At the neuromuscular junction, muscle fibers are surrounded by the sarcolemma, which is the cell membrane, and contain sarcoplasm, or cytoplasm. The sarcolemma is adapted to form microscopic tubes known as transverse tubules, or T-tubules. These structures enable electrical currents, also called action potentials, to enter the cell. Within the sarcoplasm are specialized organelles that play critical roles in muscle function.

Sarcoplasmic reticulum (SR) stores calcium ions that are essential for triggering muscle contractions. Muscle fibers also contain myofibrils, which are contractile rods. These myofibrils are made up of even smaller units called myofilaments. Myofilaments are composed of contractile proteins arranged into repeating units known as sarcomeres. 

There are two main types of myofilaments: thin and thick filaments. Thin filaments are made primarily of the protein actin. Actin subunits feature a binding site for myosin, while tropomyosin helps stabilize the actin filament and blocks the myosin binding site under resting conditions. Troponin, another component of thin filaments, binds calcium ions to initiate contractions.

Thick filaments, on the other hand, are composed of the protein myosin. Each myosin molecule includes a tail region, a flexible hinge, and a head region. The head contains a site for ATP binding and another for binding to actin, allowing the interaction that powers muscle contraction.

A patient with botulism would usually experience symptoms related to muscle weakness and paralysis, since the toxin blocks acetylcholine release (a calcium ion channel blocker) at the neuromuscular junction. Common symptoms would include:

1. Muscle weakness.
2. Drooping eyelids.
3. Blurred or double vision.
4. Facial paralysis.
5. Shortness of breath.
6. General fatigue.
7. Paralysis.