At the beginning of my career as a teacher, my knowledge of anatomy was non-existent. As if playing telephone, I picked up many of my teachers’ words. As my study of anatomy and related science has progressed, I’ve been forced to compare the language I heard and used with the established technical language related to the body.

As a yoga teacher trainer, I teach anatomical and movement science. They are often confused when comparing their old beliefs with the new information. Although I don’t find using anatomical terminology in our yoga classes necessary or helpful, we must do so accurately.

In addition to new motor skills and Sanskrit terminology, a student of yoga must also learn new words and pose names. They will also need to understand the language of human movement and anatomy. You have likely heard or used the following terms, whether you are a yoga teacher or student. They could use some clarification and demystification.

FLEXION/EXTENSION

You have likely been told to “Flex your fingers” or “Extend your biceps” to lengthen your limbs or engage your muscles. Instructing to flex or extend a muscle may have the desired result, but it is an incorrect use of anatomical terminology.

Joint positions are described by flexion and extension. The anatomical position of the joint is not the same as the extension you hear when your arms are extended overhead. Your shoulder joint (or glenohumeral joint) flexes when you extend your arms overhead. Your elbow joint flexes when you bend your arms. Extending your elbows and moving your arms backward are also forms of extension.

You could say that flexing the elbows involves a concentric contraction (they shorten) of your biceps and an eccentric contraction (they lengthen). This can lead to either muscle group being engaged. Straightening the elbows produces the opposite effect. You can also flex and extend your spine, hips, and knees, as well as your fingers, toes, and wrists.

SIT/SITTING/SITZ BONES

These are all common terms for the ischial tubes, which are bony protrusions at the bottom of the pelvis. They are attachment sites for muscles and your base of support while sitting. This is the point of reference for seated poses. You may have heard that “Root through your sit bones” would accurately describe it. The term “ischial tubes” is not the only acceptable alternative.

COMPRESSION

Compression is a mechanical force which occurs when an object or part of the body is pressed. This force is then dispersed throughout our bodies, which have many structures to cushion the force (i.e., intervertebral disks), and adaptations, such as thicker, denser bones, as we grow and evolve.

Our spines are increasingly compressed as we progress from lying down to crawling to sitting to standing. The lumbar vertebrae, for example, become much larger and denser than the thoracic or cervical spines, which are compressed less when we stand upright.

In classes, I hear the word compression used to suggest that it can cause damage. In bridge position, I was told to keep my legs parallel and hips rotating neutrally to avoid damaging or compressing my sacrum.

compresses thick bones, like the sacrum. As you read this article, your sacrum may be being compressed by the spine, which in turn is being compressed by your skull.

It can be a pleasure to suspend or hang the spine to “decompress,” but compression should not be feared unless you are doing it at a level that is beyond your tolerance. If you’ve been working on the strength necessary to handle this compression level, placing a 100-pound plate on your skull may be too much. It depends.

PSOAS/HIP FLEXORS

These two terms are often used interchangeably. Let’s look at each. Hip flexors consist of muscles that contract to produce hip flexion. The psoas is the only hip flexor. Other hip flexors include the iliacus (also known as the rectus muscle), sartorius (also known as the sartorius), and tensor facia lata. Different hip flexion angles will engage different muscle groups.

The psoas connects the lower spine with your innermost femur. Its main action is hip flexion. Your psoas will be shortened in poses such as warrior 1 (front legs), Chair pose and Boat pose. When your legs are extended, such as in crescent-lunge or Up Dog and upward-bow pose. The psoas lengthens. Our psoas may become weaker because we spend so much time sitting. Strengthening and stretching the psoas will help improve posture and mobility.

CONTRACT Vs. CONTRACT VS

Have you ever heard someone say “Contract Your Quadriceps” or “Engage Your Core”? “engage” and “contract” are also often used interchangeably. However, they are not the same. A muscle contraction is technically when the fibers of the muscle change in length. The muscle fibers can either shorten (concentric contract), lengthen or remain the same (isometric contract). It does not refer to the muscle’s activation or engagement level.

When I flex my arm, my biceps contract concentrically, and my triceps contract eccentrically. The active or passive muscles (engaged), depending on my arm’s position in space and resistance, will change.

SCAPULA PROTRACTION AND RETRACTION

The two movements that your shoulder blades can make are protraction and retraction. Scapular retraction is when your shoulder blades move toward your spine. When they move away from the spine, it’s called scapular protraction. Scapular retraction is often indicated by the instruction to “Move back your shoulders” or “Plug in your arm bones” When we are instructed to “Push away the floor” in quadruped positions or arm balances, this leads to scapular protraction. Both protraction and retraction are useful for mobilizing and strengthen. Protraction and retraction are also used elsewhere in the body. They occur about the position of the skull on the spine.