Low Back Pain?
It is important to understand that low back pain is not a distinct medical condition but a symptom caused by numerous medical illnesses and conditions. When arising from the musculoskeletal system (bones, joints, ligaments and muscles) the causes are still many, including slipped disc, facet joint syndrome, osteoarthritis, fibromyalgia, to name only a few. The cause may even be distant from the back, for example the mechanical effect of pes planus (flat feet) or a length discrepancy between one leg and the other. Consequently, the treatment of back pain may vary considerably. Back pain is mentioned in conjunction with some of the medical conditions described below.

Slipped Disc?
This condition, known properly as a prolapsed intervertebral disc, affects adults between the ages of 30 to 50 approximately. Between the bones of the spine (the vertebrae) are discs which act as shock absorbers. They are made of a hard fibrous outer shell, with a fluid centre the consistency of toothpaste. If the fibrous shell becomes damaged or cracked, the inner fluid leaks out to produce the symptoms. Although a disc in any part of the spine can prolapse (leak, or slip), commonly a low back disc is involved. The subject may go to bed at night with no problem and wake up with back pain which renders him unable to move, and is worse on coughing. Usually, after time (hours or days) the pain shifts to one or both sides of the low back and begins to radiate down the leg or legs (sciatica). This implies that the leaking central disc fluid has now leaked to one or both sides of the spine, and is irritating the nerve roots as they exit from the sides of the spine.
Sometimes, although the disc repairs itself and the leaked fluid reabsorbs, the nerve root remains irritated and the sciatica continues.

Facet Joint Syndrome?
This syndrome is often confused with a slipped disc (above) as a cause of low back pain and, indeed, has some features in common. The facet joints are situated at the back of each vertebra (spinal bone) and there are two to each bone. They represent the joints where each vertebra sits on top of the vertebra below at the very back of the spine.
Typically a facet joint syndrome comes on suddenly after or during heavy lifting, or and awkward twist. The subject then finds he/she is unable to straighten up, and the severe pain may persist for days and prevent almost any movement of the back. Although it is also possible to damage a disc is this way (see Slipped Disc, above) the pain in this scenario is usually arising from the fact that one or more facet joints have become misaligned, or jerked out of place. Muscle spasm of the surrounding area contributes further to the pain.
Although most cases of facet joint syndrome settle within weeks, recovery is aided by relatively simple manipulation (see Treatment section). Advice on prevention should also be sought.

Facet Joint or Vertebral Dysfunction?
In some ways this is similar to Facet Joint Syndrome mentioned above, but has a subtle onset. Whether caused by awkward posture, muscle strain or imbalance, injury, or unknown cause, the joints at the back of the spine become misaligned, or simply do not function smoothly. This can occur in any part of the spine - in the neck, upper back or low back - and the pain can be severe and widespread, being mistaken for problems in other organs (such as a heart attack or kidney infection). Treatment of this condition usually takes the form of simple Manipulation. Trigger Point Acupuncture may also relieve this condition, either as the sole treatment or in addition. Advice on posture, and muscle balancing or strengthening exercises will usually help prevent recurrence.

Fibromyalgia and Myofascial Pain?
There is differing opinion about the exact cause of these conditions. Sometimes they appear to arise from the muscles of the body wall or "body shell", and sometimes secondary to problems in the facet joints (see above). Whichever the cause, the sufferer feels chronic muscle pain which can be debilitating enough to prevent movement, especially when rising in the morning. Often the sufferer cannot go to work until after taking painkillers and/or time-consuming muscle stretching exercises.
In Fibromyalgia, numerous points within the muscles are found to be overactive and become painful "trigger" points arranged in a symmetrical pattern. There is often an accompanying sleep disturbance.
Myofascial Pain usually refers to one (non-symmetrical) region of the body and may follow trauma.
These condition shave, in the past, gone by other names ("Fibrositis" for example) before being thought of as a Chronic Pain Syndrome. Treatment may include specific medications, specific exercises, or "desensitization" of the individual trigger point by acupuncture/stimulation or by injecting them with specific chemical substances.

The above is a brief description of some conditions affecting the spine and trunk. Most musculoskeletal conditions, however, affect the limbs.

A general explanation about musculoskeletal conditions will now be given according to which body structures can be affected.

Joints?
Joints are the junctions between bones, which allow differing ranges of movement. Some joints are relatively small (as in fingers and toes) while others are large and complex (as with hips, knees, shoulders). The moving surfaces of the joints are covered in cartilage, and the whole joint is usually sealed by a membrane known as the "joint capsule". Many conditions and diseases can affect the joint complex. The capsule can become inflamed for no apparent reason (Capsulitis), as in the condition known as "Frozen" Shoulder. The joint surfaces can become worn (Osteoarthritis), or become infected or inflamed (other types of Arthritis), or simply be temporarily misaligned. Treatment will obviously vary from simple manipulation to more "invasive" techniques, such as intra-capsular injections, according to the type of condition and its severity.

Muscle and Tendons?
Muscles consist of bundles of soft tissue cells, which are capable of contracting in order to pull and move the body parts. They are attached to the bony skeleton by means of tendons. Various conditions can affect the muscle and tendon, anywhere from deep within the "belly" of the muscle along to where the tendon attaches to the bone. Those conditions may be the result of strain, compression, and other physical effects, or the result of infection, inflammation, diseases and disorders, perhaps arising outside of the muscles and tendons themselves. The conditions may arise quickly and suddenly, or slowly over time. Treatment obviously depends upon the underlying problem.

Ligaments?
Ligaments are fibrous bands which run across, or sometimes within, joints, contributing to their stability and correct alignment during movement. They may become lax, or be damaged by a tear or sprain, or become inflamed and irritated. Because the blood supply to ligaments is limited, ligament problems can heal slowly. While major damage to a ligament may require surgery, less severe conditions may be alleviated by other treatments such as prolotherapy, infiltration with various chemical substances or some physical treatments. Ligaments may also become damaged because of incorrect posture, abnormal mechanics, or incorrect use of muscles, in which case the underlying cause must be addressed in addition to the direct treatment of the ligament.

Bursae?
Bursae are essentially the friction pads of the body. They are fluid-filled sacs or openings between or within the layers of moving parts. Thus they are situated where one structure is moving over another, as between two layers of muscles, between tendon and bone, under ligaments etc. When a bursa becomes inflamed, the resulting condition called "bursitis" can be extremely painful. A bursitis may be seen as an obviously red and tender swelling on the surface, as at the elbow, or it may be hidden in deeper layers such as within the buttock, or in the groin or hip. Treatment consists of some means of reducing the swelling and prevention of further inflammation.