Elbow Anatomy and Positioning

Saturday, May 12, 2018

Elbow Anatomy

At first the elbow seem to work like a simple hinge. The elbow is complex joint whose motion affect the forearm and the wrist joints. It is easy to see while the elbow can caused problem when it is not functional correctly. Part of what make us human is the way we able to use are hands. Effective use of our hand requires a stable painless elbow joint. The important structure of the elbow joint can be divided into several categories this include joints, bones, ligaments, tendons, muscles, nerves and blood vessels.

The bones of the elbows includes the humerus or the upper arm bone, the ulna the larger bone of the forearm on the opposite side of the thumb, and the radius the smaller bone of the forearm on the same side as the thumb. The elbow itself is essentially a hinge joint, meaning it bends and straight like a hinge, but there’s a second joint where the end of the radius or the radial head mids the humerus, this joint is complicated because radius has to rotate as you turn your hand palm up and palm down, while at the same time it has to slide against the end of the humerus as the elbow bends and straightens.

To make this motion possible, the radial heads shapes like a smooth knob with the Sheila capitellium, the shiela cap is against the capitella a rounded knob against the humerus that forms part of the elbow joint. The smooth rim of the radial head, is also covered with articular cartilage and gland against the small indentation in the ulna.

Articular Cartilage

Articular cartilage is the material that covers the ends of the bones of any joints, articular cartilage can be 1 quart of an inch thick in the large weight bearing joint. It is a bit thinner in joint such as the elbow, which don’t support weight. Articular cartilage is white, shiny and has a rubbery consistency, it is slippery which allows the joint surfaces to slide one another without causing any damage.

Articular Cartilage Functions

Articular cartilage function is to absorb shock and to provide an extremely smooth surface to make motion easier. We have articular cartilage essentially anywhere that two bony surfaces moves against one another or articulate. In the elbow articular cartilage cover the end of the humerus, the end of the radius and the end of the ulna.

Ligament in the Elbow

There are several ligament in the elbow, ligament are soft tissue structure that connect bone to bones. The ligament around the joints are connected with a thin layer of connective tissue and form a structure called the joint capsule. The joint capsule is a water tight sac that surround the joints and contains a lubricating fluid called the synovial fluid.

Lateral and Medial Collateral Ligament

In the elbow two important ligaments are the medial collateral ligament and lateral collateral ligament. The medial collateral ligament is on the inside edge of the elbow while the lateral collateral ligament is on the outside edge. Together this two ligaments connect the humerus to the ulna and keep it tightly in place as it slide to the groove at the end of the humerus this ligaments are the main source of stability for the elbow, they can be torn when there is an injury or dislocation of the elbow, and if they do not heal correctly the elbow can be too loose or unstable.

Annular Ligament

Another important ligament for elbow function is the annular ligament. This ligament wraps around the radial head and hold it tights against the ulna. The word annular means ring shape and the annular ligament forms a ring around the radial head as it hold it in place. This ligament can be torn when the entire elbow or just the radial head is dislocated.

Tendons in the Elbow

There are several important tendons around the elbow. The bicep tendons attaches the large bicep muscle on the front of the arm to the radius. It allows the elbow to bend with force, you can feel this tendons causing the front crest in the elbow when you tighten the bicep muscles.

The triceps tendons connects the large tricep muscle on the back of the arm with the ulna, it allows the elbow to straighten with force such as when you perform a push up.

The muscles of the forearm cross the elbow and attached to the humerus. The outside or the lateral bump just above the elbow called lateral epicondyle. Most of the muscles that straighten the fingers and wrist all come together in one tendon to attach in this area. The inside or the medial bump just above the elbow is called the medial epicondyle most of the muscle that bend the fingers and wrist all come together in one tendon to attach this area. This two tendons are important because they are common location of pain cause by a condition called the tendonitis or perhaps most accurately tendinosis.

Nerves of the Elbow

All the nerves travel down the arm pass across the elbow. 3 main nerve begin together at the shoulder the radial nerve, the ulnar nerve and the medial nerve. This nerves carries signals from the brain to the muscles that move the arm and hand. The nerves also carries signals back to the brain about sensation such as touch, pain and temperature.

Common Problems of the Elbow

Some of the more common problems around the elbow involves problems with the nerves each nerves travels with each own tunnel as it crosses the elbow, because the elbow must bend the nerve must bend as well, constant bending and straightening can lead to irritation or pressure on the nerves with in their tunnel and cause problems such as pain, numbness and weakness on the arm and hand this condition is sometimes called a nerve entrapment or nerve compression syndromes.

Brachial Artery

Traveling along with the nerves, are the large vessels that supplies the arm and hand with blood. The largest artery is the brachial artery that travels across the front crest of the elbow. If you place your hand in the bend of your elbow you may be able to feel the pulsing of this large artery. The brachial artery split into two branches just below the elbow, the ulnar artery and the radial artery this two branches continues into the hand. Damage of the brachial artery can be very serious because it is the major blood supply into the forearm and hand.

As you can see the elbow is more than simple a hinge, it is design to provide maximum stability as we position our forearm to use are hand. When you realize all the different we use our hand every day and all the position in which we place our hands it is easy to understand how hard can be daily life could be when the elbow doesn’t work well.

Elbow Positioning Radiography

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