There are 5 types of bones in the human body – long, short, flat, irregular, and sesamoid.
Long bones are longer than they are wide, with a long slender shaft that is primarily compact bone and two bulky extremities that may have a large amount of spongy bone. Aided by muscles, long bones work as levers to enable movement.
Examples of long bones in humans:
- Humerus, radius and ulna of the arms
- Femur, tibia, and fibula of the legs
- Metacarpals of the hand
- Metatarsals of the feet
- Clavicle or collarbone
Short bonesare squat and roughly cube-shaped with approximately equal length and width. They are composed primarily of a thick spongy interior, with a thin layer of compact bone covering it. The main function of short bones is to provide the body with stability and support.
Examples of short bones in humans:
- Carpals in the wrist
- Tarsals in the ankle
Flat bones have a thin, flattened, curved surface. They are composed of two thin layers of cortical bone on either side of a layer of spongy cancellous tissue. Flat bones typically form broad, flat plate that serve to provide muscles with a broader surface for attachment.
Examples of flat bones in humans:
- Rib cage
- Cranium or skull bones
- Shoulder blades
- Ileum or pelvis
- Breast bone
Irregular bones that do not conform to the above three types are classified as irregular bones. They typically form unusual bony shapes in the human endoskeleton. Irregular bones are primarily spongy bones that are enclosed between a thin layer of cortical or compact bone.
Examples of the irregular bones in humans:
- Vertebrae
- Sacrum
- Mandibe
- Maxilla
- Hyoid
- Coccyx
Sesamoid Bones are the bones that are embedded directly in the tendons or muscles. This is unlike other bones that are connected to other tissues but not embedded in them.
Examples of sesamoid bones in humans:
- Pisiform bones of the wrist
- Patella or kneecap