Science · Support & movement
Skeleton and Bone Structure
Estimated time includes reading and one quiz. Take the time you need.
Start here: key ideas
- The skeleton supports, protects, stores minerals, and helps movement.
- The axial skeleton forms the center; the appendicular skeleton includes limbs and girdles.
- Compact bone is dense; spongy bone has light internal supports.
- Bone is living tissue that is continually remodeled.
What you’ll be able to do
- Compare axial and appendicular bones.
- Identify basic bone structure and marrow.
- Explain remodeling and mineral storage.
Learn how bones are grouped, built, and renewed.
Optional review
If you’d like to review the basics, visit Anatomical Orientation, Organization, and Homeostasis. You can start this lesson without completing those first.
A framework that does more than hold you up
Bones do more than hold the body up. The skeleton gives support, protects organs, and provides levers for movement. Bones store calcium and phosphate. Red marrow makes blood cells, while yellow marrow mainly stores fat. These jobs connect the skeleton with the muscular, blood, and endocrine systems.
Protection depends on location: the skull protects the brain, vertebrae surround the spinal cord, and ribs protect the heart and lungs. Movement requires a team. Bones act as rigid levers, joints allow the levers to turn, and skeletal muscles pull on them through tendons.
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