Anatomical variations of the upper limb nerves

Abstract

Introduction. The puncture and catheterization of the main arteries of the upper limb, as well as the nerve blocks that are often performed by surgeons, are considered „blind” methods, the success of which depends on their in-depth knowledge of the anatomy of the nerves and blood vessels of the given level. The existence of anatomical variations (AV) of the nerves of the upper limb (UL) must be taken into consideration when selecting the intervention tactics, otherwise the risk of mono- or polyneuropathy may increase.Aim of the study. Identification of AV of the nerves of the UL depending on gender and laterality. Materials and methods. A morphological, descriptive study of the brachial plexus (BP) branches was performed on 30 upper limbs (14 male and 16 female), collected from formalin treated adult cadavers, selected from the Department of Human Anatomy of Nicolae Testemitanu State University of Medicine and Pharmacy. By anatomical dissection method the formation of UL nerves, their interconnections, topography and relation to the accompanying arteries, as well as the existent variations were evaluated. Results. Anatomical variations were identified in 6 UL, 4 of them were male (3 right upper limbs and 1 left upper limb) and 2 female (both right upper limbs). Variations of median nerve (MN) formation were identified on 2 UL (both male, right upper limbs); in the first case MN was formed by three roots, coming from the three cords of BP, and in the second case - it was formed by a single root that started from the medial cord of the plexus. On one left UL of a male, an abnormal relationship of MN with axillary artery (AA) was determined; it was formed from its usual roots, but posterior to AA, and continued to run on the arm lateral to the brachial artery until the cubital fossa, where MN crossed it anteriorly and lied medial to it. On one right UL of a female, the formation of the ulnar nerve from the lateral cord of the BP was established; it passed below the biceps brachii muscle and reached the medial bicipital groove in the middle 1/3 of the arm, after which it passed posterior to the medial epicondyle of the humerus, and then on the forearm to continue its classic path. Variations of connection of BP nerves were found on 2 right UL (one of each gender); in one case the connection between the axillary and radial nerves was identified, and in another case – the connection between the median and musculocutaneous nerves was identified. Conclusions. More often, the right male upper limbs are exposed to variations of the median nerve.