Anatomy of Children


You may have heard the phrase “a child is not a miniature version of an adult”, but do you know the anatomical and physiological differences between kids and adults? In this blog we have investigated them for you - there are some fascinating things to learn!


Firstly, a newborn will have 94 more bones than you do! These extra bones fuse together over time as the child gets older until around the age of 25, where the quantity of bones will plateau to the normal 206.

A baby's skull is also not fully developed by the time it is born. It is actually made up of 5 separate bones that are held together by fibrous material called sutures, which allow the bones to move during childbirth. Two gaps in the skull where the sutures intersect are called fontanelles. Neither the sutures nor the fontanelles exist in an adults, as everything starts to fuse together when the child is around 2 years old.

The younger the child, the more flexible and pliable their bones are – this can be a benefit as they are less likely to break them, but also a problem for the internal organs of the chest as the rib cage is less protective. A baby's spine is not fully formed, which is why a child is unable to support the weight of its own head until around 3 months old, which is when the cervical section of the spine has finished developing. They struggle in the first year of life to hold their body weight when learning to walk due to an underdeveloped lumbar spinal section, too.


In proportion to their size, babies and children have a large surface area – greater than that of adults. Heat can be lost quickly in colder climates, especially through their heads, and they are also more affected by warm climates, with more chance of dehydration and overheating. The body’s natural response to temperature changes, in the form of sweating and shivering, is not as developed in children as it is for an adult. The insulating layer in the skin, the subcutaneous fat, is considerably thinner in children.


Children tend to have a flatter nose and face when compared to adults. Children have small airways but large tongues, which can cause difficulties in breathing. A blocked nose from a cold for a child under 6 months old can also be dangerous, as they tend to breathe exclusively through their nose.

When breathing, adults normally take between 10-15 breaths, where as a baby will take 30-40, a toddler 20-40 and slightly older children between 15-30.


A child's heartbeat is very different to that of an adult. The heart of a child under 1 year of age beats 120 times per minute, a child of 2 has 110 beats and a 4-year-old has 100 beats. Between the ages of 8-10 it slows to 90 beats a minute, and between the age of 10 to adulthood, it decreases by a further 22 beats per minute!

Other differences

- A baby's vision is not fully developed when they are born, so the first few weeks of life for them consists of very blurry shapes and images. You can get an idea of when the nerve endings in their retinas have developed as the baby will start to respond to smiles!

- In very young babies, the lacrimal gland will not have properly developed meaning they are unable to produce tears when they cry.

- Babies breathe relatively higher amounts of carbon dioxide than adults as their metabolic rate is faster.

- The amount of oxygen and glucose required by a babies brain is far greater than an adults.

- Hidden within a babies gums are a full set of teeth, 10 for the lower jaw and 10 for the upper.

- An adult has approximately 600 million alveoli, an 8 year old has 300 million alveoli and a newborn baby has only around 10 million!

Children related AnatomyStuff resources

Budget Tooth Development Model (4 part)
as30024Child Skeleton Model (14 to 16 months old)2870
Child Skeleton Model (5 years old)
2800bcChild Pelvis Model (5 years old)
4051Juvenile Female Pelvis Model

Further reading / sources

Differences between adults and children
Anatomical Differences in Children You Should Know
Paediatric anatomy
Children's Health and the Environment
Anatomy of a newborns skull

Did you Enjoy this Article?

Share it with others

Leave a Comment