Complex sentence: Damage to the accessory nerve (XI) may lead to contralateral weakness in the trapezius, which can be tested by asking the subject to raise their shoulders or shrug, upon which the scapula will move out into a winged position if the nerve is damaged.
Split into simpler sentences: Damage to the accessory nerve (XI) may lead to contralateral weakness in the trapezius. This can be tested by asking the subject to raise their shoulders or shrug, upon which the scapula will move out into a winged position if the nerve is damaged.