Many books have been written about yoga anatomy and I’ve co-authored a book about yoga physiology. But what actually is the difference between anatomy and physiology? While we’re defining things, let’s also look at biomechanics and pathology.
What is Anatomy?
Coming from Greek and meaning “cut up,” anatomy refers to the study of the body’s structures and parts. Anatomy describes what goes where. The term “cutting up” is very appropriate because in anatomical studies, we figuratively “cut out” a structure to give it a name and description. For example, to describe the biceps muscle, we separate it from the rest of the body, removing the tendons from the bone and say, “Look, this is your biceps — or more correctly, your biceps brachii.” (Side note: we say brachii because that refers to the arms. We have another biceps muscle — the biceps femoris — which is one of your three hamstrings!)
Looking at individual parts of the body has its obvious downside. Your body is a single interwoven, interconnected organism, more than just the sum of its individual parts. However, studying and naming the parts of the body is absolutely essential to being able to have a coherent discussion about what structures do what.
What is physiology?
Once you know the names of parts, the next logical pursuit is to know what they do and how. That’s what physiology is. Meaning "study of nature" in Ancient Greek, physiology is the study of the functions and mechanisms in a living system. It answers the question of how things work in the body. To give an example, the study of anatomy tells us the names of the respiratory structures, such as the trachea (windpipe), the right lung, and the left lung.
The study of physiology, however, explores how the lungs exchange oxygen and carbon dioxide. Often, physiology employs biochemistry to understand what is happening on a cellular and molecular level.
What is biomechanics?
Another buzzword around yoga circles is biomechanics. Biomechanics is the study of the mechanical aspects of biological systems, specifically forces created by and acting on the body. Though alignment in a yoga pose affects joint biomechanics, alignment and biomechanics are not the same thing and are not interchangeable terms.
Biomechanics is not the same thing as looking at a yoga pose and thinking that it looks right or wrong. Proper biomechanical studies use complex mathematical models to analyze the forces, torques, and stresses that act on biological systems. Such models can be particularly useful in improving athletic performance by, for example, improving the shape of a javelin to make it travel further or by designing a running shoe that stores elastic energy.
What is pathology?
Finally, coming from the Greek pathos which means suffering, pathology is the study of the causes and effects of disease and injury. Though it is useful to be aware of some common injuries and medical conditions, yoga teachers are not doctors and cannot be expected to understand every medical condition that exists.
Anatomy - the study of the body’s structure and parts.
Physiology - the study of the functions and mechanisms in a living system.
Biomechanics - the study of the mechanical aspects of biological systems, specifically forces created by and acting on the body.
Pathology - the study of the causes and effects of disease and injury.
Understanding these basic terms is an essential element of applying anatomy and physiology to yoga, and it's the first thing I teach whenever I lead the anatomy component of a yoga teacher training.