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BONES - PowerPoint PPT Presentation


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BONES. Functions Provides framework for form and shape of the body (Prevents soft tissue from collapsing ) Provide points of attachment for muscles (Articulation: allowing bone movement relative to one another ) Protection of vital organs

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slide2

Functions

  • Provides framework for form and shape of the body (Prevents soft tissue from collapsing)
  • Provide points of attachment for muscles (Articulation: allowing bone movement relative to one another)
  • Protection of vital organs
  • Storage areas for mineral salts and fats (Ca, P, Na, K)
  • Blood Cell production
slide3

Macroscopic Structure

  • Diaphysisis a hollow cylinder of compact bone containing yellow bone marrow (fat storage) in the centre
  • Epiphysescontain spongy (cancellous bone) in centre. Large spaces in spongy bone are often filled with red bone marrow. (Red blood cell production)
  • Periosteum: dense white fibrous covering
  • Articular Cartilage: cartilage covering each epiphysis.
slide4

Microscopic Structure

  • Bone is a connective tissue (cells separated by large amounts of non-cellular matrix) with inorganic salt deposits. (increase strength / rigidity)
  • Composed of bones cells (osteocytes)
  • Haversian System/ Osteons (compact bone):
    • Projections from bone cells enter canaliculi and make contact with adjacent cells (Material transfer)
    • Haversian/Central canal contains at least one blood capillary. (may also contain nerves / lymph capillary)
    • Haversiansystem runs parallel to long axis of bone (adds strength)
    • Lamellae: layers of bony matrix
    • Lacunae: pockets (spaces) between lamellae
slide5

Microscopic Structure

  • 2. Trabeculae(spongy bone):
  • Irregular arrangement of thin, bony plates.
  • Contains bone cells but not in concentric layers
  • Nerves and blood vessels pass through irregular spaces in matrix
slide7

Microscopic Structure

  • A connective tissue
  • Perichondrium: fibrous protective layer
  • Only external blood vessels (in perichondrium), relies on diffusion through matrix.
  • Consists of protein fibres (Collagen) which are embedded in Protein-carb complex (chondrin).
  • Chondroblasts: immature cartilage cells in the spaces in the matrix (produce matrix which will eventually surround it)
  • Chondrocytes: mature cartilage cells which are inside a pocket (lacunae) surrounded by chondrin
slide8

CLASSIFICATOIN

  • Three types (based on thickness of fibres in matrix)
  • Hyaline: Very fine and very dense for strength. E.g. larynx (part), trachea, bronchi, articular cartilage, nose (part).
  • Elastic: medium thickness with elastic properties. E.g. ear, larynx (part), epiglottis, nose (part)
  • Fibrocartilage: thick and less dense, allowing for slight compression ideal for areas which withstand high pressure. E.g intervertebral discs, knee & pelvic joint.
slide10

Fixed (Fibrous joints)

  • No movement occurs between the bones involved.
  • Held in place by fibrous connective tissue
  • On impact bone fracture rather that joint damage.
  • E.g. skull, teeth/jaw
  • 2. Slightly movable (cartilaginous joints)
  • Allows very limited movement
  • Held in place by fibrous cartilage
  • egsymphysis pubis, vertebrae joints, joints between ribs and sternum
  • 3. Freely movable (synovial joints)
  • Amount of movement is limited only by ligaments, muscles, tendons and adjoining bones.
  • Highly mobile but equally weak
slide11

Ball-and-socket joints

Spherical head of one bone fits into cup-like head of another

  • Only occur in two places: shoulder (humerus/scapula) & hip (femur/pelvis)
  • Hinge Joint

Allows movement in one plane only.

  • Convex surface of one bone fits into concave surface of another
      • E.g. elbow (ulna/Humerus), wrist (radius/carpals) , knee (femur/tibia), ankle (tibia/tarsals), fingers & toes (phalanges)
slide12

Pivot Joint

  • Rounded, pointed or conical end of one bone articulates with a ring (part bone, part ligament)
  • E.g. 1st vertebrae (head) / 2nd vertebrae & radius / ulna
  • Gliding Joint

Gliding movement in any direction (back/forth, side/side), limited only by ligaments or bony processes.

  • E.g. carpals, tarsals, sternum/clavicle, scapula/clavicle
slide13

Saddle joint

Two saddle shaped joints

  • Allows side/side and back/forth movements
  • e.g. thumb (carpal/metacarpal)
  • Condyloid (ellipsoid) joint

Slightly convex fits with slightly concave

  • Allows side/side or back/forth movements
  • e.g. radius/carpal, metacarpal/phalanges, metatarsals/phalanges
slide14

STRUCTURE OFA SYNOVIAL JOINT

  • Capsule: surrounding and enclosing the joint (2 layers):
  • 1) fibrous capsule (outer layer), dense, fibrous connective tissue attached to periosteum . Flexibility allows movement but strength prevents dislocation
  • 2) Synovial membrane (inner layer) , vascular, loose connective tissue
  • Synovial Fluid (0.5mL): Secreted by synovial membrane, fills synovial cavity. Lubricates, nourishes & contains phagocytic cells.
slide15

STRUCTURE OFA SYNOVIAL JOINT

  • Articular Cartilage: provides smooth surface for movement
  • Articular Discs: (in knee - Menisci/meniscus) fibrocartilage extending inward from articular Capsule. Divide synovial cavities into two cavities.
  • Bursae: little sacs of synovial fluid. Prevent friction between a bone and a ligament/tendon/skin
  • Accessory Ligaments: hold bones together
slide16

Factors keeping bones together:

  • fit of articulating bones
  • Strength of bone ligaments
  • Tension by surrounding muscles
slide17

Movement of a Joint:

  • Flexion: (bending) decreases angle between articulating bones
  • Extension: (Straightening) increases angle between articulating bones
  • Abduction: movement away from the body
  • Adduction: movement towards from the body
  • Rotation: Movement of a bone around its long axis.