Ulnar nerve entrapment occurs when structures, such as muscles, bones, or ligaments, put too much pressure on a nerve, leading to numbness, tingling, pain, and in severe cases, muscle weakness or atrophy (wasting away). The ulnar nerve can be entrapped in the elbow or wrist.
Shoulder pain when throwing a ball is not so surprising when you consider the complexity of the shoulder joint and what it takes to perform that motion. To move your shoulder joint, the muscles, tendons, ligaments, and bones all have to move in a synchronized and stable pattern. Because of this, subtle abnormalities can lead to shoulder pain and discomfort when you are throwing or afterward.