Neural Exam - Newborn reflexes - Moro

From Embryology
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Newborn n 23.jpg
This 5-day-old infant is in the alert, quiet state.
  • The Moro reflex or "startle reflex" is obtained by holding the baby’s head and shoulders off of the mat with the arms held in flexion on the chest.
  • The examiner suddenly lets the head and shoulders drop back a few inches while releasing the arms.
  • The arms should fully abduct and extend, then return towards the midline with the hand open and the thumb and the index finger forming a “C” shape.
  • An absent or incomplete Moro is seen in upper motor neuron lesions.
  • An asymmetric Moro is most often seen with a brachial plexus lesion.
  • The brachial plexus palsy is on the side of the poorly abducted arm.

See also movie abnormal Moro reflex.

Links: neural

Moro reflex

(startle reflex) Clinical term describing a primitive reflex, an involuntary response (reflex) that is present at birth and that normally disappears after 3 or 4 months. The reflex has 4 parts: startle; abduction of the upper limbs (spreading out arms); adduction of the upper limbs (unspreading the arms); crying (usually, but may be absent). Preterm birth infants (28 to 33 weeks) have an incomplete form of this reflex and postnatal persistence (beyond 4 or 5 months) occurs in infants with severe neurological defects.

Neural Exam Movies: normal behaviour | cranial nerves | Newborn Tone - resting posture | upper extremity‎ | arm traction | arm recoil | scarf sign | hand position | lower extremity | leg traction‎ | leg recoil‎‎ | popliteal angle‎ | heel to ear | neck tone | head lag‎ | head control | Newborn Positions - prone | ventral suspension | vertical suspension | Newborn Reflexes - deep tendon reflexes | plantar reflex‎ | suck, root | Moro | Galant | stepping‎ | grasp | Newborn Head - head shape and sutures‎ | head circumference‎ | Neonatal Diagnosis

Movie Source - Paul D. Larsen  
Movies from the PediNeuroLogic Exam website are used by permission of Paul D. Larsen, M.D., University of Nebraska Medical Center and Suzanne S. Stensaas, Ph.D., University of Utah School of Medicine. Additional materials were drawn from resources provided by Alejandro Stern, Stern Foundation, Buenos Aires, Argentina; Kathleen Digre, M.D., University of Utah; and Daniel Jacobson, M.D., Marshfield Clinic, Wisconsin. The movies are licensed under a Creative Commons Attribution-NonCommerical-ShareAlike 2.5 License.
Links: Neural Exam Movies | Movies

Cite this page: Hill, M.A. (2024, April 23) Embryology Neural Exam - Newborn reflexes - Moro. Retrieved from

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© Dr Mark Hill 2024, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G