Moro reflex
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2008-04-02T02:18:01Z
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robot Adding: [[nl:Moro-reflex]]
The '''Moro reflex''', also known as the ''[[Startle reaction|startle reflex]]'', is one of the [[infantile reflex]]es.
It 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]]). It is normally present in all infants/newborns up to 4 or 5 months of age, and its absence indicates a profound disorder of the motor 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. It was discovered and first described by Austrian [[pediatrician]] [[Ernst Moro]] (1874-1951).
This [[reflex]] is a response to unexpected loud [[noise]] or when the infant feels like it is falling. It is believed to be the only unlearned [[fear]] in human newborns. The [[little Albert]] study used the startle reflex in the famous [[classical conditioning]] experiment to make him fear white fuzzy things.
The primary significance of this [[reflex]] is in evaluating integration of the [[central nervous system]] (CNS), since the reflex involves 4 distinct components:
# Startle
# spreading out the [[arm]]s ([[Anatomical terms of motion|abduction]])
# unspreading the arms ([[Anatomical terms of motion|adduction]])
# [[Cry]]ing (usually)
Absence of any component (except crying) or any [[asymmetry]] in the movements is abnormal, as is persistence of the reflex in older infants, children and [[adult]]s. However, in individuals with cerebral palsy, persistence and exacerbation of this reflex is common.
References:
1. <references/>Adams and Victor's Neurology, Chapter 28. Normal Development and Deviations in Development of the Nervous System
==External links==
* [http://medlineplus.gov/ Medline Plus]: [http://www.nlm.nih.gov/medlineplus/ency/article/003293.htm Moro reflex]
* [http://video.google.com/videoplay?docid=-2508818082092298520&q=moro+reflex Video of the Moro Reflex by University of Nebraska (Google Video)]
* [http://www.neurology.org/cgi/content/full/68/6/437/DC1 Pathologic Moro Reflex following acute demyelinating lesion of unknown origin in medulla oblongata (Neurology)]
{{Primitive_reflexes}}
[[Category:Reflexes]]
[[Category:Obstetrics]]
[[Category:Pediatrics]]
[[da:Mororefleksen]]
[[de:Moro-Reflex]]
[[es:Reflejo de Moro]]
[[fr:Réflexe de Moro]]
[[it:Riflesso di Moro]]
[[he:רפלקס מורו]]
[[nl:Moro-reflex]]
[[ja:モロ反射]]
[[pl:Odruch Moro]]
[[zh:莫罗氏反射]]