Lavriv L. P., Yosypenko V. R.
Bukovinian State
Medical University (Chernivtsi City, Ukraine)
VARIANT ANATOMY AND TOPOGRAPHIC ANATOMICAL
FEATURES OF PAROTID GLAND HUMAN AND
PAROTID DUCT IN FETUSES
A study of the development and forming of the topography of the parotid
gland (PG) during the prenatal period human ontogenesis is for great importance
for integral understanding of the structural – functional organization of the
salivary apparatus and the oral cavity as a whole [1-3]. The prevalence of the
diseases of the salivary glands in different groups of the population makes up
from 0,6 % to 1,5 % nowadays [4]. The scientific sources report different data
concerning the features of parotid gland morphogenesis and formation of
topography components of the parotid-masticatory area in human embryogenesis [5]. Furthermore, the
data concerning normal and variant anatomy of the organs and structures of the
parotid-masticatory area as well as formation of their correlations during
human perinatal growth remains insufficiently studied [6-7]. The data about the parotid
gland syntopy and the histogenesis of the parotid-masticatory area components
are disputable and controversial.
Actually, it is the complexity of topographical and anatomical relations
as well as that of histogenesis of the parotid-masticatory area components in
human perinatal period which stipulates the need in their further anatomical
and histological study.
The
object of our research was studying the forming of the parotid
gland topography and parotid duct in fetuses of the
human.
Material
and methods of research. The study of variant anatomy and
topographical and anatomical features of the human parotid gland, and of the
buccal adipose body was carried out on 28 fetuses with 130,0-375,0 mm of crown
to rump length by means of fine preparation under the control of a binocular
magnifier: macro- and microscopy, morphometry and 3D reconstruction.
Results. It has
been established that the PG is located on the face, in a deep recess behind
the branch of the lower jaw in the retromandibular fossa. Repeating the form of
if its bed the PG has three surfaces (external, anterior and posterior) and two
bases. The skin of this particular region is thin, movable. The subcutaneous
pot is thin and fused with the skin. The posterior surface of the gland is
adjacent to all those organs and tissues that constitute the posterior surface
of the bed of the parotid gland. The PG capsule already well evident in fetuses
of the intrauterine development. Thin connective tissue interlayers deviate
from the latter inside gland. Between the outer capsule of the gland, surrounding
vascular, nerve branches and fascial formations of the investigated area in 8-10 months fetuses there are tight adhesions.
The
structure of the parotid gland in human fetuses is characterized by
considerable anatomical variation, which shows itself in a variety of shapes
(oval, leaf-like, horseshoe-shaped, triangular, irregular quadrangle), of
location and syntopy. According to the results of computer 3-D modeling of the parotid glands of the fetuses aged 6-10 -month, the most
practical is a 3-D description as the trilateral pyramid , which lies in the retromandibular
fossa and in the lateral area of the
face, turned
with its base to the zygomatic arch, its vertex going downwards - to the angle of the mandible. Upon a
preparation with the help of a binocular loupe the color of the gland is
grey-yellowish similar to the color of the fat surrounding it, the gland
distinguishing from it by a more, marked grey hue, a lobulous structure and
greater density.
At the beginning of the period under study of the development the PG
lies very close to the bony anlages up the mandible and to the anlages of the
tympanic membrane. The superior margin of the PG does not reach the zygomatic
arch by 1,0-3,0 mm. The anterior surface of the gland fills all the recesses of
the anterior surface of the bed, occasionally giving off a process between the
internal pterygoid muscle and the mandible and often over the external surface
of the masseter muscle, being a very short distance off its anterior margin. In
this case the gland covers its main excretory duct and masks its origin.
The
parotid gland duct is formed by merging two outside organ lobular branches
which (in turn) are formed by merging several superior and inferior lobular
ducts emerging from the glandular tissue itself and piercing through its
capsule. The principal
excretory duct of the PG leaves the gland primarily approximately in the middle
of the anterior margin. On leaving the gland the duct makes its way slantwise
upwards and forward, not reaching the zygomatic arch turning forward and
passing horizontally over the external surface of the masseter muscle
accompanied by the transverse facial artery located a little higher than the
duct and the branches of the facial nerve, some of them pass over the duct of
the parotid gland, others under it. Further it is directed horizontally and is
located on the external surface of the masseter muscle proper. At the anterior
margin of this muscle the duct forms a bend which is turned towards the front
with its convexity and penetrates under the fat body (the corpus adiposum
buccae). Then it proceeds ventro-medially inside, piercing the cheek muscle and
opens in the vestibule of the mouth on the mucous coat of the cheek.
A
number of anatomical variations were found in human fetuses both in the ratio
of the buccal adipose body and the parotid duct and in its shape variety. The
parotid duct may pierce the buccal adipose body or avoid it. The structure of
the buccal adipose body of fetuses aged 7-10 months is characterized by a
significant anatomical variation which can be seen in a variety of shapes
(oval, triangular, two lobular, three lobular or as serried pyramids bases) as
well as in its location. Human fetuses aged 5-10 months acquire a clear
topographical location and direction of outside gland course of the parotid
duct within the buccal area.
Practically all the time the parotid duct is adjacent to the external
surface of the masticatory muscle proper, bending its anterior edge and, in
most cases, lies on the upper medial surface of the buccal adipose body
(Bishat’s fat pad).
Conclusions. According to the results of
computer 3-D modeling of the parotid glands of the fetuses aged 6-10 -month, the most practical is a 3-D description as the trilateral
pyramid , which lies in the retromandibular fossa and in the lateral area of the face, turned with its base to the zygomatic arch, its vertex going downwards - to the angle of
the mandible. 8-10 -month-old fetuses had some indurations in fascial cellular masses of the
glandular
bed, especially in the areas
of close topographical and
anatomical interrelations of organs and structures.
Between the outer capsule of the gland, surrounding vascular, nerve branches
and fascial formations of the investigated area in 8-10 months fetuses there are tight adhesions that should be considered during
the operative interventions within the parotid- masticatory
area in newborn
infants.
Active application of perinatal prevention of congenital defects requires up-to-date approaches and methods of embryonic growth study. Embryotopographic
research, which takes into account specific and critical for some organs
periods of their growth and some peculiarities of their interrelations with
adjacent organs and structures, becomes especially important.
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