Moro reflex

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The Moro reflex in a four-day-old infant: 1) the reflex is initiated by pulling the infant up from the floor and then releasing him; 2) he spreads his arms; 3) he pulls his arms in; 4) he cries (10 seconds)
File:Moro reflex while sleeping.ogv
Moro reflex while sleeping

The Moro reflex is an infantile reflex normally present in all infants/newborns up to 4 or 5 months of age as a response to a sudden loss of support, when the infant feels as if it is falling. It involves three distinct components:

  1. spreading out the arms (abduction)
  2. unspreading the arms (adduction)
  3. crying (usually)

The primary significance of the Moro reflex is in evaluating integration of the central nervous system. It is distinct from the startle reflex,[1] and is believed to be the only unlearned fear in human newborns.[citation needed]

Interpretation

The Moro reflex may be observed in incomplete form in premature birth after the 28th week of gestation, and is usually present in complete form by week 34 (third trimester)[citation needed]. Absence or asymmetry of either abduction or adduction is abnormal, as is persistence of the reflex in older infants, children and adults. Absence indicates a profound disorder of the motor system or a generalised disturbance of the central nervous system. An absent or inadequate Moro response on one side is found in infants with hemiplegia, brachial plexus palsy, or a fractured clavicle. Persistence of the Moro response beyond 4 or 5 months of age is noted only in infants with severe neurological defects.[2] In individuals with cerebral palsy, persistence and exacerbation of this reflex is common.

History

The reflex was discovered and first described by Austrian pediatrician Ernst Moro (1874–1951).

Function

The Moro reflex may have developed in human evolution to help the infant cling to his mother while she carried him around all day. If the infant lost his balance, the reflex caused the infant to embrace his mother and regain its hold on the mother’s body.[3]

References

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External links