MACRO-MICROSCOPIC FEATURES OF THE LEG MUSCLES INNERVATION

The purpose of the study was to disclose topo graphic anatomical features of the extra- and intra muscular innervation points of the leg. itorum longus nerve in a one-month-old baby, thick-di ameter myelin fibers are absent, whereas in the long finger flexor nerve, on average, they are 0.5%. The number of thin and medium is respectively 8%, 13% and 83.5%, 16%. However, we have determined individual ana tomical variability in the location of the vessels in re lation to the main nerve trunks, as well as differences in the topography of the nerve in the corresponding muscles. Conclusion. In the nerves of the leg muscles, fea tures were found, both in quantitative and qualitative composition of the conductors forming them; in the nerves of the flexor muscles, the composition of the nerve fibers is more diverse (with a slight predomi nance of the number of medium, thick and very thick fibers), which is associated with the peculiarity of their functions; in adulthood, the % ratio in the spectrum of myelin fibers in the nerves of the lower leg changes significantly.

Relationship of work with scientific programs, plans, and topics. This study is based on the results of the PhD thesis "Morphological features of the nerves of the leg".
Introduction. Developing neurology and reconstructive surgery sciences require morphologists for further investigation of the external structural organization of peripheral nerves, in particular the nerves of the leg muscles. This is primarily due to the improvement of microsurgical techniques and the expanding range of neuro-and myoplastic operations [1][2][3][4]. Meanwhile, in classical and modern manuals, as well as in special research data on the surgical anatomy of the leg muscle nerves, there is no complete data on the topography of intramuscular nerves. The question of individual anatomical variability of intraorganic nerves of the leg is not highlighted enough [5][6][7].
The available studies have mainly identified extreme forms of variability of extraorganic nerves of the leg without the full range of variability of both extraand intraorganic nerves, which is of particular interest to surgeons currently engaged in myo-and neuroplastic operations of the leg [8][9][10].
The purpose of the study was to investigate the topographic and anatomical features of innervation of human leg muscles.

Materials and methods.
We studied the extraand intramuscular nerves of the leg at three levels: at its upper, middle and lower third, using cadaveric material from 15 adult human subjects and one-monthold baby. Methods which were used are cross-sections according to N.I. Pirogov technique, histotopographic sections, macro-microscopic method, histological staining with hematoxylin-eosin and Krutsay.
All experiments were conducted in accordance with the Council of Europe Convention "On the Protection of Human Rights and Dignity of the Human Being with regard to the Application of Biology and Medicine Application of Biological and Medicine Achievements (ETS No. 164)" dated 04.04.1997, and the Helsinki Declaration of the World Medical Association (2008).
Research results and discussion. As a result of the study of extraorganic nerves on preparations of the adult's lower specimens in the upper, middle and lower third of it, the following data was obtained.
In the upper third of the leg, the tibial nerve and the posterior tibial artery and veins located behind it lie in the cruropopliteal canal between the posterior tibial and soleus muscles. The artery is located laterally to the nerve trunk. The common peroneal nerve runs between the subcutaneous fat cell and the head of the fibula.
In the middle third of the lower leg, the tibial nerve is located between the long flexor of the big toe and the soleus muscle. Vessels lie medially to it. The superficial peroneal nerve is located anteriorly between the superficial and deep peroneal muscles. The deep peroneal nerve runs between the long extensor of the big toe and the interosseous membrane. Vessels are located medially to it.
In the lower third of the lower leg, the tibial nerve lies between the long flexor of the big toe, the long flexor of the fingers and the fascia of the lower leg. Vessels are located medially to it. The data obtained basically coincide with the literature data.
However, we have determined individual anatomical variability in the location of the vessels in relation to the main nerve trunks, as well as differences in the topography of the nerve in the corresponding muscles. The latter should be taken into account in the practice of acupuncture.
The topography of the extra-and intramuscular nerves in the region of the middle third of the adult's leg, as well as in a 1-month-old child, has been studied in more detail.
In adulthood, the tibial nerve is located between the long flexor of the big toe and the soleus muscle. An artery and vein are sequentially located medially to it.
In a 1-month-old baby, as well as in an adult tibial nerve is located in the cruropopliteal canal. However, in a 1-month-old baby unlike an adult, in the middle third of the leg, the nerve is located between the posterior tibial and soleus muscles (Fig. 1). The posterior tibial artery and two veins in succession lie in front of the nerve.
Superficial peroneal nerve in a 1-month-old baby is located between the deep and superficial peroneal muscles in their middle part, surrounded by vessels, while in adults it is displaced forward.
In one-month-old baby the deep peroneal nerve is located between the long extensor of the fingers and the big toe, the vessels are closer to the interosseous membrane and medial to it. In adults, the deep peroneal nerve lies between the long extensor of the big toe, the tibialis anterior muscle, and the interosseous membrane (Fig. 2). Such differences in the location of the leg muscles of an adult and of one-month-old baby undoubtedly related to the fact that the child's muscular belly is longer in relation to the tendon.
We studied the histotopography of intramuscular nerves on total transverse sections of antagonistic muscles: flexor and extensor digitorum longus, longus flexor and extensor of the big toe, and also investigated the spectrum of myelin fibers contained in these nerves in a one-month-old baby and an adult. These studies have shown that the nerves of the leg muscles have features both in the quantitative and qualitative composition of the conductors that form them.
On their way in the thickness of the muscle, the main nerve trunks, as evidenced by macromicroscopic preparations, give a large number of lateral branches, which makes it difficult to accurately count the myelin fibers. Therefore, only the major intramuscular nerve trunks have been studied.
On histotopographic sections of the extensor digitorum longus nerve in a one-month-old baby, thick-diameter myelin fibers are absent, whereas in the long finger flexor nerve, on average, they are 0.5%. The number of thin and medium is respectively 8%, 13% and 83.5%, 16%.
In the longus extensor nerve of the big toe, the number of thick fibers is 0.8%, medium -15%, thin -84%, in the long flexor nerve of the big toe -1%, 19% and 80%, respectively. None of the muscle nerves of myelin fibers of a very thick diameter were found.
In adulthood, the spectrum of myelin fibers changes. So, in the nerve of the long extensor of the fingers, the ratio of very thick, thick, medium and thin fibers is 5%, 12%, 43% and 40%, and in the nerve of the long flexor of the fingers -respectively 5.3%, 13.7%, 40% and 41.3%. In the nerve of the extensor longus and longus flexor of the big toe -6%, 11%, 45%, 38% and 7.2%, 13.4%, 41%, 38.4%, respectively.
Comparing the digital indicators of the flexor and extensor nerves, we found some differences: in the nerves of the flexor muscles, the set of nerve fibers is more diverse (with a slight predominance of the number of medium, thick and very thick fibers), which is apparently associated with the peculiarity of their functions, it is known that the flexor muscles are always more developed than the extensors.
Thus, the study of the nerves of the leg muscles using the methods of total cross-sections and histotopography (in combination with the data of macromicroscopic studies) allowed us to clarify the course of the neurovascular bundle of the leg at its three levels, taking into account individual age characteristics, and also to show the myeloarchitectonics of both the main nerve trunks and their intramuscular branches. The latter may be of undoubted interest in the clinic of microsurgery and acupuncture.
There are a number of studies in the literature on the distribution of nerves and blood vessels in the thickness of the leg muscles [1,2]. However, these authors, describing the topography of the main nerve trunks in the thickness of the muscle, did not pay due attention to the forms of individual anatomical variability in the distribution of intraorganic nerves. At the same time, clinicians pay special attention to variability in the distribution of nerves when developing new operational approaches to the nerve trunks in neuroand myoplastic operations [5,6,9].
In this regard, in our macro-microscopic study, the main attention was paid to the individual anatomical variability in the innervation of the lower leg muscles. Conclusion 1. The nerves of the leg muscles have features both in quantitative and qualitative composition of the conductors forming them. 2. In the nerves of the flexor muscles, the set of nerve fibers is more diverse (with a slight predominance of the number of medium, thick and very thick fibers), which is associated with the peculiarity of their functions. 3. In adulthood, the % ratio in the spectrum of myelin fibers in the nerves of the lower leg changes significantly. Perspectives of further research. We consider it expedient to start studying the features of myelination of the nerves of the muscles of the lower extremities in different age groups. The patterns of individual anatomical variability of the nerves of the lower extremities can be of undoubted interest in the clinic of microsurgery and acupuncture.