Human Anatomy (with Fundamentals of Dynamic and Sports Morphology) - Ivanitsky M. F. 2008

Age Morphology
Integral Indicators of Biological Age

When assessing biological age, human appearance is most frequently taken into account: the condition of the Skin, The Nature of Hair growth, the size of the Mammary Glands in women, the degree of Development of the laryngeal prominence (Adam's apple) in men, etc. Some of these traits are associated with The production of Sex Hormones, which is why they are called secondary sex characteristics. When determining biological age, the state of the dentition is also considered: the presence of deciduous and permanent Teeth in a child according to their categories or eruption stage, or, in an adult, the degree of dental attrition. If skeletal radiography is available, the presence or absence of skeletal ossification centers, the integrity or closure of epiphyseal plates are established in children based on its data, whereas in adults, age-related Changes in the compact Bone tissue (its thinning), spongy bone tissue (rarefaction with the disappearance of individual trabeculae), as well as the relief of the external bone surface (the appearance of bony outgrowths, or osteophytes) are evaluated.

For each of these biological age criteria—external (skin condition), dental, and skeletal—evaluation scales and normative tables have been developed, making it possible to determine chronological (calendar) age from morphological features. The criteria for dental age in children and adolescents are less dependent on environmental influences and therefore characterize chronological age more precisely. For adults, more objective results are provided by the CHARACTERISTICS OF THE Skeletal System, although the accuracy of estimating chronological age (based on biological data) is significantly lower than in children and adolescents.

Dental age. When determining age from the eruption status of deciduous and permanent teeth, one can be guided by the summary data (see Table 2)

The third large molars—wisdom teeth—are frequently delayed in eruption or absent altogether. The order of tooth eruption is sometimes disrupted; for instance, permanent medial incisors may erupt ahead of the first large molars.

Skeletal age. When determining the skeletal age of children and adolescents, the condition of various PARTS OF THE Skeleton is taken into account.

Permanent teeth

As already mentioned (see p. 51), ossification centers in the diaphysis of long bones appear prenatally, whereas in the epiphyses they appear only after birth (excluding the adjacent epiphyses of the Femur and Tibia). Fusion of the epiphyses with the diaphysis occurs at 16-18 years of age (with some variations for different bones), occurring somewhat earlier in girls than in boys. Typically, skeletal age is assessed from radiographs of the hand, which consists of A large number of bones undergoing ossification at different ages (capitate and hamate bones in the 1st year, triquetrum at 3 years, lunate at 4 years, scaphoid at 5 years, trapezium at 6 years, trapezoid at 7 years, pisiform at 12 years).

Age-related changes in body dimensions. Changes in so-called total body dimensions (body length, body mass, chest girth) and partial dimensions (trunk length, limb length and their segments, transverse trunk dimensions, etc.) are studied. Body length serves as the most integral anthropometric characteristic of a person. According to V. G. Vlastovsky (1983), referring to the medium-height Russian population of the USSR, its age dynamics (in cm) are as follows (see Table 3).

Table 4.

In boys by age 17, body length increases slightly more (3.3-fold) than in girls (3.1-fold). Annual increments up to 10 years of age are independent of sex; at 10–13 years they are higher in girls, and at 13–17 years—in boys (see p. 471).

If we take the magnitude of body length growth from 7 to 15 years as 100% and evaluate the proportion of growth for each year as a percentage, a high level of growth rate is observed in Moscow girls at 11–13 years of age, and in boys at 14–15 years. The rate of body weight gain in girls is significantly greater than in boys at 12–13 years and smaller at 14–15 years.

Upon completion of growth processes in the so-called stable period of ontogenesis, changes in total body dimensions are observed. In particular, judging by the results of generalizing studies, a decrease in body length occurs. At an older age (after 51–61 years), this is more pronounced due to the progressive thinning of articular Cartilage, intervertebral discs, flattening of the feet, and The Development of Senile kyphosis.

The decrease in body length across a successive series of age groups is associated not only with the Aging of The Musculoskeletal System, but also with differences in body dimensions among people of different generations (Fig. 146). Due to developmental acceleration (see p. 432), human body dimensions increase from generation to generation. Therefore, when comparing people of different age groups, it should be kept in mind that older individuals initially had a smaller body length.

Among the various periods, adolescence is of particular interest, spanning from 12 to 15 years in girls and from 13 to 16 years in boys. This is a period of accelerated GROWTH AND DEVELOPMENT of the child's body, critical for the development of motor qualities. However, the core content of the adolescent period is Puberty.

Puberty. Puberty is a morphofunctional reorganization of the Organism during individual development associated with the acquisition of The ability to reproduce. Although The Nervous system, endocrine apparatus, and sex Organs serve as the primary link in this process, body dimensions, body build features, and individual organs and Organ Systems also undergo changes. Anthropometric traits can characterize puberty no less informatively than the so-called secondary sex characteristics.

Puberty is characterized by:

1. An increase in the annual increments of body dimensions.

2. Sex differences in growth rates. Body growth activation occurs earlier in girls than in boys (Fig. 147), resulting in two "crossovers" of the growth curves: the first indicates the onset of puberty in girls, and the second indicates the activation of puberty in boys (against the Background of the completion of this process, or a state close to it, in girls). The first crossover for the urban population of our country occurs at 10 years 4 months, and the second at 13 years 10 months. Interestingly, children of different ethnic and territorial groups exhibit similarities in the timing of the second crossover, alongside certain differences in the timing of the first crossover.

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Fig. 146. Curves of longitudinal body growth in Moscow boys according to generalizing data from various years (after V. G. Vlastovsky)

Fig. 147. Curves of body length growth (A) and growth rate (B) in children of the city of

Moscow according to 1960–1970 data:

1 — boys; 2 — girls (after V. G. Vlastovsky)

3. Changes in body proportions, manifested in the relative shortening of the trunk and lengthening of the lower extremities.

4. Lagging of body weight gains behind body length gains, most pronounced prior to the onset of puberty.

5. Increased Variability of anthropometric traits, due to which children are divided into accelerated and delayed growth groups.

Puberty, or sexual maturation (hence the term "pubertal period": *pubertas* — maturity), manifests more vividly in girls than in boys. A qualitatively important sign of sexual maturation in females is the first menstruation, known as menarche. Because males lack such a distinct manifestation of sexual maturity (spermarche — the appearance of mature Male Germ Cells, spermatozoa, in morning urine — is difficult to detect), many correlations between anthropometric and physiological markers of puberty have been established primarily in girls.

Puberty in girls. The sequence of physical signs of sexual maturation in girls is as follows:

1) widening of the pelvis;

2) rounding of the hips and thighs;

3) breast development;

4) appearance of pubic hair;

5) axillary hair growth;

6) first menstruation (menarche).

Menarche is the most definitive milestone in the sexual maturation of the female body. The other signs are closely associated with its onset; specifically, breast development correlates more strongly with the timing of menarche than does the appearance of pubic and axillary hair.

The acceleration of linear body growth (the pubertal growth spurt) occurs approximately one year before the onset of menarche, whereas the intensified accumulation of subcutaneous adipose tissue takes place one year after it. During the establishment of menstrual function, the body faces high physiological demands; adaptation to these demands is accompanied by a decrease in somatic growth activity and the expenditure of energy previously stored in the body's fat depots.

The pubertal growth spurt in girls occurs earlier than in boys, indicating that girls outpace boys in the timing of sexual maturation. On average, the onset of the linear growth spurt occurs at 9.6±0.1 years in girls and 11.7±0.09 years in boys, with initial body lengths of 136.5±0.84 cm (82.5% of the average body length at age 18) and 147.3±0.49 cm (82%), respectively.

Body weight gain lags behind changes in body length prior to the onset of puberty. The age at the onset of the growth spurt in both height and weight differs between boys and girls by no more than 0.1 years. However, whereas body length at this age accounts for 82.5% and 82% of the 18-year-old height in girls and boys respectively, body weight reaches only 53.3% and 54.1% of the adult weight in young women and men.

It should be noted that with age, not only the absolute body mass changes, but also The ratio of its components—namely, fat mass and fat-free mass. This depends on children's dietary habits and physical activity. Increased physical activity leads to a decrease in adipose tissue and an increase in the fat-free component.

Puberty in boys. The sequence of physical signs of sexual maturation in boys is as follows:

1) enlargement of the Testes and Penis;

2) appearance of pubic hair and voice breaking (mutation);

3) temporary Swelling of the mammary glands;

4) prominence of the thyroid cartilage (Adam's apple) and completion of voice mutation;

5) appearance of facial hair on the upper lip, axillary hair, and the first nocturnal emissions (involuntary seminal emissions).

The earliest sign—enlargement of the testes—is observed starting at age 9 and peaks at 13–14 years. Secondary sexual characteristics appear 1.5–2 years after the activation of growth in the reproductive organs: pubic hair appears at age 12; hair on the upper lip and in the armpits at age 14; facial hair on the chin at age 15; breast enlargement at age 14; and the first nocturnal emissions at an average age of 14.8 years.

The subjectivity in assessing puberty markers complicates the establishment of normative standards for sexual maturity. It is safe to say that the complete absence of pubic and axillary hair at the age of 15–16 warrants medical attention.

At the same time, the adolescent's body type should be taken into account (in slender, asthenic builds, growth processes are extended over time), as well as the parents' pubertal patterns—accelerated or delayed (if the parents experienced delayed puberty, a hereditary predisposition to delayed maturation in the child may be suspected).

A clear correlation exists between the stages of puberty and the intensity of growth processes in both boys and girls. Voice mutation typically precedes the peak growth velocity; the onset of pubic hair growth and the appearance of the laryngeal prominence (Adam's apple) coincide with the maximum increase in body height; whereas facial hair growth corresponds to a deceleration in linear body growth.