Why Do Babies Have More Bones than Adults?

Table of ContentsView AllTable of ContentsBones and What They’re Made OfThe Bones That Babies Are Born WithThe Ways That Bones Change as Babies GrowOther Facts About BonesFrequently Asked Questions

Table of ContentsView All

View All

Table of Contents

Bones and What They’re Made Of

The Bones That Babies Are Born With

The Ways That Bones Change as Babies Grow

Other Facts About Bones

Frequently Asked Questions

Science Photo Library - Ian Hooton / Getty Images

Unlike bone, cartilage does not contain calcium in its matrix, the fibers and other substances that make up cartilage. Instead, cartilage contains the chemicalchondroitin, which keeps it flexible and elastic. Cartilage also does not contain blood vessels or nerves. Instead, blood flow and pain sensations come from the surrounding structures.

What Does Cartilage Do?

Over time, much of the cartilage in a child’s body hardens into bone—a process called ossification. Ossification actually begins in utero around the sixth or seventh week of gestation and continues through a person’s mid-20s.

There are two types of bone ossification. They are called intramembranous and endochondral ossification, and they are responsible for the following bone formations:

Long bones evolve through endochondral ossification. Long bones are typically tubular, and they are longer than they are wide. The arms and legs are made up primarily of long bones.

Short bones also evolve through endochondral ossification, but they are not structurally similar to long bones. Instead, they take on distinct shapes.For example, the bones of theankles,wrists,heels, and kneecaps are all short bones.

Flat bones evolve through intramembranous ossification. These bones have platelike shapes.The skull bones, the breastbone,shoulder blades,ribs, andhip bonesare examples of flat bones.

Types of Bone

The Skull

Several bones make up the skull—twofrontal bones, two parietal bones, and oneoccipital bone.Over time, these bones will fuse, but it is initially important that they remain flexible in order to go through the birth process and for brain growth.

Craniosynostosis

The Spine

A healthy adult’s spine has several natural curves—cervical(at the neck),thoracic(mid-back), andlumbar(at the base). The curves allow for proper mobility as we walk, bend, twist, and do everyday movements. However, our spines do not start out with these curves.

Spines can also curve abnormally.Kyphosisandlordosisare spine abnormalities that occur when a child’s front-to-back spinal curvature is too large.Scoliosisis a spine condition in which the spine is curved from side to side.

Scoliosis can be congenital or neuromuscular (a consequence of a muscular or neurological condition). The treatment depends on the severity of the condition and can include observation, bracing, or surgery.

Spina bifidais a neural tube defect that affects the spine. It occurs when the neural tube (which becomes the brain and spinal cord) does not close all the way during early embryonic development. When this happens, the bones that are supposed to protect the spinal cord do not form and close, which damages the spinal cord and surrounding nerves.

Spina bifida can result in physical and intellectual disabilities, but not everyone with spina bifida will have disabilities. The treatment depends on the severity of the condition and may include surgery or mobility aids, like wheelchairs, braces, crutches, and walkers.

The causes of spina bifida are not completely understood. However, one known way to reduce the risk of the condition is to takefolic acidsupplements if you are trying to conceive and while you are pregnant.

Evidence-Based Benefits of Folic Acid and How to Get Enough

Arms and Legs

Ossification of the long bones actually begins in the fetal stage. Ossification of the limbs is not complete until the late teens to mid-20s.

Long bones in children are divided into four regions: diaphysis, metaphysis, physis, and epiphysis.

Children’s bones are more flexible and have a thicker covering, making them more able to absorb shock and resist fractures. At the same time, kids are more prone to some kinds of fractures in areas that are no longer present in adults, such as growth plates.

If growth plates (tissue near the ends of bones) do not heal properly, bones maygrow crookedor more slowly. For this reason, a doctor will want to monitor a child’s bone for a year or more after a fracture.

Rare Bone DisordersAchondroplasiais a rare genetic bone disorder that prevents cartilage from being made into bone. It causes a child to develop with short arms, legs, and a larger head. The condition is a form of dwarfism. People with achondroplasia have typical intelligence and life spans.Hypochondrogenesisis a rare genetic condition that causes a fetus to develop shorter limbs, a small body, and abnormal ossification of the spine and pelvis. The condition is usually fatal before birth or shortly after.

Rare Bone Disorders

Achondroplasiais a rare genetic bone disorder that prevents cartilage from being made into bone. It causes a child to develop with short arms, legs, and a larger head. The condition is a form of dwarfism. People with achondroplasia have typical intelligence and life spans.Hypochondrogenesisis a rare genetic condition that causes a fetus to develop shorter limbs, a small body, and abnormal ossification of the spine and pelvis. The condition is usually fatal before birth or shortly after.

Achondroplasiais a rare genetic bone disorder that prevents cartilage from being made into bone. It causes a child to develop with short arms, legs, and a larger head. The condition is a form of dwarfism. People with achondroplasia have typical intelligence and life spans.

Hypochondrogenesisis a rare genetic condition that causes a fetus to develop shorter limbs, a small body, and abnormal ossification of the spine and pelvis. The condition is usually fatal before birth or shortly after.

An Overview of Dwarfism

Bones are a fascinating part of the human body. A child’s bones are constantly changing, with bones developing into new, different bones all the time.

Here are some other interesting facts about bones that you might not know:

Being a positive role model is a great way to establish good habits in your kids. Good nutrition and physical activity are the two factors that influence bone growth and health. For the first year, your child will receive adequate nutrition through breast milk or formula. After that, make sure your child gets plenty of foods that are rich in calcium and vitamin D.

8 Foods to Support Your Bone Health

The process of bones fusing is called ossification. Ossification doesn’t happen all at once. Instead, it is a process that begins in utero and continues until the skeleton is mature—usually in a person’s 20s.

There is one fontanelle in the front of the head (called the anterior fontanelle or the soft spot) and one in the back (called the posterior fontanelle).

The posterior fontanelle closes during the first few months of life. The anterior fontanelle closes at around 18–24 months.

A Word From Verywell

When your child begins eating solid foods, ensure that their diet provides sufficient calcium and vitamin D for their age. As they get older, weight-bearing activities, such as walking, running, hiking, and playing sports, and resistance exercises like lifting weights are great ways to build healthy bones.

What Are the Stages of Osteoporosis?

15 SourcesVerywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.Cowan P, Kahai P.Anatomy, bones. National Institutes of Health, National Library of Medicine.Chang L, Marston G, Martin A.Anatomy, cartilage. National Institutes of Health, National Library of Medicine.Breeland G, Sinkler M, Menezes R.Embryology, bone ossification. National Institutes of Health, National Library of Medicine.Stanford Children’s Hospital.Anatomy of the newborn skull.Centers for Disease Control and Prevention.Facts about craniosynostosis.Boston Children’s Hospital.Spine problems.American Association of Neurological Surgeons.Scoliosis – symptoms, diagnosis and treatment.Centers for Disease Control and Prevention.What is spina bifida?.Centers for Disease Control and Prevention.Health issues and treatments for spina bifida.University of New South Wales Sydney.Musculoskeletal system - bone development timeline - Embryology.Royal Children’s Hospital Melbourne.Fracture education: Anatomic differences: child vs. adult.American Academy of Pediatrics.Children and broken bones.Cedars-Sinai.Achondroplasia in children.U.S. National Library of Medicine.Hypochondrogenesis.National Institutes of Health. Kids and their bones:A guide for parents.

15 Sources

Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.Cowan P, Kahai P.Anatomy, bones. National Institutes of Health, National Library of Medicine.Chang L, Marston G, Martin A.Anatomy, cartilage. National Institutes of Health, National Library of Medicine.Breeland G, Sinkler M, Menezes R.Embryology, bone ossification. National Institutes of Health, National Library of Medicine.Stanford Children’s Hospital.Anatomy of the newborn skull.Centers for Disease Control and Prevention.Facts about craniosynostosis.Boston Children’s Hospital.Spine problems.American Association of Neurological Surgeons.Scoliosis – symptoms, diagnosis and treatment.Centers for Disease Control and Prevention.What is spina bifida?.Centers for Disease Control and Prevention.Health issues and treatments for spina bifida.University of New South Wales Sydney.Musculoskeletal system - bone development timeline - Embryology.Royal Children’s Hospital Melbourne.Fracture education: Anatomic differences: child vs. adult.American Academy of Pediatrics.Children and broken bones.Cedars-Sinai.Achondroplasia in children.U.S. National Library of Medicine.Hypochondrogenesis.National Institutes of Health. Kids and their bones:A guide for parents.

Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.

Cowan P, Kahai P.Anatomy, bones. National Institutes of Health, National Library of Medicine.Chang L, Marston G, Martin A.Anatomy, cartilage. National Institutes of Health, National Library of Medicine.Breeland G, Sinkler M, Menezes R.Embryology, bone ossification. National Institutes of Health, National Library of Medicine.Stanford Children’s Hospital.Anatomy of the newborn skull.Centers for Disease Control and Prevention.Facts about craniosynostosis.Boston Children’s Hospital.Spine problems.American Association of Neurological Surgeons.Scoliosis – symptoms, diagnosis and treatment.Centers for Disease Control and Prevention.What is spina bifida?.Centers for Disease Control and Prevention.Health issues and treatments for spina bifida.University of New South Wales Sydney.Musculoskeletal system - bone development timeline - Embryology.Royal Children’s Hospital Melbourne.Fracture education: Anatomic differences: child vs. adult.American Academy of Pediatrics.Children and broken bones.Cedars-Sinai.Achondroplasia in children.U.S. National Library of Medicine.Hypochondrogenesis.National Institutes of Health. Kids and their bones:A guide for parents.

Cowan P, Kahai P.Anatomy, bones. National Institutes of Health, National Library of Medicine.

Chang L, Marston G, Martin A.Anatomy, cartilage. National Institutes of Health, National Library of Medicine.

Breeland G, Sinkler M, Menezes R.Embryology, bone ossification. National Institutes of Health, National Library of Medicine.

Stanford Children’s Hospital.Anatomy of the newborn skull.

Centers for Disease Control and Prevention.Facts about craniosynostosis.

Boston Children’s Hospital.Spine problems.

American Association of Neurological Surgeons.Scoliosis – symptoms, diagnosis and treatment.

Centers for Disease Control and Prevention.What is spina bifida?.

Centers for Disease Control and Prevention.Health issues and treatments for spina bifida.

University of New South Wales Sydney.Musculoskeletal system - bone development timeline - Embryology.

Royal Children’s Hospital Melbourne.Fracture education: Anatomic differences: child vs. adult.

American Academy of Pediatrics.Children and broken bones.

Cedars-Sinai.Achondroplasia in children.

U.S. National Library of Medicine.Hypochondrogenesis.

National Institutes of Health. Kids and their bones:A guide for parents.

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