The whole upper limb is sub-classified into three distinct anatomical regions:
- the region between the shoulder and the elbow is referred to as the upper arm,
- the region between the elbow and the wrist is referred to as the forearm, and
- the region between the wrist and the finger tips is referred to as the hand.
The upper arm is made of many different structures. These include bone, muscles, tendons, blood vessels, nerves, connective tissue and skin. Whenever there is pain in the upper arm, the first suspects are usually the bone and the muscles that are a part of this region. A single bone, called the humerus, forms the core structure of the upper arm.
The upper region of the humerus is a part of the shoulder joint, and the lower region of the humerus is a part of the elbow joint. Four different muscle groups lie in the upper arm. These include: biceps brachii, triceps brachii, brachialis, and coracobrachialis. However, most people are familiar with only the biceps and the triceps.
Read more on forearm pain.
Reasons for Upper Arm Pain
Pain in the upper arms could arise due to many different reasons. Usually, it is not a cause for concern because we attribute pain in this region to minor aberrations that are self-resolving. For example, upper arm pain that is preceded by intense upper arm activity, is usually attributed to muscular strain and fatigue. Understandably with the arms being one of the most active appendages of the body, this type of strain and fatigue is not uncommn and also not serious.
If there is upper arm pain after we get up from sleep in the morning, we may attribute it to our faulty or awkward sleeping position that resulted in excessive pressure on the arm. However, it would be a mistake to think that all upper arm pain is benign in nature, or involves only the anatomical structures of the arms. Upper arm pain could arise due to serious problems in other regions such as the heart. It could be a warning sign of a potentially life-threatening condition.
Causes of Upper Arm Pain
Injury or trauma to the structures that constitute the upper arm is one of the most common cause of pain in this region. The trauma could be physical or chemical in nature. Examples of physical trauma include sports injuries, motor accidents, falls, violent assaults, industrial accidents, and even strenuous activities. Burns caused by corrosive chemical substances like acid is an example of chemical trauma.
Injuries can be described as affecting either the superficial structures or the deep structures of the upper arm. Superficial trauma is restricted to the skin and the subcutaneous tissues. Deeper trauma affects the bone and the muscles. Some injuries (for example, motor vehicle accidents) could result in trauma to both superficial and deep structures in the arms. Trauma may also be responsible for some of the causes of upper arm pain described next.
Muscle and tendon problems
Muscle and tendon problems could result from either trauma or overuse. Overuse of upper arm muscles in certain strenuous physical activities like sports or weight training is one of the most common causes of upper arm pain. It is also one of the least worrisome, since it resolves upon resting. Muscle cramps are another reason for upper arm pain. These are intensely painful involuntary contractions of muscles, which usually follow intense activity and dehydration.
In comparison to the dull pain that follows muscle overuse, the pain caused by muscular cramps or spasms is very intense. In addition, physical trauma could lead to muscle and tendon injuries that are quite painful. Examples include muscle tears and tendon ruptures. Inflammation of tendons, referred to as tendonitis, also causes pain. In some cases, the pain may not arise due to problems with muscles and tendons in the upper arm, but can be caused by injuries to muscles and tendons in the shoulder region. For example, shoulder pain originating in the rotator cuff muscles of the shoulder joint may also radiate down the upper arm.
Bone and joint problems
A number of bone and joint conditions can cause pain in the upper arms. Fracture of the bone is one of the most obvious suspects of intense upper arm pain, especially after a physical trauma event. Loss of bone structure in conditions such as osteoporosis and osteomalacia cause brittle and soft bones that can be painful. The weak bones in these conditions are highly susceptible to fracture, even with application of mild force.
Infection and inflammation of bone, like in osteomyelitis, is also a cause for deep pain in the upper arm. Joint disorders and dislocations that affect the elbow and shoulder joints could also cause pain in the upper arms. Apart from dislocations, arthritic conditions such as osteoarthritis, rheumatoid arthritis, septic arthritis, and post-traumatic arthritis can result in upper arm pain.
The nerves of the arm arise from the brachial plexus, which is a nerve network formed by the anterior branches of the cervical (C5, C6, C7, C8) and thoracic nerves (T1). Pain in the upper arm can be caused by problems arising anywhere along the path of the nerves that traverse the upper arm.
For example, problems in the vertebrae and the brachial plexus can cause pain in the upper arm, even though the primary cause is not present in the arm. Nerve problems may also arise due to inflammation (peripheral neuropathy), compression (pinched nerve, cubital tunnel syndrome), autoimmune disorders, diabetes, infections, nerve injuries, and some drugs.
Circulatory problems in the upper arm can also cause pain. Interruption of blood supply through the arteries that supply the tissues of the upper arm cause oxygen deprivation and ischemia. Restricted blood supply may be caused by blood clots in the arteries, thickening of walls of blood vessels due to build up of fatty plaques (atherosclerosis), infections, cancers and autoimmune diseases. Apart from circulatory problems in the upper arm, ischemia in the heart muscle (heart attack) can also cause pain that radiates down the left arm.
Other causes of pain in the upper arms include:
- angina pectoris
- acid reflux
- polymyalgia rheumatica