The neuromuscular junction is the site of the signal exchange. The steps of this process in vertebrates occur as follows:(`) The action potential reaches the axon terminal. (2) Voltage-dependent calcium gates open, allowing calcium to enter the axon terminal.he neuromuscular junction is the site of the signal exchange. The steps of this process in vertebrates occur as follows:(`) The action potential reaches the axon terminal. (2) Voltage-dependent calcium gates open, allowing calcium to enter the axon terminal.
Sudden onset pain on the outer side of the foot can be from a fracture of the 5th Metatarsal and injuries to this bone are a common sports injury. Causes of pain on the outside of the foot are listed here: 1  Midtarsal Joint Sprain A mid tarsal joint sprain is an injury to the ligaments holding the mid tarsal joint together causing pain in the outside middle of the foot. 2  Peroneus Brevis Tendon Injury The Peroneus Brevis tendon inserts into the 5th matatarsal bone on the outside of the foot.
Foot pain may be caused by many different diseases, deformities, biomechanical conditions, improper footwear, or injuries. Infectious disease, viruses, fungi, and bacteria can cause foot pain. Plantar warts on the bottom of the foot are caused by a virus and can cause irritation and pain. Athlete's foot, which is caused by a fungus, can lead to foot irritation and pain. A common cause of foot pain is an ingrown toenail.