Musculoskeletal System

• Musculoskeletal system


  Provides form, support, stability, and movement to the human body

  
• Components of the musculoskeletal system


  • Bones of the skeleton (206 bones)
  • Joints (360 joints)
  • Skeletal (voluntary) muscles (>600 muscles)

  
• Bones of the skeletal system


  • Protect the body's organs
  • Support the weight of the body
  • Give the body shape

  
• Joint


  An articulation between two bones in the body
• Skeletal (voluntary) muscles


  Attach to the bones and pull on them to allow for movement of the body
• Functions of the human skeleton


  • Protect the internal organs
  • Support and give shape to the body
  • Allow for movement
  • Site of blood cell production
• Parts of the human skeleton

  • Axial skeleton
  • Appendicular skeleton

  
• Axial skeleton


  Provides a surface for the attachment of muscles that move the head, neck, and trunk, performs respiratory movements, and stabilizes parts of the appendicular skeleton

  
• Components of the axial skeleton


  • Skull
  • Vertebral column (spine)
  • Thoracic cage (rib cage)

  
• Skull


  Protects the brain and supports facial structure
• Vertebral column


  Surrounds and protects the spinal cord, supports the head, and acts as an attachment point for the ribs and muscles of the back and neck

  
• Thoracic cage


  Encloses and protects the organs of the thoracic cavity, including the heart and lungs, provides support for the shoulder girdles and upper limbs, and serves as the attachment point for the diaphragm, muscles of the back, chest, neck, and shoulders

  
• Appendicular skeleton


  Composed of the bones of the upper limbs and the lower limbs

  
• Components of the appendicular skeleton


  • Pectoral girdle (shoulders)
  • Upper and lower limbs
  • Pelvic girdle (hip bones)

  
• Pectoral girdle


  Provides the points of attachment of the upper limbs to the axial skeleton

  
• Bones of the upper limb


  • Humerus
  • Radius and ulna
  • Carpus
  • Metacarpus
  • Phalanges

  
• Lower limb


  Consists of the thigh, the leg, and the foot

  
• Bones of the lower limb


  • Femur
  • Patella
  • Tibia and fibula
  • Tarsals
  • Metatarsals and phalanges

  
• Pelvic girdle


  Attaches to the lower limbs of the axial skeleton, responsible for bearing the weight of the body and for locomotion

  
• Types of bones


  • Long bones
  • Short bones
  • Flat bones
  • Irregular bones
  • Sesamoid bones
  • Sutural bones

  
• Compact (cortical) bone


  Hard outer layer that is dense, strong, and durable
• Cancellous (trabecular or spongy) bone


  Consists of a network of trabeculae or rod-like structures, lighter, less dense, and more flexible than compact bone

  
• Parts of a long bone


  • Diaphysis
  • Epiphysis
  • Metaphysis
  • Medullary cavity
  • Endosteum
  • Periosteum
• Osteoblast


  Cell responsible for bone formation
• Osteocyte


  Primary cell of mature bone, maintains the mineral concentration of the matrix
• Osteogenic cells


  Stem cells that differentiate into osteoblasts, important in fracture repair
• Osteoclast


  Responsible for bone resorption or breakdown
• Osteogenesis (bone formation)


  1. Intramembranous ossification

  2. Endochondral ossification
• Endochondral ossification


  Bone develops by replacing hyaline cartilage, cartilage serves as a template to be replaced by new bone
• Endochondral ossification steps


  1. Mesenchymal cells differentiate into chondrocytes

  2. Blood vessels bring osteoblasts that deposit bony collar

  3. Capillaries penetrate cartilage and deposit bone, forming primary ossification center

  4. Cartilage and chondrocytes continue to grow at ends, medullary cavity expands

  5. Secondary ossification centers develop after birth

  6. Hyaline cartilage remains at epiphyseal plate and joint surface
• Epiphyseal plate


  Area of growth in a long bone, cartilage is replaced by bone, resulting in lengthening of the bone
• Epiphyseal plate closure


  Long bones stop growing, epiphysis and diaphysis fuse
• Bone tissue is continually being remodelled and replaced when damaged
• Types of joints


  • Fibrous (fixed or immovable)
  • Cartilaginous (slightly movable)
  • Synovial (freely movable)
• Cartilaginous joints


  Bones are joined by cartilage, allow more movement than fibrous joints but less than synovial joints
• Lengthening of long bones


  • Growing long bone
  • Mature long bone
• Musculoskeletal system consists of

  • Bones of the skeleton (206 bones)
  • Joints (360 joints)
  • Skeletal (voluntary) muscles (>600 muscles)

  
• Joints


  An articulation between two bones in the body
• Types of joints


  • Fibrous (fixed or immovable joints)
  • Cartilaginous (slightly movable)
  • Synovial (freely movable)
• Cartilaginous joints


  Bones are entirely joined by cartilage, either hyaline cartilage or fibrocartilage. These joints generally allow more movement than fibrous joints but less movement than synovial joints.