While doing excision of cervical lymph nodes, inadveent injury to which nerve causes drooping of shoulder

If Cervical lymph node excision is done (may be in posterior triangle of Neck), Most common iatrogenically damaged nerve which is most superficial is spinal accessory Nerve Spinal accessory Nerve is coming from cranial cavity, passing through jugular foramen & supplies : Sternocleidomastoid - contracts while turning head to one side & Trapezius muscle - Causes elevation of the shoulder Damage to this nerve leads to paralysis of trapezius muscle & there would be drooping of shoulder (Difficulty in shrugging the shoulder & overhead abduction)