ANALYSIS OF THE ANATOMIC VARIATIONS OF THE BRACHIAL PLEXUS AND ITS BRANCHES AT THE LEVEL OF FORMATION AND BRANCHING OF ITS TRUNCI

Abstract

Although the terminal branches of brachial plexus that originate from lateral and medial fasciculus are well protected by muscle mass and vascular-neuronal petal of axilla and upper arm, the number of traumatic damage and injuries increases, according to the published reports of neurosurgeons working on pathology of peripheral nerves, as well as traumatologists, orthopedics, microsurgeons and plastic surgeons. This is certainly contributed by urbanization, industrialization, migration and increased number of traffic accidents. Knowing the microstructure of the peripheral nerve truncus leads to the possibility of applying various techniques of nerve grafting, as well as possibility of re-implantation of detached spinal roots, seen in traction injuries of brachial plexus, in which the mechanism of injury needs to be considered. Considering frequent injuries of terminal branches of lateral and medial fasciculus and a substantial pathology of plexus brachialis, the aim of our research was to study surgical-anatomical relations between terminal branches of medial and lateral fasciculus and substantial morphology of terminal branches of both fasciculi, particularly regarding the place and way of formation, as well as the number of their anastomoses. The studies of the terminal branches of medial and lateral fasciculus on our preparation materials are based on the dissection of axilla and anterior part of the upper arm, on 50 cadavers, adults of both genders, at Institute of Anatomy and Institute of Forensic Medicine at School of Medicine in Belgrade. The way of formation of the terminal branches of lateral fasciculus on our preparation materials was always the same. These branches were usually formed after the bifurcation or diverging of lateral fasciculus to radix lateralis nervi mediani and musculocutaneous nerve. Exceptionally, after fusion of lateral fasciculus and medial root of nervus medianus, there is no bifurcation, and formed nervous truncus is a result of existence of the pre- or postfixational type of brachial plexus. Analyzing our preparation materials, we determined that high bifurcation of lateral fasciculus (LF) exists in 18% of cases and that it is projected in the line of anterior edge of clavicle. Medium high bifurcation of LF is projected in the line of the top of the acromion of scapula and is seen in 61% of all cases. Low bifurcation is usually placed in the line of inferior edge of pectoral minor muscle, in 8% of cases. Fasciculus without bifurcation is noticed in 13% of cases. Measuring the shortest distance between anterior edge of clavicle and the point of bifurcation of LF resulted in a wide range from 0.5 to 9.7 cm, with 4.2 cm average. In cases of transplantation, implantation and re-implantation of nervous trunci of plexus brachialis, it is very important to consider the shape and the thickness of nervous truncus, the number of fasciculi, the number of nerve fibers, as well as the quantity and schedule of peri- and intrafascicular connective tissue, providing the normal irrigation of the nerve. Finally, we can conclude that mentioned facts prompted us to undertake a systematic research of great terminal branches of plexus brachialis that originate from lateral and medial fasciculus, trying to ensure that our anatomical findings receive a comprehensive clinical confirmation.