1. Skeletal Muscle Stimulation and Anatomy
Somatic motor neuron synapse and function
Acetylcholine mechanisms of action and breakdown
Neurotransmitter receptor mechanisms
Skeletal muscle structure from the sarcomere molecular components to the whole muscle.

2. Anatomy of the Neuromuscular Junction
Somatic motor neuron
Synapse
Motor endplate of muscle fiber membrane

3. Enlarged axon terminal =bouton Somatic motor neuron axon
A somatic motor neuron branches to multiple muscle fibers. One neuron + its target muscle fibers = a motor unit
Enlarged axon terminal =bouton
Somatic motor neuron axon
Muscle fiber (cell)
ACh (acetylcholine) is the neurotransmitter at all neuromuscular junctions. Not shown is how ACh is rapidly removed following release; otherwise, the action potentials would not cease causing continual contraction. Many drugs, including nerve gases, work at these locations by either blocking the neurotransmitter receptors or inhibiting the removal of the neurotransmitter.

5. Skeletal Muscle Fiber (=single cell)

6. Myofilaments Muscle Fibers Myofibrils Myofilaments Muscle Fibres Actin
Myosin
Myofibrils

7. Sarcomere structure

9. Scanning EM 1 5 4 2
1) Z disk; 2) length of thick filaments; 3) length of sarcomere; 4) intramuscular triglyceride droplet; 5) M-line (a cytoskeletal structure to hold the thick filaments in place. The numerous small black dots are glycogen molecule complexes. 3

10. Note the prevalence of Z-line streaming in Figure b.