REFLEXES PRESENT IN INFANTS

SANDIPAN SAHA ROYBDS IV YEAR

Contents Definition Types of reflex General body reflexes Facial reflexes Oral reflexes References

What is reflex???

A reflex is an involuntary, or automatic, action that your body does in response to something, without even having to think about it.

Types of reflex

•General Body Reflexes•Facial Reflexes•Oral Reflexes

GENERAL BODY REFLEXES

1. Moro Reflex

any sudden movement of the neck initiates this reflex

Elicited by -- pulling the baby half-way to a sitting position from the supine & suddenly let the head fall back to a short distance.

Consists of rapid abduction & extension of arms with the opening of hands. The arms then come together as in embrace.

Clinical significanceIts nature gives an indication of muscle

tone

The response may be asymmetrical if muscle tone is uneqal on the two sides, or if there is weakness of an arm or an injury to the humerus or clavicle

This reflex usually disappears in 2 or 3 months

2. Startle Reflex

Similar to moro reflex, but is initiated by a sudden noise or any other stimulus.

In this reflex, the elbows are flexed and the hands remain closed, there is less of embrace, outward and inward movement of the arms

3. Palmer/Grasp ReflexWhen the baby’s palm is stimulated, the hand closes.

There is also a corresponding planter reflex..

Both normally disappear by 24 months

Clinical significance

Exceptionally strong grasp reflex may be found in the spastic form of cerebral palsy & Kernicterus.

May be asymmetrical in hemiplagia & in cases of cerebral damage.

Persistence beyond 2-3 months indicate spastic form of crebral palsy.

4. Walking/stepping reflex

When the sole of foot is pressed against the couch, baby tries to walk.

it persists as voluntary standing.

5. Limb placement reflex

When the front of the leg below the knee, or the arm below the elbow is brought into contact with the edge of a table, child lifts the limbs over the edge

6. Asymmetric tonic neck reflex

When the baby is at rest and not crying he lies at inervals with his head on one side, the arm extended to the same side, and often with a flexion of the contralateral knee.

7. Babinski’s reflex

Stroking of the lateral surface of the planter surface of the foot from the heel to the toe results in flexion of the toe.

8. Parachute reflex

Reflex appears at about 6-9 months & persists thereafter.

Elicited by holding the child in ventral suspension & suddenly lowering him to the couch.

Arms extend as a defensive reaction.

• Clinical significanceAbsent or abnormal in children

with cerebral palsyWould be asymmetrical in spastic

hemiplagia

9. Landau reflex

Seen in horizontal suspension with the head, legs & spine extended.

If the head is flexed, the hips, knees & elbows also flex.

Normally present from 3 months, difficult to elict after 1 year.

• Clinical significance

Absence of reflex occurs in hypotonia, hypertonia or severe mental abnormality.

10. Tendon reflexes

Simple monosynaptic reflexes, which are elicited by a sudden stretch of a muscle tendon

Occurs when the tendon is tapped

Present throughout life

FACIAL REFLEXES

1. Nasal Reflex

Stimulation of the face or nasal cavity with water or local irritants produces apnea in neonates.

Breathing stops in expiration with laryngeal closure and infants exhibit bradycardia & lowering of cardiac output.

Blood flow to skin, splanchnic areas, muscles & kidney decreases.

Flow to the heart & brain remains protected.

2. Blink Reflex

Various stimuli provoke blinking.

Whether the child is awake or sleep, pupils of the eye react to changes in the intensity of light.

3. Doll’s eye ReflexThough a complex

mechanism, infants hold fixation of faces, movements or changing intensity of light within their visual fields.

During the first week they are able to maintain these fixations against passive movement of their bodies.

Eye

Head

4. Corneal ReflexConsists of blinking

when the cornea is touched.

The satisfactory demonstration of these reflexes shows that the stimulus, whether sound, light or touch, has been received, that cerebral depression is unlikely, and that the appropriate muscles can contract in response.

5. Pupil ReflexThe pupil reacts to

light, but in the preterm baby and some full term babies the duration of of exposure to the light may have to be prolonged to elict the reflex.

The light should not be bright, for a bright light will cause closure of the eyes

ORAL REFLEXES

1. Rooting Reflex When the infant’s cheekcontracts the mother’s breast, the baby’s mouthresults in vigorous sucking movements resulting in the baby rooting for milk.

When corner of mouth is touched, lower lip is lowered, tongue moves towards the point stimulated

When finger slides away, head turns to follow it

When center of lip is stimulated, lip elevates

Onset -- 28 weeks IUWell established – 32-34 weeks IUDisappears – 3-4 months

2. Sucking

Onset~ 28 weeks

iu

Well-establised~ 32-34 weeks iu

Disappear~

around 12

months

Elicited by~

introducing a

finger into the mouth

3. Swallowing Begins around 12 and

half weeks IU life.Full swallowing and

sucking is established by 32-36 weeks of IU life.

Their absence in full-term baby would suggest a developmental defect.

types

INFANTILE SWALLOW

ACQUIRED CONGENITAL REFLEX

•Until primary molars erupt, infant swallows with jaws separated and the tongue thrust forward using facial muscles.

•This is non-conditional congenital reflex.

After eruption of posterior primary teeth, from18 months of age onwards, the child tends to swallow with teeth brought together by masticatory muscle action, without a tongue thrust.

3. Gag reflex

In buccal cavity and pharynx, the

ectoderm/endoderm zone is towards the

posterior third of tongue.

Seen at 18 and half weeks of IU life.

Touching here elicits a gag reflex, a protective

reflex.

4. Cry

It is a non-conditioned reflex which

accounts for its lack of

individual character and is of sporadic

nature.

Starts as early as 21-29

weeks IU life.

5. Mastication It is a conditioned reflex, learned initiallyby irregular and poorly coordinated,chewing movements.The proprioceptive responses of TMJ and PDL of erupting dentition establishes astabilized chewingpattern, aligned tothe individual dentalintercuspation.

Reference Text book of Pedodontics by Shobha Tandon (2nd edition)

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