Structure of Skeletal Muscles; Reflexes
Learning Objectives
1. Know that skeletal muscles contain myofibrils. Myofibrils are tubular organelles with thin filaments of actin and thick filaments of myosin arranged in sarcomeres. The interaction of myosin with actin is the basis for force generation in muscle, via the sliding filament mechanism. Be able to identify the A-band, the I band, and the Z-disc and to relate these to the structure of the sarcomere.
2. Know that skeletal muscle is striated due to the alignment of myofibrils within a skeletal muscle fiber (cell). Be able to identify the neuromuscular junction.
3. Be able to identify the set of muscles responsible for moving the arm and the leg that are listed in purple boldface. Know the actions performed by each muscle based on your understanding of its attachment points.
4. Be able to describe the neuronal circuitry for the stretch reflex. Know that the muscle spindle is a proprioceptor that detects changes in muscle length. Know that information from proprioceptors is integrated in the brain to provide a sense of limb position.
5. Know why the stretch reflex is tested in neurological evaluations. Be familiar with how an upper motor neuron disorder affects the stretch reflex. Be able to describe clonus.