Palmar vs Plantar, Age And Significance


Most responses of newborns and infants are reflexive in nature. For instance, if we stroke their cheek, they turn their head, and when you give your finger, they try to hold it. These reflexes are called primitive reflexes, infantile reflexes, or newborn reflexes.

A reflex is defined as an involuntary reaction or movement to a stimulus. Infants display various innate reflexes, and one such reflex is the grasping reflex (1). As the name suggests, the reflex involves involuntary actions of the fingers. In this post, we explain the grasping reflex, its significance, when does it disappear, and when to be concerned about it.

What Is The Grasping Reflex?

The grasping reflex is an involuntary action where the baby wraps their fingers around your finger or an object that strokes their palm. It is an innate primitive, prehensile response of newborn babies to a mechanical stimulus (2).

The grasping reflex is also known as the palmar reflex, palmar grasp reflex, or Darwinian reflex. You can examine the reflex by first placing the baby on their back (supine position) when they are awake and alert. The examiner needs to stroke the infant’s palm with the index finger. You will notice the following two stages of the reflex (3).

  • Closing of fingers: The baby’s fingers undergo flexion to enclose the examiner’s finger.
  • Clinging to the object/finger: The pressure applied to the palm produces traction on the fingers’ tendons, resulting in a clinging action. It could be difficult for you to pull out your finger gently at this stage since the baby would have a firm grip.

Palmar Grasp Reflex vs. Plantar Grasp Reflex

Grasping reflex usually refers to the palmar reflex, which occurs on stimulation of the palm. However, a similar reflex can be elicited from the soles and toes. When the reflex occurs on the feet, it is called a plantar reflex, plantar grasp reflex, or Babinski reflex.

Below are the notable differences between the palmar and the plantar grasp reflex (3) (4).

 

Palmar Reflex Plantar Reflex
Palmar reflex is seen on the hands. Plantar reflex is seen on the feet.
Palmar reflex is also known as Darwinian reflex or grasping reflex. Plantar reflex is also known as Babinski reflex.
The reflex causes the baby to wrap their fingers around the object or finger stroking the palm. The reflex causes the big toe to curl upward and backward while other toes fan out when the sole is stroked from the heel to the toes.
Palmar reflex is seen from four months of gestation to six months after birth. Plantar reflex is seen up to 9-12 months but may persist in some babies for up to 24 months.

Significance Of The Grasping Reflex

The original purpose of the grasping reflex is unknown. The reflex is believed to be vestigial since it may have been significant for our arboreal, primitive ancestors. Nevertheless, the reflex may make it easier for a newborn to interact with the environment. Newborns cannot organize movements to grab an object voluntarily. Therefore, the palmar reflex creates a basic motor pattern for easier interaction with various objects.

The grasping reflex is controlled by regions of the brain and the spinal cord. A healthy grasping reflex, along with other primitive reflexes, is often considered a positive indicator of a good central nervous system (CNS) and the peripheral nervous system (nerves from the brain and the spinal cord) health (2).

Age Range Of The Grasping Reflex

The grasping or palmar reflex appears during the 16th week of gestation. The reflex may be visible during ultrasound scans with the baby grasping the umbilical cord. The grasping reflex is usually visible up to six months of age, and it may disappear by five months in some infants (5). The reflex usually appears for the same time frame in premature babies, too.

Why Does The Grasping Reflex Disappear?

The grasping reflex disappears due to reflex integration by the higher brain centers (6). Reflex integration occurs when the matured brain centers inhibit the reflex and modify it to become a voluntary action. It ultimately indicates the maturation of the baby’s motor cortex (a part of the cerebral cortex). A matured motor cortex eventually leads to better motor skills and the ability to perform voluntary action. Thus, as the baby grows older, they do not need primitive reflexes since their nervous system is mature enough to perform vital actions voluntarily.

What If The Baby Does Not Have A Grasping Reflex?

The absence of grasping reflex in newborns could indicate an underlying abnormality with the central nervous system or the peripheral nervous system. The following problems and issues could lead to an absent grasping reflex (2).

  • Injury, such as birth injury, to the brain
  • Injury to the spinal cord
  • Damage to the nerves (peripheral nervous system)
  • Prolonged compression and subsequent damage to the nerves
  • Accidental head injuries or severe concussions during the newborn phase

The baby may display a weak palmar grasp reflex if they have movement disorders, such as cerebral palsy. Your baby’s doctor will assess the presence of the reflex at birth or during subsequent checkups. If your baby suddenly stops showing grasping reflex, consult a doctor promptly.

What If The Grasping Reflex Persists?

The retention of primitive reflexes, such as the grasping reflex, beyond the normal age range indicates failure of reflex integration by the higher brain centers. Below are some of the neurological problems and conditions that could cause the persistence of grasping reflex beyond six months (7).

  • Spastic cerebral palsy
  • Neuromuscular disorders, such as spastic hemiplegia
  • Cortical lesions, such as due to brain injuries
  • Diminished cortical activity due to injury or severe illness

Many of these conditions cause other symptoms, and they may be diagnosed as the baby grows older. Speak to a pediatrician if your baby continues to show grasping reflex after six months of age.

Other Newborn Reflexes

Below are some of the other primitive reflexes present in newborns (8) (9) (10).

  • Asymmetrical tonic neck reflex: It is also known as the fencing reflex. When the baby is placed on the back, their head will turn with the arm and leg of one side extended. In the meantime, the other arm and the leg will be flexed. This reflex disappears by the age of seven months.
  • Moro reflex: It is also known as the startle reflex. The reflex causes the baby to throw their head backward while extending their arms and legs when they hear a loud sound or experience a sudden movement. The reflex lasts for up to two to six months.
  • Rooting reflex: If the newborn’s cheek is stroked, the baby will automatically open the mouth and turn their head towards the side that was stroked. This reflex helps the baby find and latch to the breast or bottle nipple. The rooting reflex lasts up to four to six months.
  • Stepping reflex: Hold the baby upright with the soles touching the ground. The baby begins to shift the feet one after the other, resembling the stepping action. The stepping reflex disappears by the age of two to three months.
  • Sucking reflex: If the baby’s palate (mouth’s roof) and lips are touched with a finger, nipple, or pacifier, the baby starts making sucking motions. The sucking reflex usually disappears by four months.

The grasping reflex is a primitive reflex that provides the baby with basic gross motor skills. You can easily elicit the reflex by stroking the baby’s palms with your finger or any object. As the baby grows older, they become adept at voluntarily grasping and releasing objects with their fingers. If you notice problems with the grasping reflex or it persists for too long, speak to the pediatrician in your next visit.

References:

MomJunction’s health articles are written after analyzing various scientific reports and assertions from expert authors and institutions. Our references (citations) consist of resources established by authorities in their respective fields. You can learn more about the authenticity of the information we present in our editorial policy.



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