ACD 15

LOWER GI TRACT: JEJUNUM, ILEUM, COLON, RECTUM & ANUS

T10

In which dermatome will pain from infection in the ileum be referred to?

Achalasia

Which condition results from degeneration of the parasympathetic (Auerbach’s) plexus in the esophagus?

Paraumbilical

In liver cirrhosis complicated by portal hypertension, which of these veins might engorge?

L2 to the right sacroiliac joint

Attachment of the root of the mesentery

One or two arcades are formed

Which feature is typical of the jejunum?

Longitudinal muscle bands converge in the base of the appendix

During a laparotomy, which is considered a normal finding?

Sigmoid

The patient is scheduled for a colostomy to relieve bowel obstruction. Which segment can be mobilized for this?

Descending

Which of the following colonic segments will become ischemic when the inferior mesenteric artery is acutely occluded?

Sacculated wall

When doing colonoscopy, which of these will be visible in the colonic segment?

Transverse

Which of these segments has an attached mesentery?

Jejunum

Match the features to the correct organ (jejunum vs ileum)

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Thicker wall

Ileum

Match the features to the correct organ (jejunum vs ileum)

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Peyer’s patches

Jejunum

Match the features to the correct organ (jejunum vs ileum)

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Plicae circulares along entire length

Ileum

Match the features to the correct organ (jejunum vs ileum)

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Numerous short vasa recta

Transverse colon

A patient has enlarged inferior mesenteric nodes from an intraabdominal abscess. Which of the following is most likely involved?

Transverse mesocolon

A middle colic artery is located in which peritoneal fold?

Rectum

Penetrating trauma at the level of **SV4** will most likely injure what?

Teniae coli

Which of the following are visible parts of the muscular layer of the large intestine?

Vagus nerve

Peristalsis of the small intestine occurs through stimulation of which of the following?

Convergence of tenia coli of the cecum

A medical intern wheels a patient for appendectomy to the operating room and asks, “what structure should be identified to trace the base of the appendix?”

Smooth mucous membrane

During virtual endoscopy of the GI tract, the viewer is certain he has arrived at the large intestine after his eyepiece presents this characteristic mucosa

Three or more arcades

In an abnormal surgery, a pre-resident was asked to place the intestines back in its position within the peritoneal cavity. Which of the following features points to the ilium?

Inferior mesenteric nodes

A elderly patient will undergo resection of the sigmoid colon due to cancer. Which lymph nodes should be removed along with the primary site of tumor?

Splenic flexure

Which area is supplied by the vagal trunk whose origin is from the right vagus?

Has long infrequent vasa recta

A reconstructive surgeon plans to harvest a segment of jejunum as graft to replace the excised esophagus. Which of the following is characteristic of jejunal mesentery?

Peritoneal folds

This structure gives rise to the recesses around the cecum

Left colic

A patient underwent resection of the proximal half of transverse colon. Blood supply to the remaining half will be provided by which artery?

Mesentery proper

What peritoneal folds contain the neurovascular structure supplying the small intestines?

Inferior mesenteric

Spread of malignant cells from a mass of the upper half of the anal canal will be to which group of nodes?

Transverse mesocolon

Ligation of the middle colic artery necessitates dissection of which peritoneal fold?

Vagus nerve

Peristalsis of the large intestines occur through stimulation of which of the following?

Arcades and vasa recta

A patient was brought to the emergency room with eviscerated bowels secondary to an abdominal gunshot wound. Which of the following features of the small intestines will best aid in identification of the probable affected part?

More numerous plicae circulares

Which characteristic of the jejunum causes its walls to appear thicker than the ileum?

Taenia coli

Which of the following characteristics of the large intestines are visible parts of its muscular layer?

SV3

What is the commencement of the rectum?

duodojejunal flexure

Jejunum commencement

ileocecal junction

Ileum termination

mesentery of the small intestine

The coils of the jejunum and ileum are **freely mobile** and are attached to posterior abdominal wall via the

Long free edge of the fold

coil that encloses mobile intestine

L2

The **short root of the fold** is continuous with parietal peritoneum on posterior abdominal

wall from left side of ______ to **right sacroiliac joint**

Root of the mesentery

permits entrance & exit of branches of the superior

mesenteric artery & vein, lymph vessels, & nerves

Superior Mesenteric artery

Arterial supply of Jejunum and Ileum are branches of

Ileocolic artery

supplies the lowest part of the lleum

Superior mesenteric vein

venous drainage of the Jejunum and Ileum

Intermediate and Superior mesenteric nodes

lymph drainage of the Jejunum and Ileum

Superior mesenteric plexuses

Sympathetic and parasympathetic (vagus) innervation of the Jejunum and Ileum are from

Large intestine

Extends from cecum to rectum that function as water and electrolyte absorption & storage

* Teniae Coli
* Haustra
* Appendices Epiplociae

Distinguishing features of the large intestine

Jejunum

lies colled in the upper part of the peritoneal cavity below the left side of the transverse mesocolon

Ileum

Found at the lower part of the cavity and in the pelvis

Teniae Coli

3 flat bands, which converge on the base of the appendix and provide for a complete longitudinal muscle coat

Haustra

Sacculations in the LI

Appendices Epiplociae

fatty projections of the omentum

Cecum

Blind-ended pouch in the **right iliac fossa** often distended with gas and can then be palpated through the anterior abdominal wall

Ileocecal valve

two horizontal folds of mucous membrane that project around the orifice of the lleum

* **Anterior:** Coils of small intestine, anterior abdominal wall in right iliac region
* **Posterior:** Psoas & iliacus muscles, femoral nerve, lateral cutaneous nerve

of the thigh, appendix
* **Medial:** Appendix

Relations of Cecum

Ileocecal sphincter

Circular muscle of the lower end of the ileum that controls the flow of contents from the ileum into the colon

Gastrin

produced by the stomach; causes relaxation of the muscle tone

Appendix

Narrow, muscular tube with large amount of **lymphoid tissue**- length varies from 3-5 in. (8-13cm)

hanging down into the pelvis against the right pelvic wall and coiled up behind the cecum

most common position of the appendix

Ascending colon

* Lies in **right lower quadrant**; 5 in. (13 cm)
* Extends upward from the cecum to the inferior surface of the right lobe of the liver

Right colic flexure

The ascending colon turns left at the surface of the right lobe of the liver forming the

* **Anterior**: Coils of small intestine, greater omentum anterior abdominal wall in right iliac region
* **Posterior**: Iliacus, iliac crest, quadratus lumborum, origin of transversus abdomini, lower pole of right kidney, iliohypogastric and ilioinguinal nerves.

Relations of Ascending colon

Transverse colon

about 15 In. (38 cm) long and ex.tends across the abdomen, occupying the umblllcal region

Phrenicocolic ligament

**Left colic flexure** is suspended from the **diaphragm** by the

* **Anterior**: Greater omentum & anterior abdominal wall (umbilica & hypogastric regions)
* **Posterior**: Second part of duodenum, head of pancreas, jejunum coils, ileum

Relations of the transverse colon

Right colic flexure

commencement of the transverse colon

Left colic flexure

Commencement of the descending colon

Pelvic brim

termination of descending colon

Descending colon

About 10 In. (25 cm) long and lies In the left upper and lower quadrants. It extends downward from the left colic flexure to the pelvic brim

sigmoid colon

The descending colon will eventually be continuous with

* **Anterior:** Small intestine coils. Greater omentum, anterior abdominal wall
* **Posterior:** Lateral border of the left kidney, origin of the transversus

abdominis, quadratus lumborum, iliac crest, iliacus, left psoas, iliohypogastric & ilioinguinal nerves, lateral cutaneous nerve of the thigh, femoral nerve

Relations of Descending colon

Sigmoid colon

A continuation of the descending colon that is 10-15 in (25-38cm); Mobile and hangs down into the pelvic cavity

Pelvic brim

Commencement of the Sigmoid colon

S3

Termination of th Sigmoid colon where it becomes continuous with the **rectum**

* **Anterior:** Urinary bladder, posterior surface of the uterus, upper part of

vagina
* **Posterior:** Rectum & sacrum

Relations of sigmoid colon

Sigmoid mesocolon

Attaches sigmoid colon to posterior pelvic wall

Rectum

5 in (13 cm); begins in front of **S3** as a continuation of the sigmoid colon

Tip of the coccyx

termination of the rectus where it pierces the **pelvic diaphragm** and becomes continuous with the **anal canal**

Rectal ampulla

lower dilated part of the rectum

Anorectal angle

formed from a sling of the **puborectalis** portion of the **levator ani muscles** at the junction of the rectum with the anal canal

First 1/3

Part of rectum that is covered anteriorly & posteriorly

Middle 1/3

Part of rectum that is covered anteriorly

Lower 1/3

Part of rectum that has no peritoneal covering

**Anterior:**

* **Upper 2/3** – sigmoid colon,

ileum; occupies

**rectovesical pouch**
* **Lower 1/3** – posterior

surface of the bladder, vas deferens &

seminal vesicle termination, prostate
* **Posterior:** Sacrum, coccyx, piriformis, coccygeus, levatores ani, \n sacral plexus, sympathetic trunks

Relations of rectum in males

**Anterior**

* **Upper 2/3** – sigmoid colon,

ileum; occupies **Pouch of**

**Douglas**
* Lower 1/3 – posterior surface of the vagina
* **Posterior:** Sacrum, coccyx, piriformis, coccygeus, levatores ani, \n sacral plexus, sympathetic trunks

Relations of rectum in females

Ileocolic artery

Arterial supply of the Cecum

Ileocolic artery and Right colic artery

Arterial supply of the ascending colon

Appendicular artery (branch of the posterior cecal artery)

Arterial supply of the appendix

Middle colic – branch of Superior Mesenteric artery

Arterial supply of the proximal 2/3 of the transverse colon

Left colic – branch of Inferior mesenteric artery

Arterial supply of the distal 1/3 of the transverse colon

Left colic + sigmoid branches of the inferior mesenteric artery

Arterial supply of the descending colon

Sigmoid branches of the inferior mesenteric artery

Arterial supply of the sigmoid colon

Superior rectal artery – from inferior mesenteric artery

chief arterial supply in the mucous membrane of the rectum

Middle rectal artery – branch of internal iliac artery

chief arterial supply in the muscular coat of the rectum

Inferior rectal artery – branch of internal pudendal

anastomoses with middle rectal at anorectal junction

* Super pancreaticoduodenal vein – drains into portal vein
* Inferior pancreaticoduodenal vein – joins superior mesenteric

Correspond to arteries and drains into **superior mesenteric vein**

Appendicular vein