When the hand closes into a fist, the last three fingers precede the index finger and close into the somewhat triangular hollow of the palm below the row of knuckles at tlx; base. Interestingly, these fingers all seem to be of equal length as closure occurs, and the tips line up in the palm hoi* low. In the second phase, as the three rear fingers go into a tight flexion, there is little room in the palm for closing the forefinger. Any attempt to do so feels uncomfortable. But the thumb closing in opposition to the fingers creates a cradle and is folded in. When the index finger is loeked into the enclosing thumb, its proximal knuckle will project beyond the line of ihc other knuckles. This projection is a marked characteristic of every flexed fist.
This six-stage sequence shows the right hand going into finger flexion toward fist closure- In the various stages the little finger begins folding down, followed by all the others in numerical order—five* four, three, twx>, one, with all fingers coming together in a graduated spiral formation. The thumb is the last to close. In phase 1, upper sketch, the palm is oser-strctched, but the little finger bends slightly. In stage 2, just below, the fifth and fourth fingers are bending in. In phase 3, center right, the bending is more developed. Phase 4, center left, shows fingers five, four, and three beginning to overlap the palm. In phase 5, lower right, the three rear fingers arc definitely in. while the index finger begins to curl and the thumb moves inward. In phase 6, lower left, closure is complete, yet not tightly flexed. The thumb has begun to press toward the little finger knuckles. To observe the opening of the fist, go back in reverse order.
This drawing demonstrates how- the index finger is virtually a prisoner of the thumb in fist closure. Note how easily live last three fingers of a closed fist can Hip out from the hollow of the palm, while the index finger stays locked into the thumb box. Try the ao tion on your own hand and fingers. Do you notice which finger Hips out first from the closed fist? The long middle finger! This follows the rule that the first finger to close is the last to open.
After looking at the finger closure sequence in the previous drawings, the sketches here show open finger variations. In the upper sketch, the index finger opens in a pointing gesture. The thumb is closed on the long middle finger, but importantly, the thumb tip is aimed at the transverse position of the little finger metacarpal palm knuckle shown by the arc of broken arrows. In the lower sketch, two finger* are open, while the thumb is closcd on the middle shank of the fourth finger. Again, note the arc developing from the thumb toward the little linger palm knuckle.
With three fingers open, the thumb is closed on the middle phalanx of the fifth finger. Note the consistency of the transverse tine of the thumb to* ward the fifth palm knuckle, with the tip of the little finger resting in the palm trench.
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