Arm recoil focuses on passive flexor tone of the biceps muscle by measuring the angle of recoil following very brief extension of the upper extremity.
Term newborns demonstrate full recoil to a position of flexion while preterm newborns show less flexion.
How to Examine Arm Recoil of the Infant
With the infant lying supine, the examiner places one hand beneath the infant's elbow for support. Taking the infant's hand, the examiner briefly sets the elbow in flexion, then momentarily extends the arm before releasing the hand. The angle of recoil to which the forearm springs back into flexion is noted, and the appropriate square is selected on the score sheet. The extremely pre-term infant will not exhibit any arm recoil. Square #4 is selected only if there is contact between the infant's fist and face. This is seen in term and post term infants.
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SIGN
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NEURO-MUSCULAR MATURITY SCORE
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SIGN SCORE
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-1
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0
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1
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2
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3
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4
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5
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Arm Recoil
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Care must be taken not to hold the arm in the extended position for a prolonged period, as this causes flexor fatigue and results in a falsely low score due to poor flexor recoil.