Chin Lock is the third of the main bandhas.
In Sanskrit jal means throat, jalan means net, and dharan means stream or flow. Jalandhara Bandha can be considered the throat lock that controls the flow of energy in the nerves and blood vessels of the neck.
It said in the Hatha Yoga Pradipika that “Chin Lock destroys old age and death and stops the downward flow of the nectar into the fire of life.” The text also states that it should be used at the end of inhalation (rechaka). Indeed, Chin Lock is essential for the practice of pranayama where the breath is held in (kumbaka). Then, by regulating the flow of prana to the head, it prevents headaches, dizziness, and a number of ailments of the eyes, throat, and ears that may otherwise develop.
To find Jalandhara Bandha sit up tall, either in a comfortable cross legged position or on your shins with your butt on your heals. Place the palm of your hands on your knees. Inhale slowly and deeply through your nose, and lower your chin into the notch between the sides of the collarbone, thus lengthening the back of the neck. This changes the shape of the throat and slows the breathing down.
To exit lift your chin, inhale the remainder of capacity into your lungs, and exhale.
Note that the neck should bend naturally, without any tension or force.
Unlike the first two, Jalandhara Bandha is normally performed in combination with specific breathing practices, and rarely done on its own. That said, it is immensely powerful, as it compresses the sinuses on the main arteries of the neck and in doing so helps regulate the circulatory and respiratory systems. The pressure on the throat helps to balance the thyroid and metabolism. And if no one is looking at you at work, engage Jalandhara Bandha as an instant trigger for mental relaxation as well as stress and anger relief.
Maha Bandha - The Great Lock.
Maha in Sanskrit means great, and Maha Bandha is the combination of the first three bandhas. It can used during pranayama and as a preparation for meditation.
Sit in a comfortable seat, on your shins or cross legged, palms of the hands on the thighs or knees. Inhale fully through your nose, and exhale completely through your nose. Squeeze squeeze squeeze until every last drop is out. Without inhaling engage Mula Bandha, then find Uddiyana Bandha. Inhale a tiny bit and lift your chest, and from there engage Jalandhara Bandha. Retain, pressing your palms down, as long as possible. When you have had enough, lift your head, inhale fully, and release all the bandhas.
Maha Bandha gives the benefits of all three bandhas and regulates the entire endocrine system.