Final answer:
The erector spinae group, which includes the iliocostalis, longissimus, and spinalis muscles and serves as the primary extensor of the vertebral column, is most likely to hypertrophy in patients with spondylolisthesis or spondylolysis.
Step-by-step explanation:
The question pertains to which muscle tends to hypertrophy when a patient has spondylolisthesis or spondylolysis. These conditions can cause changes in the muscular system of the lower back due to the instability or stress on the vertebral column. The erector spinae group forms the majority of the muscle mass of the back and is the primary extensor of the vertebral column.
Among the muscles provided as options, the erector spinae, which aids in flexion, lateral flexion, and rotation of the vertebral column, and maintains the lumbar curve, is most likely to hypertrophy. This grouping includes the iliocostalis, longissimus, and spinalis muscles. In contrast, the quadratus lumborum, while forming the posterior abdominal wall and playing a significant role in stabilizing the body and maintaining posture, is not identified as the muscle group most associated with hypertrophy due to these specific spinal conditions.