BASIC ANATOMY PART II: UNDERSTANDING SIDEWAYS MOVEMENT
By Julie Gudmestad
Published in Yoga Journal
In Part 2 of our ongoing series on basic anatomical principles, learn what abduction and adduction are, when they occur, and when they should not.
On your mission to become a better yoga teacher, you may have begun the study of anatomy. Essential to the study of how the body moves in the poses, and how the muscles work to move the joints and support the bones, is the use of the language of movement. Just as Sanskrit beautifully and efficiently names the poses, the traditional anatomical terminology concisely describes movement.
For example, how would you describe the difference between your shoulder position in Plank Pose and the shoulder position of Virabhadrasana II (Warrior II Pose)? You could use a lot of words trying to describe these positions, or you could use anatomical language and simply say that in Plank, your shoulders are flexed to 90 degrees, and in Virabhadrasana II, your shoulders are abducted to 90 degrees.
Abduction vs. Adduction
As you may remember from my last column, in traditional anatomical language, all movement in the front-back, or Sagittal plane, is called either flexion or extension. So when you're standing with your arms by your sides and you bring one knee toward your chest, you're flexing your hip and knee. Bring your arm forward and up, and your shoulder is flexing. Bend your spine backward into a backbend, and your spine is extending.
On the other hand, when you bring your arm out to the side and up 90 degrees, as you do in Virabhadrasana II, your arm is moving in the side-to-side plane, which is called the frontal or coronal plane. If you're standing with your back against a wall, the wall is parallel to the frontal plane, which actually sits from ear to ear, shoulder to shoulder, hip to hip through the center of the body. Movements in this plane are called either abduction (moving away from the central midline of the body) or adduction (pulling back in toward the midline). Therefore, when you hold your arms up and out from your sides in Virabhadrasana II, Trikonasana (Triangle Pose), or Ardha Chandrasana (Half Moon Pose), they are at about 90 degrees of abduction. One of the few poses with weight bearing on an abducted arm is Vasisthasana (Side Plank Pose): Most of the weight bearing on the arms in yoga is done with the shoulders either in flexion, in poses like Bakasana (Crane Pose) or Adho Mukha Vrksasana (Handstand), or in extension, in Chaturanga Dandasana (Four-Limbed Staff Pose), Purvottanasana (Upward Plank Pose), or similar poses.
Involving the Hips
A lot of abduction and adduction also takes place at the hip joints in yoga poses. Applying our definition from above, when you squeeze your legs together toward the midline, you're adducting your hips. A classic example is Vrksasana (Tree Pose), when you keep the sole of your foot "glued" to your inner thigh by pressing the inner thigh and sole into each other. In inversions, you're also actively adducting your hips to keep your legs from separating due to the downward pull of gravity. The hip adductors, the large group of muscles in each inner thigh, perform the pull into adduction. If you lie flat on your back with your legs out straight, about a foot apart, you can feel the adductors contract as you slide your legs in and then squeeze them together.
However, you might be more aware of your adductors when you stretch them, as there are many poses with the hips in abduction, requiring the adductors to lengthen and stretch. The right hip is clearly in abduction in Supta Padangusthasana (Reclining Hand to Toe Pose), when you lie on your back, parallel to the wall, with your right leg opened out to the side, whether you're holding the big toe or resting the right foot on the wall. The right hip is in much the same position when you're standing in Utthita Hasta Padangusthasana (Standing Hand to Toe Pose), either holding the big toe or resting the foot on a ledge, and in Trikonasana (Triangle Pose) to the right (imagine you've tipped UHPadangusthasana 90 degrees to the right). A beautiful example of both hips abducted at the same time can be seen in Upavistha Konasana (Open Angle Pose) or in Sirsasana (Headstand), with both legs opening out to the sides, away from the midline.
What Works, What Doesn't
It's important to understand that not every joint in the body can or should adduct or abduct, and they can be injured if forced in those directions. In fact, there aren't many that do move in the frontal plane, with the short list including the hips, shoulders, and a few joints in the hands, feet, and wrists. You can understand finger abduction if you hang your arms by your sides, palms facing forward. Imagine a center line extending from the wrist through the palm to the tip of the middle finger: When you spread your thumb and fingers away from that center line, you're abducting the joints at the base of each finger. That's the hand position you use in Adho Mukha Svanasana (Downward-Facing Dog), and it's the same spreading action you need in your toes in most poses.
For your own safety and that of your students, give some thought to the joints that don't adduct and abduct. These include the elbow and most of the finger joints, although probably the most notable on this list is the knee, which can easily be injured by sideways force. You'd best keep this in mind next time you—or your students—are tempted to push a bit to get into Padmasana (Lotus Pose): the torn or strained ligaments that result from bending the knee to the side as you pull up on the foot are probably the most frequent knee injuries that occur in yoga.
BASIC ANATOMY PART II: UNDERSTANDING SIDEWAYS MOVEMENT