Final answer:
Trigger points in the splenius capitis muscle can be caused by overuse, muscle imbalances, or trauma/injury.
Step-by-step explanation:
Trigger points in the splenius capitis muscle can be caused by a variety of factors. One common cause is muscle overuse or strain, which can occur from activities like poor posture, repetitive movements, or prolonged sitting. Trigger points can also develop due to muscle imbalances or biomechanical issues, such as a muscle that is too weak or too tight. Additionally, trigger points can be caused by trauma or injury to the muscle, such as whiplash from a car accident or a direct blow to the head or neck.