Yogabody: Anatomy, Kinesiology, and Asana

15. The Wrist and Hand

LISTEN TO WHAT YOU KNOW THROUGH YOUR BODY.

—FRANCES PAYNE ADLER

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ONE OF THE most important skills we can have as teachers is the ability to use our hands well. The awareness and intelligence we manifest as we gently touch and guide our students during class is at the heart of teaching compassionately. Likewise, learning how to guide our students as they strengthen their wrists and hands is a valuable gift to impart. It can improve their practice and protect them from possible injury.

BONES

The eight wrist bones are called in the aggregate the carpals or carpal bones. Viewing the two rows of carpals in the anatomical position (palmar view), the proximal row, from lateral (thumb side) to medial, consists of the scaphoid, the lunate, the triquetral, and the pisiform bones. The scaphoid and lunate bones articulate with the distal end of the radius. The distal row of carpals, from lateral to medial, are the trapezium, the trapezoid, the capitate, and the hamate bones. The distal row of carpal bones articulates with the metacarpal bones of the hand.

One way to remember the order and names of the carpals is to memorize this phrase: “Some lovers try positions that they can’t handle.” The first letters of the eight carpal bones (Figure 15.1), from lateral to medial, are the same as the first letters of the words of this sentence. Figure 15.2 describes the carpals individually.

Practice palpating the proximal row of carpals. Have a student present the posterior surface of her left hand. After asking permission to touch her, find the proximal end of the first metacarpal bone at the radial styloid side of the hand. Now move just proximally to palpate the trapezium bone. Then move your fingers laterally to find the trapezoid bone. Next over you will feel a depression under your fingers; this is the capitate bone. Passively flex and extend the student’s wrist. One more bone over is the hamate. Try palpating the palmar surface of this bone at the same time; see if you can feel the hook of the hamate on the palmar side. Do this by putting your right thumb on the posterior surface of the hamate and your right index finger on the palmar hook of the bone. The next bone is the triquetral bone. The pisiform sits on the palmar side of the triquetral, distal to the hamate (Figure 15.3).

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15.1 (ABOVE LEFT) CARPALS, METACARPALS, AND PHALANGES OF THE LEFT HAND, ANTERIOR (PALMAR) VIEW

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15.3 (ABOVE RIGHT) CARPALS, METACARPALS, AND PHALANGES OF THE LEFT HAND, POSTERIOR VIEW

The bones of the hand proper are the metacarpals. The metacarpals are the long slender bones of the body of the hand and are numbered from the thumb to the fifth finger. The metacarpals consist of a body, a base at the proximal side for articulation with the carpals, and a rounded head that articulates with the proximal phalanx.

The phalanges consist of three segments: a proximal, a medial, and a distal, except the thumb, which has only two segments, a proximal and a distal.

JOINTS

Few joint bones have as complex a relationship with each other as the carpals. They articulate with the radius and with each other at myriad joints. It is usual to omit the ulna as articulating with the carpals, as it technically articulates with an articular disc.

Note that, while the metacarpals are in full flexion, the interossei muscles cannot perform adduction or abduction. Try this for yourself. Extend your fingers fully, and try abducting and adducting them. It is easy. Now fully flex your fingers; you will be unable to either adduct or abduct them. (See Figure 15.9 for more information on the interossei muscles.) The interrosei are at a biomechanical disadvantage to adduct or abduct the joints in full flexion because the muscles are stretched and thus weakened in this position.

The interphalangeal (IP) joints are much more limited than the metacarpal joints. The IP joints are only able to flex and extend. The former movement is much greater in range; the latter movement is limited by ligaments.

15.2 CARPALS

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CONNECTIVE TISSUE

The ligamentous structure of the wrist, carpals, and metacarpals is complex and outside the scope of this book. To learn more, please consult Gray’s Anatomy. But some information about the connective tissue of the wrist can be interesting to yoga teachers. One structure that is important to understand is the retinaculum, a thickened band of connective tissue, which is shaped like a cuff that surrounds the wrist joint (Figure 15.4). It holds the long tendons around the wrist close to the bone and has two parts. The anterior part is called the flexor retinaculum and is made up of two bands, the palmar carpal ligament and the transverse carpal ligament, which is deeper and more distal. The second part is the extensor retinaculum on the posterior side. It runs from the styloid process to the lateral margin of the radius.

NERVES

The nerves to the wrist joint arise from the ulnar nerve and from the dorsal interosseous nerve (Figure 15.4). One of the common problems with nerves at the wrist is carpal tunnel syndrome (CTS), or repetitive stress injury (RSI). This is irritation of the median nerve as it passes the wrist. Here’s how it happens.

An arch is formed by the carpal bones and the transverse carpal ligament that is part of the flexor retinaculum. This arch is called the carpal tunnel. The tendons of the flexor digitorum profundus and superficialis, the flexor carpi radialis, and the flexor pollicis longus pass under the retinaculum here. Additionally the median nerve passes through this arched tunnel. Remember that that the flexor retinaculum restricts the bowing of the long flexor tendons and protects the median nerve here.

RSI is created by repeated ischemic insults to the median nerve from repeated extension of the wrist while the fingers are in flexion. This is exactly the position of the wrist and hand during computer work, when one is typing and using the mouse. Some cases of RSI can be helped by stretching gently in the other direction, that is, flexion of the wrist and simultaneous extension of the fingers. If you guess that your student suffers from RSI, send him to a health care professional for diagnosis and deep tissue work to relieve the compression.

MUSCLES

The wrist proper has no intrinsic muscles. Rather, the wrist is controlled by the muscles originating on the forearm. These muscles are presented in chapter 14.

15.4 (BELOW LEFT) FLEXOR RETINACULUM AND NERVES TO THE WRIST

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15.5 (BELOW RIGHT) MUSCLES OF THE THENAR EMINENCE

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15.6 MUSCLES OF THE THENAR EMINENCE

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The muscles of the hand are divided into three groups. The first group is the muscles of the thumb (pollex), which collectively form the thenar eminence (Figures 15.5 and 15.6). At the opposite side of the hand are the hypothenar muscles (Figures 15.7 and 15.8). The term digiti minimi refers to the “small digit,” or fifth finger. The final set of hand muscles is called the intermediate muscles (Figure 15.9).

KINESIOLOGY

Under normal circumstances, the wrist and hand are not weight-bearing structures. But in asana class, they sometimes bear weight in poses like Chaturanga Dandasana and Adho Mukha Vrksasana. There are two ways of keeping the wrists and hands healthy; one is by strengthening the forearm muscles, and the other is by paying atten-tion to the alignment of the hands, especially, during weight bearing.

15.7 MUSCLES OF THE HYPOTHENAR EMINENCE

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To keep the wrists strong, you must keep the forearm muscles, both extensors and flexors, strong. This can be done by simple resistive exercises using hand weights under the guidance of a qualified trainer.

To prevent wrist injury, pay attention to the placement of the hands on the floor in weight bearing. This is especially true for poses like Adho Mukha Vrksasana and Bakasana, when all the weight of the body is borne directly down onto the wrists. For more details on proper technique, see the Applied Teaching section in this chapter.

It is a well-known kinesiological principle that, in order to stretch the flexors of a joint, the extensors must contract, and vice versa. This is true of the wrist and hand, of course, but it is also illustrated by a special effect on the extensor tendons of the hand and wrist in flexion, called tendon fixation or binding effect. This is how it works.

Make a fist with one hand, and then fully flex that same wrist. Now, keeping the hand well flexed, use your other hand to attempt to push your fist into deeper flexion. Take care to do this slowly to avoid injury. You will find that your fingers will uncurl and extend, even while your wrist remains flexed. This is because the long extensor muscles of the wrist and fingers are overstretched by the extreme flexion you are creating. Therefore these tendons attempt to protect themselves by overriding the flexors and producing extension.

The same effect can be seen in extension of the wrist. Once again, make a strong closed fist with one hand, and then extend that wrist. Now use your other hand to attempt to pry open the fingers of the closely held flexed fist, while you keep your wrist in extension. Once again, proceed with care. With the help of your other hand, you will find that it becomes easy to open the fingers of the fist. The fingers open more easily than when the wrist is in flexion; this occurs to protect the long flexors of the wrist from being overstretched during forced wrist extension.

15.8 MUSCLES OF THE HYPOTHENAR EMINENCE

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15.9 INTERMEDIATE MUSCLES OF THE HAND

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EXPERIENTIAL ANATOMY

For Practicing

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15.10 VIRASANA, WITH HANDS IN FRONT OF THE FACE

Applied Practice 1: Stretching the Flexors of the Wrist

Prop: 1 nonskid mat or a chair

Take Care: Avoid sitting in Virasana if it is uncomfortable for your knees; practice sitting in a chair instead.

SIT IN VIRASANA on your nonskid mat or a chair (Figure 15.10). Place your hands in front of your face with your palms facing you. Bring the outer edges of the hands together, so the fifth fingers are touching. Now lean forward and put your hands on the floor, with the fingers facing toward you, the insides of the wrists pointing away, and the palms flat on the floor. The cubital fossa of the elbow is facing outward, and the olecranon is facing toward you; the thumbs are on the outside, fifth fingers on the inside.

Now lean back, as if to sit in Virasana, while keeping your hands on the floor. This will cause a strong stretch of your flexors. Hold the stretch for 3 to 5 breaths, rest, and then repeat.

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15.11 SEATED WRIST EXTENSOR STRETCH

Applied Practice 2: Stretching the Extensors of the Wrist

Prop: 1 nonskid mat or a chair

Take Care: Avoid this pose if it causes pain in the wrist.

THIS MAY seem a little complicated but it is worth the trouble. Begin by sitting in a comfortable position with your arms straight in front of you (shoulder flexion). Cross your left wrist over your right. Now turn your palms so they are facing each other and pressed together, and interlock your fingers (Figure 15.11). Be sure to keep your palms firmly together.

Inhale, and as you exhale, pull up and backwards on your left hand, so you can see the back of that hand completely and it moves closer to your face. You will likely feel a strong but pleasant stretch in the extensors of your right forearm. To increase that stretch, keep the traction of the stretch and internally rotate your right arm, so the back of your right hand faces the floor. Remember to breathe while you practice. Repeat twice on each side.

For Teaching

Applied Teaching 1: Hand Position in Adho Mukha Vrksasana

Prop: 1 nonskid mat

Take Care: Avoid this pose during pregnancy or menstruation; if you have glaucoma, retinal problems, hiatal hernia, or a wrist injury; or if you are more than thirty pounds overweight.

MANY STUDENTS are taught to flatten the palm against the floor when they practice Adho Mukha Vrksasana (Figure 15.12). But that may not be the healthiest position. To under-stand why, first note that the foot has three main arches to facilitate weight bearing. It makes sense then that, especially for a structure that is not normally weight bearing, like the wrist, it would be beneficial to create an arch there as well.

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15.12 ADHO MUKHA VRKSASANA

Have your student try this experiment. Ask her to get down onto her hands and knees on the mat and place her palms flat on the floor, directly under her shoulders, and then lean forward. She will very likely feel some compression in the extensor side of her wrists. After releasing this attempt, ask her to place her hands on the mat once again and then slide back the tips of her fingers slightly, to create an arch in the palm. Have her lean forward. The weight will now be disbursed throughout her hand, and her wrist will feel much better.

In this position, the edges of the hand are touching the floor, but the middle of the palm is not. This position will protect the wrist as well as engage the intrinsic muscles of the fingers and hand in a way that adds support to the area. Now have her move her mat to the wall and try Adho Mukha Vrksasana to experience the pose with weight bearing on the edges of the hand and an inner arch.

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15.13 TADASANA, WITH REVERSE NAMSTE MUDRA

Applied Teaching 2: Reverse Namaste Mudra

Prop: 1 nonskid mat

Take Care: Avoid this pose if you have a wrist injury.

HAVE YOUR STUDENT practice Tadasana on a nonskid mat. Instruct him to abduct his right arm and bring it behind his back. Suggest that he reach across with his left hand to help move the right hand and arm up the back. Now bring the left hand onto the back. With an exhalation, have him slide both hands up his back near the spinal column, with the palms facing outward. With an exhalation, have him externally rotate his upper arms, drop the elbows and shoulder blades, and then slowly turn his hands and press them, palm to palm, in the Namaste mudra. Hold for several breaths, release, and repeat.

LINK

A mudra is a seal that is intended to hold or direct energy in the body. The next time you teach Savasana, have your students take Gyan mudra. First suggest that your students have their arms out to the side in a comfortable position, with the palms turned upward. Now practice the mudra by placing the tip of the index finger just at the base of the distal phalangeal joint of the thumb, so the index finger is caught by the natural curve of the thumb as the hand relaxes in the pose. There should be no effort expended in keeping the mudra. The hand continues to be at ease, with the other fingers gently curled. In this mudra, the index finger represents the individual, and the thumb represents the universal. This mudra expresses their union and serves to bring attention inward in the pose.


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