T3.2 skeletal systems

• Skeletal system


  Includes cartilage, bones and joints
• Skeletal system

  • Has both mechanical and physiological functions
  • Supports body structures and anchors muscles allowing for movement
  • Protects underlaying organs - brain, heart, lungs
  • Houses red bone marrow
• Divisions of the skeletal system

  • Axial skeleton
  • Appendicular skeleton
• Vertebral regions


  • Cervical (7 vertebrae in the neck)
  • Thoracic (12 vertebrae in the thorax)
  • Lumbar (5 vertebrae in the low back region)
  • Sacrum (1 vertebra comprised of 5 fused vertebrae toward the bottom of the spine)
  • Coccyx (1 vertebra comprised of 4 fused vertebrae at the end of the spine)
• Cartilage


  Connective tissue that is semi-rigid and more flexible than bone
• Components of cartilage


  • Chondroblasts (immature and growing)
  • Chondrocytes (mature)
  • Gel (80% water, contains various proteins and sugars like proteoglycans and glycosaminoglycans)
  • Fibres
• Cartilage


  • Does not contain blood vessels or nerve fibres
  • Nutrients must reach tissue through process of diffusion
• Types of cartilage


  • Hyaline cartilage
  • Elastic cartilage
  • Fibrocartilage
• Hyaline cartilage


  • Provides support, flexibility and resilience, most abundant type, located in the respiratory tract, ribs and long bones
• Elastic cartilage


  • Similar to hyaline cartilages, but contains more elastic fibres, located in the external ear and epiglottis
• Fibrocartilage


  • Rich in collagen fibres, has great tensile strength, the strongest type, located between adjacent vertebrae, pubic symphysis and knee joint
• Functions of cartilage

  • Bind bones together
  • Support weight (joint cartilage) and transmit or resist applied forces with little damage or distortion
  • Serve as attachment sites for muscles
• Bone (osseous tissue)


  Comprised of cells (osteogenic cell, osteoblasts, osteoclasts, osteocytes), gels (glycosaminoglycans/proteoglycans, mineral salts (calcium phosphate)), and fibres (collagen)
• Functions of bone

  • Supporting and protecting soft tissues
  • Attachment site for muscles, making movement possible
  • Storage of the minerals (calcium and phosphate) – role in maintenance of mineral homeostasis
  • Blood cell production occurs in red bone marrow (haemopoiesis)
  • Energy storage (fat) in yellow bone marrow
• Bone types


  • Long bones
  • Short bones
  • Flat bones
  • Irregular bone
• Long bones

  • Diaphysis: shaft, cylinder of compact bone
  • Medullary (marrow) cavity: marrow cavity contains fat (yellow marrow)
  • Proximal and distal epiphyses: one end of a long bone
  • Articular cartilage
  • Spongy and compact bone
  • Location of red and yellow bone marrow
  • Periosteum: tough membrane covering bone but not the cartilage; composed of dense connective tissue
  • Endosteum: delicate lining of marrow cavity
• Osteocytes


  Mature cells trapped in matrix – maintain bone tissue
• Osteoblasts


  Form extracellular matrix of bone; especially active in growing bones and during fracture repair
• Osteoclasts

  Huge multinucleated cells formed from fused monocytes (WBC); function in bone resorption (breakdown)
• Osteogenic stem cells

  Multiply and develop into osteoblasts
• Bone remodelling


  Mature bone tissue broken down by osteoclast cells, replaced with new bone tissue by osteoblast cells
• Red bone marrow

  Found in spongy bone of flat bones (e.g. skull, vertebrae, ribs) in adults and most bones in children; site of the production of red blood cells
• Yellow bone marrow


  Helps store triglycerides (fat), yellow, fatty appearance; found in medullary cavity of long bones in adults
• Functions of bone


  • Protection - underlying structures (skull, sternum)
  • Storage - minerals (calcium and phosphate)
  • Support - weight, muscles to attach to
  • Movement - attachment to muscle
  • Blood cell formation
• Calcium homeostasis


  • Bone comprised of organic (living) and inorganic (non-living) components
  • Organic components - cells, gels, and fibres; contribute to structure by providing tensile strength and flexibility
  • Inorganic components - mineral salts (calcium and phosphate); make up 65% of bone mass, responsible for hardness and resistance to compression
  • Storage site for calcium and phosphate
  • If blood lose too much calcium or gains too much, body homeostatic mechanisms will work with bone to store it or remove it
• Joint classifications by structure

  • Fibrous
  • Cartilaginous
  • Synovial
• Joint classifications by range of movement

  • Synarthroses - immobile joints
  • Amphiarthroses - slightly mobile joints
  • Diarthroses - freely mobile joints
• Types of synovial joints

  • Prince - Planar
  • Harry - Hinge
  • Pulled - Pivot
  • Charles - Condylar
  • Saddle - Saddle
  • Bag - Ball and socket
• Synovial joint classifications by range of movement


  • Uni-axial
  • Bi-axial
  • Multi-axial
• Vertebral column


  • Cervical vertebrae (7)
  • Thoracic vertebrae (12)
  • Lumbar vertebrae (5)
  • Sacrum (5, fused)
  • Coccyx (4, fused)
• Ribs


  • 1-7 are vertebrosternal/ true ribs (join sternum directly)
  • 8-10 are vertebrochondral/false ribs (do not join sternum directly but via 7th rib)
  • 11-12 are vertebral/ floating (not bound anteriorly)
• Bones of the upper extremity

  • humerus (the arm)
  • ulna and radius (the forearm)
  • 8 carpal bones (the wrist)
  • 5 metacarpal (the palm)
  • 14 phalanges (finger bones)
• Joints of the upper extremity

  • shoulder (glenohumeral)
  • elbow (cubital)
  • wrist (radiocarpal)
  • metacarpophalangeal and interphalangeal
• Bones of the pelvic girdle

  • sacrum, coccyx, right and left os coxae (hip bone)
• Bones of the lower extremity

  • femur and patella (the thigh)
  • tibia and fibula (the leg)
  • 7 tarsal bones (the foot)
  • 5 metatarsals (the forefoot)
  • 14 phalanges (the toes)
• Joints of the lower extremity

  • hip (coxal; acetabulofemoral)
  • knee (tibiofemoral)
  • ankle (talocrural)
  • proximal & distal tibiofibular
  • metatarsophalangeal & interphalangeal