Yoga is an ancient and diverse practice that predates archaeological evidence, but is said to be about 5,000 years old. Over time, yoga has been adopted as a spiritual practice by Hindus, Buddhists, and Jains, but in the West has been almost completely divorced from its spiritual roots and used primarily as an exercise. Attached to the yogic practice are certain asanas, or poses, that have been adapted to be used mostly for their physical benefits. Some benefits of practicing yoga include increased strength, flexibility, weight loss, and even to calm the mind. Because there are several poses that stretch and open the spine and neck, you can use yoga as a remedy to relieve neck pain.
Prone Poses
Prone poses are poses in which you are facing the ground, often on your hands and knees or lying on your stomach. Two poses that can aid in relieving neck pain are upward facing dog and the cat/dog pose. To practice upward facing dog, lie flat on your stomach with your hands below your shoulders. Push into your arms and lift your entire body off the ground, with only your hands and feet on the ground, and then arch your back and bring your belly almost to the ground. Pull your shoulders back, and if it is comfortable, allow your head to roll back gently. Practice neck rolls in the pose as you see fit to help release tension in your neck. Cat/dog poses are done by resting on your hands and knees, and then inhale deeply and bend backwards; opening the neck and spine -- this is your "dog" position. On your exhale, round the back as much as possible and draw your navel inward, engaging the abdominals -- this is your "cat" pose.
Supine Poses
Supine poses refers to poses practiced on your back. Poses that help open and relax the neck include the bridge pose. To practice bridge pose, lie flat on your back and bend your knees so that your heels are directly below your knees. On your inhale, push down on your feet and lift your pelvis towards the ceiling -- keep your knees hip distance apart, no more or less. This pose will strengthen your legs and abdominal muscles, but it will also lengthen your spine while your head lies flat and supported on the ground, which may aid in neck pain.
Inversions
Inversions refer to poses in which you are upside down, or whenever your heart is higher than your head. Be careful when practicing these poses because they are for more advanced practitioners. One pose that helps lengthen and stretch the neck is called plow pose. To practice plow pose, lie on your back, feet extended out in front of you. Then bend your knees and lift your back up, placing your hands under your lower back to support yourself. Gradually lift your knees overhead, and then your hips, extending your feet behind you.
Precautions
If you have chronic neck pain, consult your local physician before you attempt to practice yoga. With all yoga poses, exercise caution before attempting, particularly if it is a pose you have not tried before. Do not listen to your yoga instructor more than your doctor or your own instinct, because while yoga has been known to aid in neck pain, your yoga instructor may not be sufficiently trained to help you with your injury. Yoga is a completely unregulated industry, and so you do not know what kind of training your instructor has had, particularly if you are taking yoga at a gym.


