Tuberculosis or TB (short for tubercles bacillus) is a common and often deadly infectious disease caused by various strains of mycobacteria, usually Mycobacterium tuberculosis in humans. Tuberculosis usually attacks the lungs but can also affect other parts of the body.

Atelectasis is defined as the lack of gas exchange within alveoli, due to alveolar collapse or fluid consolidation. It may affect part or all of one lung. It is a condition where the alveoli are deflated, as distinct from pulmonary consolidation.

A retrolisthesis is a posterior displacement of one vertebral body with respect to the adjacent vertebrae to a degree less than a luxation (dislocation). Clinically speaking, retrolisthesis is the opposite of spondylolisthesis (anterior displacement of one vertebral body on the subjacent vertebral body). In the past this clinical pathology was also called a "retrospondylolisthesis". (2) Retrolistheses are most easily diagnosed on lateral x-ray views of the spine. Views, where care has been taken to expose for a true lateral view without any rotation, offer the best diagnostic quality.

Spondylolisthesis describes the anterior displacement of a vertebra or the vertebral column in relation to the vertebrae below. It was first described in 1782 by Belgian obstetrician, Dr. Herbinaux. He reported a bony prominence anterior to the sacrum that obstructed the vagina of a small number of patients. The term “spondylolisthesis” was coined in 1854, from the Greek “spondyl” for vertebrae and “olisthesis” for slip. The variant "listhesis" is sometimes applied in conjunction with scoliosis. These "slips" occur most commonly in the lumbar spine.

X-ray picture of a grade 1 isthmic spondylolisthesis at L4-5