Chokes and strangles are often confused, since they both involve applying pressure the the neck. Strangles are applied to the one or both of the carotid arteries at the side of the neck. Strangles are used to reduce or stop blood flow through the arteries to cause the person to feel faint or pass out. Chokes are applied to the trachea to block the flow of air to and from the lungs.
Forensic literature says that to kill a person by interrupting blood flow to the brain, you need to hold pressure for minimum two minutes, although the person may blackout much sooner. If applied to a person under stress during a struggle, a strangle may make the person unconscious almost immediately, while it may take several seconds for a calm person to pass out. Reay and Eisele's 1983 article in the American Journal of Forensic Pathology "Death from law enforcement neck holds" states that with the Judo-derived police carotid sleeper hold, blood flow to the head is reduced by an average of 85% in approximately six seconds.
Pressure to the carotids is applied to the lateral side of the neck which the anatomists call the "carotid triangle." This triangle is formed by the midline, anteriorly (front) from the apex of the chin to the upper part of the sternum (breast bone), superiorly (above) by the line formed by the lower border of the mandible (lower jaw bone) and posteriorly (behind) by the anterior border of the sternocleidomastoid muscle (strap muscle between the clavicle and to the bone of the skull behind the ear). In the center of this triangle are the common carotid artery and branches, the carotid bodies, internal jugular vein, vagus nerve and branches, superior laryngeal nerve, and cervical sympathetic trunk. No strong muscle protects this area.
Overlying this superior carotid triangle is only skin, superficial fascia which is usually thin, although there may be an appreciable amount of subcutaneous fat. Within the superficial fascia is an exceedingly thin (paper-thin) muscle, platysma muscle, which begins in the tela subcutaneous over the upper part of the thorax, passes over the clavicle (collar bone), and runs upward and somewhat medially in the neck and across the mandible to blend with superficially located facial muscles. The platysma muscle has no very important action, but will wrinkle transversely the skin of the neck and help to open the mouth. This muscle does not protect the underlying vital structures.
The pressure is applied in a certain manner, depending upon the technique, directly on these structures. It may from using be the fist or the collar of any clothing. Very often, it is the pressure of the distal end of the radius and the wrist which compresses the soft structures of the neck. Neck pressure of 250 mm of Hg or 5 kg of rope tension is required to occlude carotid arteries. The amount of pressure to collapse the airway is six times greater.
Koiwai, E. K. (1999). How Safe is Choking in Judo?
Ohlenkamp, Neil. (1995). Principles of Judo Choking Techniques. [Online]. Available: http://Judoinfo.com/chokes.htm [2004, December 31 ]. Used with permission.