal surgeons when performing surgical interventions.
Tags	internal thoracic artery, fetus, topography, anatomical variability
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Publication of the article	«World of Medicine and Biology» №2(64), 2018 year, 176-181 pages, index UDK 611.135.013-053.15
DOI	10.26724/2079-8334-2018-2-64-176-181