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Infant reflexes

Definition

A reflex is an involuntary muscle reaction to a certain type of stimulation. Certain sensations or movements are known to produce specific muscular responses.

Alternative Names

Primitive reflexes; Reflexes in infants

Considerations

The presence and strength of a reflex is an important sign of neurological development and function.

Many infant reflexes disappear as the child grows older, although some remain throughout adulthood. The presence of an infant reflex after the age at which the reflex normally disappears can be a sign of brain damage or damage to the nervous system.

Infant reflexes are reflexes that are normal in infants, but abnormal in other age groups. Such reflexes include:

• Moro reflex
• Sucking reflex (sucks when area around mouth stimulated)
• Startle reflex (pulling arms and legs inward after loud noise)
• Step reflex (stepping motions when sole of foot touches hard surface)

Other infant reflexes include:

The TONIC NECK REFLEX is elicited when the head of a relaxed child, lying on his back, is rotated to the side. The arm toward which the infant is facing extends straight away from the body with the hand partially open, while the arm on the side away from the face is flexed and the fist is clenched tightly. Reversing the direction in which the face is turned reverses the position. The tonic neck position is often described as the fencer's position because it resembles the stance of a fencer.

The GRASP REFLEX is elicited by placing a finger on the infant's open palm. The hand will close around the finger. Attempting to remove the finger causes the grip to tighten. Newborn infants have strong grasps and can almost be lifted from the examination table if both hands are used.

The ROOTING REFLEX is elicited by stroking the cheek. The infant will turn toward the side that was stroked and begin to make sucking motions with its mouth.

The PARACHUTE REFLEX occurs in the slightly older infant, and is elicited by holding the child upright then rotating the body quickly face forward (as if falling). The arms are reflexively extended as if to break a fall even though this reflex appears long before walking.

Examples of reflexes that persist into adulthood are:

• Blinking reflex -- you blink your eyes when they are touched or when sudden bright light appears
• Cough reflex -- you coughs when your airway is stimulated
• Gag reflex -- you gag when the throat or back of mouth is stimulated
• Sneeze reflex -- you sneeze when nasal passages irritated
• Yawn reflex - you yawn when the body needs additional oxygen

Common Causes

Abnormal presence of infant reflexes can occur in adults with:

• Brain damage
• Stroke

Call your health care provider if

Abnormal infant reflexes are usually discovered by the health care provider during exams performed for other reasons. The parents of an infant may be aware of the condition.

What to expect at your health care provider's office

The health care provider will perform a physical examination and ask questions about the child's medical history.

Questions may include:

• What reflexes were present?
• At what age did each infant reflex disappear?
• What other symptoms are also present? (For example, decreased alertness or seizures.)

Review Date:11/9/2007
Reviewed By:Deirdre O’Reilly, M.D., M.P.H., Neonatologist, Division of Newborn Medicine, Children’s Hospital Boston and Instructor in Pediatrics, Harvard Medical School, Boston, Massachusetts

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