Bauhaus-Universität Weimar

Titel:
The Cyclopaedia of Anatomy and Physiology, vol 1: A-Dea
Person:
Todd, Robert Bentley
PURL:
https://digitalesammlungen.uni-weimar.de/viewer/image/lit25759/21/
ABDOMEN. 
and the external, the largest of the three, 
into the inferior edge of the cartilage of the 
fifth rib. This muscle is remarkable for its 
tendinous intersections, which cut the fibres at 
right angles, and are called lineœ transversa: ;* 
they vary in number from three to five, and are 
always more numerous above than below the 
umbilicus. In general there is one on a level 
with the umbilicus; the superior one being 
about an inch below the superior attachment of 
the muscle, and a third midway between these 
two : when a fourth and a fifth exist, they are 
below the umbilicus. They adhere to the an¬ 
terior wall of the sheath closely, and but very 
slightly or not at all to the posterior. Some¬ 
times the intersection does not go completely 
through the thickness of the muscle so as to 
appear on its posterior surface, and thus the 
posterior fibres are longer than the anterior; 
but as Bichat remarks, it never happens that 
any of the muscular fibres pass from one extre¬ 
mity of the muscle to the other without 
uniting at least one of these intersections^ 
Sometimes, too, the intersection does not go 
through the breadth of the muscle, and this is 
generally the case with that below the umbili¬ 
cus. The effect of these intersections is to 
convert the muscle into so many distinct bellies, 
each of which has its proper action, and is, as 
Beclard asserts, provided with a separate 
nerve.f 
The rectus muscle is enveloped in a fibrous 
sheath, the mode of formation of which the 
reader must have collected from the description 
of the oblique muscles. The anterior wall of 
this sheath is formed by the aponeurosis of the 
external oblique alone over the chest, and by the 
same aponeurosis and the anterior layer of that of 
the internal oblique, from the xiphoid cartilage 
to the inferior fourth of the muscle ; (both which 
aponeuroses over the internal half of the muscle 
are so adherent to each other as to form but 
one lamina;) and in its inferior fourth by the 
conjoined aponeuroses of the two obliqui and 
transversalis. 
The posterior wall of the sheath is deficient 
superiorly where the muscle covers the carti¬ 
lages of the ribs with which it is in contact, 
and inferiorly for a space corresponding to the 
inferior fourth of the muscle. So much of it as 
exists is formed by-the tendon of the transver¬ 
salis and the posterior lamina of that of the 
internal oblique, so that the rectus appears to 
have passed at its inferior extremity through a 
transverse slit in these conjoined tendons, so as 
to get between them and the peritoneum. 
The rectus muscle covers, at its superior ex¬ 
tremity, the cartilages of the two last true ribs 
and a part of those of the two first false, and 
also the xiphoid appendix. The internal mam¬ 
mary and epigastric arteries are found behind it 
in the sheath. 
Between the recti muscles is the fibrous cord 
called linect alba, produced by the interlace- 
* Also called enervations.— Winsluw. They are, 
says Meckel, incontestably incomplete repetitions of 
the ribs in the walls of the abdomen. 
t Hence Meckel classes it among the polygastric 
muscles. 
9 
ment of the aponeuroses of the opposite sides, 
noted in surgery as being in its inferior half the 
seat of the operations of paracentesis abdominis, 
paracentesis vesicæ supra pubem, the supra¬ 
pubic lithotomy, and the Caesarean operation. 
This cord extends from the xiphoid cartilage to 
the symphysis pubis, with the anterior liga¬ 
ment of which articulation it is identified. It 
does not present the same breadth in its whole 
course, being broader in the umbilical region 
than elsewhere. In this region we find in the 
linea alba the perforation which gave passage to 
the umbilical vessels in the foetus and the 
urachus, and through which the fibrous remains 
of those vessels pass to be inserted into the 
skin, whereby is formed the cutaneous depres¬ 
sion which marks the situation of this opening. 
In the adult the umbilicus may be considered 
as a point of considerable strength ; in the esti¬ 
mation of some it is the strongest point in the 
abdominal parietes : in dissecting away the skin 
at this point, we find subjacent to it a very con¬ 
densed cellular tissue, to which and to the 
skin the fibrous cords into which the umbilical 
vessels have degenerated adhere closely ; these 
cords, too, adhere not only to the skin, but 
likewise to the margin of the fibrous ring 
through which they pass. “ The umbilical 
opening, therefore,’' says Scarpa, “ in the 
infant two months after birth, and still 
more in the adult, is not only like the other 
natural openings of the abdomen, strength¬ 
ened internally by the application of the peri¬ 
toneum and of the cellular substance, and on 
the outside by the common integuments, but it 
is likewise plugged up in the centre by the 
three umbilical ligaments and by the urachus ; 
these ligaments form a triangle, the apex of 
which is fixed in the cicatrix of the integuments 
of the umbilicus, the base in the liver, in the 
two ilio-lumbar regions, and in the fundus of 
the urinary bladder ; by this triangle is formed 
a strong and elastic bridle, capable of itself 
alone of opposing a powerful resistance to the 
viscera attempting to open a passage through 
the aponeurotic ring of the umbilicus, which 
apparatus does not exist at the inguinal ring or 
femoral arch.”* 
In the fœtus the ring of the umbilicus is 
proportionally larger than at any period after 
birth when the cicatrix is fully formed : it is, 
however, at the full term, or even at the seventh 
or eighth month, and in the healthy state of the 
parts, equally filled up by the umbilical vessels 
and urachus, and we would say is equally 
capable of resisting intestinal protusion as at 
any subsequent period. Hence it may be in¬ 
ferred that congenital umbilical ruptures are 
always of very early date, being attributable to 
the persistence of the opening at the umbilicus, 
and the continuance in it of the intestinal pro¬ 
longation which exists there naturally at a very 
early period. It may likewise be inferred that 
the rupture in the adult can much more easily 
occur in the vicinity of, than through the umbi¬ 
lical ring; and experience confirms this deduc¬ 
tion from the anatomy of the parts. 
* Scarpa on Hernia, p. 373.
        

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