Bones

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  • Bones
    • Types of Bones
      • Long Bones
        • Longer than they are wide EXAMPLES: Tibula, Fibula, Femur
        • Found mostly in limbs
        • Made up of a shaft and 2 extremities
        • Has an outer layer layer of compact bone to give strength and surrounds central cavity
        • Bone articulates with another forming a joint covered by articular cartilage which provides friction free movement
        • Covered with tough outer membrane (periosteum) which carries blood supply to bones and provides attachment to tendons
        • Examples: Humerus, Ulna, Phalanges, Tibia, Radius, Metacarpal, Femur, Fibula
        • Development of long bones
          • Long bones develop from 2 centres of ossification (bone growth)
            • The extremities is called epiphyses
          • Ossification begins in the diaphysis and then in the epiphyses after birth
          • A long bone is developed ager 12 years  but there is still a line of cartilage left between the shaft and the extremity (The epiphyseal plate)
          • Between 18-25 years the line of cartilage turns to bone and so no further growth takes place
      • Short Bones
        • Subject to pressure
        • made of cancellous bone with a thin shell of hard, compact bone
        • They are roughly the same dimensions in all directions which include the carpal and tarsal bones in the hands and feet.
        • EXAMPLE: Carpal and Tarsal
      • Flat Bones
        • in between an inner and outer layer of compact bone (scapula)
        • 2 layers of compact bone joined by a layer of cancellous bone
        • EXAMPLES: Ribs, sterum, wrist
      • Irregular Bones
        • Bones with complex shapes that can't be put into a category
        • EXAMPLES: Vertebrae and Hip bones
      • Sesamoid Bones
        • Usually small and rounded and found embedded in tendons
        • Main function is to protect the patella (knee cap)
        • EXAMPLES: Patella and Pisiform
    • The Skeleton
      • Function
        • Support soft tissue and organs
        • Protect organs
        • Blood cell formation (carried out by red bone marrow)
        • Movement
        • Storage as the bones act as a mineral reservoir
      • Made up of cartilage and bone
      • Cartilage
        • Softer than bone, less rigid and slightly elastic
        • A foetus has a temporary Skeleton made of cartilage which gets replaced by bone
        • Cartilage is kept throughout life on the articular surface over another
        • EXAMPLES: Nasal, Tracheal, bronchial
        • Cartilage lines joint surfaces to help gliding over one surface to another
        • Is present at the junction from bone to bone where resilience is needed
        • Is a shock absorber where bone is replaced with discs of cartilage
      • Bone
        • Made of an outer shell of compact bone tissue which is rigid, hard and dense
        • The compact bone surrounds the porous centre called cancellous bone
        • The spaces in cancellous bone is usually filled with red bone marrow
        • The medullary canal is the shaft of long bone filled with yellow bone marrow
        • LIGAMENT is bands of tissue binding bones together to form a joint and stretch but eventually go back to their original shape
        • CAPSULE is ligament tissue enclosing a joint
      • Types of Joint
        • Hinge: Movement in one place (Ankle)
        • Balland Socket: Movement in all 3 places (shoulders)
        • Gliding: Small foot bones in front of ankle joint
        • forcing too much movement in a joint opens it up to early wear and tear
      • Ribcage
        • 12 Pairs of ribs
        • Attached behind thoracic vertebrae forming articulating joints
        • The upper 7 ribs are attached to the sternum by costal cartilages
        • Ribs 11 and 12 pair are called floating ribs  as they aren't connected
        • the elastic allows movement
        • the ribcage must protect the lungs and heart
      • Hand
        • lower end of radius and ulna articulate with 3 of the 8 small carpal bones to form the wrist joint
        • The carpal bones are arranged in 2 rows
      • The Pelvic Girdle
        • Sacrum
          • 5 Sacral vertebrae fused together to form a single mass of bone
          • The upper end joins with the hip bone for the sacro-iliac joint, the slower end joins with the rib cage
        • Coccyx
          • formed by fusion of 4 small coccygel vertebrae a.k.a the tailbone
        • hip bone is a large irregularly shaped bone which articulates in front with the corresponding hip bone on the other side
        • Pelvis - 2 hip bones, sacrum and coccyx
      • The Spine
        • Vunerable Parts
          • Where one curve joins the next
          • bottom of the neck, bottom, chest, ribcage and coccyx
        • The natural curves of the spine
          • Spine functions to protect the spinal cord and transmits body weight to the pelvis and allowing range of movement
          • body weight is transmitted through intervertebral discs
          • The curves give the spine more shock absorption
        • The spinal cord
          • Part of the CNS below the brain
          • starts at the base of the skull and ends at the level of the 1st lumbar vertebra in the intervertebralcanal
          • cord gives off nerves in pairs throughout the spinal cord
          • 31 pairs of nerves
        • The vertebrae
          • The Intervertebraldiscs
            • The bodies of adjoining vertebrae are firmly connected to one another by discs of fibrocartilage
            • The centre part of the disc, the nucleolus pulpous is gelatinous and surrounded by outer bands of tough springy fibre cartilage
            • The structure contributes to the vertebras column to absorb axial compression forces
          • The lumbar vertebrae
            • lower part of the spine is large and sturdy
            • used for rotation, but is restricted
          • Cervical vertebrae
            • Built for lightness and mobility
            • large and triangular to accommodate the spinal cord which enlarges in this region
            • movement is free
          • Thoracic Vertebrae
            • Heart shaped and consists of a mass of cancellous bone covered by a thin shell of compact bone
            • Fairly large body as the lower vertebrae, the more weight it has to bare.
          • Each Vertebrae has a cylindrical body
          • A neural arch projecting backwards enclosing a space called vertebrae canal which the spinal cord passes
        • Atlas and Axis
          • 1st and 2nd vertebrae are different
          • The 1st, the atlas supports the sky;; and is a ring of bone with no body, but 2 facets articulate the side of the skull
          • The 2nd, the axis has a peg like process going upwards from the body to the atlas. It's anchored
          • Most rotation of the cervical spine is between the spine and atlas and the atlas pivots on the Axis.
        • Intervertebraldiscs bear gravitational pressures
        • The vertebral column consists if 33 irregular bones called vertebrae
        • Vertebrae are firmly connected to one another, but are capable of limited movement
        • The central axis protects the spinal cord it surrounds
        • The spine is made up of 7 cervical vertebrae in the neck
        • Curves are named primary and secondary according to development
          • When born the primary curve but develops into secondary curve in the cervical region
      • The Lower Limb
        • Foot
          • Talus
            • The lower ends of the tibia and Fibia (strongly bound together) sit on the Talus which is the uppermost Tarsal bones forming an ankle joint
          • The Calcenus
            • The heel is formed by backwards projecting mass of calcenus articulated Talus
          • Big  Toe
            • Made up of 2 phalanges (other toes are made up of 3)
            • Its metatarso- phalangeal joint is the biggest in the toes and the most vulnerable
            • Underneath it is reinforced by 2 sesamoid bones embedded in the tendons of the short muscles of the big toe
          • Made of small, irregular bones (tarsal bones)
        • The Femur
          • The thigh bone and the longest bone in the body
          • Articulates the pelvis to form the hip joint and the tibia to form the knee joint
        • The Tibia and Fibula
          • Tibia is the shin bone which forms the main skeleton of the leg
          • It has an expanded upper end to provide good bearing surface for the weight of the body
          • The Fibula is slender compared with the Tibia
          • Fibia lies on the otside of the leg and provides attachment for muscles of the front
        • Patella
          • On the front knee joint in the tendon of the quadriceps
          • muscle which straightens the knee
      • The Upper Limb
        • Clavicle
          • a.k.a The collar bone (underneath the skin)
          • Forms the anterior(bone near the front of the body) of the shoulder girdle
          • Keeps the scapula in position and provides attachment for some of the muscles of the neck and shoulder
        • Scapula
          • Forms the posterior (near the back) of the solder girdle and is extremely mobile
          • Floats on the chest wall
        • Sternum
          • Long flat bone runs down the front of the thorax a.k.a the breast bone
          • Gives attachment to the ribs anteriorly with the upper end supporting the clavicle

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