When a newborn infant is touched on the cheek the infant will turn its head to the source of the stimulation and open its mouth this behavior is known as?

We all have reflexes. They are a type of involuntary movement or action that occurs in response to a stimulus.

When you go to the doctor and they hit your knee with a light hammer, your leg automatically kicks outward in response. That’s a reflex.

Certain reflexes are unique to newborns, depending on their stage of development. But a lack of certain reflexes can sometimes signal problems with the baby's brain or nervous system. 

Root reflex. This newborn reflex is triggered by touching the corner of the baby’s mouth. Your baby will turn their head in the direction of the touching. With their mouth open, they’ll “root” in that direction. This rooting aids in feeding, as it helps the baby find the bottle or breast that will nourish them. This reflex lasts about 4 months. 

Sucking reflex. The rooting reflex sets the stage for the sucking reflex, which allows the baby to breastfeed safely. When the nipple touches the roof of the baby’s mouth, they automatically begin to suck. The sucking reflex helps coordinate the rhythms of sucking, breathing, and swallowing. This reflex gets stronger the more the baby does it and will evolve into habits like sucking their thumb for comfort.

The sucking reflex develops before the baby is born. It begins around week 32 of pregnancy and fully develops around week 36. 

Moro reflex. The Moro reflex, also called the startle reflex, is the baby’s reaction to being startled. The cause is often a loud sound, a sudden movement, or even their own cry. As an adult, you may jump and blink when something startling happens. When the Moro reflex is triggered, the baby throws their head back, throws out their arms and legs, cries, and quickly pulls their limbs back in. This reflex lasts for only the first 2 months. 

Tonic neck reflex. The tonic neck reflex is sometimes called the fencing position because the baby holds their arms in a position like they’re fencing. The tonic neck reflex happens when the baby turns their head to one side with their arms stretched out. If their head is turned to the right, the right arm will stretch out while the left arm bends up at the elbow. ‌

This reflex might be difficult to notice. The movements can often be subtle. Your baby may not do it at all if they are fidgeting or crying. This reflex lasts until 5 to 7 months of age. ‌

Grasp reflex. You’ve probably noticed this reflex when you put your finger into your baby’s hand and they grasp it. The grasp reflex happens when you lightly touch the palm of their hand. The sensation causes the baby to close their fingers. This reflex lasts until around 6 months of age. 

Babinski reflex. This reflex is similar to the grasp reflex. When you stroke the bottom of your baby’s foot, the big toe will bend back while the other toes fan out and away. This reflex disappears between 12 months and 2 years of age. 

Stepping reflex. You probably get a bit surprised when you hold your baby upright on the floor and they try to walk. This is simply the stepping reflex at work. It is also called the walking or dancing reflex. You'll want to be wary of this reflex, as your newborn still cannot support their own weight. Helping them stand upright by holding underneath their arms will trigger the stepping reflex. They’ll start to step forward as if walking.

The reflex will disappear after the first 2 months and reappear after the first year, when the baby begins learning how to walk. 

The Importance of Reflex Symmetry

Because the tonic neck, grasp, Moro, Babinski, and stepping reflexes use each half of the body, it’s important to know that they’re symmetrical. If the reflexes are not equally strong or quick on both sides of the body, there may be a problem with the baby’s central nervous system. Talk with your doctor if you notice a lack of symmetry in your baby's reflexes.