THE CREMASTER-REFLEX. 
S. Weir Mitchell, M. D. 
Member of the National Academy of Sciences. 
[Reprinted from Journal of Nbrvous and Mrntal Disease, October, 1879.] 
TN 1864 my attention was first called to the reflex move- 
ments of the cremaster muscles by a case in which a bul- 
le wound of the inside of the thigh and of the sciatic nerve, 
caused retraction of the testicle for several hours. 
In 1872, in my work on " Nerve Injuries," p. 137, I men- 
tioned this case and briefly described the cremaster-reflex and 
the region of skin capable of producing it. 
Within a year I have more carefully re-studied the subject 
with the hope of finding new and useful diagnostic help in 
cases of spinal disease. I have been disappointed in attaining 
valuable results in this direction, but I have learned enough 
that is curious and physiologically interesting to make it 
worth while to state with brevity the results of my observa- 
tions. 
The muscle slips which constitute the cremaster are por- 
tions of the lower edge of the belly of the internal oblique 
muscle and transversalis. The reflex arc arises on one hand 
in the skin of a large part of the thigh by twigs of the anterior 2 
Mitchell- Th e Cremaster- Reflex. 
crural, internal cutaneous, middle cutaneous, two saphenous, 
and anterior twig of obturator. 
Through the lumbar enlargement of the cord the arch is 
completed by means of the genital branch of the genito-crural 
trunk, which innervates the cremaster. 
In boys the cremaster muscle acts in many cases rhythmically 
with the other abdominal muscles, so that the testicles rise 
during inspiration and fall during expiration, as occurs in the 
ram, the*goat, and the dog, in which animals section of the cord 
arrests this movement.*- A like rhythmical activity is some- 
times seen in adults, but usually it is lost before the age of 
twenty. Most young lads and many adults enjoy voluntary 
power to raise the two testicles at once, and a few persons can 
at will elevate either testicle singly. 
In very few, however, even of the young, is the control of the 
will equal over both testicles. One rises quicker or more com- 
pletely than the other, and nearly always one hangs lower than 
the other at all times. 
The cremaster-reflex I described simply in 1872 as capable 
of being awakened by a touch or pinch of a definite region 
of the thigh extending from the groin nearly to the knee. 
Jastrowsky in 1875 describes this reflex as arising on irrita- 
tions of the inner side of the thigh, and that it is best ob- 
tained in the area of the saphena major nerve about a hand's 
breadth above the internal condyle in the notch between the 
inner border of the sartorius and the vastus internus. Bosen- 
bach's and Ilinze's papers I have been unable to obtain, and 
do not know how far these authors have studied the limits of 
this reflex. According to very careful observations made by 
Drs. Sinkler, Alison, and myself, the region within which we 
are capable of causing cremaster movement when the skin is 
touched or pinched is quite extensive in a lad of six to ten 
years, in whom it is best seen. To learn its limits the observer 
must bear in mind that certain precautions are necessary. 
As the scrotum acts at once in a cold atmosphere, and by draw- 
ing up the gland obscures the results of cremaster motion, it is 
* Jastrowsky, Berlin, klin. Wochenschrift, Aug., 1875. "On Cremaster- 
Reflex." Mitchell- The Cremaster- Reflex. 
3 
well to examine the phenomena when the parts are relaxed 
and pendant, in a warm room, and this is especially needful 
in young and strong adults in whom the scrotal purse acts 
well and steadily. 
It is also desirable to make the examination so as not to tire 
the muscle or exhaust the centres, as happens in adults more 
than in boys. In young lads the cremaster-reflex is easily caused 
by touching or pinching the whole thigh, with the exception 
of a band of skin which nearly always may be represented as 
forming the postero-lateral third of the circumference of the 
thigh. Within this area no touch or pinch causes cremas- 
ter reflex until as we approach the edge of the imaginary 
boundary, it begins to show and increases as we come around 
the thigh, until we enter a band of excessive sensitiveness. 
This region, bounded by the groin and perinaeum, is broad 
above and narrows below, and ceases at or below the knee. 
Within this area, according to Jastrowsky, lies a limited and 
most sensitive region. I think him wrong, however, as to 
this being always the most excitable region, since in many 
people-boys as» well as adults-the best cremaster-reflex is 
had from irritations addressed to parts on the inner aspect of 
the thigh, and very high up. 
These, then, are the usual limits of the cremaster-reflex 
region, although it is sometimes far. less and sometimes far 
more extensive; but extreme limitations of its area are more 
apt to occur in adults. When least extensive in the healthy 
boy it is found to cover the inner third of the thigh, and to 
cease anteriorly near the middle line of the front of the thigh, 
and also to fail us above the knee. When largest, it covers 
the lower third of the belly, all of the space first mentioned 
by me as its u#ual territory, and descends down the inside of 
the leg-over a space which narrows as it goes down, and 
sometimes includes a large part of the calf of the leg. 
In adults, as 1 have said, the excitor region becomes more 
restricted. When smallest it occupies a space on the inner 
thigh, which is broad above and sometimes begins at the line 
of the perinaeum, and sometimes a little below-is irregular 
in shape, but commonly narrows below and ends above the 
inner side of the knee. In a few people the excitor region is 4 
Mitchell- The Cremaster-Reflex. 
even less than this, and in numbers of adults it does not ex- 
ist at all. Jastrowsky thinks that cremaster-reflex is apt to 
be lost in the fat. I am sure that in old age it is diminished, 
or even destroyed, and that something in adult life, perhaps 
the constant contact of our clothes, lessens its activity-as I 
have never seen it absent in the young, and have many times 
seen none in vigorous adults. 
Wearing- of trusses, old hernia, and extreme cases of vari- 
cocele, all lessen or destroy it, and as a rule, though not a con- 
stant one, when the cremaster-reflex is absent the volitional 
control is feeble or absent; while on the other hand, a very 
few healthy people who move the testicles easily by will have 
no cremaster-reflex. 
It is, I think, most remarkable that the excitor region, 
never, as far as I have seen, includes the scrotum or penis. 
I am quite well satisfied that the eremaster-reflex varies 
from day to day in the same region. I mean that it varies 
not only as to intensity, but even in some persons as to its ex- 
istence, and for this there may be some easily conceivable 
causes. I shall also be able to show that it exhibits like varia- 
tions in some cases of disease. 
The readiness of the reflex response differs also in different 
persons. In boys the least touch anywhere in the excitor 
region causes an instantaneous and very complete movement 
of the testicle, which remains drawn up as long as the irrita- 
tions are repeated. It is in fact very difficult in the young to 
wear out the power of reflex response. In the mature adult, 
however, the cremaster movements are more tardy and less 
complete, and in some persons there is no movement when we 
merely touch the skin-a decided pinch of the irritable region 
being needed to cause motion of the testicle. ♦ In the grown 
man having a good capacity of reflex cremaster motion, when 
we pinch or touch the skin, at first the testicle rises well, but 
as we continue to excite the same space, the cremaster res- 
ponds more and more feebly until at last it entirely ceases to 
move, no matter how severely the skin be irritated. If now 
we touch or pinch the skin an inch or two away, the testicle 
is again drawn up, thus showing that we have worn out the 
capacity of the skin nerves and not that of the motor centre Mitch ell-The Cremaster- Reflex. 
5 
or of the muscle itself. Returning in a few minutes to the 
exhausted area we find it again capable of evoking cremaster 
motion. In others, the first effort to produce the cremaster- 
reflex totally fails, and it is only after a number of repetitions 
of the excitation that we succeed in bringing about move- 
ment of the testicle. 
As a rule which has infrequent exceptions, irritation of one 
side produces unilateral movement of the testicle of the same 
side. There are two forms of violation of this law. In 
the first, irritation of one thigh causes motion of the testicle 
of the same side and also, a moment later, less complete ac- 
tion on the testicle of the opposite side. In the other case, 
touching or pinching certain parts of the inner and usually' 
the lower half of the thigh causes reflex-cremaster motion on 
the other side only; while like irritations in other parts 
higher up give rise only to unilateral activity on the same side. 
The above statements sum up briefly all that I have been 
able to learn in regard to the normal cremaster-reflex. The 
extreme irregularity and uncertainty of this reflex in health, 
prepares us to find that it is of very little value in disease, 
and so far as I have carried my studies they but serve to illus- 
trate this view. Jastrowsky-op. cit.-says that in hemi- 
plegia there is sometimes no cremaster-reflex on either side 
during the stupor, but usually, on the day after attack, there 
is no motion on the hemiplegic side, and increased cremaster- 
reflex on the sound side-or rarely-irritation of the palsied 
side gives rise to crossed reflex, which lessens as the palsy 
improves, but may last for years. If, then, the palsied side 
becomes hypermsthetic the reflex relations are apt to be re- 
versed and the lame cremaster acts best. 
llinze (xS7. Peters!). Med. Wochenschrift, No. 35,1876) quotes 
Rosenbach (Arch. f. Psych., VI., 845), to the effect that in 10 
cases of hemiplegia cremaster-reflex and adominal-reflex were 
absent on the paralyzed side. The ages are not given. Of 
his own 21 cases the cremaster-reflex was absent in 18. 
My own observations correspond in substance with these. 
In four cases of recent and very decided hemiplegia, the cre- 
master-reflex was lost on the palsied side during the first few 
weeks. 6 
Mi ichell- The Cremaster-Reflex. 
I have met with the following cases of this palsy exhibiting 
a crossed reflex : 
Mr. L., set. 60, had a right hemiplegia which has so far re- 
covered that he remains slightly lame in arm and leg. The 
tendon-reflex is very good. The cremaster-reflex excellent on 
both sides, but a sharp pinch of the left inner side of the 
thigh causes flrst a good response from the left cremaster, and 
about two to three seconds later a slower but complete move- 
ment of the right testicle. No other than a limited region of 
skin gave rise to this phenomenon-which may have been a 
normal peculiarity. 
No. 1, set. 42, left hemiplegia from embolism; no hemi- 
anaesthesia ; cremaster-reflex, right, very good; cremaster- 
reflex, left, good reaction of both cremasters to touch of thigh. 
When the irritation is frequently repeated the left cremaster 
ceases to respond and the right still moves well, but a sharp 
pinch of left thigh again gives rise to bilateral cremaster ac- 
tion. Pinch of left knee inside, and of inner side left calf, 
causes left cremaster alone to move. 
No. 2. Syphilis; albuminuria; right hemiplegia, complete; 
nearly perfect recovery ; no hemianaesthesia ; cremaster-reflex, 
right, good ; cremaster-reflex, left, good on upper inner side of 
thigh for touch and pinch. The same excitations of lower third 
of inner thigh give rise to bilateral cremaster movement. 
No. 3 is a very curious case, and is the only one on record, 
as yet known to me, of clonic convulsive movements of the 
cremaster. It will induce me to ask attention to the condi- 
tion of this muscle in epileptic spasms. 
The patient, a man set. 72, a sea captain, had mitral disease 
and indurated arteries. I saw him in consultation with Dr. 
Betts. He was attacked March 17 with left hemiplegia, 
which, although complete, became rapidly better. March 24, 
he could move the leg and arm freely. At 4 a. m., he 
was seized with loss of consciousness, but without any new 
motor disturbance and without convulsion. When seen by 
me, at 3 p. m., he was moving all his limbs uneasily. He felt 
a pinch and showed annoyance in his face. He swallowed well 
but lay most of the time with closed eyes, the pupils sensitive 
to light and equal in size. Mitch ell- The Cremaster- Rejlex. 
7 
Cremaster-reflex, right, good, to touch. A pinch caused bi- 
lateral cremaster movement tardily on left. At intervals the 
left cremaster muscle exhibited a singular state of incessant 
motion. The testicle was drawn up, then fell, then rose and 
fell rapidly, while the right remained at rest. The cremaster 
in the belly-wall could be seen to be in almost constant motion, 
and the lower third of the abdominal wall was also twitching 
with some slighter display of like movements in the anterior 
face of the upper fourth of the left thigh. The urine dribbled 
away from an empty bladder. 
PARALYSIS OF INFANCY. 
E. S., aet. 3.-Two years' duration. Limited to right leg. 
There is some slight atrophy of the thigh muscles, but E. 
S. can move usefully all the leg and thigh muscles, although 
the triceps has not full power. Tendon-reflex perfect right 
and left; cremaster-reflex very good over an unusually large 
area of skin. - 
H. E., aet. 7.-Four years' duration. Complete loss of power 
to extend right thigh; with great wasting; can extend and 
flex foot; left leg sound ; tendon-reflex, right, absent; tendon- 
reflex, left, good ; cremaster-reflex, right, good; cremaster-re- 
flex, left, good, and is accompanied with crossed reflex. 
J. T., aet. 6.-Paralysis with atrophy of right leg for one 
year. The thigh muscles move well and are but little wasted ; 
the leg muscles are completely palsied; tendon-reflex was not 
studied by the observer; cremaster-reflex, right and left, good. 
J. M., aet. 6.-Palsy for five years. Left leg only affected ; 
atrophy of thigh and leg muscles (extensors); cannot extend 
leg or foot at all; muscles of calf partially palsied; plantar 
reflex, good ; tendon-reflex, absent, right and left; cremaster- 
reflex, absent, right and left. 
W. McC., aet. 4.-Palsied two and a half years. General 
palsy at first and limited to right leg in five weeks ; no mus- 
cular power in right leg or thigh, save just to stir the toes; 
leg wasted; tendon-reflex, absent, right and left; cremaster- 
reflex, absent, right; cremaster-reflex, slight, left. 
The cremaster-reflex was studied in four cases of incomplete 
paraplegia, with, more or less spastic contractions of the muscles. 8 
Mitchell-The Cremaster-Reflex. 
THE ERB-CHARCOT GROUP. 
No. 1, set. 42.-Typical case of the Erb and Charcot symp- 
tom-group, with extreme tendon-retlex in many situations; 
the cremaster-reflex, right, a trace ; cremaster-reflex, left, none. 
No. 2, set. 43.-Well marked case. Tendon-reflex exagger- 
ated ; cremaster-reflex, right, good-not unusual ; cremaster- 
reflex, left', good, and accompanied by crossed reflex, i. e., left 
thigh irritation gives bilateral cremaster-reflex. 
No. 3, set. 70.-Typical case of old spastic paraplegia, with 
convulsive actions in legs on irritation of soles. Exaggerated 
and violent tendon-reflex; cremaster-reflex, none right or left. 
No. 4, set. 56.-Posterior sclerosis, complicated as it ad- 
vanced with rigidity of legs; tendon-reflex, exaggerated; 
cremaster-reflex, right, a trace; cremaster-reflex, left, a trace. 
No. 5, a man set. 60. Much loss of sensation ; general 
wasting of legs; lessening power; feeble ' bladder; no eye 
lesions; no neuralgia; staggers with closed eyes; slight 
rigidity; tendon-reflex exaggerated; cremaster-reflex entirely 
absent; abdominal-reflex, absent; plantar-reflex, excessive. 
The latter case carries us into the ataxias. 
There were studied ten cases of well marked posterior scle- 
rosis-none of them in the paralytic stage. 
No. 1, set. 47.-Old case-has lasted 15 years. Tendon- 
reflex, none; cremaster-reflex, right, none; cremaster-reflex, 
left, none. 
No. 2, aet. 42.-Seven years' standing. Tendon-reflex, none ; 
cremaster-reflex, right, a trace ; cremaster reflex, left, none. 
No. 3, set. 40.-Three years; mild case; slight neuralgia; 
no eye symptoms, or bladder troubles. Tendon-reflex, right, 
none; tendon-reflex, left, quite distinct; cremaster-reflex, 
right, a trace; cremaster-reflex, left, none. 
No. 4, set. 17.-Posterior sclerosis with rare epileptic fits. 
Tendoij-reflex, none; cremaster-reflex, right, none; cremaster- 
reflex, left, good. 
No. 5, set. 38.-Rapid case, one year's duration. Tendon- 
reflex, none; cremaster-reflex, right, none; cremaster-reflex, 
left, a trace. 
No. 6, aet. 38.-Posterior sclerosis of three years' duration. 
Tendon-reflex, none ; atrophy of right testicle from mumps, Mitchell-The Cremaster-Reflex. 
9 
cremaster-reflex, right, good, but varies daily and is easily 
exhausted; cremaster-reflex, left, none; no left testicle, but 
well seen in the belly-region of cremaster on tickling thigh. 
No. 7, set. 48.-Six years' duration. Tendon-reflex and 
cremaster-reflex absent. 
No. 8, set. 42.-Early stage. Tendon-reflex, none: cre- 
master-reflex, right, good ; cremaster-reflex, left, perfect. 
No. 9, Mr. N., set. 35.-Commencing locomotor ataxia. 
Stands well, eyes shut; tendon-reflex, none; cremaster-reflex, 
right, is slight; cremaster-reflex, left, none; the left being 
the worst side. 
No. 10, set. 60.-Posterior sclerosis, earliest stage. Slight 
neuralgia; no eye symptoms; tendon-reflex absent; cremas- 
ter-reflex perfect on both sides. 
Except in Cases 8 and 10 the cremaster-reflex was lessened 
or lost in all of the instances given, but had not the certainty 
of the tendon-reflex, which was lost in all cases save one, and 
in that was absent in one leg.* 
In a case of dementia paralytica, set. 30, the tendon-reflex 
was utterly gone; cremaster-reflex was good, but not perfect. 
In a case of acute paralysis of the adult, limited to the right 
leg and quite complete, the tendon-reflex on right was absent; 
good on left; cremaster-reflex, right, good; cremaster-reflex, 
left, fair. 
It is clear enough, from what I have here said, that the ex- 
treme uncertainty of the cremaster-reflex in healthy adults, 
its variability, as well as its normal irregularities, such as 
double-reflex, and single crossed reflex, make it of little value 
in symptomatology-a conclusion re-enforced by all that I 
have seen of it in disease. 
In ataxia it is not lost as is tendon-reflex, nor in spastic spi- 
nal paralysis is it increased. In hemiplegias its history is 
curious rather than useful, and my conclusion is, that cremaster- 
reflex has as yet little or no value in symptomatology. The 
* The tendon-reflex has been examined with care at my clinic, and in 
my private practice in a far larger number of cases, and may, I think, be 
regarded as one of the most sure, and also one of the earliest signs of un- 
complicated posterior sclerosis. 
Case 3, of this series, is the only ataxic I have seen who had any rem- 
nant of tendon-reflex. Mitchell- The Cremaster-Reflex. 
10 
frequency of crossed reflex in hemiplegia is very interesting, 
as well as the fact of the area for double excitation being 
usually on the left side. Except in extreme cases of infantile 
palsy the cremaster-reflex does not seem to be disturbed, but 
in the graver examples of general loss of power in a limb, the 
cremaster-reflex appears to be absent or weakened on both 
sides. A larger experience is needed as to this point, since 
my attention having been but lately given to it I have here 
noted only five cases. 
Jastrowsky expresses his surprise that a reflex arc, which is 
presumed to complete itself in the lumbar cord, should be 
broken by cerebral disease causing hemiplegia. I had myself 
made a like reflection before reading the abstract of his paper, 
and I yet find difficulty in comprehending that, while the 
plantar-reflex should be exaggerated, the cremaster-reflex 
should be lessened or lost. 
To suppose that it alone of all reflex phenomena should be 
diminished by removal of cerebral influence seems to me so 
inconceivable, that I would prefer to believe that the cre- 
master-reflex track is completed in the brain-a somewhat 
violent supposition, but without which these anomalous phe- 
nomena seem to be incomprehensible.