Musculoskeletal system

• What is the structure of the system?

  ▪ cranium

  ▪ vertebrae

  ▪ clavicle

  ▪ sternum

  ▪ rib cage

  ▪ humerus

  ▪ radius

  ▪ ulna

  ▪ carpals

  ▪ metacarpals

  ▪ phalanges

  ▪ pelvis

  ▪ femur

  ▪ tibia

  ▪ fibula

  ▪ tarsals

  ▪ metatarsals
• What are the types of bones involved?

  ▪ long

  ▪ short

  ▪ flat

  ▪ irregular

  ▪ sesamoid
• What are long bones?

  These are cylinders of hard bone with soft sponges marrow inside. They are wider at each end than the middle.

  These form limbs.
• What are short bones?

  These are shorter and more square versions of long bones.

  They give a variety of movement with no loss of strength.
• What are flat bones?

  Hard bone sandwiching a layer of soft bone.

  This protects vital organs.
• What are irregular bones?

  They vary.

  Box shaped vertebrae which are strong and contain marrow or air filled cavities.
• What is a sesamoid bone?

  Small bones in the tendons, at regions where there is a lot of pressure.
• What are the types of joints involved?

  ▪ fibrous

  ▪ cartilaginous

  ▪ synovial
• What are fibrous joints?

  Also known as ‘immovable joints’ are where bones are fused together to create a structure. They’re joint by strong fibrous tissue.
• What are cartilaginous joints?

  They have bones connected by relatively flexible cartilage (fibrocartilage and hyaline cartilage) that allows some degree of movement, like the rib cage where the ribs are joined by cartilaginous joints that allow the ribs to move during breathing.

  Two main types:

  Primary (Immovable)

  • Secondary (Slightly moveable)
• What are synovial joints?

  These are found between bones that slide against eachother with little friction, to absorb compressive forces.

  They are flexible and moveable, like the hip joint.

  Synovial joints have cartilage providing cushioning between bones that are joined. They also have a synovial capsule consisting of connective tissue containing synovial fluid, which helps lubricate the joint, allowing smoother movement and reducing wear on bones.
• What are the functions of the system?

  • skeleton - provides support, protection, attachment for muscles/ligaments, is a source of blood production and stores minerals
  • muscles – facilitate movement and provide support
  • the sliding filament theory of musculoskeletal function in terms of thick and thin filaments sliding over one another to bring about contraction and relaxation, and their working as antagonist pairs
• How does ATP become ADP?

  During reactions requiring energy ATP is spent, making ADP. This is helped by ATPase.

  An ATP molecule looses its final phosphate due to ATPase, causing it to become ADP.

  . (ATPase)

  ATP———> ADP + Pi (energy)
• How does ADP become ATP?

  During respiration ADP is recharged into ATP, via the enzyme ATP synthesise.

  . (ATP synthesise)ADP + Pi ———> ATP
• What happens to muscles during contraction?

  The muscle gets shorter. The myosin stays the same length, as well as the actin. But they’re pulled towards the m-line of the sarcomere.
• Muscle contraction


  1. At rest the actin-myosin binding site is blocked by the tropomyosin

  2. When contracting an impulse arrives down a motor neurone, and calcium ions are released and bind to the troponin

  3. This causes the whole protein to move, revealing the binding site

  4. The myosin head then enters the binding site, forming an actin-myosin cross bridge, a type of bond

  5. The calcium activates the enzyme ATPase, which breaks down ATP to ADP. Energy is released, moving the myosin head to the side, pulling the actin with it

  6. ATP also provides energy to break the actin-myosin cross bridge

  7. The head then detaches and pings back to its starting position

  8. This whole process can then be repeated with the next binding site
• Explain the structure of the sarcomere proteins.

  The myosin has a globular head which has two binding sites. One for actin and one for ATP.

  The actin has an actin-myosin binding site, and two proteins called troponin and tropomyosin.
• What is an additional use of ATP in muscle contraction?

  ATP removes and pumps away all calcium ions, so the troponin and tropomyosin don’t always block the binding sites.
• How is rheumatoid arthritis caused?

  • genetics

  • hormones as it is 2-4 times more common in women

  • smoking
• How does rheumatoid arthritis impact the body?

  • oral health conditions like gum disease

  • heart inflammation and failure

  • inflammation of the lungs resulting in a difficulty breathing

  • bumpy skin

  • finger pain

  • hip pain

  • rheumatoid vasculitis (inflammation of the blood vessels causing organ and tissue damage)

  • an uneven stance

  • dry eyes

  • chest pain due to the inflamed lung lining

  • knee weakness and swelling.
• How do anti-rheumatic drugs relieve symptoms?

  These reduce inflammation, relieve pain, slow joint damage and enable activity through suppressing the immune system.

  These take a few months to relieve symptoms.

  Types of drugs include DMARD’s and biological treatments. A combination of DMARD (disease modifying anti rheumatic drugs) drugs will be offered to block the effects of the chemicals.

  Examples of anti rheumatic drugs are methotrexate, leflunomide and sulfasalazine. Methotrexate is typically prescribed first along side steroids.
• How do biological treatments relieve symptoms?

  Examples include monoclonal antibodies such as adilamumab. This binds to and inhibits the protein TNF-alpha that is released when the immune system attacks the joints.

  They are typically taken with methotrexate and if other DMARD’s aren’t working on their own.

  These are injections which stop the chemicals that cause the immune system to attack the joints.
• How does physiotherapy relive symptoms?

  This improves overall fitness, muscle strength and flexibility.

  This is a face to face session with a professional where hand/leg exercises may be done.

  They can also use heat and ice packs to soothe the affected areas. They also offer transcutaneous electrical nerve stimulation (TENS), which is a small pulse of electricity sent to the affected joint, numbing the nerves in the joint to ease pain.
• How does surgery relieve symptoms?

  This can treat joint damage

  Examples include carpal tunnel surgery, arthroscopy and an arthroplasty.
• Explain how rheumatoid arthritis works.

  The immune system mistakenly sends antibodies to the lining of the joints, where they then attack the tissue surrounding the joints. Specifically the synovial membrane and the cartilage of synovial joints.

  This causes thin layers of cells (synovium cells) to covers the joints, causing them to become sore and inflamed.

  This releases chemicals which damage nearby bones, cartilage, tendons, and ligaments. If this is not treated the chemicals can eventually cause the joints to loose shape and alignment, destroying them completely.
• What are the causes of muscular dystrophy?

  MD’s are caused by mutations in the genes for muscle proteins, particularly dystrophin which strengthens the muscle fibres and protects them from injury as they contract and relax.

  This causes changes to the muscle fibres and interferes with the muscles ability to function.
• How does MD impact the body?

  This causes muscle weakness and wasting due to the degeneration of the muscle cells.

  It typically starts with a particular group of muscles and then progresses to others.
• How do steroids relieve symptoms of MD?

  They can improve muscle strength and function for 6 months to 2 years in those with Duchenne MD, as they slow the process of muscle weakening.

  These are a tablet or a liquid and a daily dose is required.

  They have significant side effects when used long term like weight gain and excessive hair growth.
• How does physiotherapy relieve symptoms of MD?

  It can help maintain muscle strength and preserve flexibility, preventing stiff joints.
• How does low impact exercise relieve symptoms of MD?

  Things like swimming, walking and stretching can help gain and maintain muscle strength, movement and flexibility.

  This can also reduce fatigue, soreness and better their sleep.
• How does corrective surgery relieve symptoms of MD?

  It can correct physical problems that may occur in severe cases of MD.

  Children with Duchenne MD can develop scoliosis (curvature of the spine) and surgery can correct this, or prevent it from worsening.

  Other surgeries:

  • Tight joints: these can be loosened by lengthening or releasing tendons, improving movement.

  • Weak shoulder muscles: these may be improved through a scapular fixation, where the shoulder blades are fixed to the back of the ribs. Its effectiveness has not been evaluated.
• What is Collagen VI-related MD?

  This affect the muscles in the fingers, elbows, shoulders and ankles.
• What is oculopharyngeal MD?

  This affects the muscles in the upper eyelids and pharynx.

  Symptoms:

  • Droopy eyelids

  • Dysphagia

  • Progressive restriction of eye movement

  • Limb weakness around shoulders and hips.
• What is Distal MD?

  This affects the muscles in the lower legs and arms.
• What is Duchenne MD?

  The proximal muscles are affected (upper leg, pelvic, upper arms and shoulder area).

  This is caused by sex-linked alleles and is therefore more common in men.

  Symptoms typically appear between the ages of 1 and 2.

  • Difficulty walking

  • Difficulty standing

  • Difficulty climbing stairs

  • Behavioural or learning disabilities

  • Muscles around the pelvis and thighs appear bulkier