Physical Education Mrs Reynolds 9A/Pe1 Chapter 1 pg 1-9

The Function of the Skeleton

  • Support - the bones are solid and rigid. They keep us upright and hold the rest of the body - the muscles and organs - in place.
  • Protection - certain parts of the skeleton enclose and protect the body's organs from external forces, e.g. the brain is inside the cranium, the ribs protect the heart and lungs.This function is especially important in activities that involve contact, such as rugby or boxing.
  • Movement - the skeleton helps the body move by providing anchor points for the muscles to pull against. The long bones in the arms and legs work as levers to allow certain movements.
  • Structural shape and points for attachment - the skeleton gives us our general shape such as height and build. Tall people have long legs bones and larger vertebrae. People with a heavy build have larger clavicles and scapula as well as bigger pelvises. The skeleton also provides anchorage points for the muscles to attach, so when they contract we move.
  • Mineral storage - bones stores several minerals, including calcium and phosphorus, which can be released into the blood when needed.
  • Blood cell production - the inner marrow of the long bones and ribs produces red and white blood cells. Red blood cells are important in activities because they carry oxygen to the working muscles. White blood cells are important to fight off infections in other to keep healthy.
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Synovial Joints

  • Synovial joints are characterised by having a fluid-filled space between smooth cartilage pads at the end of the bones that form the joint.
  • Surrounding the joint is a tough joint capsule that is lined with a synovial membrane.
  • The outer layer of the capsule often includes ligaments that join bones to bones and strengthen the joint to prevent unnecessary movements and possible dislocations.
  • The synovial membrane lining the capsule produces an oily synovial fluid that lubricates the joint and reduces friction and wear.
  • In addition to the joint capsule and ligaments that support a synovial joint, there are several important structures surrounding the joint that help cushion and protect the joint from friction and outside forces.
  • Small bags of synovial fluid, known as bursae, surround the joint to reduce the friction from movement of tendons across the surface of the joint.
  • There are many different classes of synovial joints in the body, including hinge joints and ball and socket joints.
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The Head-Neck Joint

  • There is a joint where the neck meets the head.
  • The bones in the neck are the vertebrae, and the uppermost of these joints with the cranium.
  • This joint allows a person to move their head.
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The Elbow Joint

  • The elbow joint is a complex hinge joint formed between the end of the humerus in the upper arm and the ends of the ulna and radius in the forearm.
  • The inner side of the end of the humerus forms a hinge joint with the ulna, while the outer side meets the end of the head of the radius.
  • The meeting of the humerus, radius and ulna at the elbow allows the lower arm to bend and straighten in relation to the upper arm.
  • The correct term for bending at the elbow is flexion and extension
  • Several ligaments surround the elbow joint which help the joint maintain its stability, allowing movement while resisting dislocation of the bones.
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The Shoulder Joint

  • The shoulder joint is a ball and socket joint.
  • It has the greatest range of movement of any joint in the body.
  • Only ball and socket joints can move forwards and backwards, side to side and rotate around their axis.
  • The correct terms for forwards and backwards is flexion and extension.
  • The correct terms for side to side is abduction and adduction.
  • However, the big drawback of a ball and socket joint is that its extensive range of movement makes it more likely to dislocate than other, less mobile synovial joints.
  • The shoulder joint is formed from two bones, the humerus and the scapula.
  • The round head of the humerus forms a ball and socket joint like a cup-like depression of the scapula.
  • The joint is held together by ligaments and muscles, but the joint is vulnerable to dislocations from sudden jerks of the arm.
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Chest Joints

  • When breathing the chest cavity changes size because of the action of the breathing muscles.
  • To allow that movement to happen there are joints between the ribs and the sternum, and the ribs and the vertebrae. 
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The Hip Joint

  • The hip joint forms where the femur meets the pelvis.
  • The head of the femur fits into a depression in the pelvis, called the acetabulum, and forms a ball and socket joint (like the shoulder), which allows the leg to move in several different directions.
  • The main movements of the hip that occur in sport are flexion and extension.
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The Knee Joint

  • The knee joint allows the lower leg to move relative to the upper leg while supporting the body's weight.
  • The knee is a hinge joint formed between two bones: the femur and the tibia.
  • The patella lies in front of the femur and is the bone we feel at the front of the knee.
  • It is not actually part of the knee joint.
  • Between the femur and tibia is a layer of tough, rubbery cartilage known as the meniscus, which is the cartilage that often talked about when describing knee injuries.
  • The meniscus acts as a shock absorber inside the such as running and jumping.
  • Many strong ligaments surround the knee to reinforce its structure and hold its bones in place.
  • Two internal ligaments (the anterior and posterior cruciate ligaments) also help to keep the bones of the knee in their correct positions, and again are well-known to sportspeople as they are often damaged.
  • As the knee is a hinge joint, its function is to permit the flexion and extension of the lower leg relative to the thigh. 
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The Ankle Joint

  • The ankle joint is formed by the lower leg bones (the tibia and fibula) and the talus bone of the foot.
  • These three bones form a synovial hinge joint.
  • The ankle works as a hinge joint, but the forward and backward movements have special names,(plantar flexion and dorsiflexion).
  • Numerous ligaments work together to limit extreme movements and dislocations of the ankle joint while providing sufficient flexibility that helps the body walk on uneven surfaces and maintain its balance.
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Key Terms

  • Support - Bones keep us upright and hold muscles and organs in place.
  • Protection - Some bones surround and protect vital organs from damage.
  • Long Bones - The bones of the legs and arms. Long bones support the weight of the body and help with gross movements.
  • Movement - Muscles contract to pull the bones of the skeleton.
  • Joint - Place where two or more bones meet.
  • Synovial Joint - Type of joint commonly found in the limbs; contains a synovial membrane that produces synovial fluid.
  • Synovial Membrane - Produces synovial fluid to lubricate the joint.
  • Cartilage - Covers ends of bones providing a smooth, friction-free surface.
  • Synovial Fluid - Produced by the synovial membrane to lubricate the joint.
  • Capsule - Tough fibrous tissue - surrounds synovial joints; usually supported by ligaments.
  • Ligaments - Join bone to bone.
  • Dislocation - When the bones of a joint separate from their normal position.
  • Bursae - Fluid-filled bag that helps reduce friction in a joint. 
  • Tendon - Attaches muscles to bones.
  • Hinge Joint - Joint that allows flexion and extension.
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Key Terms

  • Flexion - Movement where the angle between bones reduces.
  • Extension - Movement where the angle between bones increases.
  • Vertebrae - Bones that form the spine or backbone.
  • Ball And Socket Joint - Joint that allows many movements - flexion and extension; abduction and adduction; and rotation.
  • Range Of Movement - A measure of the flexibility of a joint in terms of the different movements allowed.
  • Abduction - Movement where limbs are moved away from the body.
  • Adduction - Movement where limbs are moved back towards the body.
  • Rotation - Turning a limb along its long axis.
  • Meniscus - Cartilage acting as a shock absorber between the tibia and femur in the knee joint.
  • Cruciate Ligaments - Attach tibia to femur in the knee joint.
  • Plantar Flexion - Movement at ankle where the toes are pointed towards the ground.
  • Dorsiflexion - Movement at the ankle where the toes are pulled up towards the knee. 
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