Everyone has at one time or another applied too much pressure to the "funny bone" in their elbow which is actually the ulnar nerve. This physical pressure disrupts the nerve's function causing pain, tingling, numbness or weakness from the elbow into the fingers of the hand. Too much pressure applied for too long to a nerve along the spinal results in much the same sensations. Where these sensations occur naturally depending upon the pathway of the specific involved nerve as illustrated above.
Nerve pain resulting from direct physical pressure is called an entrapment neuropathy because the nerve is trapped or pinched by some structure. This term helps to differentiate them from neuropathies resulting from infection or disease where the nerve pain is more often referred to as neuritis or neuralgia.
Radiculitis / Radiculopathy
These are not specific conditions, but rather describe a nerve that is being pinched at or very near the spinal cord at the beginning or '' root '' of the nerve. Radiculitis is from Latin radiculo for root plus itis for inflammation. Radiculopathy comes from the same Latin radiculo for root plus Greek pathos for suffering. There may be slight technical differences between the two words but in truth they are often used interchangeably without clear distinction.
In a radiculitis or radiculopathy the pinch is occurring at or near the root of the nerve along the spinal cord. The most common cause of this physical pressure is a herniated or protruding spinal intervertebral disc crushing the nerve against the bone resulting in pain at that level of the spinal in the neck or back, and of course, along the pathway of the adjacent nerve root itself resulting in arm pain or leg pain through a process called referred pain or radicular pain. For example, a nerve root impingement in the neck, or cervical spine, can produce pain, motor fatigue, or sensory paresthesia in the shoulder, arm or hand which is called brachial radiculitis from Latin brachio for arm or more simply a cervical radiculitis or cervical radiculopathy. Likewise, a nerve root impingement in the lower back or lumbar-sacral spine can be characterized with symptoms in the lower extremity, a lumbar radiculitis or lumbar radiculopathy. This can result in pain, weakness, numbness, or paresthesia in the butt, hip, leg or foot. This is often called sciatica, a reference to the nerve that is being pinched. Sciatica due to compression of one of the lumbar nerve roots is one of the most common forms of radiculopathy.
Neuritis / Neuralgia
Neuritis is from itis for inflammation and neuro for nerve. Neuralgia is from the Greek algos for pain and neuro for nerve. The difference between neuritis and neuralgia are again technical and these terms too are often used interchangeably. The most common cause of neuritis or neuralgia are generalized metabolic issues such as those that occur as a result of diabetes or alcoholism, and as such, the nerve dysfunction is generalized and widespread as opposed to being one specific nerve root such as in sciatica that is caused by direct physical pressure. Acute or chronic Poisoning most commonly by lead, arsenic, mercury, copper and phosphorus also results in widespread nerve dysfunction also correctly termed a neuritis or a neuralgia.