The Surprising Complexity of a Baby’s Suck

At the Upledger Pediatric CranioSacral Therapy Level 2 seminar, one of my biggest takeaways was how much is happening when a baby learns to suck.

From the outside, feeding can look effortless. Inside the body, the lips, jaw, tongue, throat, and breath have to work together. A baby must create suction, move milk, swallow, and return to breathing—all in a coordinated rhythm. The brainstem helps organize that rhythm through several cranial nerves: the trigeminal nerve (V) supports jaw movement, the facial nerve (VII) helps control the lips and face, the hypoglossal nerve (XII) moves the tongue, and the glossopharyngeal (IX) and vagus (X) nerves help coordinate the throat and swallow. Research on infant sucking and feeding describes how these nerves work together. PMC

We explored this in a wonderfully simple exercise. We tied a knot in a straw, then tried to drink water through it—first with our eyes open and then with our eyes closed. The knot made us work harder to draw the water up. As we repeated the exercise, we paid attention to what happened throughout our bodies, including a change we noticed in how our eyes moved while we sucked.

I loved that moment. Something I usually think of as an action of the mouth suddenly felt connected to my eyes, my breathing, and my whole sense of effort. It gave me a more vivid appreciation for the coordination an infant is developing during feeding. Researchers have also studied the relationship between newborns’ sucking rhythms and eye movements, although our straw exercise was an experience of that connection, not a clinical test. pubmed.ncbi.nlm.nih.gov

Sucking is about more than getting milk, too. Babies also suck when they are seeking comfort. The familiar rhythm of sucking can be soothing; nonnutritive sucking has been studied as a way to help infants settle and cope with stressful or mildly painful procedures. PMC

I came home thinking differently about the babies and families I see. When feeding feels difficult, there is so much to be curious about: how the baby uses their jaw and tongue, how sucking and swallowing flow together, when they pause to breathe, and what helps them feel settled. The seminar reminded me that even an everyday action can tell a rich story about a developing nervous system—and that listening to the family is part of understanding it.