The effects on the eyes may be such as to be followed by changes in the retina, and optic atrophy leading to loss of vision.
Parts of the neck pressed upon by clothing may escape ecchymosis, and present a white mark of almost normal skin.
HANGING
Death by hanging is caused by the more or less perfect suspension of the body by a cord applied around the neck, the weight of the body acting as the constricting force.
The body need not hang completely, partial suspension is sufficient to cause death. The ligature surrounds the neck above the thyroid cartilage, the epiglottis is pushed against the back of the pharynx, the base of the tongue and the soft parts are pressed into the cavity of the pharynx, so that the obliteration of the naso-pharyngeal and the laryngeal passages is complete. Death is due to asphyxia and pressure on the cervical blood-vessels, even if the air-passages be not completely occluded; stoppage of the cerebral circulation being sufficient to cause death; in such a case the signs of asphyxia are absent.
Consciousness is quickly lost, due to pressure on the vessels, and, for this reason, in accidental or suicidal hanging the person is prevented from making any effort to save himself.
Post-mortem Appearances.—The external appearances are more or less those described under “Death from suffocation.” In the greater number of cases the face bears a quiet, placid expression, no turgidity or lividity being noticeable. The eyes are usually half open, but not protruded, and the condition of the pupils variable. The tongue may be protruded, but just as often not. The face may be pale or livid, and a bluish colour present on the free border of the lips. Cyanosis and swelling of the face are only present when the death agony has been long; they soon disappear.
Ecchymosis of the conjunctiva, and on the outer surfaces of the lids may be present. The escape of urine, fæces, and semen may take place, but are not characteristic, and are extremely rare.
Casper states that in not one of the many cases he had examined of persons hanged has he ever “found an erection of the male organ,” and he also asserts that the emission of semen is extremely rare. Seminal emissions take place more frequently in persons who have been shot, and also in those who have been poisoned by irrespirable gases or by hydrocyanic acid. As a test of strangulation, it is therefore worthless. Tardieu, however, only noticed the escape of urine and fæces in two out of forty-one cases; it is by no means a test of hanging, as it may occur after death if the body is shaken in a cart, or roughly used when first found. A fat person dying of apoplexy may have a mark round the neck as if strangled. Injury to the spinal cord due to fracture or dislocation of the cervical vertebræ is rare in suicidal hanging. Fracture of the spinal ligaments and of the hyoid bone is also rare. Rupture of the internal and middle coats of the carotid arteries sometimes occurs. But it appears that considerable damage is done to the soft parts of the neck by the present judicial mode of hanging with the “long drop.”
Dr. Dyer has recorded (New York Medical Journal, vol. iii., 1866) some experiments he made on the eyes of a man and some dogs killed by hanging. He found certain transverse fissures across the lens, which he is inclined to think are characteristic of this mode of death. Dr. R. F. Hutchinson states that an invariable sign of death from hanging is the flow of saliva out of the mouth, down the chin, and straight down the chest. The appearance is unmistakable and invariable, and could not occur in a body hung up after death, the secretion of saliva being a living act (Chevers). Death from hanging may take place although the toes or other parts of the body rest on the ground. Death is complete in four or five minutes.