Module 3 Musculoskeletal System

• Sagittal plane


  Divides the body into left and right sides
• Mid-sagittal plane


  Divides the body into equal halves
• Frontal (coronal) plane


  Divides the body into anterior (front) and posterior (back) portions
• Making anatomical terms


  1. Adjectives from nouns (e.g. humeral head)

  2. Plurals from nouns (e.g. femora, alveoli, foramina)

  3. Diminutives from nouns (e.g. venule, canaliculi, lobule)
• Functions of the human skeleton

  • Protection
  • Support
  • Movement
  • Mineral storage
  • Blood cell production
  • Fat (energy) storage
• Mineral storage function


  • Bone is made of organic and inorganic material
  • Stores minerals like calcium and phosphorus for physiological and biochemical processes
• Blood cell production function

  • Red bone marrow produces blood cells
  • Yellow bone marrow stores fat for energy
• Mineralization (Calcification)


  1. Hardening of bone extracellular matrix

  2. Mineral salts bind to collagen, forming crystals
• Compact (cortical) bone


  Outer edge of bone, prominent in diaphysis, contains osteons

  
• Compact (cortical) bone


  • Outer edge of bone
  • Prominent composition/type in diaphysis
  • Contains Osteons

  
• Spongy (trabecular) bone


  Internal bone latticework, prominent in heads of long bones and other bone structures, contains trabeculae

  
• Spongy (trabecular) bone


  • Internal bone latticework
  • Prominent composition/type in heads of long bone & other bone structures
  • Contains Trabeculae (bony struts)

  
• Long bones share many common features irrespective of location, as their primary function is mobility
• How Osteons Form


  1. Osteoblasts come to the area around vessels due to growth factor being released into the local environment

  2. Osteoblasts begin to lay down bone

  3. Osteoblasts lay down more bone

  4. Osteoblasts trap themselves in small cavities (Lacunae)

  5. Osteoblasts differentiate into Osteocytes

  6. Osteoclasts exit the blood stream and resorb bone around vessel (forms Haversian canal)

  7. Osteoblasts enter Haversian Canal and fill in a single ring/layer of bone (lamellae)

  8. Another Osteoblast creates another layer of bone within Haversian Canal (Concentric lamellae)

  9. Osteocyte projections form and tunnel through the bone to receive nutrients, remove wastes & communicate (Canaliculi)
• Diaphysis


  Shaft of long bone, made of cortical (compact) bone

  
• Trabeculae


  • Individual "strut" like bony units
  • Spongy (i.e. Trabecular) bone is a latticework of trabeculae
  • Each Trabeculae contains lamella (layers of bone) arranged in plates or sheets, lacunae & canaliculi for osteocytes

  
• Epiphysis


  Ends of long bone, contains trabecular (spongy) bone

  
• Bone cell nutrition


  • Osteoprogenitors, Osteoblasts and Osteoclasts - diffusion of nutrients from local fluid environment
  • Osteocytes - nutrients travel through canals in bone (canaliculi) connecting with blood vessels outside of bone or within the Haversian (central) canal

  
• Cartilage is also a Supportive Connective Tissue
• Cartilage cells


  • Chondroblast: Secrete cartilage extracellular matrix
  • Chondrocyte: Chondroblast trapped in cartilage matrix
• Medullary cavity


  Marrow cavity in diaphysis
• Articular cartilage


  Covers epiphyses, provides smooth frictionless movement at joint
• Cartilage extracellular matrix


  • Collagen type II & Chondroitin
  • Retains water - thus rubbery
• Periosteum


  Tough outer fibrous membrane covering bone, protects vessels & nerves, anchors muscle to bone

  
• Cartilage tissue


  • Avascular - diffusion of nutrients & waste to external source
  • Healing and repair is slow
• Endosteum


  Thin, delicate membrane lining medullary cavity, maintains cellular environment during bone repair/remodelling

  
• Types of cartilage tissue

  • Hyaline (articular) cartilage
  • Fibrocartilage
  • Elastic cartilage
• Fibrocartilage


  • Rows of chondrocytes in lacunae; extensive parallel bundles of collagen
  • Resist compression & absorb shock
• Elastic Cartilage


  • Web-like mesh of elastic fibres amongst lacunae
  • Provides flexible, elastic support; maintains shape