Typically musculoskeletal - meaning the cause is due to the biomechanical physical system of muscles, ligaments, tendons and skeleton.
This can include cervical spine, discs, supporting musculature or nerves in this area
May be traumatic, meaning it has developed post-injury/ accident, and indicates temporary or permanent damage to the musculoskeletal structures. Your doctor will assess this based on your history and exam findings
Most likely if it has been long standing and not traumatic in origin, it is biomechanical, meaning it has developed over a period of time, due to weaknesses, imbalances, adaptive changes due to prolonged postures. This usually results in some structures underworking, leading to other structures over working and becoming fatigued or damaged.
Prolonged postures being the main cause of this type of neck pain can include sitting at a desk the majority of your day and sleeping postures and positions.
Other causes of neck pain can include joint irritation, nerve entrapment, shoulder injuries, visceral referral or neurological conditions.