Based on the mechanisms that trigger pain, it can be

classified according to its origin or neurophysiological nature as pain

nociceptive, neuropathic, and psychogenic.

Nociceptive pain is caused by persistent stimulation or sensitization.

of nociceptors or afferent pathways, being divided into nociceptive pain

somatic and visceral.

Somatic nociceptive pain is pain in cutaneous and deep tissues. It is pain

A sensation felt when the person twists their ankle, burns their finger, or fractures a bone. Very

linked to the musculoskeletal system. It can be a localized pain, having been

manifested in the place where it is felt or referred to.

Referred pain manifests itself distant from the site of the stimulus and can be explained by the theory of metameric organization of mammalian organisms, where each transverse segment of the body, called a metamere, comprises a portion of skin (dermatome), bone (sclerotome), muscle (myotome), and viscera (viscerotome). These segments receive innervation originating from the same spinal segment. To exemplify this theory, one can cite various pains of visceral origin, such as myocardial infarction, which is referred pain in the arm and hand.

Visceral nociceptive pain is pain felt when the affected organs are the thoracic, abdominal, and pelvic viscera. It is a deep, diffuse, poorly localized pain, and can often be felt in other parts of the body, as happens in pancreatic cancer, which can commonly be initially interpreted as simple back pain, or even in other visceral problems such as compression of the mesenteric artery of the intestines, which will reflect back pain.

Neuropathic pain results from disease or injury to nerve tissue. It is a lesion occurring in the sensory pathways of the central and peripheral nervous systems, which can occur due to irritation of C fibers. It is usually a radiating pain, causing a burning sensation, tingling, heaviness, stinging, and is also described as sharp and shock-like, and may be accompanied by tingling or numbness. Radiating pain manifests along a nerve pathway, such as the pain felt in sciatica. Other examples of radiating pain are the pain present in carpal tunnel syndrome and trigeminal neuralgia, herpes zoster, and post-stroke pain.

Pain can also be classified as mixed, which is pain that presents somatic and neuropathic nociceptive components, this being the most common of all. There is also psychogenic pain, which does not have an apparent organic cause and is rare in nature, being associated with emotional factors, and projected pain, which includes phantom pain, where the patient feels pain in a part of the body that has been amputated.