muscle does not exist. (Cloquet, op cit.) From this we infer, that those
parts of the muscles, E F, Plate 30, which at a subsequent period are
converted into a cremaster, entirely occupy the space L h. In the adult
body, where one of the testicles has been arrested in the inguinal
canal, the muscles, E F, do not present a defined arched margin, above
the vacant space L h, but are continued (as in the foetus) as low down
as the external abdominal ring. In the adult, where the testicle has
descended to the scrotum, the cremaster exists, and is serially
continuous with the muscles, E F, covering the space L h; the meaning of
which is, that the cremasteric parts of the muscles, E F, cover this
space. The name cremaster therefore must not cancel the fact that the
fibres so named are parts of the muscles, E F. Again, in the female
devoid of a cremaster, the muscles, E F, present of their full
quantities, having sustained no diminution of their bulk by the
formation of a cremaster. But when an external inguinal hernia occurs in
the female body, the bowel during its descent carries before it a
cremasteric covering at the expense of the muscles E F, just in the same
way as the testicle does in the foetus. (Cloquet.)
From the above-mentioned facts, viewed comparatively, it seems that the
following inferences may be legitimately drawn:--1st, that the space L h
does not naturally exist devoid of a muscular covering; for, in fact,
the cremaster overlies this situation; 2nd, that the name cremaster is
one given to the lower fibres of the internal oblique and transverse
muscles which cover this space; and 3rd, that to separate the
cremasteric elongation of these muscles, and then describe them as
presenting a defined arched margin, an inch or two above Poupart's
ligament, is an act as arbitrary on the part of the dissector as if he
were to subdivide these muscles still more, and, while regarding the
subdivisions as different structures, to give them names of different
signification. When once we consent to regard the cremaster as
constituted of the fibres originally proper to the muscles, E F, we then
are led to the discovery of the true relations of the cord in respect to
these muscles.
On removing the transverse muscle, we expose the inguinal part of the
transversalis fascia--the sixth inguinal layer, L h, Plate 30--K k,
Plate 31. This fascia or membrane affords a general lining to the
abdominal walls, in some parts of which it presents of a denser and
stronger texture than in others. It is stretched over the abdomen
between the muscles and the peritonaeum. The fascia iliaca, the fascia
pelvica, and the fascia transversalis, are only regional divisions of
the one general membrane. On viewing this fascia in its totality, I find
it to exhibit many features in common with those other fibrous
structures which envelope serous cavities. The transversalis fascia
supports externally the peritonaeum, in the same way as the dura mater
supports the arachnoid membrane, or as the pleural fascia supports the
serous pleura. While the serous membranes form completely shut sacs, the
fibrous membranes which lie external to those sacs are pierced by the
vessels which course between them and the serous membranes, and afford
sheaths or envelopes for these vessels in their passage from the
interior to the external parts. The sheath, H h, Plates 30 and 31, which
surrounds the spermatic vessels, and the sheath, R, Plate 31, which
envelopes the crural vessels, are elongations of the fascia
transversalis.
In the groin, the transversalis fascia, K k, Plate 31, presents, in
general, so dense a texture as to offer considerable resistance to
visceral pressure. Here it is stretched between the transverse muscle,
F, Plate 31, and the peritonaeum, I. It adheres to the external surface
of the peritonaeum, and to the internal surface of the transverse
muscle, by means of an intervening cellular tissue. It is connected
below to Poupart's ligament, along the line of which it joins the fascia
iliaca. It lines the lower posterior aspect of the rectus muscle, where
this is devoid of its sheath; and it is incorporated with f, the
conjoined tendon, thereby fencing the external abdominal ring.
Immediately above the middle of Poupart's ligament, this membrane, at
the point marked h, Plate 30, is pouched into a canal-shaped elongation,
which invests the spermatic vessels as far as the testicle in the
scrotum; and to this elongation is given the names "fascia spermatica
interna" (Cooper), "fascia infundibuliform" (Cloquet). The same part,
when it encloses an external oblique hernia, is named "fascia propria."
The neck or inlet of this funnel-shaped canal is oval, and named the
"internal abdominal ring." As this ring looks towards the interior of
the abdomen, and forms the entrance of the funnel-shaped canal, it
cannot of course be seen from before until we slit open this canal.
Compare the parts marked H h in Plates 30 and 31.
The inguinal and iliac portions of the fascia transversalis join along
the line of Poupart's ligament, A C. The iliac vessels, in their passage
to the thigh, encounter the fascia at the middle third of the crural
arch formed by the ligament, and take an investment (the sheath, R) from
the fascia. The fore part of this sheath is mentioned as formed by the
fascia transversalis--the back part by the fascia iliaca; but these
distinctions are merely nominal, and it is therefore unnecessary to
dwell upon them. The sheath of the femoral vessels is also
funnel-shaped, and surrounds them on all sides. Its broad entrance lies
beneath the middle of Poupart's ligament. Several septa are met with in
its interior. These serve to separate the femoral vessels from each
other. The femoral vein, O, Plate 30, is separated from the falciform
margin, S s, of the saphenous opening by one of these septa. Between
this septum and the falx an interval occurs, and through it the crural
hernia usually descends. These parts will be more particularly noticed
when considering the anatomy of crural hernia.
Beneath the fascia transversalis is found the subserous cellular
membrane, which serves as a connecting medium between the fascia and the
peritonaeum. This cellular membrane may be considered as the seventh
inguinal layer. It is described by Scarpa (sull' Ernie) as forming an
investment for the spermatic vessels inside the sheath, where it is
copious, especially in old inguinal hernia. It is also sometimes mixed
with fatty tissue. In it is found embedded the infantile cord--the
remains of the upper part of the peritoneal tunica vaginalis--a
structure which will be considered in connexion with congenital herniae.
By removing the subserous cellular tissue, we lay bare the peritonaeum,
which forms the eighth layer of the inguinal region. Upon it the
epigastric and spermatic vessels are seen to rest. These vessels course
between the fascia transversalis and the peritonaeum. The internal ring
which is formed in the fascia, K h, may be now seen to be closed by the
peritonaeum, I. The inguinal canal, therefore, does not, in the normal
state of these parts, communicate with the general serous cavity; and
here it must be evident that before the bowel, which is situated
immediately behind the peritonaeum, I, can be received into the canal, H
h, it must either rupture that membrane, or elongate it in the form of a
sac.
The exact position which the epigastric, L, Plate 31, and spermatic
vessels, M, bear in respect to the internal ring, is a point of chief
importance in the surgical anatomy of the groin; for the various forms
of herniae which protrude through this part have an intimate relation to
these vessels. The epigastric artery, in general, arises from the
external iliac, close above the middle of Poupart's ligament, and
ascends the inguinal wall in an oblique course towards the navel. It
applies itself to the inner border of the internal ring, and here it is
crossed on its outer side by the spermatic vessels, as these are about
to enter the inguinal canal.
The inguinal canal is the natural channel through which the spermatic
vessels traverse the groin on their way to the testicle in the scrotum.
In the remarks which have been already made respecting the several
layers of structures found in the groin, I endeavoured to realize the
idea of an inguinal canal as consisting of elongations of these layers
invaginated the one within the other, the outermost layer being the
integument of the groin elongated into the scrotal skin, whilst the
innermost layer consisted of the transversalis fascia elongated into the
fascia spermatica interna, or sheath. The peritonaeum, which forms the
eighth layer of the groin, was seen to be drawn across the internal ring
of this canal above in such a way as to close it completely, whilst all
the other layers, seven in number, were described as being continued
over the spermatic vessels in the form of funnel-shaped investments, as
far down as the testicle.
With the ideas of an inguinal canal thus naturally constituted, I need
not hesitate to assert that the form, the extent, and the boundaries of
the inguinal canal, as given by the descriptive anatomist, are purely
conventional, and do not exist until after dissection; for which reason,
and also because the form and condition of these parts so described and
dissected do not appear absolutely to correspond in any two individuals,
I omit to mention the scale of measurements drawn up by some eminent
surgeons, with the object of determining the precise relative position
of the several parts of the inguinal region.
The existence of an inguinal canal consisting, as I have described it,
of funnel-shaped elongations from the several inguinal layers continued
over the cord as far as the testicle, renders the adult male especially
liable to hernial protrusions at this part. The oblique direction of the
canal is, in some measure, a safeguard against these accidents; but this
obliquity is not of the same degree in all bodies, and hence some are
naturally more prone to herniae than others.
DESCRIPTION OF THE FIGURES OF PLATES 30 & 31.
PLATE 30.
A. The anterior superior iliac spine.
B. The umbilicus.
C. The spine of the pubis.
D. The external oblique muscle; d, its tendon. .
E. The internal oblique muscle; e, its tendon.
F. The transverse muscle; f, its tendon, forming, with e, the conjoined
tendon.
G. The rectus muscle enclosed in its sheath.
H. The fascia spermatica interna covering the cord; h, its funnel-shaped
extremity.
I, K, L, M. See Plate 31.
N. The femoral artery; n, its profunda branch.
O. The femoral vein.
P. The saphena vein.
Q. The sartorius muscle.
R. The sheath of the femoral vessels.
S. The falciform margin of the saphenous opening.
T. The anterior crural nerve.
U. The pubic portion of the fascia lata.
V. The iliac portion attached to Poupart's ligament.
W. The lower part of the iliacus muscle.
[Illustration: Abdomen and leg, showing blood vessels, muscles
and other internal organs.]
PLATE 30
PLATE 31.
A. The anterior superior iliac spine.
B. The umbilicus.
C. The spine of the pubis.
D. The external oblique muscle; d, its tendon; d*, the external ring.
E. The internal oblique muscle.
F. The transverse muscle; f, its tendon; forming, with e, the conjoined
tendon.
G. The rectus muscle laid bare.
H h. The fascia spermatica interna laid open above and below d*, the
external ring.
I. The peritonaeum closing the internal ring.
K. The fascia transversalis; k, its pubic part.
L. The epigastric artery and veins.
M. The spermatic artery, veins, and vas deferens bending round the
epigastric artery at the internal ring; m, the same vessels below
the external ring.
N. The femoral artery; n, its profunda branch.
O. The femoral vein, joined by--
P. The saphena vein.
Q. The sartorius muscle.
R. The sheath of the femoral vessels.
S S. The falciform margin of the saphenous opening,
T. The anterior crural nerve.
U. The pubic part of the fascia lata.
V. The iliac part of the fascia lata.
W. The lower part of the iliacus muscle.
[Illustration: Abdomen and leg, showing blood vessels, muscles
and other internal organs.]
Plate 31
COMMENTARY ON PLATES 32, 33, & 34.
THE DISSECTION OF THE OBLIQUE OR EXTERNAL AND
THE DIRECT OR INTERNAL INGUINAL HERNIAE.
The order in which the herniary bowel takes its investments from the
eight layers of the inguinal region, is precisely the reverse of that
order in which these layers present in the dissection from before
backwards. The innermost layer of the inguinal region is the
peritonaeum, and from this membrane the intestine, when about to
protrude, derives its first covering. This covering constitutes the
hernial sac. Almost all varieties of inguinal herniae are said to be
enveloped in a sac, or elongation of the peritonaeum. This is accounted
as the general rule. The exceptions to the rule are mentioned as
occurring in the following modes: 1st, the caecum and sigmoid flexure of
the colon, which are devoid of mesenteries, and only partially covered
by the peritonaeum, may slip down behind this membrane, and become
hernial; 2nd, the inguinal part of the peritonaeum may suffer rupture,
and allow the intestine to protrude through the opening. When a hernia
occurs under either of these circumstances, it will be found deprived of
a sac.
All the blood vessels and nerves of the abdomen lie external to the
peritonaeum. Those vessels which traverse the abdomen on their way to
the external organs course outside the peritonaeum; and at the places
where they enter the abdominal parietes, the membrane is reflected from
them. This disposition of the peritonaeum in respect to the spermatic
and iliac vessels is exhibited in Plate 32.
The part of the peritonaeum which lines the inguinal parietes does not
(in the normal state of the adult body) exhibit any aperture
corresponding to that named the internal ring. The membrane is in this
place, as elsewhere, continuous throughout, being extended over the
ring, as also over other localities, where subjacent structures may be
in part wanting. It is in these places, where the membrane happens to be
unsupported, that herniae are most liable to occur. And it must be
added, that the natural form of the internal surface of the groin is
such as to guide the viscera under pressure directly against those parts
which are the weakest.
The inner surface of the groin is divided into two pouches or fossae, by
an intervening crescentic fold of the peritonaeum, which corresponds
with the situation of the epigastric vessels. This fold is formed by the
epigastric vessels and the umbilical ligament, which, being tenser and
shorter than the peritonaeum, thereby cause this membrane to project.
The outer fossa represents a triangular space, the apex of which is
below, at P; the base being formed by the fibres of the transverse
muscle above; the inner side by the epigastric artery; and the outer
side by Poupart's ligament. The apex of this inverted triangle is
opposite the internal ring. The inner fossa is bounded by the epigastric
artery externally; by the margin of the rectus muscle internally; and by
the os pubis and inner end of Poupart's ligament inferiorly. The inner
fossa is opposite the external abdominal ring, and is known as the
triangle of Hesselbach.
The two peritonaeal fossae being named external and internal, in
reference to the situation of the epigastric vessels, we find that the
two varieties of inguinal herniae which occur in these fossae are named
external and internal also, in reference to the same part.
The external inguinal hernia, so called from its commencing in the outer
peritonaeal fossa, on the outer side of the epigastric artery, takes a
covering from the peritonaeum of this place, and pushes forward into the
internal abdominal ring at the point marked P, Plate 32. In this place,
the incipient hernia or bubonocele, covered by its sac, lies on the
forepart of the spermatic vessels, and becomes invested by those same
coverings which constitute the inguinal canal, through which these
vessels pass. In this stage of the hernia, its situation in respect to
the epigastric artery is truly external, and in respect to the spermatic
vessels, anterior, while the protruded intestine itself is separated
from actual contact with either of these vessels by its proper sac. The
bubonocele, projecting through the internal ring at the situation marked
F, (Plate 33,) midway between A, the anterior iliac spine, and I, the
pubic spine, continues to increase in size; but as its further progress
from behind directly forwards becomes arrested by the tense resisting
aponeurosis of the external oblique muscle, h, it changes its course
obliquely inwards along the canal, traversing this canal with the
spermatic vessels, which still lie behind it, and, lastly, makes its
exit at the external ring, H. The obliquity of this course, pursued by
the hernia, from the internal to the external ring, has gained for it
the name of oblique hernia. In this stage of the hernial protrusion, the
only part of it which may be truly named external is the neck of its
sac, F, for the elongated body, G, of the hernia lies now actually in
front of the epigastric artery, P, and this vessel is separated from the
anterior wall of the canal, H h, by an interval equal to the bulk of the
hernia. While the hernia occupies the canal, F H, without projecting
through the external ring, H, it is named "incomplete." When it has
passed the external ring, H, so as to form a tumour of the size and in
the situation of f g, it is named "complete." When, lastly, the hernia
has extended itself so far as to occupy the whole length of the cord,
and reach the scrotum, it is termed "scrotal hernia." These names, it
will be seen, are given only to characterise the several stages of the
one kind of hernia--viz., that which commences to form at a situation
external to the epigastric artery, and, after following the course of
the spermatic vessels through the inguinal canal, at length terminates
in the scrotum.
The external inguinal hernia having entered the canal, P, (Plate 32,) at
a situation immediately in front of the spermatic vessels, continues, in
the several stages of its descent, to hold the same relation to these
vessels through the whole length of the canal, even as far as the
testicle in the scrotum. This hernia, however, when of long standing and
large size, is known to separate the spermatic vessels from each other
in such a way, that some are found to lie on its fore part--others to
its outer side. However great may be the size of this hernia, even when
it becomes scrotal, still the testicle is invariably found below it.
This fact is accounted for by the circumstance, that the lower end of
the spermatic envelopes is attached so firmly to the coats of the
testicle as to prevent the hernia from either distending and elongating
them to a level below this organ, or from entering the cavity of the
tunica vaginalis.
The external form of inguinal hernia is, comparatively speaking, but
rarely seen in the female. When it does occur in this sex, its position,
investments, and course through the inguinal canal, where it accompanies
the round ligament of the uterus, are the same as in the male. When the
hernia escapes through the external abdominal ring of the female groin,
it is found to lodge in the labium pudendi. In the male body, the
testicle and spermatic cord, which have carried before them investments
derived from all the layers of the inguinal region, have, as it were,
already marked out the track to be followed by the hernia, and prepared
for it its several coverings. The muscular parietes of the male inguinal
region, from which the loose cremaster muscle has been derived, have by
this circumstance become weakened, and hence the more frequent
occurrence of external inguinal hernia in the male. But in the female,
where no such process has taken place, and where a cremaster does not
exist at the expense of the internal oblique and transverse muscles, the
inguinal parietes remain more compact, and are less liable to suffer
distention in the course of the uterine ligament.
The internal inguinal hernia takes its peritonaeal covering (the sac)
from the inner fossa, Q R, Plate 32, internal to the epigastric artery,
and forces directly forwards through the external abdominal ring,
carrying investments from each of such structures as it meets with in
this locality of the groin. As the external ring, H, Plate 34, is
opposite the inner peritonaeal fossa, Q R, Plate 32, this hernia, which
protrudes thus immediately from behind forwards, is also named direct.
In this way these two varieties of hernia, (the external, Plate 33, and
the internal, Plate 34,) though commencing in different situations, P
and R, Plate 32, within the abdomen, arrive at the same place--viz., the
external ring, H, Plates 33 and 34. The coverings of the internal
hernia, Plate 34, though not derived exactly from the same locality as
those which invest the cord and the external variety, are, nevertheless,
but different parts of the same structures; these are, 1st, the
peritonaeum, G, which forms its sac; 2nd, the pubic part of the fascia
transversalis; 3rd, the conjoined tendon itself, or (according as the
hernia may occur further from the mesial line) the cremaster, which, in
common with the internal oblique and transverse muscles, terminates in
this tendon; 4th, the external spermatic fascia, derived from the
margins of the external ring; 5th, the superficial fascia and
integuments.
The coverings of the internal inguinal hernia are (as to number)
variously described by authors. Thus with respect to the conjoined
tendon, the hernia is said, in some instances, to take an investment of
this structure; in others, to pass through a cleft in its fibres; in
others, to escape by its outer margin. Again, the cremaster muscle is
stated by some to cover this hernia; by others, to be rarely met with,
as forming one of its coverings; and by others, never. Lastly, it is
doubted by some whether this hernia is even covered by a protrusion of
the fascia transversalis in all instances. [Footnote]
[Footnote: Mr. Lawrence (Treatise on Ruptures) remarks, "How often it
may be invested by a protrusion of the fascia transversalis, I cannot
hitherto determine." Mr. Stanley has presented to St. Bartholomew's
Hospital several specimens of this hernia invested by the fascia.
Hesselbach speaks of the fascia as being always present. Cloquet
mentions it as being present always, except in such cases as where, by
being ruptured, the sac protrudes through it. Langenbeck states that the
fascia is constantly protruded as a covering to this hernia: "Quia
hernia inguinalis interna non in canalis abdominalis aperturam internam
transit, tunicam vaginalem communem intrare nequit; parietem autem
canalis abdominalis internum aponeuroticum, in quo fovea inguinalis
interna, et qui ex adverso annulo abdominali est, ante se per annulum
trudit." (Comment, ad illust. Herniarum, &c.) Perhaps the readiest and
surest explanation which can be given to these differences of opinion
may be had from the following remark:--"Culter enim semper has partes
extricat, quae involucro adeo inhaerent, ut pro lubitu musculum
(membranam) efformare queas unde magnam illam inter anatomicos
discrepantiam ortam conjicio." (Camper. Icones Herniarum.)]
The variety in the number of investments of the internal inguinal hernia
(especially as regards the presence or absence of the conjoined tendon
and cremaster) appears to me to be dependent, 1st, upon the position
whereat this hernia occurs; 2nd, upon the state of the parts through
which it passes; and 3rd, upon the manner in which the dissection
happens to be conducted.