Musculoskeletal Flashcards
What is the anatomical relationship between the following joints?
a. The elbow in relation to the shoulder joint?
b. The elbow in relation to the metacarpalphalangeal joint?
c. The shoulder in relation to the sterno-clavicular joint?
d. The sterno-clavicular joint in relation to the acromioclavicular
joint?
What is the anatomical relationship between the following joints?
a. The elbow in relation to the shoulder joint?
Distal
b. The elbow in relation to the metacarpalphalangeal joint?
Proximal
c. The shoulder in relation to the sterno-clavicular joint?
Lateral
d. The sterno-clavicular joint in relation to the acromioclavicular
joint?
Medial
Name two long bones, one short bone, and one flat bone in the upper limb:
Long bone = Humerus, Ulna, Radius, metacarpals;
Short Bone = any of the Carpal bones;
Flat bone = Scapula
Name two long bones, one short bone, and one flat bone in the upper limb:
Long bone = Humerus, Ulna, Radius, metacarpals;
Short Bone = any of the Carpal bones;
Flat bone = Scapula
What factors are responsible for the appearance of tuberosities, tubercles, ridges and grooves on a typical long bone?
Tuberosities, tubercles and ridges –
Grooves –
What factors are responsible for the appearance of tuberosities, tubercles, ridges and grooves on a typical long bone?
Tuberosities, tubercles and ridges – mechanical forces resulting from
attachment of muscles, tendons and ligaments to bone.
Grooves – pressures from adjacent structures e.g. nerves and blood vessels
State the 3 mechanical functions of bones?
State the mechanical functions of bones?
Provide the rigid framework that supports the body.
Protect vulnerable internal organs (e.g. brain, heart, lungs, womb – developing pregnancy (pelvis) etc.).
Make body movements possible by providing anchoring points for muscles and by acting as levers at the joints.
What is the function of red bone marrow and erythropoietin?
What is the function of red bone marrow and erythropoietin?
Production of erythrocytes (erythropoiesis) occurs in red bone marrow.
Erythropoietin is released from the kidney when blood oxygen levels are low (e.g., anaemia) to stimulate red blood cell production
Joints may also be classified by their structure. Give the distinctive features of cartilaginous and fibrous joints and give an examples of each.
Joints may also be classified by their structure. Give the distinctive features of cartilaginous and fibrous joints and give an examples of each.
fibrous joints e.g the suture between the bones of the skull- tight union dense connective tissue. Fixed.
cartilaginous joints e.g. the intervertebral discs of the spine, pubic symphysis allow for more movement between 2 bones than a fibrous joint but not as much as a highly mobile synovial joint.
synovial joints e.g. knee joint
Why do childrens fractures heal more quckly than adult fractures?
Why do childrens fractures heal more quckly than adult fractures?
In children the periosteum is relatively thicker, stronger and more active than in an adult.
The periosteum is a vascular membrane and is a major source of blood supply to the bone.
In children the supply of blood and oxygen is better.
The periosteum can be intact even when a bone has fractured because in children it is thicker thus helping reduce (align) the fracture fragments, allowing more rapid union.
What are the three main components of ALL synovial joints and what are the functions of synovial fluid?
What are the three main components of ALL synovial joints and what are the functions of synovial fluid?
Articular surfaces cornered by hyaline cartilage, separated by joint cavity
Synovial membrane (lining cavity) that secretes synovial fluid
Protective capsule surrounds the joint
A man is trapped under a car, there are no tools to help free him but a witness tries to move the car. However despite significant effort the individual cannot move the car at all. What type of muscle contraction is occurring in the bicep during this scenario?
A man is trapped under a car, there are no tools to help free him but a witness tries to move the car. However despite significant effort the individual cannot move the car at all. What type of muscle contraction is occurring in the bicep during this scenario?
Isometric contraction, as the muscle is exerting a force but is at a constant length.
Describe the sliding filament theory of muscle contraction and why it is called the sliding filament theory. Describe the action of the cross bridges that cause a power stroke. What is the role of calcium and ATP in muscle contraction and relaxation? –
Include these keywords in your description: actin, myosin, myosin head, ATP, ADP+P, power stroke, cross bridges, tropomyosin, troponin, Ca2+, sarcoplasm, sarcoplasmic reticulum.
The M line provides an attachment for myosin filaments and the Z line provides attachment for actin filaments. When the muscle is relaxed the protein, tropomyosin blocks the myosin binding site on the actin
Ca2+ binds to troponin on the actin myofilament, which undergoes a conformational change, this causes tropomyosin to move and reveal binding sites on actin for the myosin head groups.
The extended myosin heads bind to the actin and the bound ADP and phosphate molecule are released. The resulting formation is called a crossbridge.
The release of the ADP and phosphate cause the myosin heads to change back to their relaxed shape, so pulling the actin filaments toward the centre of the sarcomere. This movement is called the powerstroke.
The binding of another ATP molecule to the myosin heads trigger the release of myosin heads from the actin attachment sites.
The myosin heads acts as an ATPase. The breakdown of ATP to ADP and a single phosphate releases energy which extends the myosin head again.
If there is calcium present and there is a supply of ATP the cycle will repeat again. After the action potential has passed, the calcium channels close, calcium is pumped back into the sarcoplasmic reticulum, this allows troponin to return to its previous state and the muscle relaxes.
Bisphosphonates in the long-term treatment of osteoporosis can cause femoral fractures (high stress area) as they block osteoclast activity. Why is this the case?
This is rare but is a known but paradoxical side effect.
Osteoblasts and osteoclasts are coupled together and continually turn over bone, replacing old bone with new bone.
This is important in maintaining bone strength as the bone matrix doesn’t then fatigue over time and fracture.
The uncoupling of this activity eventually leads to poorer quality bone being layed down and micro fractures that eventually may cause overt fracture.
A 12-year-old boy is referred urgently by his GP. He has developed a limp. He has hip and knee pain too. There is no history of trauma, in fact he is rather overweight and sedentary. It’s got gradually worse over the last month. On examination he is holding his hip in passive external rotation and is out toeing on walking. He can weight bear to a degree. Although the hip can be passively externally rotated, internal rotation is very painful. The junior doctor orders an x-ray of his hip.
What might the doctor suspect?
What x-ray might he order?
What might the doctor suspect?
Slipped upper femoral epiphysis. During growth especially growth spurts the forces across the epiphyseal plate change resulting in increased chance of fracture and slippage.
Line of klein
What x-ray might he order?
Frog leg lateral xray of the hip. It is most sensitive at picking up the SUFE
A 6 year old boy has developed a mildly painful hip and is limping. He is not pyrexial and there has been no trauma. There are no other joints involved. It’s been some weeks. It’s mildly painful on rotation of the hip.
What key disease is important to exclude?
Perthes Disease
What other conditions can present with limp?
septic arthritis
proximal femoral osteomyelitis
proximal femoral fracture
acute or chronic slipped upper femoral epiphysis ( age of child main
difference)
transient synovitis ( often associated with a viral infection)
A 6 year old boy has developed a mildly painful hip and is limping. He is not pyrexial and there has been no trauma. There are no other joints involved. It’s been some weeks. It’s mildly painful on rotation of the hip.
What key disease is important to exclude?
What other conditions can present with limp?
It has been claimed that the cyclist Lance Armstrong changed the muscle fiber typing in his leg muscles via a training regime. In sprint and endurance cycling which fiber types would give you benefits and why?
It has been claimed that the cyclist Lance Armstrong changed the muscle fiber typing in his leg muscles via a training regime. In sprint and endurance cycling which fiber types would give you benefits and why?
Sprint cycling – fast fibers for short intense cycling the high levels of mitochondria and rich blood supply will be helpful
Endurance cycling- Slow fibers and they resist fatigue
In sprint and endurance athletes which sources of energy might you expect to be utilized by the skeletal muscle?
In sprint and endurance athletes which sources of energy might you expect to be utilized by the skeletal muscle?
Sprint- creatine phosphate for short bursts, followed by anaerobic conditions utilizing the glycolytic pathway
Endurance- in general oxidative phosphorylation is utilized but in defined periods, glycolytic pathways but be utilized.
What does the term claudication mean?
What does the term claudication mean?
Pain in the leg is induced by exercise, typically caused by obstruction of the arteries
Explain the difference between the two types of skeletal muscle contraction?
Explain the difference between the two types of skeletal muscle contraction?
Isotonic- where the muscle changes length under a constant force
Isometric- where the muscle maintains a constant length whilst exerting a
force.
What are the 4 sources of energy that muscles can utilize for contraction?
What are the 4 sources of energy that muscles can utilize for contraction?
Local ATP stores
Creatine phosphate
Glycolytic pathway
Oxidative phosphorylation
Which ion channels are involved in generating an action potential?
Which ion channels are involved in generating an action potential?
Voltage-dependent sodium channels
and
voltage-dependent potassium channels
What do you understand by the terms absolute refractory period and relative refractory period of a nerve fibre?
What do you understand by the terms absolute refractory period and relative refractory period of a nerve fibre?
The absolute refractory period is the period immediately following an action potential during which it is impossible to cause it to fire another AP no matter how strong a stimulus is applied.
The relative refractory period is the period which follows the absolute refractory period, during which a nerve fibre will fire a second action potential, but needs a stronger stimulus than usual to do so. In other words it is a period during which the threshold is raised.
Callum, aged 12, was paying football. He did a penalty and as he did so felt a sudden pain in the front of his thigh. He limped off the pitch. He localised his pain to his groin and upper thigh and pain on hip flexion and knee extension.
Which muscle is likely to be damaged?
Rectus femoris.
In adolescence the muscles and tendons are strong but the growth plates of the bones are still open and therefore a weak point. They are unmineralised and are still cartilaginous. Therefore these injuries can result in tendon avulsion. In children the muscles and tendons are not strong enough to damage the tendon or bone and generally don’t have the contractile force for muscletears. (If they fall / have a force applied across a bone they fracture.
In adults the growth plates have fused and the bone is therefore no longer vulnerable. The muscle contraction is strong enough to cause Muscle tears and this occurs rather than a tendon avulsion.
In what tissues is creatinine kinase found?
In what tissues is creatinine kinase found?
CK is found in the mitochondria and cytoplasm (sarcoplasm) of skeletal muscle (predominantly), cardiac muscle, brain, and other visceral tissues
In what conditions might the creatinine kinase level be raised in the blood?
In what conditions might the creatinine kinase level be raised in the blood?
Increased CK is predominantly used to diagnose neuromuscular diseases and acute myocardial infarction. Myocarditis also.
Neuromuscular disorders include: myopathies, muscular dystrophy, rhabdomyolysis, drug-induced myopathies, euroleptic malignant syndrome, malignant hyperthermia, and periodic paralyses.
Why do we use cardiac troponin as a measure of damaged cardiac muscle now and not the cardiac specific creatinine kinase (CKMB)?
CK-MB makes up 5-7% of CK in skeletal muscle. Therefore, skeletal muscle injury can sometimes cause elevated CK-MB levels, leading to misinterpretation.
CK can also be elevated in the absence of neuromuscular diseases or cardiac injury, such as after strenuous exercise, intramuscular injection, and with renal disease. There is also a wide range of normal depending on muscle mass. Because of this, the sensitivity and specificity are not as high as for troponin levels.
What is a motor unit?
What is a motor unit?
A motor unit is a motor neuron an (efferent lower motor neuron )and the muscle cells it innervates. This can be few or many cells (2000). The synapse between the LMN and the muscle cell is called the NM junction.
What’s the difference between the motor units of the quadriceps femoris and the flexors of the hand
What’s the difference between the motor units of the quadriceps femoris and the flexors of the hand
Large Motor Unit and small Motor Unit - power vs agility.
What causes mucles wasting?
What causes mucles wasting?
Continual synthesis and breakdown of proteins in muscle is part of the normal metabolism and homeostasis. Disuse alters the metabolism. With disuse There is a reduction in synthesis of muscle protein. The driving force for atrophy seems to be reduction in synthesis. Rather than an increase in protein breakdown.
With disuse there is a decrease in muscle mass and a reduction in the crosssectional area of muscle fibres. There is no decrease in numbers of fibres.
Conversely increase in contractile load increases muscle mass and strength.
Insulin resistance within the muscle secondary to disuse has a role in driving atrophy as well as other less well understood molecular mechanisms.
This is different from wasting secondary to nerve damage – do not get confused. LMN damage causes atrophy hypotonia fasciculation and weakness and hyporeflexia
Explain the terms spatial summation and temporal summation.
Explain the terms spatial summation and temporal summation.
Spatial summation- the recruitment of more motor units within a muscle so the muscle contracts with more force
Temporal summation- increase in the frequency of action potentials from a single motor unit towards a muscle.
Label dermatomes C5 to T1 and L1 to S3 on the following diagrams.
Indicate by shading precisely where you would test these nerves in a suspected lesion (e.g., radial nerve, dorsum of the hand, first web space).
