Bethania Bacigalupe

My Right Elbow – Radioulnar joint anatomy

Elbow Joint Anatomy: The X-ray (Anterior View)

My right elbow doesn’t lie straight.

Or more accurately, my right arm doesn’t lie flat.

Or more pleasingly, there is something funky about my elbow.

The impetus

Today, as I lay in this marvelous savasana variation my lower body and low back felt great. I was super grounded into the floor in a state of serene ease… Sacrum bubbling. But about six minutes into savasana I realized that while the back of my left hand lies completely and comfortably on the floor, only the outer side of my right hand rests on the floor.

Woah.

I tried to supinate my forearm [definitions below] to let the back of my right hand rest on the floor, but nope, it wants to roll right back to its original position thank you. Place flat, roll back; place flat, roll back. Like those toys you give babies to knock down only to bob right back up again.

The history & the practice

Now, this isn’t surprising. I smashed my right elbow when I was a little kid. My smahed + dislocated elbow falls under “previous injury”. Long story, but the fact that it moves is a miracle. And I’ve had curious, intelligent teachers occasionally stare at my elbows in plank or down dog and puzzle over the alignment. My right elbow looks funny.

It’s something I work with during shoulder work (such as extending the arms in warrior two) and during handstand refinements.

I’m sure my elbow effects everything where my arms are weight-bearing. Inside, I pretend that it’s the reason arm balances are hard for me (even though it’s probably not). I haven’t worked out all the details in every posture. It’s on my list of future things to work out. But I get along just fine mostly.

Frankly, elbow anatomy has not been the most exciting thing calling my attention. I’m much more excited about kidneys and livers and spines. But when your arms in savasana are distinctly asymmetrical while your body feels grounded and amazing, then the laser focus goes on.

I actually had no idea what’s going on.

Snap Crackle Pop

Well, maybe a little idea.

When I get quiet and listen I can feel my right elbow clicks and clacks inside on moving. Snap crackle pop.

When I straighten my elbow and work with the orientation of my hands and the internal and external rotation of my shoulders my right arm resists symmetry. For example, externally rotating the shoulders and pronating the forearm to plant the index finger knuckle into the floor, as in downward facing dog or handstand, creates major resistance in my right arm. If I don’t pay attention, then the orientation of my right elbow, radius, and ulna will not match the left. Actually, if there is no floor to push against, then the asymmetry is much more distinct and the work in my right arm much more acute.

In sum, there is something funky about my elbow.

For starters, in savasana, while at rest, it tends to pronate.

An Elbow anatomy journey

So I went into my lovely collection of anatomy books to review and explore elbow joint anatomy.

At the top of the elbow joint you have the humerus. The forearm is composed of the radius and ulna.The primary action of the elbow is to flex and extend. Try bending (flexing) and straightening (extending) your left elbow. Now place your right hand around the elbow and try bending and extending the elbow again. Can you feel which bones are moving over each other? Or which muscles are engaged? (This is where I sense the snap crackle pop in my right elbow.)

There’s a lot going on here, but I have elected to focus today on the juncture where the radius and ulna meet. This is what I’ve sketched out. (And X-rayed out in the picture above.)

The head of the radius is a part of the radius near the elbow joint. This part of the bone is shaped like a squashed disc or cylinder. It’s covered in cartilage.

The flat part of the cylinder/disk is called the articular fovea. Its surface is depressed and receives the capitellum of the distal end of the humerus.

The surface of this cylinder’s rim (i.e. its circumference) sets into the radial notch of the ulna. This is known as the proximal radioulnar joint. (Note there is a also a distal radioulnar joint near the wrist, but I assume mine is as normal as normal is.) The anular ligament encircles the rim of the cylinder and and keeps the head and the notch in contact. The ligament is, crudely, like a rope or rubber band holding the radius to the ulna. In all, this setup is not unlike a pulley system. The head of the radius is the cylinder or wheel of the joint that rotates. The radial notch of the ulna is the surface the head slides in. The anular ligament holds the two together.

Thus the radius and ulna of the forearm slide over each other at the radioulnar joints. This enables the radius to cross the ulna in pronation, and return to a non-crossed position in supination [definitions below].

The drawing below is a study of the proximal radioulnar joint. It’s based on a couple of my anatomy books and my own experience with my elbow.

Note that the axis of rotation for supination/rotation (dotted line in picture) passes through the head of the radius. The axis runs down to the styloid process of the ulna by the wrist (not shown).

In the drawing, the fat, semi-circular double arrow shows the direction of movement (rotational about the axis) of the head of the radius on the radial notch of the ulna. The mini double arrow shows where these two surfaces connect when the radius and ulna are brought together.

Click the pictures for full image and comments.

Elbow Joint Anatomy: Sketch of Proximal Radioulnar joint (Anterior View)

Anatomy Definitions

Anatomical movements of hand / forearm:

Forearm: start with arms hanging by your sides, palms facing forward.

• Pronation: keep the upper arm and elbow where they are. Move the forearm so the palms face backward.
• Yoga Example: palms turn to floor in warrior two.
• Supination: turn the palms to face forward again, thumbs away from the body.
• Yoga Example: turn palms to sky in extended child’s pose.

Other of anatomical terms defined

• Proximal: closer to the body’s midline
• Distal: further away from the body’s midline

Let me know if you have any questions or feedback in the comments below.
Cheers!
-b

Related posts:

• Yoga Sutras: Santosha means Contentment
• Yoga Art: Grounding Study. Earth Center of Gravity. Center Line
• Boston New Years Yoga Classes and Events 2012

This entry was posted on Monday, February 20th, 2012 at 8:55 pm. It is filed under Anatomy, Sketches, Yoga, Yoga Art and tagged with Anatomy, Bones, Elbow, Injury, Joints, Radius, Sketches, Ulna. You can follow any responses to this entry through the RSS 2.0 feed.