A&P - 6.2 Bone Classification

how many bones are in the human body

• total 206 bones

  • in axial skeleton: 80 bones

  • in appendicular skeleton: 126 bones

classification of bones

• bone are classified according to their shape

• five categories:

  • long

  • short

  • flat

  • irregular

  • sesamoid

long bone

• FEATURES: cylinder-shaped bone that is longer than it is wide

• FUNCTIONS: leverage

• EXAMPLES: femur, tibia, fibula, metatarsals, humerus, ulna, radius, metacarpals, phalanges

short bone

• FEATURES: cube-like shape, approximately equal in length, width, and thickness

• FUNCTIONS: provide stability, support, while allowing for some motion

• EXAMPLES: carpals, tarsals

flat bone

• FEATURES: thin and curved

• FUNCTIONS: points of attachment for muscles; protectors of internal organs

• EXAMPLES: sternum, ribs, scapulae, cranial bones

irregular bone

• FEATURES: complex shape

• FUNCTIONS: protect internal organs from compressive forces

• EXAMPLES: vertebrae, facial bones

sesamoid bone

• FEATURES: small and round; embedded in tendons

• FUNCTIONS: protect tendons from compressive forces

• EXAMPLES: patellae (largest sesamoid bone)