Insight Into The Elbow Joint

                                                                                         

The elbow is the central joint of the arm and divides it up into two convenient halves, looking initially merely like a backwards and forwards hinge. On closer examination the elbow shows itself to be a remarkably clever and multi-talented joint. The humerus or upper arm bone connects with the two lower arm bones, the radius and the ulna. The elbow joint itself is formed from the lower end of the humerus and the upper end of the ulna which makes up the bony point of the elbow which can be easily felt. The upper end of the ulna has a ladle like shape which carries in its bowl the end of the humerus.

The major part of the elbow joint is composed of the the humerus and the enlarged upper end of the ulna, which gradually gets smaller as it travels down towards the wrist where the much larger bone is the radius. Up at the elbow the radial head performs the rotational movements of the forearm which are functionally so useful. This added dimension to the mobile joints of the fingers, thumb and wrist allows the high level of mobility and co-ordination available to the hand. The soft tissues around the elbow are usually dominant in a flexing direction, giving a degree of natural elbow bend at rest.

A bony protrusion on the cylindrical end of the humerus articulates with the upper part of the radius which is on the outer side of the elbow when the hand is facing upwards. The radial head is the other part of that articulation, a rounded part somewhat like a cotton reel, placed close to the ulna and held in place during rotatory movements by the radial ligament, a band of ligament surrounding the head. Forearm rotation is predominantly performed by the radius, beginning with it lying in parallel with the ulna and then turning and crossing over that bone to achieve the full pronation movement with the palm down.

The ability to rotate the forearm is a vital ability in the manipulation of objects. Much human activity and dexterity involves the thumb and fingers which are relatively restricted to forward and back movement. This means other movements are necessary to allow the endlessly varied positions we need to access with our hands. Elbow function combines flexing and extending the joint in combination with rotation, allowing smooth and coordinated movement of the hand. This precision and adaptability can have a negative side because it is so useful it can be repeated many times and to excess.

When we decide to reach forward for something we extend the elbow, turn the hand over, extend the wrist and position the fingers above the object, permitting at the same time the maximum power from the fingers. If you try and grip something firmly whilst flexing the wrist downwards you will find yourself unable to exert much strength. Pronation is the name given to the action of twisting the forearm so the palm faces down, and as these muscles only do this action they are not very strong.

This means that the pronators are not powerful muscles as the only job they have to do is position the arm, a bit like the muscles which pull our feet up when walking. A lack of pronation or the ability to extend the wrist back when reaching makes gripping objects a clumsy procedure, with the primary power muscles of gripping inhibited in use.

Elbow supination and flexion, the opposite of pronation and extension, occurs when the elbow is actively bent and the palm brought to face up. Typical functions involving this movement are taking food to the mouth with a fork and screwing in screws, so this is both a very common action indeed and one with much more strength than pronation. Supination and flexion of the elbow is primarily performed by the biceps muscle with a contribution from a smaller but strong muscle termed supinator. The common extensor origin is the area on the outer part of the elbow which has the origin of the extensor muscles of the wrist and supinator.

About the author:
Jonathan Blood Smyth is the Superintendent of Physiotherapists at an NHS hospital in the South-West of the UK. He writes articles about back pain, neck pain, and injury management. If you are looking for physiotherapists in Brighton visit his website.

Article Source: http://www.Free-Articles-Zone.com