MEMOIRS 
OF THE 
' ' . 
BOSTON SOCIETY OF NATURAL HISTORY; 
VOLUME IV, NUMBER X. 
FUSION OF HANDS. 
WITH PLATES XUII — XLIV. 
By THOMAS DWIGHT, ' M.I)., LL.D. 
Parkman Professor of Anatomy at Harvard University. 
BOSTON: 
PUBLISHED BY TIIE SOCIETY. 
August, 1892. XIII. Fusion of Hands. 
Br Thomas Dwight, m. d., ll.d. 
Paekman Professor of Anatomy at Harvard University. 
Cases of polydactylism in which the increase of the number of fingers clearly springs 
from the fusion of two more or less complete hands and forearms are extremely uncom- 
mon. There are several, for the most part rather imperfect, accounts of this condition 
as seen in living persons, or in undissected specimens, or recorded in the plates of old 
authors, but there seems to be no dissection like the one about to be described in any 
museum, nor any description of a similar dissection in literature. This one, indeed, was 
described forty years ago by Harvard’s distinguished Professor of Morbid Anatomy, the 
late Dr. J. B. S. Jackson, but the dissection had not been carried far enough to show 
some of the most important features, the account was inadequate, and in parts wanting 
in the anatomical accuracy which is so essential, but can hardly be expected from any 
other than a trained anatomist. Moreover the account appeared merely in an abstract of 
» the Proceedings of the Boston Society for Medical Improvement which was published in 
the American Journal of the Medical Sciences, Vol. XXV, January, 1853, p. 91. It is 
practically buried. It is indexed in the Journal as “Malformation” without any 
qualification whatever. Thus this most remarkable case is not mentioned by the most 
exhaustive writers on the subject. The specimen originally belonged to the Cabinet of 
the Boston Society for Medical Improvement which some years ago came into the pos- 
session of the Harvard Medical School. It seems proper to bring it forth from the 
obscurity in which it has remained so long, especially as it is particularly valuable in 
connection with a recent observation on the living by Dr. F. Jolly of Berlin. 
A preliminary glance at the bibliography will help to the better appreciation of this 
case. The literature is far from satisfactory. It is all the more obscure from the diversity 
of interpretations and from the difficulty which often exists in deciding in which class a 
particular case belongs. The following seem to be undoubted cases of the fusion of two 
more or less perfect hands. In some of these cases we have no question that the fusion 
extends into the forearm and even beyond the elbow. 
[Read April 20, 1892.] 
MEMOIRS BOSTON SOC. NAT. HIST., VOI„. IV. 2 
THOMAS DWIGITT ON THE 
1. Rueff. Be Conceptu. Frankfurt, 1587, Plate 41. In the text it is stated that 
there are. twelve fingers but, according to Morand and to Taruffi, the plate shows a child 
having two hands joined by the ulnar side, each with five fingers. There were also 
double feet. 
2. Ambrosini in Aldrovandi. Mon.strorum Historia. Bonn, 1642, pp. 495 and 
497. A foetus with two hands on each arm with five fingers each and joined on the ulnar 
side. 
3. Kerkring. Observat. Anat. Amsterdam, 1670, p. 15, Obs. XX, with plate. 
A skeleton of a boy with seven fingers on each hand of which the longest were in the 
middle. On the right there were seven metacarpals but a thumb could not be recognized. 
On the left hand there were apparently five metacarpal bones. The first phalanx of 
the thumb arose on the outside of the 7th finger. One foot had eight toes and the 
other nine. [This is on the authority of Taruffi. It seems the least certain of these 
cases.] 
4. Du Courai. Journal des Savants. 1696. An infant with eight fingers on the 
right hand, of which the two indices were joined together as well as the two little fingers. 
[It is not easy to see how this could occur unless the hands were put face to face. | There 
were seven fingers on the left hand of which the indices were joined and the rest separate. 
It seems from the context that there were no thumbs. Both hands were bent inwards 
on the wrists and could not be extended. The metacarpus was a third longer than usual. 
Each foot had seven toes, of which the great toes of each foot were united. The head 
was monstrous. 
5. Giulio Obsequente. Grammatico Latino. Deprodigiis. A girl with four hands 
and four feet. 
6. Wirtensotin J. Bissertatio. Berlin, 1855. A human monster with four hands and 
four feet in the Berlin Museum. [Taruffi, from whom this reference is taken, states that 
he was not able to verify this observation.] 
7. Murray. Medico-Chirurgical Trans. Vol. XLVI, London, 1863. This is a very 
noteworthy case especially in connection with the one which is the subject of this paper. 
A woman, thirty-eight years old, living at Brighton, had two hands of four fingers each 
on the left arm, united at the radial side. ‘‘The fingers of both hands are clubbed at 
their tips. The middle and ring fingers of the supernumerary hand are webbed as far as 
their proximal joints and the movements of the fingers of this hand are somewhat stiff 
and imperfect. The thumbs seem to be represented only by the prominence on the dor- 
sal surface seen in figure 3.” This is a very poorly shown little projection apparently on 
the back of the proximal phalanx of the index of the normal hand. [It may be advis- 
able to point out that when, as in this case, we have two hands united by corresponding 
sides, one of them must be a right hand and the other a left hand. The one which is of FUSION OF HANDS. 
3 
the same side as the arm is the normal hand; the other the extra one.] The two sets of 
fingers could be opposed to each other. It seems that the woman when at work scrubbing 
the door rested on the back of the flexed carpus. Mr. Murray says: “From the rigidly 
arched conformation of the metacarpal portion of the double hand, it is evident that 
she could not lean on the palm.” The woman was otherwise well-formed. There was 
nothing of the kind in her family as far as she knew, and she had a normal child. The 
rest may be given in Mr. Murray’s own words. “The shoulder joint is natural. The ex- 
ternal condyloid ridge of the humerus is strongly defined. The elbow joint may be fully 
extended, but flexion cannot be carried further than is represented in Fig. 1,” [say to an 
angle of 120° with the humerus] “and the impediment seems to be the unusually large 
coronoid process of the ulna. The muscles and tendons of the forearm are so prominent 
that it is not easy to decide whether there is a second radius or ulna; but after numerous 
examinations made under favorable circumstances, I feel sure that the duplicity of bony 
structure begins at the carpus. Pronation and supination are freely performed.” It will 
be necessary to review these statements in the light which the present case throws on the 
internal structure of the forearm. 
8. Giraldes. Maladies Chirurgiccdes des Enfants. A case of a child’s hand with 
eight fingers in two sets and no thumb.1 A clear case of two nearly perfect hands fused at 
the radial sides. Giraldes refers to two similar specimens which, having injected and dis- 
sected, he placed in the musee cle Vamphitheatre des hopitaux. Of these Fort2 says in 
1869, uNous ne les civons pas trouvees. 
9. Giraldes. Bull. Soc. Chirurcj. Nov. 1865. M. Giraldes said: “I have had an op- 
portunity to see in my service a case of two entire hands on a single forearm. M. Gner- 
sant has seen the same person.” 
10. Fumagalli. Salle deformita congenita, della ditta. AnnaliUniv. cli Med. Milano. 
Vol. CCXVL, p. 305. 1871. A girl of four months without family predisposition had the 
right hand with eight fingers and no thumb. The two sets were united by the radial side. 
The double hand was anchylosed at a right angle to the forearm. The extra fingers had 
less motion than the normal ones. Their metacarpal bones were incomplete. 
11. Kuhxt. Virchow's Archiv. Band L VI, 1872. A German recruit twenty-one years 
old. Each hand consists of the ulnar half of two hands fused. The left hand consists of 
five fingers and no thumb. Three of the fingers apparently are of the left hand to which 
are added the ring and little fingers of a right hand. The right hand is less symmetrical. 
There are the three normal fingers of the ulnar side to which are added two fingers and a 
rudiment of a third of a left hand. According to the drawing, there is no abnormal flexion. 
1 This is the case erroneously attributed to Lanceraux 2 Des difl'ormites congenitales et acquise des doigts. 
in Ziegler’s Lehrbuch der pathologisclien Anatomie, 1892. These, Paris, 18G9. 4 
THOMAS DWIGHT ON THE 
The man was a workingman, and it is stated could do only coarse work (grobe Arbeiten). 
Nothing is said of the motions of the elbow. 
12. Gerriiini. Gazetta Med. Ital-Lombardo. No. 51. 1874. A boy live years old 
had six fingers on each hand divided into two groups. It is a clear case of the fusion of 
the ulnar sides of two hands. 
13. Langalli. La scienza elapratica. Pavia, 1875. An account of a wax model of 
a girl’s right hand found in a museum. Four fingers of three phalanges represent the nor- 
mal hand. The other four represent the absent thumb. Again there seems no doubt that 
this is a case of fusion. 
14. F. Jolly. Festschrift, Rudolf Virchow gewidmet. Band I. Berlin, 1891. This 
case is the most important one. The individual presenting the peculiarity was a living 
man, twenty-five years old, without hereditary predisposition, but of peculiar and deficient 
mental organization. The deformity was on the left arm, which from the shoulder down 
was smaller and shorter than the right. The fingers were in two groups of three, each 
consisting of a middle, ring, and little finger. The fingers of the group on the outer, or 
radial side, were those of a right hand. One proximal phalanx of the extra set was broad at 
its base so as to articulate with two metacarpal bones, of which there were seven in all. 
The internal condyle of the humerus and the normal ulna were easy to feel. There was 
no distinct external condyle and no head of the radius could be made out. Along the front 
of the humerus in the region where the biceps should be “ there is felt instead of that 
muscle a strong bony ridge which runs to the bend of the elbow and ends in a blunt prom- 
inence.” As well as could be judged on the living, it would seem as if on about the 
lower two thirds of the humerus there was an outgrowth, or another bone fused with it on 
the front and outer side. The outer bone of the forearm feels at the wrist more like an 
ulna than a radius. The man can raise his arm at the shoulder but little above a horizon- 
tal line. It can, however, be brought passively to a vertical position. The photograph 
shows a flattening in the deltoid region. The elbow can be flexed actively only to an 
angle of about 150°. Passive flexion does not exceed 120°, the above mentioned bony 
process locking the joint. There is next to no pronation and supination. The hand can be 
both actively and passively flexed and extended. So can, also, the fingers either individ- 
ually or in groups. The photograph shows a tendency to flexion and pronation of the 
hand which the author does not mention. Dr. Jolly thinks one would be inclined to be- 
lieve that the ulnar parts of two hands and two forearms had been fused together while the 
radial constituents had in part been lost. He says that whether his interpretation, made 
on the living, is the correct one will be shown certainly when there is a chance to examine 
an analagous case. 
It should be noticed that of the preceding cases in 1, 2, 5, 6, and 9 there are two practi- 
cally complete hands. In cases 1 and 2 (if there be no mistake) these are joined on the 5 
FUSION OF HANDS. 
ulnar side. The point is not mentioned in cases 5, 6, and 9, which are of little value. 
Case 3 is unsatisfactory. It is certainly allowable to question whether the phalanx grow- 
ing in one case from the seventh finger is rightly called the thumb. If it be not a thumb 
this case may be considered the result of the fusion of the ulnar portions of two hands. 
Case 4 is also wanting in clearness. This leaves cases 7, 8, 10, 11, 12, 13, and 14 showing- 
fusion of the ulnar parts of the hands with suppression of more or less of the radial parts. 
For reasons which will appear later it is probable that in several of these, the duplication 
of one side and the suppression of the other are not limited to the hand. 
The next case is placed last, out of the chronological order, because, though the poly- 
dactylism is also due to the fusion of a part of an extra hand, it differs extremely from 
the others. 
15. Caere. Seance publique de la Societe Royale de Medecine, Chirurqie, et Phar- 
macia de Toulouse. 1838, ppj. 28-30. A goldsmith had on his right arm, beside the normal 
hand, an extra thumb and index finger. The latter thumb was next to the normal one 
and the index further from it showing that of course they belonged to a left hand. In- 
deed the two thumbs were united and had, according to Carre a common metacarpal joint. 
They were of equal size. They were flexed and extended together and had the power of 
spreading apart. The next finger arising from the outer side of the thumb was shaped 
like an index and had free motion in flexion, extension, and abduction. Besides the radius 
and ulna of the normal arm there was an extra radius on the outer side of the former, 
joined to it at the wrist, but separated from it above by an interval that could be felt. It had 
a joint of its own at the elbow. The motion of each bone could be felt, though pronation 
was impaired. The wrist was broad, implying the presence of additional bones. Nothing 
is said of a metacarpal bone for the new index. 
The present specimen is the left arm of a German machinist thirty-seven years old who 
died of chronic diarrhoea at the Massachusetts General Hospital in Boston in March, 1852. 
The arm was dissected by the late Dr. Ainsworth and made into an old-fashioned dried 
and varnished preparation showing most of the muscles of the upper extremity and the 
chief arteries and nerves of the forearm and hand. The parts, of course, are much 
shrunken and distorted, but the specimen has kept unchanged. There is no account of 
any deformity excepting of the left arm. From a hint in the Hospital Records and from 
an anecdote told by a physician who remembered him, it may be inferred that the patient 
was of loose morals and of a peculiar temperament, which is recorded from the similarity to 
Dr. Jolly’ s case. Figures 1 and 2 of plate 43 represent a cast taken after death which also is 
in the Museum of the Harvard Medical School. It shows a left forearm and a very broad 
hand having four normal fingers and, in place of the thumb, the three inner fingers of a right 
hand which were smaller than the others. The hand is flexed and somewhat pronated. 6 
THOMAS DWIGHT ON THE 
The dissected specimen is in much the same position but less strongly Hexed. The carpus 
and metacarpus are arched transversely so as to form a deep hollow in the hand. Dr. 
Jackson said in his report of the case to the Boston Society for Medical Improvement in 
the summer of 1852: “ the hand was not merely very useful to him in the way of his busi- 
ness, but gave him some advantages, he thought, in playing upon the piano, upon which 
instrument he was a performer. The three upper fingers, supposing the hand to be laid 
in a state of semipronation, were used efficiently as a thumb to oppose the three1 others. 
Various observations were made upon the motions of the hand and fingers.” Unfortu- 
nately these were not recorded in the hospital records and no notes bearing on them can 
be found among Dr. Jackson’s papers. The left arm was shorter than the right. Dr. 
Jackson gives the length of the left forearm as inches and that of the humerus as 10 
inches, the right ulna measuring nearly 10 inches and the humerus 13 inches. The 
scapula (Plate 43, fig. 3) is very peculiar. The supra-scapular notch is broad and so deep 
as to pass below the spine. The spine is so slanted that what is called the upper surface 
of the acromion looks almost directly outward. It is moreover very slight. The supra- 
spinous fossa is rudimentary. Its anterior portion is wanting and most of the posterior 
part of the floor is convex instead of concave. Dr. Jackson had perfectly recognized that 
the bones of the forearm were two ulnae, and that there was no radius; but the parts 
about the elbow were so hidden by the dried muscles that very important features could 
not be made out. I therefore had the specimen photographed before it was disturbed 
and rewrote the description of the soft parts. Then softening the dried muscles by a 
steam of almost boiling water I examined thoroughly the bones at the elbow and finally 
separated the arm from the forearm. The bones were then photographed. The wrist 
and hand were not further dissected as the preparation gave a good view of the dorsal 
aspect of the carpal bones. 
The Boxes. The forearm consists of the normal left ulna and of a right one in the 
place of the radius. The left one shows little that calls for comment, excepting that there is 
a projection outward at the place of the lesser sigmoid cavity to join a corresponding pro- 
jection from the other ulna. The upper surface of this projection articulates with the 
humerus. At the lower end the styloid process is less prominent than usual, and the head 
rather broad. The right or extra ulna is put on hind side before, that is the back of 
the olecranon projects forward over the front and outer aspect of the humerus. If the 
reader will place his right forearm on the outer side of the left one he will see that it is 
necessary for the ulna to be thus inverted if the thumbs are to touch and the palms to be 
continuous. This olecranon is thinner, flatter, and longer than normal. The coronoid 
1 Dr. Jackson says “ three ” instead of “four” as he though it lias some support in the plan of the extensor 
looked on the normal index as a central linger with three tendons, 
on either side of it—a view to which I cannot agree, FUSION OF HANDS. 
7 
process is rudimentary. From the side of this process and from the shaft just behind it 
arises the projection already referred to which meets a similar one from the normal ulna. 
(Plate 43, figs. 4, 5.) On the front of this there is a small articular surface looking forward 
which suggests a part of the convexity of the head of the radius. (Plate 44, fig. 1.) The 
upper articular surface shows a fissure separating it from the side of the olecranon which 
is not found in the normal ulna. These projections which touch each other are held to- 
gether by a strong interosseous ligament. The lower end of this ulna is very like the 
other only somewhat broader. The mode of union of the lower ends could not be seen 
without unwarrantable injury to the specimen. There can hardly have been any definite 
movement between these bones. Perhaps the ligaments may have permitted some irreg- 
ular sliding, but it is impossible to know. These bones have been described first because 
their nature is very clear and, once understood, is a key to the more difficult interpre- 
tation of the lower end of the humerus. 
The upper end of the humerus, concealed as it is by dried muscles, presents nothing note- 
worthy. There is no roughness for the attachment of the deltoid though the place for it 
is exposed. At the lower end the internal condyle is normal. It is quite unmistakable 
and is the most evident starting point. On the posterior surface is an olecranon fossa 
containing the normal olecranon. Beyond this is a thick rounded swelling, which, 
however, can hardly have been prominent before dissection. This is the normal outer 
condyle of the humerus jrfus another of a right humerus applied to the normal bone at 
nearly a right angle. A prominence somewhat to the outer side of the front of the nor- 
mal humerus represents the internal condyle of the right one. Between this and the 
fused external condyles is the joint for the right olecranon. There is but a faint trace 
of a fossa above it. Between the two internal condyles is a very small coronoid fossa on 
the front of the normal humerus. (Plate 43, fig. 4 ; plate 44, figs. 2, 3.) Thus it appears 
that to this left humerus is added a part of the lower end of a right one, so applied that 
the outer condyles are fused and the right inner condyle projects forward. To illustrate 
this I have made a model (Plate 44, fig. 4), by sawing off obliquely a great part of the 
outer condyle of a left humerus and applying to it a part of the lower end of a right hu- 
merus cut in the same way. Each humerus bears its own ulna. If the lateral expan- 
sions from the side of the coronoid processes and of the shaft behind them could be put 
on this would represent strikingly the relation of the bones at the elbow. 
The dorsal side of the carpus was well exposed in the original dissection but the 
description was not anatomically correct. The palmar aspect cannot be studied. The 
carpus is so convex that it is not possible to- get a satisfactory photograph. The 
relations of the bones are shown in the diagram in which they are represented 
as in a level plane. The proximal row consists of three bones besides the two 
pisiforms. At either side of the wrist is a cuneiform (os triquetrum), the dorsal 8 
THOMAS DWIGHT ON THE 
surface of which is uncommonly large. Between them is a bone which evidently is 
the result of the fusion of two semilu- 
nars. Its upper border is slightly 
notched. The pisiforms in the tendons 
of the ulnar flexors are displaced above 
the wrist on to the ulnae. Extension of 
the hand would have brought them on 
to the cuneiform bones. At each end 
of the second row there is an unciform 
bearing the little and ring fingers. Each 
rests on the corresponding cuneiform 
and touches the semilunar. Next come 
the two ossa magna, very symmet- 
rically disposed, each bearing the 
metacarpal bone of the middle finger. 
Their anterior halves diverge so as 
to leave an interval between them, 
behind which they touch each other, 
their heads resting side by side in the middle bone of the first row. In the notch 
between these bones is the trapezoid (os multanguhim minus) bearing the left index 
finger. Each middle finger touches it, the extra one by a broader surface than the 
normal one of the left hand. Still it is very symmetrically placed, so that from a 
view of the carpus alone it would be very hard to say to which side it belongs, 
but a glance at the specimen or at the cast is enough to show that the index 
finger belongs to the left hand. The metacarpal bones and phalanges require no 
special description. Those of the extra hand are somewhat smaller than the normal 
one. 
The Muscles. In this account Dr. Jackson’s description is followed as closely 
as possible. “The tendons of the latissimus clorsi, teres major and minor, sub- 
scapularis, infraspinatus, pectoralis major and minor are shown in the prepar- 
ation.” No mention is made of the supraspinatus. It has been stated that its fossa 
is rudimentary, if present at all it must have been very small. Dr. Jackson says 
that the deltoid had been removed. The absence of the roughness for its insertion 
and the lightness of the spine of the scapula and the acromion have been noted. 
These facts imply that it was small; an interesting point to be returned to later. 
uCoraco-brachialis small.” The biceps is obscure. There seems to be a small long 
head with probably a short head from the coracoid joining it low down. The long 
head is tendinous in the middle of the arm. This muscle is inserted into the extra 
DIAGRAM OF THE DORSAL ASPECT OF THE WRIST, FUSION OF HANDS. 
9 
internal condyle on the front of the humerus and perhaps also into the bone above 
it. “ One triceps sufficiently developed, with its three heads, and inserted into the 
perfect ulna. A second triceps, however, exists which is quite imperfectly developed; 
one head arises from just below the head of the humerus and a second 
from the lower part of the humerus. It is inserted into the imperfect olecranon 
but sends a tendon to the corresponding inner condyle, and receives a large slip from 
the other triceps; in structure it is muscular at each extremity and tendinous 
midway. A supernumerary slip of muscles,” appears through the capsule of the 
shoulder joint, like the long head of another biceps, “passes under the tendon of the 
pectoralis major and is inserted into the” extra internal condyle. “There was no well 
defined brachialis anticus." 
“In the foreaim the nancies usually connected with the radius and thumb are 
of course wanting. The superficial flexor of the fingers arises from the inner condyle 
corresponding to the perfect ulna; and sends a tendon to each finger, excepting the 
little finger of the imperfect side" [i. e. of the extra hand] “also a slip from the 
tendon of the index finger to the deep-seated tendon of the same.” The deep flexor 
arises in two parts. That for the normal hand arises chiefly from the normal ulna, 
partly from the interosseous membrane. The portion for the index has its muscular 
belly to a great extent separate from the rest. The part for the extra fingers arises 
almost if not quite exclusively from the inverted ulna. The little finger has only a 
small slip given off from the side of the tendon to the ring finger. “Flexor carpi 
ulnaris well developed on the perfect side, but on the other indistinct.” This indis- 
tinctness probably applies to the muscular belly, for the tendon is perfectly plain, 
and about as large as the normal one. Each goes to the pisiform bone and probably 
further. The second one seems to arise from the fibrous or muscular expansion at 
the outer side of the forearm near the inverted olecranon. No mention is made of a 
palmaris longus but a prominence in the cast indicates that it existed. “Pronator 
quadratus quite well marked, and also the interossei.v There is a slip of muscle or 
fascia, now dried and shrunken, running from the muscular mass below the internal 
condyle to the inverted ulna just below the elbow, strongly suggesting a rudimentary 
pronator radii teres. 
The system of the extensors is very complicated, and owing to the distortion of 
the dried muscles, not easy to make out perfectly. Still a good deal can be added 
to the original description. No extensores carpi idnares are found, nor is there any 
mention of them. They probably existed, however, as the groove for the tendon is 
slightly marked at the lower end of each ulna. A muscle, which may represent one 
of them, runs along the outer border of the forearm. It springs from a muscular mass 
on the free edge of the inverted ulna and is inserted apparently into the outer side of its 10 
THOMAS DWIGHT ON THE 
head sending a small slip to the base of the little finger. No such muscle has been 
preserved on the normal side. The common extensors of the fingers may be described 
as follows: A fleshly mass arises from the outer side of the normal olecranon, 
between it and the fused outer condyles, which sends extensor tendons to the four 
normal fingers. The one to the index is very small and soon separates from the 
others. There are the usual cross connections over the metacarpus between 
the tendons of the inner three fingers. An extensor proprbus indicts arises from the 
middle of the ulna and the interosseous membrane. The extensor of the extra hand 
arises partly in common with the other from the fused outer condyles and partly 
from the region of the inverted olecranon. It sends tendons, more or less fused, to 
the three extra digits and a small slip to the index of the normal hand which joins 
near its insertion the tendon of the extensor proprius indicis already mentioned. 
There arises also from the back of the inverted ulna and perhaps from the inter- 
osseous membrane a second extensor proprius indicis which is very much the largest 
of the four extensor tendons going to that finger. The next largest is the extensor 
proprius of the normal hand. There arises also from the back of the inverted ulna 
near the wrist another small muscle with a tendon going to the back of the mid- 
dle finger of the extra hand. Near this, but still lower, was another small muscle, the 
tendon of which had been cut near the base of the metacarpus. 
The Arteries. The brachial divides at about the junction of the middle and lower 
thirds of the humerus. The main continuation, which is the ulnar proper, runs deeply 
under the band thought to represent the pronator radii teres, to the deep part of the fore- 
arm where it gives off the interosseous. Above the elbow there is a branch running back- 
ward between the internal condyle and the olecranon. The interosseous branches are not 
easy to trace. There seems to be an anterior interosseous and three branches on the back 
of the forearm, one running on the membrane and one along each bone. At least two of 
these share in a network on the back of the carpus. Having reached the hand the ulnar 
artery runs obliquely across the palm to the cleft between the two sets of fingers, sup- 
plying the four normal fingers and the nearer side of the extra middle finger. * (Plate 44 
fig. 5.) The other branch of the brachial crosses the median nerve and runs, apparently 
superficially, to the outer side of the forearm. It supplies the little and ring fingers and 
the corresponding side of the middle finger of the supernumerary set. There is no 
anastomosis in the palm between the superficial branches of the two arteries. Each gives 
off a deep branch at the usual place, which forms a deep palmar arch from which some 
interosseous arteries spring. There is also an arterial network over the front of the carpal 
bones. The arteries of the deep parts of the hand cannot all be seen. 
The Nerves. The ulnar nerve proper, pursues a normal course and supplies the 
palmar aspect of the little finger and half the ring finger of the normal hand. Near the 11 
FUSION OF HANDS. 
wrist it gives off a very small posterior branch, which is not well preserved but which 
seems to have had less than the usual distribution. 
The median nerve is normal as far as the elbow, running to the inner side of the extra 
internal condyle. It is then lost in the dried fibers of the flexor sublimis, from which it 
emerges in two main divisions near the middle of the forearm. The inner of these soon 
divides into two, of which one supplies the adjacent sides of the ring and middle fingers 
and the other those of the middle and index fingers of the normal hand. The outer division 
of the median supplies the outer side of the index and both sides of the extra middle 
finger and one side of the extra ring finger. One of the branches to the index gives off 
a dorsal branch, and there is a doubtful one for the extra middle finger. The musculo- 
spiral nerve .passes behind the humerus as usual. A nerve which is undoubtedly continuous 
with it emerges from the hardened muscles over the fused outer condyles. It seems to 
be the radial branch changed into an ulnar. It runs with the extra ulnar artery to the 
hand, and sending a deep branch into the palm, goes to the little finger. Its continuation 
is plain along the side of the little finger nearest to the ring finger. There is a detached 
branch on the other side of the little finger which in all probability came from it. The 
deep branch sends a twig along the metacarpal bone of the ring finger. It probably sup- 
plied the side of the ring finger left unprovided for, but this is uncertain. Assuming this 
to have been the case, each ulnar nerve supplies the palmar surface of one finger and a half, 
the median supplying the remaining fingers of both hands. Unfortunately no dorsal branches 
except those mentioned have been preserved. 
Precisely of what nature and how extensive the movements in this extremity may 
have been is not easy to determine, but certain main facts are pretty evident. It is very 
probable from the structure of the spine of the scapula and the want of a deltoid ridge on 
the humerus that this muscle was a weak one. It is certain that the joint at the elbow 
allowed but a very limited amount of flexion. There can have been no true pronation and 
supination whatever, though some irregular movement of the two ulnae on the humerus 
•may have been possible. The cast with the strong cords at the front of the wrist, made 
probably by the ulnar flexors of the wrist and thepalmaris longus, seems to show conclusively 
that the hand was habitually flexed on the wrist and that no great extension can have 
been possible. The movements of the carpus are entirely a subject for speculation. It 
seems probable, however, that they were very free in various directions. Pronation 
and supination wrere doubtless performed at the shoulder and wrist, with the help of 
some change in the amount of extension at the elbow aided by vague lateral move- 
ments. 
A very curious feature of this extremity is the evident attempt of the extra ulna to 12 
THOMAS DWIGHT ON THE 
imitate a radius. On the front of the projection of the coronoid process is a surface 
resembling a part of the head of a radius and the lower end is broader than that of the 
ulna proper. Evidently the bone which developed as a supernumerary ulna made, so to 
speak, an effort to adapt itself to the functions of a radius. 
It is curious also to notice the change in the arteries from the normal type. Thus 
the brachial after a high division gave off an ulnar which runs deeply and gives origin to 
the interosseous, as is natural. The other branch runs at first superficially like a radial and 
then changes into an ulnar giving, as does the other, a characteristic deep branch to the 
palm. 
Still more curious is the origin from the musculo-spiral nerve of a branch in the place 
of the radial which becomes an ulnar. 
We now come to the most important part of the discussion, namely, to the resem- 
blance of the best described of the cases of this deformity to each other. It is more 
important than the aetiology, for any prospect of solving that question is extremely remote, 
while there is reason to hope that this dissection will serve as a clue to some of the cases 
already described. We shall now take in turn several of the features of this case. The 
one with which it shows a very striking resemblance is that recently reported by Jolly. 
In both the persons were German males and in both the deformity was on the left side. Dr. 
Jolly’s patient was of a peculiar mental and moral organization. There is some (but not 
conclusive) reason to think that the same could be said of this individual. In Dr. Jolly’s 
case there was flattening in the deltoid region and an inability to raise the arm above a 
horizontal line. The scapula is peculiar in this case and there is indication of weakness 
in the same region. In both cases the affected arm was shorter. What can be felt about 
the elbow in Jolly’s case agrees almost perfectly with the conditions of this one. Dr. 
Jolly states that where the biceps should be there is felt a strong bony ridge ending in a 
blunt prominence. This is the supernumerary internal condyle which may have had a 
stronger development than in this case. It is perhaps not impossible that the strong 
muscular or tendinous band running to it may have given the impression that the bone 
extended higher than was really the case. The restriction of angular motion and the 
almost complete absence of pronation and supination give strong confirmation of the 
similarity of the joints. The photograph shows something of a tendency to flexion and 
pronation of the hand at the wrist, which Dr. Jolly does not allude to, but it certainly is far 
less marked than in this case. It is hardly possible to doubt that, except in the condition 
of the wrist, the cases were similar in all important respects. It is not easy to guess what 
relation there can be between want of development of the shoulder muscles and this mal- 
formation of the hand and arm; but the simultaneous occurrence of these conditions in 
two cases cannot be regarded as accidental. 
Mr. Murray’s case is less fully reported and seems somewhat difficult to class with FUSION OF HANDS. 
13 
these two, but I believe it belongs with them. In two respects the case agrees with the 
present one : flexion at the elbow is very limited, and when working on the floor the 
woman supported herself on the back of the flexed carpus. This suggests a flexed position 
of the hand. The metacarpus was also, as in this case, strongly arched. Mr. Murray 
says that after many examinations he feels sure that the duplicity begins at the carpus. 
This means that there is no third or fourth bone in the forearm. It implies no reflection 
on him, to say that the idea of there being two ulnae and no radius may never have occurred 
to him. He finds a bony impediment to flexion at the elbow which he thinks is an 
unusually large coronoid. But such a malformation is, so far as I know, unheard of. 
Is it not more plausible in the light of these observations to believe that the obstacle was 
the supernumerary internal condyle or perhaps the inverted olecranon? Pronation and 
supination, he says, were freely performed. This is certainly a very serious difficulty. 
One might question, however, in the first place whether “freely” is equivalent to “per- 
fectly” ; and it must be remembered that to one not very much on his guard these move- 
ments are very deceptive. The part played by the shoulder is greater than is often 
believed. It is moreover not impossible that the articular surfaces at the elbow may have 
been such as to allow a certain amount of irregular motion, which with the aid of the 
shoulder and wrist joints, may have permitted a fair amount of twisting of the hand. With 
all respect to Mr. Murray I can but think it most likely that the forearm consisted of 
two ulnae. 
In the cases of Du Courai and of Fumagalli (Nos. 4 and 10) the hands could not 
be extended. As has been already pointed out, seven of these cases showed fusion of the 
ulnar sides of the hands with more or less suppression of the radial sides. The de- 
scriptions of most of the cases are very inadequate. Many of them are in children, in 
whom perhaps a want of the proper motions of the elbow would be more easily overlooked. 
It is probably more likely that such an oversight occurred, than that cases in which the hands 
were evidently fused, as in this specimen, should have had forearms of the normal struc- 
ture. The chief importance of this observation is that in connection with Dr. Jolly’s case 
it goes far to establish a type of a certain kind of polydactylism resulting from the fusion 
of the ulnar portions of two hands. As has been pointed out, in all the cases recorded in 
this paper, in which there is any statement of the fact, the fusion was of the ulnar portions 
of the hands, excepting in cases 1 and 2 and in 1*5, the remarkable observation by Carre, in 
which there was an additional thumb and forefinger and an extra radius. It is to be 
noticed in all these cases, which are at all adequately described, that the hands are fused 
by corresponding sides. There is no instance of the ulnar side of one hand being joined 
to the radial side of the other. 
The question as to the cause and the process of production of this deformity is very 
interesting but very obscure. The theory that amniotic folds may have caused a muti- 14 
THOMAS DWIGHT ON THE FUSION OF HANDS. 
lation, probably a splitting, which is followed by an attempt at duplication, is at first sight 
a very attractive one. Certain experiments on lizards’ tails give it support from analogy. 
It accounts for cases in which the lesion was so slight that but a part of one finger is 
involved, or so deep as to affect a whole extremity. There are, however, certain very serious 
difficulties. What, it may be asked, becomes of the parts that should form the radial 
side of the hand in a case like the present one ? Another difficulty is that in a large pro- 
portion of-the cases both hands and both feet are affected. Zander1 argues that there is 
no impossibility in the occurrence of symmetrical lesions by the amnion. In support of his 
views it may be stated that very often, perhaps usually, these malformations of both 
sides are not absolutely symmetrical, and therefore the more likely to have such an injury 
for their proximate cause. If these objections can be met this seems the most promising 
theory. Taruffi. while admitting our ignorance, speaks of “exaggerated gemmation.” which 
conveys no explanation. All are now agreed that there is nothing to be said in favor of a 
double germ. It is remarkable that this view should have survived so long. A century 
and a half ago M. de Mairan2 wrote on this subject: “II faut devorer bien des prodiges, 
lorsque on dit du bout des levres que la formation des monstres pent etre expliquee par 
la confusion des germes.” 
DESCRIPTION OF PLATES. 
The following letters have always the same significance. E, the fused external condyles; I, the normal internal 
condyle; I2, the extra internal condyle; 0,the normal olecranon; 02, the extra olecranon. 
PLATE 43. 
1. Cast of forearm and hand, showing the back of the elbow and the palm of the hand. 
2. The same cast, showing the back of the hand. 
3. The scapula and upper part of humerus. 
4. Back and outer side of elbow. 
5. Front of elbow. 
PLATE 44. 
1. Front of the upper end of the ulnae. R indicates an articular surface on the front of the extra ulna simulating 
a part of a radius. 
2. Lower end of the humerus seen from below. The anterior surface is above. 
3. Lower end of the humerus seen from the outer side. 
4. A model, showing the nature of the malformation. The piece of the extra humerus should, perhaps, have been 
put on so as to form more nearly a right angle with the left humerus. 
5. The front of the wrist and hand. IT A, ulnar artery; U A2, extra ulnar artery; U N, ulnar nerve; U Na. extra 
ulnar nerve. M, M, branches of median nerve. 
1 Virchow’s Archiv, Bel. 125, s. 479 and 480. 1891. 2 Hist. Acad., 1742. Memoirs Boston Soc. Nat. Hist., Vol. IV 
Plate 43 
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