EXPERIMENTS 
ON 
TIIE LARYNGEAL NERVES AND MUSCLES OF 
RESPIRATION, ETC., IN A CRIMINAL 
EXECUTED BY HANGING. 
By 
W. W. KEEN^U^ 
LECTURER ON ANATOMY IN TI SCHOOL OF ANATI^iK 
LECTURER ON PATHOLOGICAL ANATOMY IN TIIE JEFFERSON 
MEDICAL COLLEGE, ETC. 
[Read February 3, 1875.] 
In January, 187o, Dr. S. Weir Mitchell called my 
attention to a paper by Dr. George Johnson, read 
before the Royal Medical and Chirurgical Society, 
Dec. 8, 1874 {Med. Times and Gaz., Dec. 19, 1874, 
|). 700), “On the Laryngeal Symptoms which result 
from pressure of Aneurismal and other Tumors on 
the Vagus and Recurrent Nerves.” In this paper 
Dr. Johnson quotes two cases of bilateral palsy of 
the larynx observed during life by the laryngoscope, 
in which the post-mortem showed that the vagus and 
recurrent nerves of one side only, and not on both 
sides, were compressed, and he expressed the belief 
that “pressure on one recurrent nerve, which is an 
efferent motor nerve, will cause direct unilateral 
palsy of the larynx, but cannot cause either bilateral 
spasm or bilateral palsy; pressure on the trunk of 
the vagus, involving its afferent fibres, may cause 
both bilateral spasm and bilateral palsy of the 98 
KEEN, 
larynx.” The reason for this bilateral action he con- 
sidered to be the intimate connection between the 
nerve nuclei of the two sides, so that, according to 
Broadbent’s hypothesis, each nucleus possesses bi- 
lateral activity. Dr. D. Powell stated that he had 
obtained similar results in the dog, but called atten- 
tion to the difference that existed in different ani- 
mals, and that faradization of the recurrent in the cat 
produced abduction of the cords, and that Dr. J. 
Reid had produced bilateral spasm in the dog on gal- 
vanizing one recurrent only. 
Some years ago Dr. Mitchell had discovered the 
remarkable chiasm in the recurrent laryngeal nerves 
in the Chelonia. He had sought it in the cat and 
rabbit, but had not found it. lie had not, however, 
examined the dog, and these statements of Dr. John- 
son, coupled with Dr. Mitchell’s former discoveries, 
prompted the proposal that I should assist him in a 
few experiments to determine the facts in the dog, 
and the probabilities in man, of a chiasm of the 
minuter fibres of the recurrents, which, though not 
demonstrated anatomically, might yet be proved phy- 
siologically. 
A few days later, by the courtesy of Dr. F. F. 
Maury, I was invited to be present at the execution 
of Frederick Heidenblut, and it occurred to me that 
here was an opportunity to test the question on man 
himself, instead of the dog. Accordingly it was ar- 
ranged that Dr. Carl Seiler should make the laryn- 
geal examinations, while I dissected the nerves and 
faradized them, according to directions drawn up by 
Dr. Mitchell. I was also assisted by Drs. Maury, 
Butcher (the prison physician), T. H. Andrews, EXPERIMENTS ON THE LARYNGEAL NERVES, ETC. 
99 
T. G. Morton, and Kirkbride, and Messrs. Garrett 
and Biddle, medical students. 
Heidenblut was hanged at 10.45 A. M., January 20, 
1875. Alter hanging half an hour, his body was cut 
down and carried into a small room near by, when I 
dissected the left vagus and recurrent laryngeal 
nerves as low down as possible in the neck (being 
very careful not to cut any branches, or injure them 
by the forceps, etc.), and slipped a small piece of 
pure india-rubber cloth under each, as an insulator. 
The body was then placed in a chair, and the attempt 
made to observe the vocal chords in the ordinary way, 
but the mechanical disturbance caused by the rope, 
and the tenacious mucus which had gathered in the 
larynx, made this impossible, so that I was com- 
pelled to open the larynx between the thyroid carti- 
lage and the hyoid bone by a very small opening, 
just large enough for the mirror, when an excellent 
view of the chords was had by Dr. Seiler. Repeated 
faradization, both with weak and with strong cur- 
rents, and galvanization with from four cells up to 
•forty, of the recurrent and also of the vagus, pro- 
duced decided movements of the left chord only, and 
none of the right. I applied the two wires directly 
to each nerve, so that no other part should be in- 
volved, as might be the case if sponges were used. 
By these means I simulated the irritating action of a 
tumor as nearly as possible, and I found on later 
careful dissection that none of the fibres of the vagfus 
were probably injured, and the cerebral circuit 
broken. The knot in the rope had been tied under 
the left ear, the head was thrown to the right, and 
thus the main injury to the soft parts was on the 100 
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right side. The right sterno-mastoid muscle was 
cut completely in two, its two ends being held to- 
gether only by the connective tissue of its sheath. 
The left was only bruised. The vagus was not, so 
far as I could perceive, mechanically injured on 
either side. The superior laryngeal nerve was not 
mechanically injured, nor cut by opening the larynx. 
The hyoid bone was broken on both sides at the 
junction of the body and greater cornua. The verte- 
brae were neither broken nor dislocated, a condition I 
have verified in two other cases of judicial hanging. 
The definite conclusion to be drawn from the ex- 
periment is that no chiasm of the inferior laryngeal 
nerves exists. No reflex motion was observed in the 
larynx, but the mechanical violence in such a mode 
of death is so great, and yet its effects may so easily 
escape observation, that, I think, as yet, no rigorous 
conclusion can be stated until other similar experi- 
ments are made, in which this source of error is 
absent. 
At 12.10 P. M., having finished with the larynx, I 
proceeded to experiment on the muscles of respira- 
tion, a subject I had long desired, to investigate. I 
first dissected the left phrenic, and insulated it with 
rubber, as before. I tried both wires to the nerve, 
but neither with the eye nor with a tape measure en- 
circling the chest at the ensiform cartilage (marking 
291 inches), was the slightest movement observed. 
I tried then a wire to the nerve, and with a sponge 
followed the border of the diaphragm, and then with 
both sponges to the diaphragm ; but in no instance 
did I obtain the least response, either with the con- 
stant or the interrupted current. No reason could EXPERIMENTS ON THE LARYNGEAL NERVES, ETC. 
101 
be assigned for this failure to respond. Further dis- 
section of the nerve showed everything normal and 
apparently uninjured. 
I then proceeded to the intercostals. Probably no 
other muscles have been so variously interpreted as 
to their action, whether the inferences were drawn 
from theory as to how they must act mechanically, 
from direct dissection on the human body, from vivi- 
sections on the lower animals, from experiments on 
the dead body, or from faradization on the living. 
The most noteworthy modern observations are by 
Hutchinson (Todd's Cyc.Anat. andPhys. “Thorax”); 
Beau and Maissiat (Archiv. Gen., 1842); Sibson 
(Philos. Trans., 184(i); Traube (Beitray. zur Exp. 
Path. u. Phys., 184(i); Donders (Ilandb. tot der 
Natuurk. van der Gezond. J\Iensch., Utrecht, 1853); 
Ludwig (Lehrb. der Physiol., ii. 308); Budge (Die 
Wirkuny der Intercost. Muskeln), and Duchenne (Phy- 
siol. des Mcmvements, 1807, p. 041). The variety of 
opinion is seen in quoting these and other authors, as 
follows:— 
1st. Both the intercostals are inspirators. Borelli, 
Senac, Boerhaave, Winslow, Haller, Cuvier, Budge, 
Duchenne. 
2d. Both are expirators. Vesalius, Diemer- 
broeck, Sabatier, Beau and Maissiat, Longet (though 
he is in doubt). 
3d. The externals are expirators and the internals 
inspirators. Bartholin. 
4th. The externals arc inspirators and the internals 
are expirators. Spigelius, Vesting, Hainberger, 
Marcacci, Hutchinson, Donders, Ludwig, Flint, 102 
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Huxley, Marshall, Sibson (the last four especially, 
however, with modifications). 
5th. The internals and externals are both expira- 
tors and inspirators. Mayer, Magendie, Bouvier, 
Burdach, Cruveilhier. 
6th. They act together, but in one part of the chest 
are both inspirators, and in another both expirators. 
Behrens. 
7tli. They are neither expirators nor inspirators, 
but simply mechanically form a part of the chest- 
wall. Van Helmont, Arantius, Neucranzius. 
No one, however, that I can discover, has before 
faradized the dissected muscles directly on the re- 
cently dead body, as in this instance. 
At 12.26 P. M. I dissected oft* all the other mus- 
cles, and exposed the intercostals from the median 
line to the line of the axilla, and applied the inter- 
rupted current by two very small wet sponges, from 
the first intercostal space to the eighth. I first ap- 
plied them to the intercartilaginous portion of the 
internal intercostals, and found that they all raised 
the cartilage below them. The external intercostals 
were then faradized, when the upper rib was pulled 
down very markedly, while the lower was just per- 
ceptibly raised. The depression of the first rib was 
very slight, but, as each external intercostal was ex- 
amined in turn, the movement increased from the first 
to the seventh (the last four were not examined), 
while the elevation of the rib below varied but little. 
By means of hooks the fifth rib was fixed, and after- 
ward the sixth rib, and the fifth external muscle fara- 
dized, with the same result as before. In order not 
to confuse the action of the external with that of the EXPERIMENTS ON THE LARYNGEAL NERVES, ETC. 
103 
underlying internal intercostal, nor the action of the 
intercartilaginous portion of the internal with the 
remainder of tlie internal, the external intercostals in 
the fourth, fifth, and sixth spaces were now carefully 
dissected away, and the internal muscles faradized 
from the cartilages to the axillary line, and in each 
case with very slight depression of the upper rib and 
marked elevation of the lower rib. Hence the con- 
clusion was irresistible that the internal intercostals 
are inspirators, and the external expirators. I am 
aware of the imperfections of the observations. 
Nearly two hours had elapsed since death had oc- 
curred; the posterior half of the muscles was not 
examined, only three of the internals were examined 
where covered by the externals, no rigorous measure- 
ments were taken of the range of movement, etc.; 
but so far as they go they seem to warrant the con- 
clusion already stated, and to point out the road to 
the proper method of determining decisively the ac- 
tion of these muscles. 
Having but little time for further observation, I 
examined carefully but one muscle of the face. All 
had as yet perfectly retained their electro-muscular 
contractility. I placed one pole on the seventh 
nerve, and passed the other small sponge in the 
median line of the face, from the hair to the tip of 
the nose. I then placed one sponge on the middle of 
the nose, and passed the other up and down the middle 
line. At no point did I get any upward movement 
of the frontal muscle in its middle portion, but from 
just between the eyebrows down'to the middle of the 
nose, the pyramidalis nasi always pulled the skin 
down. Subsequent dissection showed a well-developed 104 
KEEN, EXPERIMENTS ON THE LARYNGEAL NERVES, ETC. 
pyramidal is and no interruption in the fibres of the 
occipito-frontal on the forehead, in the median line. 
I am disposed, therefore, with Mr. Darwin (Expres- 
sion in Man and Animals, p. 190), to regard the pyra- 
midalis nasi as the direct antagonist of the central 
portion of the occipito-frontal, and vice versa. 
I would also take occasion to point out what im- 
portant results this new method of investigation— 
the faradization of the muscles on the recently dead— 
promises to yield. In the living it is almost impossi- 
ble to obtain the action of one muscle alone, espe- 
cially in the face, where the emotions, pain, amuse- 
ment, etc., involuntarily arouse the action of other 
muscles. In the recently dead the results will be far 
more accurate, and therefore for the anatomist, the 
artist, and the physiologist, they are of the greatest 
interest and importance.