We examine the gastrointestinal tract of a donkey in
dorsal recumbency (on its back) much as one might
do this in abdominal surgery. For the exposure that
we use in this presentation, the incisions are
different and, as the specimen is preserved, the
midventral abdominal incision is much larger than it
would be were we actually performing the surgery.
Exploration of the viscera would not be markedly
different in a horse. See the presentation, “Equine
Abdominal Topography”, for review.
1. Cut
along
long
axis.
R
2. Cut along
transverse
axis (at leve
of last rib).
L
epidermis
subcutaneous c.t.
(superficial fascia)
dermis
The skin is made up of two layers, a superficial
epithelial layer, the epidermis, which is thin, and the
dermis, which is a much thicker layer of connective
tissue on which the epidermis rests.
The epidermis is usually pigmented and probably no
more than 100 microns thick.The dermis is the deeper
layer of the skin, continuous with the underlying
subcutaneous tissue (superficial fascia).
Different from the fairly uniform epidermis, the
thickness of the dermis is variable and depends on
the area of the body. In the case of the abdomen, the
dermis is thin ventrally, perhaps two to four millimeters
thick on average, and becomes gradually thicker as
the dorsal midline is approached.
Ventral body
wall.
At the sternal end of your
longitudinal incision, make
a stab incision through the
ventral body wall. Go only
Use the blunt
end of
hemostatic
forceps to push
through the
peritoneum to
enter the
abdominal
cavity.
Now put your
finger through
the hole that
you’ve made
and lift the
abdominal wall
away from the
viscera.
You’re still not through
the peritoneum. You’re
looking at the internal
lamina of the rectus
sheath.
Now you’ve
carefully cut through
the internal lamina
and the peritoneum
and you’re looking
at abdominal viscera.
Lifting the body wall
away from the
viscera, cut along
your longitudinal
and transverse
incisions to expose
Abdominal
viscera
exposed:
cecum
L
R
Right
parts of
large
colon.
Left
parts of
large
colon.
large colon,
right parts
cecocolic
fold
large colon,
left parts
cecocolic
fold
right ventral
colon
left ventral
colon
jejunum
desc/sigmoid
colon
cecocolic
fold.
Lift up on the apex of the cecum to demonstrate the
cecocolic fold.
cecocolic fold
???
Pull on the apex of the cecum to demonstrate the
cecocolic fold. The fold extends from the lateral
tenia of the cecum to the right ventral colon.
cecocolic fold
???
Draw the cecum away from
the viscera as shown.
??? must be the right ventral colon.
jejunum
ileum
cecum
The cecum is turned back, to
the right, to show the
ileocecal fold.
ileocecal fold
The ileocecal fold extends from the
dorsal tenia of the cecum to the ileum. As
a matter of definition, the ileojejunal
junction is where the ileocecal fold ends.
RTRT
VENT
VENT
COL
COL
LEFT VENT
LT
VENT COL
COL
CECUM
CECUM
Follow
Followthe
theleft
leftparts
partsofofthe
thelarge
largecolon
coloncaudally.
caudally.
Note
Notethat
thatthey
theycurve
curvetotothe
theright
rightororenter
enterthe
thepelvic
pelvic
inlet.
inlet.Find
Findthe
thepelvic
pelvicflexure
flexureand
anddraw
drawititout.
out.
RT VENT COL
LT VENT COL
CECUM
Follow the left parts of the large colon caudally.
Note that they curve to the right or enter the pelvic
inlet. Find the pelvic flexure and draw it out.
LT VENT COL
LT DORS COL
Pelvic flexure
single tenia,
mesentery
left dors colon
no haustra
left vent colon
with haustra
left parts of
large colon
rt dors col
rt vent col
cecum
Pelvic flexure
and left parts of
the large colon
drawn to the
right with the
cecum out of the
body cavity.
coils of
jejunum
(no teniae)
desc/sigmoid
colon (with
teniae)
cecum
cecum
Pelvic
pelvicflexure
flexure
Cecum, pelvic flexure,
right
leftView
parts,from
and athe
little
of
theside.
right parts of large
colon drawn out of
abdomen, right view.
From: Anatomie des
Pferdes, W. Ellenberger,
H. Baum; 1897. Verlagsbuchhandlung Paul Parey
Left Side
Right Side
right
ventral
colon
sternal flexure
diaphragmatic flexure
cecum
left
ventral
colon
jejunum
small colon
Coils of jejunum
moved out of the way
to show the ileum
joining the base of the
cecum.
ileocecal
junction
Following the
jejunum to the
jejunum
duodenojejunal
flexure at the
cranial end of the
duodenocolic
fold.
ascending duodenum
jejunum
ascnd
duod
duodenojejunal flexure
transv
colon
desc
colon
coils of small colon leading to the rectum
right
dorsal
colon
mesocolon of
desc/sigmoid colon
jejunum
Replace coils of small colon….
right
ventral
colon
cecum
transv
colon
right
dorsal
colon
jejunum
Replace coils of jejunum ventral to coils of small colon…
Replace left parts of large colon ventral to jejunal coils…
Replace the cecum.