Skeleton | Skeletal System Overview

Last update: Oct 20th, 2022

Introduction:

The adult human skeleton is a framework of 206 bones and is anatomically divided into two parts, the axial skeleton, and the appendicular skeleton.

Axial Skeleton:

The axial skeleton is the core of the skeleton, it consists of the following 80 bones:

Skull: 22 bones
Hyoid: 1 bone
Vertebrae: 32 bones
Ribs: 24 bones
Sternum: 1 bone

anterior view of the skeleton with the hyoid bone magnified and labeled.

How well do you know all 206 bones in the body? Start learning with free skeleton diagrams, bone labeling exercises and skeletal system quizzes.

Appendicular Skeleton:

The appendicular skeleton is attached to the axial skeleton. It consists of 126 bones.

Pectoral girdle: 4 bones (Scapula and clavicle).
Arms and forearms:: 6 bones (Humerus, ulna, and radius).
Wrists and hands:: 54 bones (Carpals, metacarpals, and phalanges).

Bony Pelvis: 2 bones (Os coxae).

Thighs and legs: 8 bones (Femur, patella, tibia, and fibula).
Ankles and feet: 52 bones (Tarsals, metatarsals, and phalanges).

Anterior view of the leg bones with the foot magnified and the phalanges, metatarsals and tarsals labeled.

Functionally, the bones primarily give support to the appendages and protect the fragile organs of the body such as the brain, spinal cord, heart, and lungs.
They also store calcium and phosphorus in the hard bone matrix, which can be released when needed elsewhere.

The bumps, ridges, and grooves on the surface of bones provide attachment sites for the skeletal muscles.

Additionally, many bones contain a soft tissue called marrow that produces new blood cells and stores fat.