Muscle

Muscle & Skeletal Development

The arrow in the CT scan above indicates which of these findings?

  1. Abnormal findings, compression fracture of the vertebral arch
  2. Normal findings, thoracic spinal cord enlargement
  3. Normal findings, unfused neural arch in a child
  4. Abnormal findings, osteoporotic costal facets
  5. Normal findings, unfused neurocentral joint in a child

Spina bifida is a result of which structure failing to fuse?

  1. Spinal cord
  2. Vertebral arch
  3. Dura mater
  4. Vertebral body
  5. Arachnoid mater

The cranium, mandible, vertebral column, ribs, and sternum are derived from which of the following?

  1. Myotome
  2. Dermatome
  3. Sclerotome
  4. Dermomyotome
  5. Mesenchyme

 

What developmental process has occurred in a case of acrania?

  1. Failure of the cranial end of the neural tube to close
  2. Significant fusion of cranial sutures
  3. Failure to develop a neurocranium
  4. Failure of neural crest cells to develop the viscerocranium
  5. Early ossification of the 1st pharyngeal arch and temporal bones

 

The T3 vertebrae is formed by which embryological precursors?

  1. T3 loose mesenchymal cells and T4 dense mesenchymal cells
  2. T3 loose mesenchymal cells and T4 loose mesenchymal cells
  3. T3 dense mesenchymal cells and T4 dense mesenchymal cells
  4. T3 dense mesenchymal cells and T4 loose mesenchymal cells
  5. Strong independent T3 mesenchymal cells that don’t need no man

Skeletal Muscle Physiology 

What is the difference between a motor end plate potential and an action potential at the neuromuscular junction?

  1. The motor end plate is ligand-gated; the action potential is ligand-gated.
  2. The motor end plate is ligand-gated; the action potential is voltage-gated.
  3. The motor end plate is voltage-gated; the action potential is ligand-gated.
  4. The motor end plate is voltage-gated; the action potential is voltage-gated.
  5. The motor end plate has no potential; the action potential generates all of the reactions in the neuromuscular junction.

Exposure of Ryanodine receptors to high concentrations of insecticides completely disable the RYR1 channel. What effect does this have on contraction?

  1. Paralysis of skeletal muscle
  2. Paralysis of cardiac muscle
  3. Decreased contraction of skeletal muscle
  4. Decreased contraction of cardiac muscle
  5. Increased contraction of cardiac muscle

Which of the following statements about the control of contraction in skeletal muscles is correct?

  1. In skeletal muscles, contraction is initiated by a nerve impulse closing voltage-gated Ca2+ channels in the plasma membrane.
  2. In skeletal muscles, contraction is initiated by a nerve impulse opening voltage-gated Ca2+ channels in the plasma membrane.
  3. In skeletal muscles, contraction is initiated by a nerve impulse closing voltage-gated Ca2+ channels in the sarcoplasmic reticulum membrane.
  4. In skeletal muscles, contraction is initiated by a nerve impulse opening voltage-gated Ca2+ channels in the sarcoplasmic reticulum membrane.
  5. In skeletal muscles, contraction is initiated by phosphorylation of the myosin light chain.

Tetrodotoxin is a potent neurotoxin. Which site of action does this neurotoxin manipulate?

  1. Acetylcholine release
  2. Acetylcholinesterase
  3. Endplate Potential
  4. Muscle Contraction
  5. Nerve action potential

Which of the following statements about the contraction of skeletal muscle is correct?

  1. The power stroke of skeletal muscle contraction occurs when the myosin head hydrolyses ATP.
  2. The power stroke of skeletal muscle contraction occurs when the myosin head binds ATP.
  3. The power stroke of skeletal muscle contraction occurs when the myosin head releases ATP.
  4. The power stroke of skeletal muscle contraction occurs when the myosin head releases ADP and Pi.
  5. The power stroke of skeletal muscle contraction occurs when the actin binds ATP

Hypocalcemia leads to which of the following?

  1. Increased excitability of motor neurons caused by hypocalcemia leads to tetany.
  2. Increased excitability of motor neurons caused by hypocalcemia leads to twitch.
  3. Decreased excitability of motor neurons caused by hypocalcemia lead to tetany.
  4. Increased membrane potential caused by hypocalcemia leads to twitch.
  5. Decreased membrane potential caused by hypocalcemia leads to twitch.

Gastrocnemius has a significantly shorter fiber length than tibialis anterior. Which of these best describes the relationship between these two muscles?

  1. Velocity and force are independent of length.
  2. Gastrocnemius has a greater velocity and less force than tibialis anterior.
  3. Gastrocnemius has less velocity and a greater force than tibialis anterior.
  4. Gastrocnemius has a greater velocity and a greater force than tibialis anterior.
  5. Gastrocnemius has less velocity and less force than tibialis anterior.

Which type of muscle has a high mitochondrial density and consists of small fibers?

  1. Slow-oxidative
  2. Fast-Oxidative
  3. Fast-Glycolytic
  4. Very Fast-Glycolytic
  5. Slow-Glycolytic

Which intracellular factor plays a role in skeletal muscle fatigue?

  1. Increase in glycogen circulation
  2. Decrease in ADP/ATP ratio
  3. Inorganic phosphate concentration increase
  4. Decrease in lactic acid
  5. Increased electrolyte concentration within the cell

Cross Bridging is influenced by which of these?

  1. Velocity of contraction
  2. Muscle fiber recruitment
  3. Force production
  4. A & C
  5. All of the above

Slow-oxidative muscle fibers include the recruitment of which of the following?

  1. Type Ia
  2. Type I fibers
  3. Type IIa fibers
  4. Type IIx fibers
  5. Type IIb fibers

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