Date post: | 07-May-2015 |
Category: |
Education |
Upload: | shayonisen2012 |
View: | 1,899 times |
Download: | 2 times |
REFLEXES PRESENT AT BIRTH
SUBMITTED BY:SHAYONI SEN
BDS IIIRD YEAR
DEPARTMENT OF PEDODONTICS
CONTENTS INTRODUCTION GENERAL BODY REFLEXES FACIAL REFLEX ORAL REFLEXES REFERENCE
INTRODUCTION A REFLEX is defined as
an involuntary, or automatic, action that your body does in response to something, without even having to think about it.
Types of reflexes present at birth:
1. General body reflexes2. Facial reflexes3. Oral reflexes
GENERAL BODY
REFLEXES
MORO REFLEXES Any sudden movement
of the neck initiates this reflex.
A way of eliciting the reflex is to pull the baby half-way to sitting position from supine and suddenly let head fall back to a short distance.
Reflex consists of rapid abduction and extension of arms with opening of hands.
CLINICAL SIGNIFICANCE
Its nature gives an indication of the muscle tone.
• The responses may be asymmetrical if muscle tone is unequal on two sides or there is a weakness of an arm or injury to humerous or clavicle
This reflex disappears in 2-3 months.
STARTLE
REFLEX
•It is similar to moro reflex, but it is initiated by sudden noise or any other stimulus•In this, the elbows are flexed and the hands remain closed, there is less of embrace, outward and inward movement of arms.
WALKING/ STEPPING REFLEX
•When the sole of the foot is pressed against couch, the baby tries to walk.•It persists as voluntary standing.
PALMER/ GRASP REFLEX
When the baby’s palm is stimulated, the hand closes.
There is also a corresponding planter reflex.
Both normally disappear by 24 months.
CLINICAL SIGNIFICANCE
An exceptionally strong grasp reflex may be found in the spastic form of cerebral palsy and in kernicterus.
It may be asymmetrical in hemiplegia and in cases of cerebral damage.
It should have disappeared in 2-3 months and persistence may indicate the spastic form of cerebral palsy.
LIMB PLACEMENT REFLEX•When the front of the leg below the knee, or arm below the elbow is brought into contact with edge of the table, the child lifts the limb over the edge.
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.
ASYMMETRIC TONIC NECK REFLEX When the baby is at rest
and not crying, he lies at intervals with his head on one side, the arm extended to the same side, and often with a flexion of the contra lateral knee.
This reflex normally disappears after 2 or 3 months, but may persist in spastic children.
PARACHUTE REFLEXIt
appears at about 6-9 months
and persists
thereafter
.
The reflex is
elicited by
holding the child in ventral suspension and suddenl
y lowerin
g him to
couch. The arm
s extend as defensive a defensive
reaction
.
In children
with cerebral palsy,
the reflex may be absent or
abnormal.
It would be asymmetri
cal in spastic
hemiplegia.
LANDAU REFLEX It is seen in vertical
suspension, with the head, spine and legs extended.
If the head is flexed, the hips, knees and the elbows also flex.
It is normally present from 3 months and is difficult to elicit after 1 year.
Absence of reflex occurs in hypotonia, hypertonia or severe mental abnormality.
FACIAL REFLEX
NASAL REFLEX
Stimulation of the face or nasal cavity with water or local irritants produce apnea in neonates.
Breathing stops in expiration with laryngeal closure and infants exhibit bradycardia and lowering of cardiac output.
Blood flow to skin, splanchic areas, muscles and kidney decreases, whereas the flow to the heart and brain is protected.
CORNEAL REFLEX •Consists of blinking when cornea is touched
PUPIL REFLEX•Pupil reacts to light, but in preterm baby and some full term babies the duration of exposure to the light may have to be prolonged to elicit the reflex.
ORAL REFLEXES
ROOTING REFLEX When the infant’s cheek
contacts the mother’s breast, the baby’s mouth results in vigorous sucking movements resulting in baby rooting for milk.
When the corner of mouth is touched, the lower lip is lowered, the tongue moves towards the point stimulated.
When the finger slides away, the head turns to follow it.
Onset is 28 weeks IU
Disappears by 3-4 months
Well-establised by 32-34 weeks IU
SUCKING
Onset~ 28 weeks iu
Well-establised~ 32-34 weeks
iu
Disappear~ around 12
months
Elicited by~ introducing a finger into the
mouth
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.
TYPESINFANTILE 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.
GAG REFLEX
Seen at 18 and half weeks of IU life.
In buccal cavity and pharynx, the ectoderm/endod
erm zone is towards the
posterior third of tongue.
Touching here elicits
a gag reflex, a protective
reflex.
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.
MASTICATION
It is a conditioned reflex, learned initially by irregular and poorely coordinated, chewing movements.
The proprioceptive responses of TMJ and PDL of erupting dentition establishes a stabilized chewing pattern, aligned to
the individual dental intercuspation.
REFERENCE SHOBHA TONDON (FOR PEDIATRICS
DENTISTRY) 2nd EDITION.