Anterior Abdominal Wall and Inguinal Canal Learning Objectives 1/5/09

Anterior Abdominal Wall and Inguinal Canal Learning Objectives – 1/5/09 [LANE]

1. Define the boundaries of the abdominal cavity and the skeletal components related to the abdominal wall.

a. Boundaries:

i. Superior: Diaphragm

ii. Anterior: Aponeuroses

iii. Inferior: Superior pelvic aperture (imaginary)

iv. Posterior: Anterior longitudinal ligament of vertebral bodies

b. Skeletal components

i. Lumbar vertebrae

ii. Lower ribs

iii. Pubic bones

1. Iliac crest

2. Describe the major surface landmarks of the anterior abdominal wall.

a. Linea semilunaris: On the lateral side of each rectus abdominus muscle

b. Umbilicus: Remnant of the umbilical cord

c. Linea alba: “happy trail.” Medially between rectus abdominal mm.

3. Describe the lines and planes that are used to divide the abdomen into quadrants and regions.

a. Quadrants

i. Dividers

1. Transumbilical plane (TUP)

a. IV disk L3/L4

2. Median plane (follows linea alba)

ii. Regions (4)

1. Right upper quadrant (RUQ)

2. Left upper quadrant (LUQ)

3. Right lower quadrant (RLQ)

4. Left lower quadrant (LLQ)

b. Regions

i. Dividers

1. Mid-clavicular lines (2): Middle of clavicle down

2. Subcostal plane: Tangent to lowest ribs (L2)

3. Transtubercular plane: Midway between the upper transverse and the upper border of the symphysis pubis. Between iliac tubercles. (L5)

ii. Regions (9)

1. Epigastric

2. Right/Left hypochondriac

3. Umbilical

4. Right/Left lumbar

5. Hypogastric

6. Right/left inguial

c. Other planes

i. Transpyloric: L1, just above subcostal at L2

ii. Interspinous plane: Connects right/left ASIS, just above transtubercular

4. Describe the attachments, orientations, relative positions, actions, and fascia of the four major abdominal muscles.

a. External oblique

i. Attachment

1. 5th-12th ribs, inferiorly

2. (Linea alba)

3. Pubic tubercle

4. Anterior ½ of iliac crest. “jumps across” inguinal ligament

ii. Orientation

1. Like a “V”, or “hands in pockets”

iii. Relative position

1. Superior lateral, membranous tendon inferior medial

iv. Action

1. Compress abdominal contents

v. Innervation

1. Ventral rami T7-T12 (Thoracoabdominal nn.) +/- L1

vi. Fascia

1. Superficial:

a. Camper’s: Fatty (superficial) layer of superficial fascia

b. Scarpa’s: Membranous (deep) layer of superficial fascia

c. Deep fascia

2. Deep:

a. Deep fascia

b. Internal oblique

i. Attachment

1. Thoracolumbar fascia

2. Anterior 2/3 of iliac crest

3. Inginal ligament (lateral ½)

4. Lower ribs

ii. Orientation

1. Upside-down “V”

iii. Relative position

1. Inferior lateral, membranous tendon superior medial

iv. Action

1. Unilateral: same side rotation/bending

v. Innervation

1. Ventral rami T7-T12 (Thoracoabdominal nn.) +/- L1

vi. Fascia

1. Superficial/Deep: Deep fascia

c. Transverse oblique

i. Attachment

1. Ribs/costal muscle

2. Thoracolumbar fascia

3. Iliac crest

4. Lateral 1/3 of inguinal ligament

a. Important b/c it does NOT contribute a layer to the spermatic cord

ii. Orientation

1. Horizontal

iii. Relative position

1. Lateral, membranous medial

iv. Action

1. Raise abdominal pressure

v. Innervation

1. Ventral rami T7-T12 (Thoracoabdominal nn.) +/- L1

vi. Fascia

1. Superficial: Deep

2. Deep: Transversalis fascia

d. Rectus Abdominus

i. Attachment

1. Costal cartilage of ribs 5-7

2. Xyphoid process

3. Pubic crest

ii. Orientation

1. Vertical

iii. Relative position

1. Segmented, with 4 sets of membranous aponeurosess

iv. Action

1. Flexes trunk, compresses abdomen

v. Innervation

1. Ventral rami T7-T12 (Thoracoabdominal nn.) +/- L1

vi. Fascia

1. Above arcuate line:

a. Superficial/Deep: Internal oblique aponeurosis

2. At/below arcuate line:

a. Superficial: All abdominal aponeuroses

b. Deep: Perietal peritoneum

5. Define the blood supply, nerve supply, fascial layers, muscle layers, extraperitoneal fat, and parietal peritoneum of the anterior abdominal wall. How do these relate to the various surgical approaches to the abdominal cavity?

a. Blood supply

i. Superior

1. Internal thoracic a.

a. Musculophrenic a. branches laterally along subcostal angle

b. Superior epigastric a. branches medially along rectal sheath

ii. Inferior

1. External Iliac a.

a. Inferior epigastric a. branches superior medial. Supplies more of rectus abdominus than superior epigastric because it is deep.

b. Deep circumflex iliac a. branches superior medial

c. Femoral a. continuation inferior to inguinal ligament

i. Superficial epigastric a. branches superior medial

ii. Superficial circumflex iliac a. branches superior lateral along iliac crest superficially

iii. Lateral

1. Intercostal aa. Even those of false ribs

2. Subcostal a.

b. Nerve supply

i. Pathway:

1. Between internal oblique mm. and transverse abdominis mm., pierce the rectus sheath to supply rectus ab. Mm. + provide anterior cutaneous branches

ii. Thoracoabdominal nn. (T7-T11)

1. Cutaneous innervation separately of medial/lateral portions

iii. Iliohypogastric n. (L1) supplies mons pubis

iv. Ilioinguinal n. (L1) supplies scrotum/labia majora

v. T10 supplies of umbilicus

vi. T5 supplies skin over xyphoid process

c. Surgical approaches

i. General goals

1. Try not to transect arteries/nerves

2. Use “Gridiron technique” in appendix surgery with McBurney’s point

ii. Landmarks

1. Subcostal: outdated way for spleen surgery

2. Median: linea alba

3. Paramedian: just lateral to linea alba

4. Super pubic: just above mons pubis, used in C-sections

5. McBurney’s point

a. Line between ASIS and umbilicus

b. 1/3 of the way from ASIS to umbilicus

c. Used for appendix surgery

6. Describe the configuration of the anterior and posterior walls of the rectus sheath superior and inferior to the arcuate line.

a. Superior to the arcuate line, the internal oblique aponeurosis surrounds the abdominus rectus

b. Inferior to the arcuate line, the internal oblique aponeurosis is only superficial to the abdominus rectus since it pierces it

7. Define the inguinal canal, including the location of the deep and superficial inguinal rings.

a. Know the structures forming the walls of the inguinal canal.

i. Superficial inguinal ring

1. Medial Crus

2. Lateral Crus

3. Intercrural fibers (not very pronounced in most cadavers)

ii. Borders:

1. Anterior: External oblique

2. Posterior: Internal oblique/conjoint tendon

3. Superior: Internal oblique

4. Inferior: Inguinal ligament

b. Define the function and mechanics of the inguinal canal.

i. Route of passage for the testes from posterior abdominal wall to scrotum

ii. Contains the spermatic cord in males and the round ligament in females

c. Describe the contents of the inguinal canal. How do these differ between the sexes?

i. Males: spermatic cord, (gubernaculums)

ii. Females: round ligament

d. Describe the borders of the inguinal triangle (Hasselbach’s Triangle).

i. rectus abdominis muscle (medially)

ii. inguinal ligament (inferiorly)

iii. inferior epigastric vessels (superior and laterally).

8. Define the anatomy and relationships of the:

a. Process vaginalis

i. Portion of peritoneal cavity that “follows” the testes as they descent. Normally is obliterated, but can be patent in adults.

b. Spermatic cord

i. Fascia layers

1. External spermatic fascia

2. Cremasteric fascia

3. Internal spermatic fascia (continuous with transversalis fascia)

ii. Contents

1. Ductus (Vas) deferens

2. Testicular arvery, artery of Vas

3. Pampiniform plexus of veins

a. Helps cool temperature in testicles

4. Lymph vessels

5. Nerves

c. Epididymus

i. Narrow, tightly-coiled tube connecting the efferent ducts from the rear of each testicle to its vas deferens.

ii. Storage of sperm

d. Cremaster muscle

i. Originates from the internal oblique

ii. Surrounds the testes

iii. Helps regulate testes temperature to optimal for spermatogenesis

e. Testes

i. Site of spermatogenesis

ii. Consist of seminiferous tubules

f. Scrotum

i. Surrounds the testes

ii. Layers

1. Skin

2. Tunica dartos Dartos fascia/muscle

a. Colles’ fascia and dartos m. (smooth m.)

3. External spermatic fascia External oblique

4. Cremaster muscle/fascia Internal oblique

5. Internal spermatic fascia Transversalis fascia

6. Tunica vaginalis (parietal/visceral) Peritoneum

9. Describe the coverings of the spermatic cord and their role in the descent of the testes during development. How do these layers relate to the coverings of the scrotum?

a. Many of the layers of the testes are continuous with analagous layers in the spermatic cord. However, the tunica vaginalis of the scrotum is a remnant of the peritoneum which is sealed off from the testes in normal adults

10. Chart the blood supply and lymphatic drainage of the testis. How do they differ from that of the scrotum?

a. Testes

i. Blood: Testicular arteries

ii. Lymphatic: Inguinal Nodes

b. Scrotum

i. Blood: Anterior/posterior scrotal arteries

ii. Lymphatic: Deep lumbar nodes

11. What is an inguinal hernia? What features distinguish a direct from an indirect inguinal hernia?

a. Direct

i. Through the inguinal triangle

ii. Transversalis fascia forms hernia sac

iii. Occurs medially to epigastric artery

iv. Less common than indirect hernias

b. Indirect

i. Through the deep/superficial inguinal rings

ii. Covered by all three layers of spermatic cord

iii. Remains of the process vaginalis forms the hernia sac

iv. 20x more common in males than females

v. More common in younger people

Peritoneum and Major Vessels -1/6/2009 [LANE]

1. Define the peritoneum and peritoneal cavity.

a. Peritoneum

i. Large, thin, transparent sheet of serous membrane which lines the walls of the abdominopelvic cavity and is reflected onto the viscera

b. Peritoneal cavity

i. Potential space between adjacent layers of peritoneum usually containing a small amount of fluid

2. Understand what distinguishes parietal from visceral peritoneum.

a. Parietal peritoneum lines the abdominal and pelvic walls

b. Visceral peritoneum covers abdominal and pelvic organs

3. Describe the shape and extent of the peritoneal cavity

4. Know what the borders of the greater and lesser sac are.

a. Lesser sac borders

i. Anterior

1. Lesser omentum

2. gastrocolic ligament

ii. Inferior

1. Trasverse mesocolon

iii. Superior

1. Caudate lobe of liver

iv. Posterior

1. Pancreas

2. Aorta

3. Celiac trunk

4. Splenic a. and v.

5. Gastrosplenic fold

6. Left suprarenal gland

7. Left kidney

v. Right

1. Liver

2. Duodenal bulb

vi. Left

1. Spleen

2. Gastrosplenic ligament

b. Greater sac borders

i. Everything else within the peritoneum

5. Describe the components of the greater and lesser omentums.

a. Greater Omentum

i. Attaches the stomach (along the greater curvature) to the posterior abdominal wall.

ii. Subdivided into 3 ligaments: (PCS)

1. Gastrophrenic

2. Gastrosplenic

3. Gastrocolic

b. Lesser Omentum

i. Attaches the stomach (along the lesser curvature) to the liver.

ii. Subdivided into 2 ligaments:

1. Hepatogastric

2. Hepatoduodenal

6. Know what forms the borders of the epiploic foramen. What spaces does it connect?

a. It connects the greater and lesser sacs

b. Also known as the Foramen of Winslow

c. Borders:

i. Anterior

1. Hepatoduodenal ligament

ii. Posterior

1. Peritoneum covering the inferior vena cava

iii. Superior

1. Peritoneum covering the caudate lobe of the liver

iv. Inferior

1. Peritoneum covering the duodenum/proper hepatic a.

7. Know what organs and structures within the abdomen are intraperitoneal (peritoneal) and which are primarily and secondarily retroperitoneal?

a. Primarily retroperitoneal

i. Esophagus

ii. Suprarenal glands

iii. Kidneys

iv. Rectum

b. Secondarily retroperitoneal

i. Pancreas

ii. Duodenum (except for superior portion)

iii. Ascending colon

iv. Descending colon

c. Intraperitoneal

i. Everything else

8. Be able to describe and give examples of peritoneal pouches, folds, recesses and gutters.

a. Folds

i. Lateral umbilical fold (2) (inferior epigastric)

ii. Medial umbilical fold (2) (obliterated umbilical a.)

iii. Median umbilical fold (1) (urachus)

b. Recesses

i. Subphrenic recess

1. Between liver and diaphragm

ii. Superior recess of omental bursa

1. Posterior part of liver

2. Part of the lesser sac

3. Borders the greater sac via the coronary ligaments

iii. Inferior recess of omental bursa

1. Between stomach and transverse colon

c. Pouches (pouch of peritoneum formed by peritoneal folds or ligaments)

i. Rectovesical pouch

1. Everything eventually drains here

ii. Hepatorenal pouch

d. Gutters

i. Right paracolic gutter

ii. Left paracolic gutter

e. Spaces

i. Supracolic compartment

ii. Infracolic compartment

iii. Right infracolic space

1. Leaks can stay localized here for a while

2. Bordered by mesentery

iv. Left infracolic space

9. Distinguish between mesentery, mesocolon, greater omentum, lesser omentum and the various peritoneal ligaments.

a. Mesocolon

i. Transverse + Sigmoid à sections of colon that are intraperitoneal

b. Greater omentum

i. Hangs down from front of stomach

ii. Gastrophrenic + gastrosplenic + gastrocolic ligaments

c. Lesser omentum

i. Between stomach and liver

ii. Hepatogastric + hepatoduodenal ligaments

10. Describe the causes and relations of the peritoneal reflections located on the anterior abdominal wall.

a. Lateral umbilical folds (L + R)

i. Houses the inferior epigastric artery

b. Medial umbilical folds (L + R)

i. Houses the obliterated umbilical artery

c. Median umbilical fold

i. Houses remnant of urachus, an embryological canal connecting the urinary bladder of the fetus with the allantois

11. List the three unpaired branches of the abdominal aorta. Know the terminal branches of these main arteries.

a. Splenic a.

i. Short gastric aa.

ii. Left gastro-omental a. (gastropiploic) (on the greater curvature)

iii. Pancreatic a.

iv. Posterior gastric a. (60-80% of people)

b. Proper hepatic a.

i. Right gastric a.

ii. Left hepatic a.

iii. Right hepatic a.

iv. Cystic a.

c. Gastroduodenal a.

i. Supraduodenal a.

ii. Superior pancreatocoduodenal a.

iii. Right gastro-omental a. (gastroepiploic) (on the greature curvature)

12. Describe the venous drainage from the abdominal viscera. What is the hepatic portal system?

a. Begins at the venous ends of capillaries in the organs of the GI tract and ends at the venous sinusoids in the liver

b. Formed bythe joining of the plenic vein with the superior mesenteric vein

c. Inferior mesenteric vein usually joins the splenic vein

d. NO VALVES in portal vein

13. What is a portal-systemic anastomoses? Where do four major portal-systemic anastomosis occur in the body and what is the clinical significance of varicosities at these sites

a. Esophageal varices

i. Portal: Esophageal branch of left gastric v.

ii. Systemic: Esophageal branch to Azygous v.

b. Anorectal varices

i. Portal: Superior rectal branch of inferior mesenteric v.

ii. Systemic: Middle and inferior rectal to internal iliac v.

c. Caput medusa

i. Portal: Paraumbilical (in falciform ligament) branch of portal

ii. Systemic: Superior and inferior epigastric vv.

d. Retroperitoneal varices (Veins of Retzius)

i. Portal: Colic, duodenal, and pancreatic vv.

ii. Systemic: Lumbar and renal vv. to inferior vena cava

GI Tract and Associated Organs - Lane

1. Abdominal part of esophagus

a. Comes through the diaphragm at T8

2. Stomach: