Moro reflex
McGraw-Hill Science & Technology Dictionary:
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Moro reflex
(′mör·ō ′rē′fleks)
(physiology) The startle reflex observed in normal infants from birth through the first few months, consisting of abduction and extension of all extremities, followed by flexion and abduction of the extremities.
American Heritage Stedman's Medical Dictionary:
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startle reflex
n.
- The reflex response of an infant in which the limb and neck muscles contract when the infant is allowed to drop a short distance or is startled by a sudden noise or jolt. Also called Moro's reflex, parachute reflex.
- See cochleopalpebral reflex.
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Moro reflex
The Moro reflex, which is distinct from the startle reflex, is one of the infantile reflexes. 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). In human evolutionary history, the Moro reflex may have helped the infant cling to his mother while she carried him around all day. If the infant lost its balance, the reflex caused the infant to embrace its mother and regain its hold on the mother’s body.[1]
This reflex is a response to a sudden loss of support, when the infant feels as if it is falling. It is believed to be the only unlearned fear in human newborns[citation needed]. The primary significance of this reflex is in evaluating integration of the central nervous system (CNS), and it involves 3 distinct components:
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 adults. However, in individuals with cerebral palsy, persistence and exacerbation of this reflex is common.
References
1.
- ^ Berk, Laura E.. Child Development. 8th. USA: Pearson, 2009.
Adams and Victor's Neurology, Chapter 28. Normal Development and Deviations in Development of the Nervous System
External links
- Medline Plus: Moro reflex
- Video of the Moro Reflex from the University of Utah (Google Video)
- Pathologic Moro Reflex in an adult following acute demyelinating lesion of unknown origin in medulla oblongata (Neurology)
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McGraw-Hill Dictionary of Scientific and Technical Terms. Copyright © 2003, 1994, 1989, 1984, 1978, 1976, 1974 by McGraw-Hill Companies, Inc. All rights reserved.
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American Heritage Stedman's Medical Dictionary
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company.
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