Bone & joints


Anatomy-bone & joints

Last author update: 1 January 2012
Last staff update: 21 July 2023

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PubMed Search: Bone normal anatomy

Dariusz Borys, M.D.
Vijay Shankar, M.D.
Page views in 2022: 1,757
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Cite this page: Borys D, Shankar V. Anatomy-bone & joints. website. Accessed September 26th, 2023.
  • Basic function of bone
    • Bone is the basic unit of the skeletal system and provides shape and support for the body, as well as protection for some organs
    • There are 206 bones in the human skeleton: 80 axial skeletal bones (e.g., skull, vertebral column and sacrum) and 120 appendicular skeletal bones (e.g., bones of extremities, scapula, pelvis)

  • Gross structure of bone
    • Epiphysis: region between the growth plate or growth plate scar and the extended end of bone, covered by articular cartilage
    • Metaphysis: region between the growth plate and diaphysis; contains abundant trabecular bone, but the cortical bone thins here comparing to diaphysis
    • Diaphysis or shaft: region between metaphyses, composed mainly of compact cortical bone
    • Physis (epiphyseal plate, growth plate): region of bone that separates the epiphysis from metaphysis
    • Zone of endochondral ossification in actively growing bone or the epiphyseal scar in a full grown bone
    • Cross section: periosteum, cortex (composed of cortical bone or compact bone), medullary space (composed of cancellous or spongy bone)
    • Bone composition: 35% organic (cells, proteins), 65% calcium hydroxyapatite (contains 99% of body's calcium, 85% of phosphorus, 65% of sodium, also magnesium)
    • Hydroxyapatite crystal is formed via phase transition; 12 day lag between matrix deposition and mineralization
    • Collagen resists tension, hydroxyapatite and proteoglycans in cartilage resist compression
    • Thicker cortex in middle of long bones resists bending; cancellous bone at ends of long bones resists compression
  • Junction between adjacent bones that provide painless range of motion and stability
  • Synovial or nonsynovial

  • Synovial joints:
    • Also called diarthroses
    • Contain joint space between ends of bones formed by endochondral ossification
    • Joints covered by hyaline cartilage, strengthened by dense fibrous capsule continuous with periosteum of bones and an inner synovial membrane
    • Joint is reinforced by ligaments and muscles
    • Presence of joint space allows wide range of motion and maintains stability during use

  • Nonsynovial joints:
    • Also called solid joint or synarthrosis
    • No joint space present
    • Provides structural integrity and minimal movement
    • May be fibrous / synarthrosis (cranial sutures, bonds between roots of teeth and jaw bones) or cartilaginous / amphiarthrosis (manubriosternalis and pubic)

  • Bursae:
    • Found when muscles, tendons and skin glide over bony prominences
    • Subject to same diseases as large joint spaces

  • Menisci:
    • Composed of collagen arranged circumferentially with some radial fibers
    • In young adults, are white, translucent and supple
    • Become more opaque, yellow, less supple in elderly
  • Bones are divided on the basis of their location, shape, size and structure

  • Based on location, bones can be classified as
    • Axial skeleton: bones of the skull, scapula, vertebral column
    • Appendicular skeleton: bones of the pectoral girdle, pelvis and limbs

  • Based on shape, bones can be classified as
    • Flat bone: bones of the skull, sternum, pelvis and ribs
    • Tubular bone: long tubular bones are bones of the extremities (e.g., femur, humerus); short tubular bones are bones of hands and feet
    • Irregular bone: bones of the face and vertebrae
    • Sesamoid bones: patella

  • Based on size, bones can be classified as
    • Long bone: tubular bones of extremities (e.g., femur, humerus)
    • Short bone: cuboidal in shape, in the foot (tarsal bones) and wrist (carpal bones)
Blood supply
  • The blood supply of bone varies with different types of bone, but vascular supply is especially rich in bones rich in red bone marrow

  • Long bones
    • Diaphyseal nutrient artery: most important arterial supply, passes obliquely through cortical bone
    • Metaphyseal and epiphyseal arteries: numerous small arteries supply the ends of bones; these blood vessels arise from arteries that supply adjacent joints, anastomose with the diaphyseal capillaries and terminate in bone marrow
    • Periosteal arterioles: these vessels supply the outer layers of cortical bone

  • Large irregular bones, short bones and flat bones
    • These bones are supplied by superficial periosteal arterioles

  • Venous and lymphatic drainage
    • Blood is drained from the bone via venous and lymphatic vessels that accompany arteries and frequently leave through foramina near the articular end of the bones

  • Nerve supply of bone
    • Nerves are most rich in articular extremities of long bones, vertebrae and larger flat bones
    • Nerves accompany the blood vessels to the interior of the bone and to the perivascular spaces of the haversian canals
    • The periosteal nerves are sensory, causing periosteum to be particularly sensitive to tearing or tension
Bone tissue types and structure
  • Bone tissue can be classified based on texture, matrix arrangement; also maturity and developmental origin (see Histology topic)

  • Based on texture, bone can be classified as
    • Compact bone (dense bone, cortical bone): dense bone that surrounds trabecular bone in the center, contains Haversian system and secondary osteons
    • Sponge bone (trabecular bone, cancellous bone): sponge-like with numerous cavities, located in the center of bone cavity, consists of connected bony trabeculae

  • Based on matrix arrangement bone can be classified as
    • Lamellar bone: mature bone with collagen fibers arranged in lamellae
      • Lamellae of sponge bone are arranged parallel to each other
      • In contrast, lamellae of compact bone are organized concentrically to around vascular canal (haversian canal)
    • Woven bone: immature bone; collagen fibers in woven bone are arranged in irregular random arrays and contain smaller amounts of mineral substance and a higher proportion of osteocytes to lamellar component
      • Woven bone is eventually converted to lamellar bone
Diagrams / tables

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Pelvis: left-male, right-female

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Tibia and fibula

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Radius and ulna

Shoulder joint

Different types of synovial joints

Gross images

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Elbow joint; deep dissection; anterior view

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