The terribly misunderstood but beautiful baby tongue: anatomy, resting posture, movement, and function in breastfeeding

What does your baby's tongue do in breastfeeding?

Babies love to suck. Your baby's tongue lights up great swathes of her brain as she settles into the joy of rhythmic suckling. Here, I want to defend the competence of your baby's moist, supple, sensitive little tongue, which loves to suck.

Your baby's tongue (and your own) is a three dimensional structure known as a 'muscular hydrostat'. This means that the tongue can change shape easily, without changing volume. As the tongue changes shape, it's layers glide over each other.

In breastfeeding the tongue is before all else a sensory organ. It doesn’t compress nipple up against the palate to hold the breast tissue in place or to generate milk flow. The tongue merely moves

• Downwards as the lower jaw moves down, anterior and mid-tongue moving together in one block, and then moves upwards as the jaw muscles contract and

• Upwards in tandem with the lower jaw moving upwards, moulding around the breast tissue that is already inside the baby’s mouth, cushioning it.

The tongue is just one sensitive and supple organ functioning dynamically in a symphony with other anatomic structures, most of them changing shape as sucking progresses, and some (like the hard palate) remaining fixed and unchanging, both in the woman and her baby. All of these anatomic features work together to bring milk from a woman's body into her baby's gut.

• You can find out about the function of the different parts of your baby's tongue in breastfeeding here.

• You can find out about the frenulum under the tongue here.

• You can find out about the fascia and baby's mouth here.

• You can find out why its best to think of you and your breastfeeding baby as a single biological system here.

Your baby's front or anterior tongue

The anterior tongue is the part of your baby's tongue which moves freely up from the floor of his mouth, projecting upwards, forward or from side to side like a wing.

• During breastfeeding, your baby's tongue-tip rests either on the lower gum or sometimes further forward. (The tongue-tip doesn't need to project further forward than the lower gum line though for successful breastfeeding.)

• The lingual nerves and their fine branches under the tongue enable the sensitive, moulding movements of baby's anterior tongue as it interacts with your nipple and breast tissue.

• Sometimes your baby's anterior tongue might reach more than halfway up the oral cavity when she is crying. Othertimes, this doesn't happen. The way babies place their tongues when crying is variable (since normal is a diverse human condition) and doesn't tell us anything helpful about the tongue's capacity for movement.

Your baby's mid-tongue

Your baby's mid-tongue lies between the anterior tongue and the base of the tongue. You can see the top surface of your baby's mid-tongue when you look in his mouth.

• The mid-tongue moves dynamically depending upon what the task is. Sometimes the mid-tongue is trying to protect against an intrusive finger or teat, in which case it might hump up, sometimes it is closing off the seal by touching the back of the hard or even the soft palate, sometimes it is moulding around the nipple and breast tissue inside your baby's mouth.

• The highest point of your baby's mid-tongue typically touches the palate in a very small area near the junction of the hard and soft palate at the end of each suck cycle. The tongue, in this case, is touching the palatine bones, which aren't connected to the maxilla (other than by connective tissue). In 10% of babies, however, the tongue touches only the soft palate at the end of the suck, when the jaw comes up. It doesn’t make sense to think that the tongue which scarcely touches the bony hard palate during feeds (or in 10% of babies only touches the soft palate) is responsible for bony shaping of the palate and maxilla, either in the womb or after, as you might often hear.

• The anterior and mid-tongue enfold around and bathe your nipple and breast tissue in warm moist support, following your baby's jaw down as it drops to create the vacuum.

The base of your baby's tongue (or the posterior tongue)

There is so much confusion about the posterior tongue, also known as the base of your baby's tongue!

• The base of the tongue can't be seen when you look in a baby's mouth, because it plunges backwards and downwards. Sometimes the tonsils on the base of the tongue can be glimpsed, but neither you nor your health professional can visualise the base of the tongue unless you use a special instrument.

• The base of the tongue plunges downwards at an angle which is close to vertical. During sucking the base of the tongue moves slightly back and forwards, unrelated to swallowing.

• The soft palate closes onto the base of the tongue during sucking at the breast, probably as a result of gentle contraction of the soft palate muscles.

• For many years advocates of frenotomy for breastfeeding problems talked about 'posterior tongue humping' as a sign of 'posterior tongue-tie'. Actually, they were making a mistake. They were looking at the mid-tongue, not the posterior tongue.

Is there a relationship between tongue oral rest posture, mouth breathing, and narrow palates?

You might hear a number of claims made about your baby's tongue and orofacial development which are worrying, but which aren't science-based. It's commonly said that

• A tongue-tie - even if there are no signs of a classic tongue-tie - affects the oral resting posture of your baby's tongue. However, there is no anatomic or functional basis to the belief that a posterior tongue-tie, or even a classic tongue-tie, can affect the way your baby's tongue rests inside his mouth. This has been shown in Dr Nikki Mill's groundbreaking research.

  • If your baby's mouth is closed, you can't see how the tongue rests. However, you can be confident that your baby's tongue fills much of the oral cavity and also touches against the palate.

  • If her mouth is open, then her mid-tongue needs to touch the back of the hard palate or even the soft palate to create a seal if baby is to breathe through her nose. Otherwise, when baby's mouth is open, she will breathe through her mouth.

• The tongue needs to rest touching the roof of the mouth, because this will lead to proper facial development. If the tongue doesn't rest touching the roof of the mouth, your baby might develop mouth breathing, or a narrow and high palate, and other orthodontic issues.

  • If your baby is a habitual mouth-breather, this needs to be reviewed by your doctor, as it is likely there is some kind of nasal obstruction occuring e.g. chronic upper respiratory tract inflammation.

  • The pressure of a resting tongue on the palate does not shape bony change. High and narrow palates relate to longer and narrower facial shapes and are not sculpted by the soft tissue of the tongue, despite its muscularity. You can find out more about this here.