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.
Ball of Foot Pain. Pain in the ball of the foot is a common result of tight calf muscles and overpronation. The most causes of ball of foot pain are: Metatarsalgia: a catch-all term for pain in the ball of the foot, metatarsalgia is generally used to describe pain and inflammation at the joints in the ball of the foot.