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.
List of references:
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