PATCH UP THINE OLD BODY FOR HEAVEN.
—DOLL TEARSHEET, IN KING HENRY IV, PART 2, BY WILLIAM SHAKESPEARE
MANY STUDENTS COME to asana class having never stood on their hands, and it is a revelation when they learn to do it. For others, standing upside down on the hands or forearms is empowering and fun, recreating the freedom of childhood. But the forearms, wrists, and hands need special attention when they are used for weight bearing in order to protect against injury. Begin cultivating that attention now by learning more about the structures of the area.
BONES
The elbow joint is made up of the humerus (discussed in chapter 13), the ulna, and the radius (Figures 14.1 and 14.2). The ulna is located on the medial side of the forearm. At its proximal posterior end, it forms a point called the olecranon process, which can be felt on the skin as the point of the elbow. When the elbow joint is extended, the curved olecranon glides into the olecranon fossa of the posterior humerus bone.
On the anterior proximal end of the ulna is the coronoid process, which articulates with the coronoid fossa of the anterior humerus on flexion of the elbow joint.
Between the olecranon process and the coronoid process is the trochlear fossa, which is the site of the articulation with the trochlea of the humerus on extension of the joint.
The ulna has a long shaft. At the distal end of the bone are two eminences. The lateral one is termed the head of the ulna, even though it is at the distal end; it articulates with the ulnar notch of the radius. The distal end of the ulna does not articulate directly with the wrist but rather with a fibrocartilage disc that separates it from the carpal bones. The medial eminence is the styloid process.
The radius is so called because during pronation it radiates over the ulna. Regardless of the position of the forearm, the radius bone is on the thumb side. The radius at its proximal end articulates with the capitulum of the humerus at its structure called the circular head of the radius.
14.1 ELBOW JOINT, ANTERIOR VIEW
14.2 ELBOW JOINT, POSTERIOR VIEW
Just below this structure is the neck of the radius, and below that on the medial side is the radial tuberosity, a roughened surface for the attachment of the biceps brachii muscle. On the anterior side is a bursa that pads the tendon of the biceps from the bone.
The distal end of the radius has two articular surfaces. The articular surface on the medial side articulates with the ulna. The other articular surface is on the underside or distal surface of the radius. It serves to articulate with two carpals: the lunate and the scaphoid. The lateral surface of the distal radius is elongated into a prominent process called the styloid process. The process limits radial deviation on the lateral side.
The ulna and the radius are held in place in part by a specific connective tissue called the interosseous membrane. For more information, see the Connective Tissue section in this chapter.
To understand the effect the radial styloid process has on movement at the wrist, try this. Place your palm up, about 18 inches from your face, with a slightly abducted shoulder joint. Now flex your wrist, bringing it toward your face. Notice how the medial or ulnar side flexes more, and the radial (thumb) side is able to flex less. This is because the radial styloid process is long and interferes with flexion on the thumb side.
Start in the same position, and attempt radial deviation. This is the movement of trying to bring your thumb toward the radius. Next try the movement in the other direction, toward the ulna. Note how much more freedom there is in ulnar deviation. Again, radial deviation is limited by the length of the radial styloid process.
JOINTS
The elbow joint is actually made up of three different joints. These are the ulnar-humeral, the radio-humeral, and the radio-ulnar joints. The ulnar-humeral joint is a hinge joint, and thus only flexion and extension occur there (Figure 14.3). Because of joint structure, no lateral movement of any kind is allowed at that joint.
14.3 ULNAR-HUMERAL JOINT
14.4A RADIO-HUMERAL JOINT
The radio-humeral joint is a gliding joint and very shallow (Figure 14.4a). The joint is held in place by an annular ligament (see Connective Tissue in this chapter). Flexion and extension occur at this joint as well. Flexion is limited at this joint by surrounding soft tissue. However, pronation and supination are free, in part because in these motions the joint surfaces have deep congruence. In other words, a large portion of the joint surfaces of the radius and humerus are fitted together in pronation and supination, thus contributing to the stability of this joint during movement.
The radio-ulnar joint is a pivot joint that allows the radius to radiate, or pivot, over the ulna (Figure 14.4b). The head of the radius is held by the annular ligament against the radial notch on the lateral ulna. This is the point where the radius rotates over the ulna during pronation and supination.
CONNECTIVE TISSUE
Two of the most important ligaments of the elbow joint are the radial and ulnar collateral ligaments. They support the connection of the radius to the humerus and the ulna to the humerus, respectively. The elbow capsule originates around the distal humerus and attaches around the proximal ulna. The annular and collateral ligaments help to reinforce the capsule.
14.4B RADIO-ULNAR JOINT
The annular ligament connects the head of the radius to the radial notch of the ulna on the lateral proximal ulna and serves to prevent the separation of the radius and the humerus in a lateral direction. The interosseus membrane connects nearly the entire line of the ulnar and radial shaft by broad flat fibers. Its fibers are oblique and downward from the radius to the ulna. Not only does this membrane connect the bones; it also allows for the attachment of deep muscles.
For a detailed discussion of the additional ligaments of this area, please consult Gray’s Anatomy.
NERVES
The nerves of the elbow and forearm are the median, the musculocutaneous, the ulnar, and the radial nerves. The elbow joint proper is innervated by small branches from the ulnar, median, and musculocutaneous nerves. Figure 14.5 illustrates the paths these nerves take down the arm, forearm, and into the hand. Of special note at the elbow joint is the ulnar nerve. This nerve passes distally down the medial side of the arm. As it passes the elbow area, it is found in the groove between the olecranon and the medial epicondyle of the humerus. Because it is very near the surface here, with only a skin and fascial covering, the exposed nerve itself is occasionally hit—what we call hitting the funny bone.
MUSCLES
The muscles of the arm and forearm are a complex group of muscles. The entire first group, which are the superficial flexors, arise from the medial epicondyle of the humerus by a common tendon (Figures 14.6 and 14.7). These muscles on the medial surface of the forearm can be thought of as the flexors of the wrist and hand. Asana and adjustments that require flexion of the wrist require a strong group of flexor muscles. The next group of muscles is deep to the previous one but is still in the flexor group (Figures 14.8 and 14.9).
On the posterior side of the forearm is another group of forearm muscles. The superficial group originates from the lateral supracondylar ridge of the humerus and is part of the extensor group of muscles of the forearm (Figures 14.10 and 14.11). The final and deep group of extensors is listed in Figures 14.12 and 14.13.
KINESIOLOGY
One of the most common positional faults of the elbow joint can become apparent when students take up the practice of yoga asana. It is called hyperextension of the elbow, and it refers specifically to the relationship between the humerus and the ulna on extension of the joint. Normally this angle is approximately 180 degrees. Hyperextension occurs when the elbow is extended past this angle (Figure 14.14). It is created in large part by ligament laxity, and it is unlikely to change.
14.5 (RIGHT) PATH OF THE MEDIAN, MUSCULOCUTANEOUS, ULNAR, AND RADIAL NERVES OF THE RIGHT ELBOW
14.6 (FAR RIGHT) SUPERFICIAL FLEXORS OF THE RIGHT ELBOW JOINT
14.7 SUPERFICIAL FLEXORS OF THE ELBOW JOINT
Another positional fault that can occur at the elbow joint is caused by the relationship of the ulna and the humerus and is called the carrying angle (Figure 14.15). The carrying angle has to do with the way the ulna is carried, or attached, to the humerus. It is more common in women.
The carrying angle can be observed when you flex your shoulders to 90 degrees, supinate your forearms, and place your fifth fingers together. There should be a straight line from the inner shoulder joint running distally to the medial wrist. If the elbows are inside this line or even touch during full extension of the elbow joint, then a carrying angle is present. An increased carrying angle can contribute to the instability of the elbow joint and is frequently found in conjunction with hyperextension.
Another structural aspect of the elbow joint is important to understand in order to prevent injury. In flexion of the elbow joint, the head of the radius is kept down in the radio-humeral joint by the healthy restriction of the annular ligament. During flexion and pronation at the radio-humeral joint, the radius is being pulled upward by the biceps brachii. If you add to this strain by simultaneously lifting something heavy, it is possible to overstretch the annular ligament as the head of the radius moves up against it. Make sure that, when you make adjustments with students and when you carry props, you are careful not to strain this ligament in positions of pronation and flexion.
14.8 (RIGHT) DEEP FLEXORS OF THE RIGHT ELBOW JOINT
14.10 (FAR RIGHT) SUPERFICIAL EXTENSORS OF THE RIGHT ELBOW JOINT
14.9 DEEP FLEXORS OF THE ELBOW JOINT
14.11 SUPERFICIAL EXTENSORS OF THE ELBOW JOINT
14.12 DEEP EXTENSORS OF THE RIGHT ELBOW JOINT
14.13 DEEP EXTENSORS OF THE ELBOW JOINT
14.14 (ABOVE) HYPEREXTENDED ELBOW
14.15 (RIGHT) CARRYING ANGLE OF THE ELBOW
ESSENTIAL EXPERIENTIAL ANATOMY
For Practicing
14.16 ADHO MUKHA SVANASANA
Applied Practice 1: Observing the Relationship of Hand and Elbow Position in Adho Mukha Svanasana
Prop: 1 nonskid mat
Take Care: Do not proceed if this pose causes discomfort in the elbow joints. KNEEL ON your nonskid mat and, with an exhalation, lift up into Adho Mukha Svanasana (Figure 14.16). Place your hands so that your middle fingers point forward in the pose—in other words, your middle fingers are parallel to the edge of your mat. Now turn your fingers inward, and note the effect on the shoulder joints. Finally, try the pose with your fingers turning out.
Pay attention to the parallel relationship between the hands and shoulder joints. As your hands turn inward, so do the shoulder joints; as your hands turn outward, the shoulder joints rotate externally. This connection can be used to improve your shoulder function as well as to ameliorate pain in the elbows in the pose. By turning your hands outward in the pose, you can help to reduce the possibility of increasing hyperextension in the elbow joint.
Applied Practice 2: Observing the Position of the Elbow in Urdhva Dhanurasana
Prop: 1 nonskid mat
Take Care: Do not practice this pose during menstruation, after the first trimester of pregnancy, or if it causes lower back pain.
14.17 URDHVA DHANURASANA
LIE ON your back on your nonskid mat. Bend your elbows, and place your hands on the mat so they are slightly wider than your shoulder joints (Figure 14.17). Turn your fingers about one-third of the way out. Make sure your elbows are held in. Often students place their hands close to the body, and then their elbows drop out. This decreases the power at the elbow joint as the elbow joints extend, because the triceps are no longer able to contract in the plane in which they lie when the elbows are not over the hands. Better to practice with the hands wider and the elbows narrower, rather than the opposite.
Now bend your knees, placing your feet next to your hips, with your feet turned inward. As you exhale, bring your lower back toward the floor and hold it there. With the next exhalation, push with your hands to move your pelvis in a diagonal direction up and out over your feet, and come up into the pose. Keep your breath even. Press your hands into the floor and, while not moving them, imagine that you are turning them out more, as if you were screwing them into the floor. This action of externally rotating the upper extremities with the hands fixed will help the scapula become fixed to the rib cage in such a way as to create more stability in the shoulder joint. Hold for up to 7 breaths and then come down. Repeat and experiment with the degree to which you turn your hands out.
14.18 SALAMBA SIR SASANA, LATERAL VIEW
Applied Practice 3: Elbow Position in Salamba Sirsasana
Prop: 1 nonskid mat
Take Care: Do not practice this preparatory pose during menstruation or after the first trimester of pregnancy.
FOLD YOUR NONSKID MAT into fourths, and place it on a level surface. Get down on your hands and knees and prepare to place your arms down for Salamba Sirsasana (Figure 14.18), but do it in this very particular way. First place your right elbow on the mat, with your forearm perpendicular to the edge of the mat and your palm pointing toward the ceiling. Once you have placed you elbow on the mat, press down firmly and roll outward on this elbow. You will feel the skin and flesh around the elbow joint move. Do this same procedure with your left elbow.
Now keep your palms facing toward you (supination) and carefully lay your forearms down on the mat, so the tips of your fifth fingers touch and the forearms create a triangular shape. Again press firmly outward with your forearms, so you are resting fully along the shaft of the ulna. Now begin to pronate your forearms, so your thumbs point upward. Interlock your fingers, so your fifth fingers are not completely meshed at the base. This will help you keep your wrists perpendicular in the pose. Remember, the key bone is the distal radius; this is the focal point of awareness when you place your head into your hands for Salamba Sirsasana. This is the key bone to press against the head to keep the forearms active in the pose.
For Teaching
14.19 TADASANA, ABDUCT THE UPPER EXTREMITY AND EXTEND THE ELBOW, WITH THE PALMS FACING UPWARD
Applied Teaching 1: Observing Hyperextension and the Carrying Angle of the Elbow Joint
Prop: 1 nonskid mat
Take Care: Do not force the elbow joint into hyperextension.
TO OBSERVE the degree of hyperextension, if any, ask your student to perform the following. Have him abduct his upper extremity and extend the elbow fully with the palm facing upward (Figure 14.19). Now note the degree of extension. If past 180 degrees, hyperextension is present. This condition is more common in women.
What hyperextension means to asana practice is that, because of the relationship of the bones in hyperextension, the joint is a little more unstable. With hyperextension, the soft tissue and joint structure is allowing the bones to move past the point of maximum congruence on extension. When the joint surfaces are in maximum congruence, stability at the joint is also maximized. To create more elbow stability in Adho Mukha Vrksasana (Figure 14.20), ask your student to bend his elbows slightly to recreate a position of greater congruence.
14.20 ADHO MUKHA VRKSASANA
Applied Teaching 2: Observing and Improving Hyperextension in Adho Mukha Vrksasana
Props: 1 nonskid mat • a wall
Take Care: Avoid this pose during menstruation, pregnancy, and up to three months postpartum.
AS A TEACHER, you may know that students with hyperextended elbows have more difficulty with poses in which the elbow is bearing weight, such as Adho Mukha Vrksasana (Figure 14.20). When teaching this pose, attempt to create an alignment of 180 degrees at the elbow joint, even if the elbow feels a little bent to the practitioner. If the student is hyperextended in full extension, then flexing her elbows actually increases congruence at the joint surfaces.
Ask the student to practice the pose with the short side of a nonskid mat placed against a sturdy, smooth wall. When she is standing on her hands (and supported by the wall), make sure that her wrists, elbows, and shoulders are in one line. To do this, it may be necessary to have her slightly bend her elbows, or it may help to have her experiment with rotating her arms externally. Remember that hyperextension cannot be fixed but, through careful practice, students can avoid making it worse.
LINKS
An injury to the elbow that is usually only seen in children is called a pulled elbow. This occurs when the head of the radius is pulled out of its annular ring, such as when the forearm is pulled or jerked suddenly. Symptoms include pain and difficulty in pronation and supination; flexion and extension are usually possible. For a full discussion of this injury, see Caring for Your Baby and Young Child: Birth to Age Five by Steven P. Shelov, M.D., and Robert E. Hannemann, M.D. (New York: Bantam, 2004). If you suspect this injury, consult a health care professional at once. To prevent it, remember to swing or playfully pull a child by both of his arms evenly, instead of by just one arm at a time.