Understanding Primitive Reflexes

Posted by on Feb 21, 2015 in Swavalamban Blog

#reflexes #newborn #cerebralpalsy #primitive #infant

reflexes

A reflex is a muscle reaction that happens automatically in response to stimulation. Certain sensations or movements produces specific muscle response. Many infant reflexes will disappear as the child grows older, although some remain intact throughout adulthood. A reflex that is present after a certain age will when it is supposed to disappear will be considered as a sign of damage to brain or nervous system.

Reflexes are the most objective part of neurological examination as these are extremely helpful in determining the level of damage to the nervous system.All reflexes when reduced to their simplest level are sensorimotor arcs. Simple reflex involves direct synapse between sensory fiber and motor neuron i.e. monosynaptic, many reflexes have several neurons interposed i.e. polysynaptic reflexes.

Primitive reflexes also known as infant or newborn reflexes are exhibited by normal infants in response to particular stimuli, as the child grows older, these will gradually disappear.Infants with cerebral palsy have persistent or delay in the disappearance of primitive reflexes and pathological or absent postural reactions.Lesions that damage the sensory or motor limb of a reflex arc will diminish that reflex. This can occur at any level of sensory or motor pathway.

Primitive Reflexes are :

1. Tonic Neck Reflex
Head of the lying child is moved to one side, the arm on the side where the head is facing will reaches away from the body with the hands partly open. the arm on the side away from the face is flexed with tightly clenched fist. turning the baby’s head in opposite direction will reverse the position. TNR is a precursor to hand eye coordination of infant.

2. Moro response
present at birth and began to disappear by 2 months of age. It is also known as startle reaction , appears when infant suddenly changes his head position, head and legs extend whie the arms jerk up and out with the palm up n thumb flexed, followed by arms brought together, clenched fist and infant cries loudly.

3. Rooting
occurs when the baby’s cheeks are stroked,as infant will tun towards the side of stroking and make sucking motion.

4. Sucking
presents at birth,child began to suck when area around the mouth is touched.

5 Palmar grasp
present at birth and persist until 5-6 months of age.when an object is placed in infant’s hand, the fingers will close and baby will grasp it.Causing to remove the object will make the grip tighten.New born infants have strong grasp and can be lifted up if both hands are grasping your fingers.

6. Galant/ Truncal incurvation
occurs when the side of spine of infant is stroked or tapped while the infant lies on stomach. the infant will twitch his hips towards the touch in a dancing pattern. If reflex persist beyond 6 months then it is a sign of pathology.

7. Parachute
occurs in slightly older infants, child is held upright and his body is rotated quickly to face forward as in falling then baby will extend his arms forward as if to break a fall. this reflexes appears long before the baby walks.

8. Walking/ stepping
present at birth, when sole of infant’s feet is touched on ground or a flat surface, they will attempt to walk by placing one foot in front of other.It disappears at 6 weeks and reappears at 8 to 12 months as a voluntary behavior.

9. Planter reflex/ Babinski
normal planter reflex involves planter flexion of foot which moves toe away from shin and curls them down. Babinski results in dorsiflexion of foot and in adults its presence is considered as a sign of upper motor neuron lesion.

effects of persistent reflexes

10. Some reflexes that lasts into adulthood are:

– Blinking reflex: blinking the eyes when they are touched or when sudden bright light appears

– Cough reflex: coughing when airway is stimulated

– Gag reflex: gagging when throat or back of the mouth is stimulated

– Sneezing reflex: sneeze when nasal passage is irritated

– Yawn reflex: yawing when body needs more oxygen

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