The human elbow comprises three bones and these are the humerus of the upper arm and the radius and ulna bones of the forearm. Together, the three bones give rise to a joint complex in which the main movement is unidirectional. Therefore, the elbow joint is considered a hinge joint while the rest of the movements taking place in the human elbow are the direct results of rotational movements of the forearm bones.
Overall, the entire human elbow is covered by a synovial membrane, which is tough on either side and less stiff in front, and from behind. Within the synovial membrane, a slight fluidity is maintained and pockets of fat deposits can also be noticed. These arrangements allow the joint to move fluidly and without much friction.
The humerus, ulna and the radius:
The humerus forms two joints with both the ulnar and the radius while both radius and ulnar forms a joint by themselves. The joint between the trochlear of the humerus and the trochlear notch of the ulnar is known as the ‘humero-ulnar’ joint while the joint between the capitulum of the humerus and the radial head is known as the ‘humero-radial’ joint. The proximal radio-ulnar joint is the one formed between the radial head and the radial notch of the ulna bone. This joint is responsible for the pronation and supination of the forearm as in the case of rotating a doorknob.
There are three main ligaments providing stability to the human elbow and among them, the radial collateral ligament extends from the lateral epicodyle of the humerus to the annular ligament while the ulnar collateral ligament extends from the medial epicondyle of the humerus towards the front and back portions of the top of the ulnar. The annular ligament covers the lower portion of the humerus and the upper portion of the radius, horizontally.
The muscles and the tendons:
Many muscles attach themselves to the bones of the elbow joint via its tendons and among them, the biceps, and the triceps are the major contributors towards its movements. Apart from these two, flexors and extensors of the hand are also attached to the elbow joint.
The nerve supply:
There are three nerves, which extend downwards through the elbow joint and these include the radial nerve, the ulnar nerve, and the median nerve.
Blood supply of the elbow joint:
Blood supply to the elbow joint is mainly thorough the tributaries of the brachial artery and its divisions known as the radial artery and the ulnar artery. The division takes place soon after the elbow joint and the brachial pulse can be felt over the front elbow crease as it crosses the vicinity. The tributaries arising from these arteries forms an anastomosis around the elbow joint to effectively supply blood and oxygen to all tissues in the region.