Features of the Cubital Joint Capsule Innervations in Human Fetuses

Clarifying the features of the innervation of the cubital joint capsule is important both theoretically and practically, as it is often involved in the pathological process. Therefore, in resolving the issue of the genesis of these changes, comprehensive knowledge is required on the distribution of nerves in the capsule of the cubital joint. The purpose of the study was to establish topographic and anatomical features of the distribution of articular branches from the ulnar, median, musculocutaneous and radial nerves in the capsule of the cubital joint in 4-7-month-old human fetuses. Material and methods. Macroscopic examination was carried out on specimens of the upper limbs of 19 human fetuses with 81.0-270.0 mm of crown-ramp length (CRL). Results and discussion. In the region of the lower third of the upper arm the ulnar nerve branches into 1-3 articular parts going in the caudal direction to the site of the cubital joint, parallel to the main trunk of the nerve. In this case, each articular branch gives out 2 branches, which go to the anterior and posterior surfaces of the capsule of the cubital joint. In the area of the median epicondyle of the humerus, or 1.5-3.0 mm below the trunk of the ulnar nerve, or from one of its muscular branches, 2-3 articular branches leave, which, before entering the capsule of the cubital joint, also branch into 2-3 slender branches. The median nerve on the border of the middle and lower third of the upper arm gives out the branches that go to the upper sections of the anterior surface of the articular capsule of the cubital joint. At the level of the median epicondyle of the humerus from the trunk of the median nerve or from its muscular branches, 1-2 articular branches arise, going to the lower parts of the anterior surface of the cubital joint capsule. Before entering the articular capsule of the cubital joint the articular branches of the median nerve, in turn, branch into 2-4 rather slender branches. In the region of the upper or middle third of the upper arm 1-3 articular branches leave the musculocutaneous nerve. They go parallel or obliquely to the muscle fibers of the brachial muscle, which go round the median edge of this muscle at the level of the median epicondyle of the humerus and branch out in the middle of the anterior surface of the articular capsule of the cubital joint. The trunk of the radial nerve or its muscular branches or a deep branch of the nerve give out 2-3 branches to the capsule of the cubital joint, which also branch out into 2-4 slender branches that enter the lateral portions of the front surface of the articular capsule of the cubital joint. A variant anatomy of the branches of the subclavian part of the brachial plexus was found in the fetus with 250.0 mm of CRL. Conclusions. The articular branches of the ulnar nerve innervate the capsules in the area of the posterior median cubital fossa, the posterior and anterior median surfaces of the capsule of the cubital joint. The median nerve gives out branches to the median and middle parts of the anterior surface of the articular capsule, the musculocutaneous nerve sends branches to the middle part of the front surface of the capsule, and the branches of the radial nerve go to the lateral part of the front surface of the capsule of the cubital joint. At the same time, the articular branches arise from the main trunk of the above nerves or from their muscular branches.