Craniometric characteristic of the visceral skull in adulthood

In relation with the development of clinical endovasive surgery, neurosurgery, maxillofacial surgery there is an urgent need for their improvement. Recent year's osteological and orthopedic areas of medicine have been rapidly developed; it requires an additional data on the age-related and individual anatomical variability. The purpose of the study is to establish the range of anatomical variability of facial skull in adulthood taking in account the extreme forms, sizes and relations according to skull shapes. The research was conducted on a study of 100 bone samples of coherent and fragmented skulls from the collections of anatomy department of Kharkiv National Medical University. It was investigated 58 male skulls and 42 female skulls in 25-60 years old age. To establish an individual anatomical variability of the bone structures, was determined a number of main indices using the well-known craniodivider. All calculations performed by computer program "SPSS Statistics 17.0" using the digital standard package of the tables and initial data. It is proved that the highest range of the arithmetic average of zygomatic sizes (zy-zy) related with representatives of brachycephalic type of the skull, in adulthoods with mesocephalic type it decreases, the minimal range has been found in dolichocephalic type of the head and skull. The lower zygomatic diameter the size between points go-go, also decreases in the arithmetic average from brachycephalic to dolichocephalic types that is associated with the gradual narrowing and lengthening of the visceral skull in adulthood. More stable results were found determining the forehead width (ft-ft). This parameter tends to decrease from brachycephalic to dolichocephalic. More advanced type of facial structure is defined in brachycephalic adulthoods, the narrowed forehead shape related with dolichocephalic type. For modern craniological estimation of the visceral skull, the size n-pr used to calculate special indices. According to our data, in brachycephalic males this parameter varies from 5.0 to 6.9 cm; females between 4.8-6.6 cm. In representatives of mesocephalic type, the n-pr ranges in 10.0-11.6 cm. In people with dolichocephalic type, this altitude parameter increased in males from 5.7 to 7.9 cm, females from 5.5 to 7.6 cm. It was also established that Ind1 has a wide range of variability, especially in brachycephalic males 83.50 ± 9.70 and in females 87.00 ±7.80, which includes a variety of visceral skull structure in people of different age. The range of this index in mesocephalic people is less 86.00 ± 3.20 (males) and 85.30 ± 3.40 (females). Accordingly, in dolichocephalic type complete visceral index is observed in range 91.20 ± 4.40 (males) and 91.10 ± 2.90 (females). Thus, it is proved that the specific type of visceral skull europrosopic is specific for the people of Kharkiv region. It is characterized by increased latitudinal sizes: zy-zy, po-po and go-go, with a slight decrease in altitude parameters of the visceral skull n-gn and n-pr. Depending on the range of variability of individual parameters of the visceral skull it will be possible to suggest the most effective and rational ways of surgical interventions and accesses.


Introduction
Nowadays, specific directions of medicine become more popular, which associated with various operational or aesthetic interventions on the regions of the face, especially in adulthood.In relation with the development of clinical endovasive surgery, neurosurgery, maxillofacial surgery (that is often performs in adulthood) -appears the difficulties represented by differences in the visceral skull structures [1][2][3][4][5][6][7][8][9][10].
Features of the visceral skull formation, age-related transformations of its bony structures depend on gender and an individual human origins, has been found their place in the works of famous morphologists [12, 14, 15, 16-18, 19, 22, 23].It is important to mention that in recent years osteological and orthopedic areas of medicine have been rapidly developed.It requires an additional data on the age-related and individual anatomical variability for the further development of academic V.N.Shevkunenko studies [10,13,17,[19][20][21][24][25][26].
The purpose of the study -to establish the range of anatomical variability of facial skull in adulthood taking in account the extreme forms, sizes and relations according to skull shapes.

Materials and methods
The research was conducted on a study of 100 bone samples of coherent and fragmented skulls from the collections of anatomy department of Kharkiv National Medical University.It was investigated 58 male skulls and 42 female skulls in 25-60 years old age.To establish an individual anatomical variability of the bone structures, was determined a number of main indices using the well-known craniodivider.
The main cranial index calculated using the formula: Ind = cranial transverse dimension (width) / skull's longitudinal size (length) x 100, where the width is set between the parietal tubers corresponding to craniological point eurion (eu) and the length corresponding to the size from the bridge of the nose -point glabella (gl) to the external occipital protuberance, related with a point opisthokranion (op).The ranges of primary cephalic index under 75examined skulls related to dolichocephalic type; 75-79.9mesocephalictype; 80 and over -brachycephalic.
One of the most important craniometric indicators -is facial index that is determined by the Garson's formula: Ind.
1 (visceral) = morphological height of visceral skull / width of visceral skull (zygomatic size) x 100.According to this, the height of the visceral skull was measured between the junction of the fronto-nasal suture (on the root of the nose) at nasion point (n) and the most protruding part of the lower margin of the mandible, corresponding to the craniological point gnation (gn), and the width of the face corresponds to the zygomatic size (zy-zy).
If the above craniological points reflect everything, then we would get the Coleman's formula to determine the visceral index: Ind. visceral = n-gn / zy-zy x 100.
For a more detailed analysis of individual anatomical variability of the visceral skull's shape and size, used an index to determine the height of upper part of the face using the formula: Ind.
2 (upper part of the face) = height of the upper part of the face (n-pr) / zygomatic size (zy-zy) x 100, where the height of the upper part of the face corresponds to the distance between the craniometric points nasion (n) and prosthion (pr), and zygomatic width is -zygion-zygion (zy-zy).This index is depending on the main facial index with the subtraction of the mandible size.
Variation-statistical analysis of data measurements was carried out using the computer program "SPSS Statistics 17.0", which is one of the most well known and widely used nowadays.In our study, we used a common statistical analysis program that allowed us to determine the required parameters: the middle arithmetic (X), the square deviation (σ), and the middle error (m).To confirm the reliability and to determine the correlation between the data obtained according individual anatomical variability, the Fischer-Student criterion used, and the reliability criterion (ρ) was determined according to special tables.All indicators were considered reliable at a value of ρ < 0.05.

Results
Obtained results of visceral skull craniometric measurements were analyzed and confirmed by statistical analysis (table 1).
It can be found from the table below that the highest range of the arithmetic average of zygomatic sizes (zy-zy) related with representatives of brachycephalic type of the skull: x = 13.70 сm with σ = 2.80 and m = 0.91 (males) and x = 12.80 cm with σ = 1.99 і m = 0.88 (females).In adulthoods with mesocephalic type, it decreases to the level of statistical parameters: x = 12.46 cm with σ = 2.86 and m = 0.86 in males and x = 12.10 cm with σ = 2.03 and m = 0.75 in females.The minimal range has been found in dolichocephalic type of the head and skull, where x = 10.90 cm with σ = 3.30 and m = 0.98 (males) and x = 10.50 cm with σ = 2.87 and m = 0.86 (females).
The lower zygomatic diameter -the size between points go-go, also decreases in the arithmetic average from brachycephalic to dolichocephalic types that is associated with the gradual narrowing and lengthening of the visceral skull in adulthood.So, in males with the brachycephalic type of the skull go-go reaches: x = 11.21cm with σ = 1.88 and m = 0.43, in femalesx = 10.93 cm with σ = 1.54 and m = 0.66.With mesochephalic type respectively x = 10.18 cm with σ = 1.39 and m = 0.77 and x = 9.883 cm with σ = 1.012 and m = 0.691; dolichocephalic type of visceral parameter is x = 9.463 cm with σ = 1.720 and m = 0.661 (males) and x = 9.010 cm with σ = 1.380 and m = 0.510 (females).
More stable results were found determining the forehead width (ft-ft).This parameter tends to decrease from brachycephalic to dolichocephalic.More advanced type of facial structure is defined in brachycephalic adulthoods: x = 8.600 cm with σ = 3.010 and m = 0.781 and x = 8.203 cm with σ = 2.844 and m = 0.662.The narrowed forehead shape related with dolichocephalic type: x = 7.480 cm with σ = 2.234 and m = 0.773 (males) and x = 7.184 cm with σ = 2.010 and m = 0.891 (females).
In addition, it is established the height range variability, which are directly dependent on the individual structure and shape of the visceral skull (table 1).
So, in males with the brachycephalic type of the skull determined the minimal range of the br-po arithmetic average x = 13.95 cm with a significant sigmatic deviation σ = 4.38 and m = 0.21.Similarly, in females the range of brpo has the following statistical average: x = 13.89cm with σ = 4.01 and m = 0.22.In representatives with a mesocephalic type of the skull, this parameter is in the average x = 14.31 cm with σ = 3.21 and m = 0.25 (males) and x = 14.76 cm with σ = 3.99 and m = 0.198 (females).In people with dolichocephalic skull type, the size br-po slightly increased: x = 14.90 cm with σ = 2.81 and m = 0.693 (males) and x = 14.80 cm with σ = 2.36 and m = 0.71 (females).
To understand the limit of morphometric variability of the visceral skull of, some longitudinal parameters are of particular importance: n-po, pr-po and pg-po.They have the following range of variation in adulthood people (table 1).
The obtained data indicate that the distance between the points of intersection of the median plane with the frontonasal suture (n) and the point of the external acoustic opening (po) is the smallest in males and females with brachycephalic type: x =10.39 cm, σ = 1.12, m = 1.41 and x = 10.47 cm, σ = 1.10, m = 1.48.This parameter slightly increased in mesocephalic type: in males x = 10.58 cm with σ = 1.05 and m = 0.98; in females x = 10.65 cm, σ = 1.28, m = 0.87.The largest range of the size n-po are in the representatives of both genders dolichocephalic type: x = 11.47 cm (σ = 1.31 and m = 0.65) and x = 11.30cm (σ = 1.21 and m = 0.81).These features emphasize the existing individual differences in the structure of the adulthood face, due to the significant range of variability of longitudinal parameters of the skull.In our opinion, this is due to the specific lengthening and narrowing of the upper part of the face in dolichocephalic people.
An important longitudinal size of the facial skull is the distance pr-po (table 1).From the mentioned table we can find that the size pr-po is the largest in males with brachycephalic structure of skull: x = 11.66 cm with σ = 1.03 and m = 0.95; in females x = 11.52 cm, σ = 1.10, m = 1.48.In mesocephalic structure of the skull a gradual decrease in the arithmetic average of this parameter is determined: x = 11.01 cm (with σ = 1.21 and m = 0.89) and x = 11.00 cm (with σ = 1.19 and m = 0.89).In dolichocephalic type, the greater decrease in the facial distance observed: for males x = 10.12 cm (σ = 1.11 and m = 0.91); in females x = 9.981 cm (σ = 1.087 and m = 0.961).
The above-mentioned facts indicate a predominance of the pr-po distance in brachycephalic adulthood (round head); there is a specific convexity of the two halves of the maxilla along the midline with the pr point moving forward due to the particular curvature of the upper alveolar arch and position of the medial incisors.Therefore, in brachycephalic males the range of pr-po variability is determined -from 11.4 to 12.6 cm, females -from 11.0 to 12.2 cm.In mesocephalic of both genders, these longitudinal parameters gradually decrease and do not exceed -9.4-11.7 and 9.0-11.2cm (males and females).In the dolichocranic, the above parameters of the visceral skull is in the range between 8.90 to 11.6 cm and 8.8-11.4cm (males and females).
The distance between points pg-po in craniomety become the most important, that is between protrusion of the mandible (or mental protuberance) to the external  1).It has been established that males with brachycephalic type of skull has an average of x = 12.66 cm (with σ = 2.01, m = 0.99), in females x = 12.48 cm (with σ = 1.86, m = 0.99).In males with mesocephalic type of visceral skull, there is a tendency to slight increase of x = 12.86 cm (with σ = 1.12 and m = 0.99); x = 12.70 cm (with σ = 1.20 and m = 0.69) in females.The maximal range of this size are typical for representatives of the dolichocephalic shape of head: x = 13.90 cm with σ = 1.02 and m = 0.85 (males); x = 13.82cm with σ = 1.28 and m = 0.76 (females).The data mentioned above is associated with an increase in longitudinal parameters in dolichocephalic type, the narrowing and lengthening of the visceral skull is determined.
These latitudinal, longitudinal and high-altitude dimensions of the visceral skull allow us to establish the range of main indices variability depending on the three types of skull structure (table 2).
According to this table we can say that Ind 1 (complete) has a wide range of variability, especially in brachycephalic males -83.50 ± 9.70 and in females -87.00 ±7.80, which includes a variety of visceral skull structure in people of different age.The range of this index in mesocephalic people is less -86.00 ± 3.20 (males) and 85.30 ± 3.40 (females).Accordingly, in dolichocephalic type complete visceral index is observed in range -91.20 ± 4.40 (males) and 91.10 ± 2.90 (females).
The additional visceral index (Ind 2 ) also repeats the existing features of the variability of individual structure and morphometric ratios (table 2).

Discussion
Analyzing the obtained data in adulthood the peculiar roundness of the oval of the visceral skull is determined, which is typical for the brachycephalic structure of the head; intermediate ovality -for mesocephalic type and narrowed oval face -for dolichocephalic type.The above results of our study greatly complement the information of outstanding morphologists and craniologists [2,20,21].
For the first time determined the range of variability of longitudinal parameters of the visceral skull, which is characteristic for males and females of adulthood.This all greatly complements our understanding about the structure and shape of the skull in people who live in our geographic area.Investigated parameters reflect the existing individual variability of the gradual extension and narrowing of the upper part of the facial skull, which is characteristic for representatives of dolichocephalic head type.On the contrary, this parameter of the facial skull more pronounced in brachycephalic adulthood due to the enlarged convexity of the two halves of the maxilla, the curvature of the upper alveolar arch and the forward displacement of the point (pr).
Calculated Ind 1 and Ind 2 allowed establishing that in males and females between the ages of 25 and 60, who have a brachycephalic type of the skull, the most commonly defined euriprosopic type of the skull with a characteristic increase in all transverse parameters and, more rarely, the mesoprosopic type with moderate values of parameters.Otherwise, broad-head people have an enlarged or average shape of the skull, which depends on the established morphometric indices and the range of their differences.
In adulthoods with mesocephalic type of the skull, the mesoprosopic type of the facial skull with moderate values are often detected.
In dolichocephalic people of this age, the most common is leptoprosopic type of the visceral skull with a characteristic predominance of longitudinal parameters.Less commonly, there is a mesoprosopic type with a set of averaged indicators.The narrow-head people determined with combination of a narrow or middle shape of the visceral skull, which is fully confirmed by the obtained variationstatistical data.The obtained data are important for further studying the shape, size, position, relationship with the visceral part of the skull and the craniometric features of the upper and lower jaws.Without this, it is impossible to establish the existing range of individual anatomical variability of the visceral skull and its structures [19,26].
So, a further investigation of individual anatomical variability is considered to be important, the shape, size, localization, features of visceral skull in adulthood males and females.Depending on the range of variability of individual parameters of the visceral skull -it will be possible to suggest the most effective and rational ways of surgical interventions and accesses.shape head.In mesocephalic type, there are a gradual decrease in facial indicators in average of 0.6-0.8cm, which is associated with the tendency of midhead formation.In case of dolichocephalic type, the width decreases over all specified visceral distances and appeared the formation of narrow head.
2. Thus, it is also proved that the specific type of visceral skull -europrosopic is specific for the people of Kharkiv region.It is characterized by increased latitudinal sizes: zyzy, po-po and go-go, with a slight decrease in altitude parameters of the visceral skull n-gn and n-pr.This evidenced by the range of the complete and additional visceral indices (Ind 1 and Ind 2 ).Representatives of mesoprosopic type also belong to this type of visceral skull structure, characterized by increased latitudinal dimensions depending on the shape of the head (round head).The similar features of visceral skull morphological structure are determined in females of this age.Less often, there are leptoprosopic types of face in young people, characterized by an increase in altitude and longitudinal parameters (n-gn and n-pr) with a marked decrease in zygomatic sizes (zy-zy).

Conclusions 1 .
It was proved that the obtained morphometric consistent patterns reflect the existing ratio of transvers parameters, determined by the type of visceral skull.In brachycephalic type, all indicators of visceral width are greater due to an increase in the head size and round №32, Page 5-12 Sazonova O. M., Vovk O. Yu., Vovk Yu.M., Hordiichuk D. O., Dubina S. O. 9

Craniometric characteristic of the visceral skull in adulthoodTable 1 .
Statistical data of the visceral skull in adulthood (cm).This parameter reflects the longitudinal size of the lower part of the visceral skull (table

Table 2 .
The range of individual visceral indices variability in adulthood.