Bones and Skeletal Tissues

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• Bones and Skeletal Tissues
• Part A

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Skeletal Cartilage

• Contains no blood vessels or nerves
• Surrounded by the perichondrium (dense irregular
  connective tissue) that resists outward expansion
• Three types hyaline, elastic, and fibrocartilage

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Hyaline Cartilage

• Provides support, flexibility, and resilience
• Is the most abundant skeletal cartilage
• Is present in these cartilages
• Articular covers the ends of long bones
• Costal connects the ribs to the sternum
• Respiratory makes up the larynx and reinforces
  air passages
• Nasal supports the nose

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Elastic Cartilage

• Similar to hyaline cartilage but contains elastic
  fibers
• Found in the external ear and the epiglottis

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Fibrocartilage

• Highly compressed with great tensile strength
• Contains collagen fibers
• Found in menisci of the knee and in
  intervertebral discs

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Bones and Cartilages of the Human Body
Figure 6.1
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Classification of Bones

• Axial skeleton bones of the skull, vertebral
  column, and rib cage
• Appendicular skeleton bones of the upper and
  lower limbs, shoulder, and hip

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Classification of Bones By Shape

• Long bones longer than they are wide (e.g.,
  humerus)

Figure 6.2a
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Classification of Bones By Shape

• Short bones
• Cube-shaped bones of the wrist and ankle
• Bones that form within tendons (e.g., patella)

Figure 6.2b
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Classification of Bones By Shape

• Flat bones thin, flattened, and a bit curved
  (e.g., sternum, and most skull bones)

Figure 6.2c
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Classification of Bones By Shape

• Irregular bones bones with complicated shapes
  (e.g., vertebrae and hip bones)

Figure 6.2d
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Function of Bones

• Support form the framework that supports the
  body and cradles soft organs
• Protection provide a protective case for the
  brain, spinal cord, and vital organs
• Movement provide levers for muscles
• Mineral storage reservoir for minerals,
  especially calcium and phosphorus
• Blood cell formation hematopoiesis occurs
  within the marrow cavities of bones

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Bone Markings

• Bulges, depressions, and holes that serve as
• Sites of attachment for muscles, ligaments, and
  tendons
• Joint surfaces
• Conduits for blood vessels and nerves

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Bone Markings Projections Sites of Muscle and
Ligament Attachment

• Tuberosity rounded projection
• Crest narrow, prominent ridge of bone
• Trochanter large, blunt, irregular surface
• Line narrow ridge of bone

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Bone Markings Projections Sites of Muscle and
Ligament Attachment

• Tubercle small rounded projection
• Epicondyle raised area above a condyle
• Spine sharp, slender projection
• Process any bony prominence

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Bone Markings Projections Projections That
Help to Form Joints

• Head bony expansion carried on a narrow neck
• Facet smooth, nearly flat articular surface
• Condyle rounded articular projection
• Ramus armlike bar of bone

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Bone Markings Depressions and Openings

• Meatus canal-like passageway
• Sinus cavity within a bone
• Fossa shallow, basinlike depression
• Groove furrow
• Fissure narrow, slitlike opening
• Foramen round or oval opening through a bone

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Gross Anatomy of Bones Bone Textures

• Compact bone dense outer layer
• Spongy bone honeycomb of trabeculae filled with
  yellow bone marrow

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Structure of Long Bone

• Long bones consist of a diaphysis and an
  epiphysis
• Diaphysis
• Tubular shaft that forms the axis of long bones
• Composed of compact bone that surrounds the
  medullary cavity
• Yellow bone marrow (fat) is contained in the
  medullary cavity

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Structure of Long Bone

• Epiphyses
• Expanded ends of long bones
• Exterior is compact bone, and the interior is
  spongy bone
• Joint surface is covered with articular (hyaline)
  cartilage
• Epiphyseal line separates the diaphysis from the
  epiphyses

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Structure of Long Bone
Figure 6.3
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Bone Membranes

• Periosteum double-layered protective membrane
• Outer fibrous layer is dense regular connective
  tissue
• Inner osteogenic layer is composed of osteoblasts
  and osteoclasts
• Richly supplied with nerve fibers, blood, and
  lymphatic vessels, which enter the bone via
  nutrient foramina
• Secured to underlying bone by Sharpeys fibers
• Endosteum delicate membrane covering internal
  surfaces of bone

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Structure of Short, Irregular, and Flat Bones

• Thin plates of periosteum-covered compact bone on
  the outside with endosteum-covered spongy bone
  (diploë) on the inside
• Have no diaphysis or epiphyses
• Contain bone marrow between the trabeculae

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Structure of a Flat Bone
Figure 6.4
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Location of Hematopoietic Tissue (Red Marrow)

• In infants
• Found in the medullary cavity and all areas of
  spongy bone
• In adults
• Found in the diploë of flat bones, and the head
  of the femur and humerus

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Microscopic Structure of Bone Compact Bone

• Haversian system, or osteon the structural unit
  of compact bone
• Lamella weight-bearing, column-like matrix
  tubes composed mainly of collagen
• Haversian, or central canal central channel
  containing blood vessels and nerves
• Volkmanns canals channels lying at right
  angles to the central canal, connecting blood and
  nerve supply of the periosteum to that of the
  Haversian canal

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Microscopic Structure of Bone Compact Bone

• Osteocytes mature bone cells
• Lacunae small cavities in bone that contain
  osteocytes
• Canaliculi hairlike canals that connect lacunae
  to each other and the central canal

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Microscopic Structure of Bone Compact Bone
Figure 6.6a, b
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Chemical Composition of Bone Organic

• Osteoblasts bone-forming cells
• Osteocytes mature bone cells
• Osteoclasts large cells that resorb or break
  down bone matrix
• Osteoid unmineralized bone matrix composed of
  proteoglycans, glycoproteins, and collagen