Vertebral subluxation is a term that is commonly used by some chiropractors (specifically, "straight chiropractors") to describe signs and symptoms

Syndrome

In medicine and psychology, a syndrome is the association of several clinically recognizable features, signs , symptoms , phenomena or characteristics that often occur together, so that the presence of one or more features alerts the physician to the possible presence of the others...

 of the spinal column. Those chiropractors who assert this concept also add a visceral component to the definition. Chiropractors maintain that a vertebral subluxation complex is a dysfunctional biomechanical spinal segment (lesion

Lesion

A lesion is any abnormality in the tissue of an organism , usually caused by disease or trauma. Lesion is derived from the Latin word laesio which means injury.- Types :...

) the same as medical doctors do, but additionally assert that the dysfunction actively alters neurological function, which in turn, is believed to lead to neuromusculoskeletal and visceral disorders.