The reasons behind pain in the left arm are many ; starting from sprained muscles (as a result of excessive workouts , pressure or stretching of the arm muscles ) , pinched neck nerves (many times pain in the neck or a pinched nerve there can lead to pain in the upper left arm) , bicipital tendonitis (which is caused because of tearing of a tendon near the shoulder and is very painful) , heart problems (many times the first symptom of a heart problem is pain in the left arm ), angina , arthritis and poor posture (this can lead to muscular tension) etc.
When discussing reasons behind pain in the left arm, the first thing that comes to a persons mind is heart problems. As most of the other pain causing problems like poor blood circulation to the left arm , muscular strain or torn tendons etc are common for both the left as well as the right arm , but in case of heart and coronary ailments its only the left arm which tingles and causes pain. Although a serious indication towards myocardial infarction, the reasons behind pain in the left arm are mostly sprain , strain , neck nerve pinching , poor supply of blood to the arm of over stretched muscles of the arm.
One of the many reasons behind pain in the left arm is poor supply of blood to the arm. The main reason behind it is excessive muscular tension in several muscular areas like scalene muscles. The blood vessels that branch into the arm have to first pass through these areas via a particular artery known as the subclavian artery. Poor circulation of blood in the left arm can also be caused because of wrong positioning of wrong alignment of the shoulder as that puts stress on the blood vessels and thus prevents appropriate blood supply to the arm. It is one of the most common reasons behind pain in the left arm. And can be cured with the help of a chiropractor ( a person who helps cure biomechanical problems inside ones body). A pinched neck nerve is also a serious factor among reasons behind pain in the left arm as if it is not treated for some time , it can cause a long lasting damage.
Other reasons behind pain in the left arm are tendonitis, angina , migraine ( a severe kind of headache accompanied with a feeling of nausea) , . fibromyalgia or chronic fatigue syndrome , mini stroke (transient ischemic attack) , Reynaud’s disease ( a peculiar disease in which blood vessels responsible for circulation in the left arm get constricted and cause ones finger to turn white and numb because of lack of blood, Cervical nerve herniation (that can cause pain and numbness in the left arm) and carpel tunnel syndrome.
Migraine (hemiplegic migraine)
Stroke, Transient Ischemic Attack (mini-stroke)
Reynaud’s disease causes constriction of the blood vessels and usually your fingers get numb, turn whitish in color.
Repetitive Strain Injury, Carpal Tunnel Syndrome- Using a mouse or keyboard, or other tools, in the same position for an extended period of time can be harmful. Google ergonomics or Carpal Tunnel Syndrome.
Cervical Disc Herniation
Cervical Disc Herniation can cause tingling, arm numbness and pain. It might be helpful to see a Neurosurgeon. They may run MRI's, Myelograms etc.
There could be some reason for poor blood circulation to the arm / hand. This is very commonly caused by too much muscle tension in the scalene muscles or the pec minor muscles. The blood vessels that supply the arm/hand have to pass through these areas, via the subclavian artery, to branch off into the arm. It could also be due to a misalignment of the shoulder. If a shoulder is misaligned in external rotation, it can put a stretch on the blood vessels that pass through that area to supply the arm/hand. In any case, a chiropractor is the professional to seek to correct any biomechanical problems within the body. Chiropractic adjustments can also have a valuable effect on the autonomic system, which affects the cardiovascular system. Apart from Chiropractor adjustments, one can even go for massage to ease the pain the left arm.