block I: midgut & hindgut Flashcards
Describe jejunum and ileum
Features
* coiled parts of small intestine
* 6-7 meters long
jejunum - initial 2/5
ileum - remaining 3/5
* covered by greater omentum
Surface Anatomy
* jejunum tends to be located in the LUQ
* ileum occupies much of the
hypogastric and right inguinal
regions (RLQ).
The jejunum and ileum are suspended from the posterior abdominal wall by
a mesentery. This mesentery is shorter at each extreme, ie. @ the beginning
of jejunum (duodenojejunal flexure) and @ the end of ileum (iliocecal
junction), rendering these parts of small intestine less mobile
The mesentery is fan-shaped. Its root is directed obliquely, inferiorly and to
the right, from the left side of L2 vertebra to the right sacroiliac joint.
Describe the large intestine
Secondarily retroperitoneal:
*ascending colon
*descending colon
Intraperitoneal:
*cecum (but no mesentery)
*vermiform appendix(mesoappendix)
*transverse colon(transverse mesocolon)
*sigmoid colon(sigmoid mesocolon)
The rectum is covered by peritoneum
only on its most superior surface; most
of it is found within the pelvic cavity.
features of large intestine:
Tenia coli - three thickened
bands of longitudinal muscle
(except in rectum)
*Haustra - sacculations of its
wall between the tenia
*Omental (epiploic)
appendages - small pouches
of peritoneum filled with fat
*Semilunar folds
*You can also see the
proximal portion of the
Ileum (I), Ileal orifice
(IO), & of the appendix (A)
criteria of differece between jejunum and ileum
*Plicae circulares (circular folds) -
large and more abundant in the
jejunum
*Branching pattern of vessels
*arcades - larger and
a single row in the
jejunum
*vasa rectae - longer in the
jejunum
*Vascularization of wall - denser in
the jejunum
*Fat content of mesentery - less fat
in jejunum
* Peyer’s patches - in the ileum
describe cecum and appendix
The cecum contains the ileocecal junction (tonic contraction). Associated structures
include the iliocecal lips and the frenulum.
The vermiform appendix (6-10 cm) joins the cecum about 2-3 cm inferior to the ileocecal junction. The three tenia coli of the cecum (omental, free, and mesocolic tenia) converge at its base and form an outer longitudinal muscle coat for it.
position of appendix
The position of the base of the
vermiform appendix is fairly
constant. It is usually found deep to
the point 2/3 of the way from a line
joining the umbilicus and the
anterior superior iliac spine (ASIS).
This is known as McBurney’s point.
The position of the tip of the
vermiform appendix is much more
variable, since both its angle and
length can differ significantly
among individuals. In general, it can
be found deep to an area close to
the right side of a line joining both
ASISs.
explain pain of appendix and inflammation
Pain from the viscera can vary
from dull to severe but is usually
poorly localized. Pain from the
visceral peritoneum is also of this
type. However, pain from the
parietal peritoneum is similar to
that felt in the body wall and
limbs, i.e. it is sharply localized.
In cases of infection or
inflammation of the vermiform
appendix, the pain is initially
referred to the umbilical region
(T10). It only becomes sharp and
localized to the area of
McBurney’s point when it has
touched and irritated the layer of
parietal peritoneum that lines the
anterior abdominal wall.
what are portacaval anastomoses?
When the portal circulation is
obstructed, for example in clinical
conditions involving liver disease
such as cyrrhosis, blood from the
GI system can still reach the right
side of the heart through the
inferior vena cava via a number of
collateral routes.
This is possible because the portal
vein and its tributaries do not have
valves (and thus direction of blood
flow can be inverted) and because
there are various points of
communication between the portal
venous system and the caval or
general venous system.
What are the 4 portacaval anastomoses?
- Esophageal
Esophageal branches of left
gastric vein anastomose with
esophageal veins that drain
into the hemiazygous veins. - Paraumbilical
The paraumbilical veins (portal) in the
falciform ligament anastomose with
subcutaneous veins in the anterior
abdominal wall and also with branches
of the inferior epigastric veins (systemic). - Anorectal
The superior rectal veins (portal) anastomose with
the middle and inferior rectal veins, which
are tributaries of the internal iliac and
internal pudendal veins (systemic), respectively - Retroperitoneal
Tributaries of the colic veins (portal) draining
the ascending and descending colon anastomose
with tributaries of the gonadal and renal veins
(systemic), found in the posterior abdominal
wall.
which are the lymph nodes in the abdomena and pancreas?
which organ is the major lymph producing organ?
liver
Superiorly – towards the mediastinum
Midline – Celiac trunk
Inferiorly- towards lumbar region
whcih are the lymph nodes in stomach?
celiac nodes
lymph from celiac lymph nodes goes into?
cysterna chyli (a dilated sac at the inferior end of the thoracic duct)
explain lymphatics
what is diverticulosis?
Diverticulosis most commonly occurs in the Sigmoid Colon
Standard approach: colonoscopy
Solution: CT colonography
Approach: Patient drinks bowel-emptying fluids
CO2 gas is pumped into the bowels
X rays + computer software
