White blood cells, known as leukocytes, are mainly produced in the bone marrow and are involved in protecting us against infection.

If the average heart rate is 75 beats per minute, a human heart would beat approximately 108,000 times in one day, more than 39 million times in one year, and nearly 3 billion times during a 75-year lifespan.

The lymph does not have a pump like the heart to help keep it circulating, although the presence of one-way valves within the lymph vessels do prevent back flow of lymph.

The sacroiliac (SI) joint is the largest axial joint in the body and is formed by the crescent-shaped articulation between the medial surface of the ilium and the lateral surface of the sacrum.

The lumbar spine is typically comprised of five vertebrae that lie between the pelvis and the ribcage.