A. Moro’s reflex.
B. Crossed extension reflex.
C. Tonic neck reflex.
D. Grasp reflex.
Ans:B. Crossed extension reflex.
- A number of primitive neonatal reflexes can be elicited in healthy term neonate.
- These disappear as the child grows → These reflexes are inhibited by frontal lobes as child grows. Absence of reflex responses indicates dysfunction of central or peripheral motor function.
- Abnormal persistence of neonatal reflexes is pathognomonic of central motor lesions.
A. Reflexes present at birth
Rooting, sucking & swallowing reflexes
- The rooting reflex : disappears around four months of age
A newborn infant will turn its head toward anything that strokes its cheek or mouth, searching for the object by moving its head.
- The sucking reflex: It causes the child to instinctively suck anything that touches the roof of their mouth, and simulates the way a child naturally eats.
The walking or stepping reflex
- When the soles of their feet touch a flat surface they will attempt to walk by placing one foot in front of the other.This reflex disappears at six weeks
- The crossed extensor reflex is a withdrawal reflex.
- When the bottom of the foot is held and flicked, the baby will flex,adduct and then extend the opposite leg and appear to try to push the object away.
- This is sometimes referred to as the startle reaction, startle response, startle reflex or embrace reflex.
- The Moro reflex is present at birth, peaks in the first month of life, and normally disappears by three to four months of age
- It is likely to occur if the infant’s head suddenly shifts position, the temperature changes abruptly, or they are startled by a sudden noise.
- The legs and head extend while the arms jerk up and out with the palms up and thumbs flexed. Shortly afterward the arms are brought together and the hands clench into fists, and the infant cries loudly.
Assymmetric tonic neck reflex
- The asymmetrical tonic neck reflex, also known as ‘fencing posture’, is present at one month of age and disappears at around four months. When the child’s head is turned to the side, the arm on that side will straighten and the opposite arm will bend .
Palmar grasp (grasp reflex)
- The palmar grasp reflex appears at birth and persists until five or six months of age.
When an object is placed in the infant’s hand and strokes their palm, the fingers will close and they will grasp it with a palmar grasp.
Trigger: A gentle stroke on the sole of the foot (from heel to toe)
Response: Foot turns in and toes flare up
Appears at birth and lasts until baby is 6 to 24 months old
B. Reflexes appear after birth
Symmetric tonic neck
- The symmetric tonic neck reflex normally appears and develops around 6-9 months of age and should integrate by around 12 months.
- When the child’s head flexes forward, extending the back of the neck, the upper extremities will contract and the lower extremities will extend.
- Conversely, when the child’s head is extended backward, contracting the back of the neck, the upper extremities will extend and the lower extremities will contract.
- This occurs from about 9 months of age and persists.
- If the baby is held in a position where he is dropped forward, he will outstretch his hands.
- This is one of the baby milestones that is protective for falling.