Jalandhara bandha compresses the carotid sinuses. These are bodies located on the carotid arteries in the neck, which are the main arteries supplying blood to the brain. These carotid bodies are called baroreceptors and help to regulate and match the heart rate and blood pressure with the respiration system. These receptors feed messages to the brain through the sinus nerves, which in turn takes the necessary actions to balance the circulatory and respiratory systems. The carotid bodies become compressed if the blood pressure rises. This sends a message to the brain which takes steps to prevent this high blood pressure. In jalandhara bandha, these receptors are artificially compressed. This tends to prevent a sudden rise in blood pressure which would be expected when the breath is held for some time. This increases the duration of breath retention and so increases the effectiveness of practices such as nadi shodhana pranayama.
These carotid sinuses were well known in ancient times, as were also the sinus nerves. In the Shiva Samhita it says: “Stop the flow of the vijnana nadis (sinus nerves) with the second fingers (that is, press the side of the neck with your fingers). This gives siddhi (perfection) in the form of happiness and bliss.” (55, 56) We don’t suggest you try this for you will more than likely become unconscious if you are not careful. This is caused by reducing or preventing the blood flow to the brain. But the implications of the above verses are obvious; if you gently press these carotid sinuses then you will become very relaxed and perhaps a little faint. This can be a help in various other yogic practices that lead to meditational experience.
These carotid sinuses are widely known in modern times. Many people have fainted by mere pressure of these bodies. Some people seem to be more sensitive than others; a slight pressure is sufficient to put some people on their back. It is also widely known in wrestling, boxing, etc. where through discreet pressure on the opponent’s neck, it is possible to almost instantly finish the match. This is regarded as foul play.
It is also interesting to note that these carotid sinuses can be pressed to prevent or counteract tachycardia (fast heartbeat beyond the normal limit). This is often used in medical circles. A gentle massage of the carotid sinuses slows down the heart rate and brings about a faster normalization. However, this is not always the case. It depends on the ability to select exactly the right place for massage and to do it gently enough to prevent an increase in tension. That is, overpressurization of the carotid bodies could easily bring into mobilization the emergency activities of the body to induce greater flow of blood to the brain. This will tend to increase the heartbeat again which is exactly the opposite to that which is required. So care must be taken.
We have not discussed the carotid sinuses to encourage you to tamper with them. We have discussed them to show how jalandhara bandha acts directly on the physical body, and how one must be careful of overexertion during the practice.
Jalandhara bandha influences the individual at all levels: physical, psychic and mental. It controls the flow of prana in the body. This induces mental relaxation and can help to induce meditation. The pressurization of the carotid sinuses also helps to bring mental balance by slowing down the heart. Furthermore, this encourages introversion – one tends to become oblivious to the outside world. The whole nervous system and brain become sedated. One tends to become more one-pointed. All this is a great help in meditational practices.
Jalandhara bandha allows one to hold the breath for longer periods of time. Normally decrease of oxygen and increase of carbon dioxide in the system lead to an increase of the heart rate and harder breathing to compensate. This is initiated through the carotid sinuses. The artificial pressure of these sinuses during jalandhara bandha prevents this tendency. Therefore, one is able to hold the breath for much longer periods. This also helps to induce one-pointedness of mind for meditational practices.
This bandha closes the windpipe and compresses various organs in the throat. Notably it massages the thyroid gland which is located in the cavity of the throat. The whole body depends on this gland for perfect development and maintenance. Jalandhara bandha massages this gland and helps to render it efficient.