Медицина\8.Морфология

 

Skoruk A.G., Gavriluk A.О.

Vinnitsa National Medical University named after M.I. Pirogov

department of pathomorphology

Vinnitsa, Ukraine

VARIANT ATYPICAL LOCATION OF ORGANS

AND STRUCTURES OF THE UPPER MEDIASTINUM

IN THE FETUS 6-MONTHS OF FETAL DEVELOPMENT

 

 

Actuality of the theme. A study of the consistent patterns of the formation of the structure and topography of a fetus is of particular importance for interpreting of a true orientation of the processes of organogenesis [1], the mechanisms of the normal form-building of organs [2, 3], the emergence of anatomical variants and congenital malformations [4].

Materials and research methods. The object of the research – to ascertain the variants of the form-building and topography of the organs and vessels of the superior mediastinum in fetuses of different age groups. We used methods makro- and mikroskopy, delicate preparation, macro- and microphotography.

Results and discussions. The thyroid gland in a fetus, measuring 225,0 mm of the parietcoccygeal length has the form of a semiring without a well defined differentiation into the right and left lobes. The inferior border of the gland (of the transverse band) is located at the level of the IIId tracheal cartilage. Behind the right vertical portion of the thyroid gland the right neurovascular fascicle is to be found, the right common carotid artery occupying a medial position inside it, the right vagus nerve an intermediate position, whereas the internal jugular vein being located laterally from it (at a distance of 3,0 mm). The left common carotid artery adjoins tightly the left vertical portion of the thyroid gland on one side, the left internal jugular vein and the left vagus nerve being located more laterally from it. The apex of the left lobe of the thymus is located 9,0 mm below the left vertical portion of the thyroid gland. The thymus is represented by two isolated portions – the right and left ones, different according to the form and size. The right lobe of the thymus has a rounded form, the left one is of a pear-shaped form. The inferior borders of the thymic lobes are located 6,5 mm above the coronary sulcus of the heart. Every lobe of the thymus has a separate capsule which is loosely connected with its parenchyma. The interlobar septa, dividing the glandular lobes into poorly marked lobules deviate from the capsules to the middle of the thymus. The length of the right lobule of the thymus equals 12,0 mm, the width – 11,0 mm and the thickness – 3,5 mm. The anterolateral surface of this lobe is covered by the anterior margin of the superior lobe of the right lung for a distance of 4,0 mm. The superior vena cava and the right auricle adjoin the posterior surface of the right lobe. The right internal thoracic vein flows into the superior vena cava. At the level of the IVth thoracic vertebra the azygos vein rounds the right main bronchus at the top and in front, forming an arch and disgorges into the superior vena cava. The lenght of the left lobe of the thymus makes up 18 mm, the width in the region of the base – 13,0 mm and the thickness is 4,0 mm. The anterolateral surface of the left lobe is covered by the mediastinal surface of the superior lobe of the left lung along the distance of 6,0 mm. The pulmonary trunk is adjacent to the postero-medial surface of the left thymic lobe, whereas its posterolateral surface is adjacent to the left auricle. The upper portion of the left lobe is narrowed in the cranial direction and is represented by the apex of the left lobe whose posterior surface adjoins the left brachiocephalic vein. The left internal thoracic vein flows into the latter. The arch of the aorta and its branches are located behind the left brachiocephalic vein: the brachiocephalic trunk, the left common carotid and the left subclavian arterios. The brachiocephalic trunk is located in front of the trachea and adjoins the VIII-VIIth tracheal rings.

Findings. Therefore, the atypical localization of the thymus, thyroid gland and the vessels of the upper mediastinum can cause the severities during surgical manipulations in this region.

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