Week 10: Regional Anatomy: The Abdominopelvic Cavity

Question 1

The abdominopelvic region:

Answer 1

• The anterior region of the trunk between the thoracic diaphragm superiorly and the pelvic diaphragm inferiorly
  
  • Limited by the abdominal wall anteriorly and the vertebral column and muscle posteriorly
  • The superficial anterior structures of the abdominopelvic region are referred to as the abdominal wall
    Composed of: Skeletal muscle, connective tissue

Question 2

The abdominopelvic cavity:

Answer 2

• The abdominopelvic cavity is located deep to the abdominal wall
  
  • It is the largest cavity in the body
  • It is made up of two individual cavities: Abdominal cavity, pelvic cavity
  • Contains organs and tissues that function within various body systems

Question 3

Major body systems of the abdominopelvic cavity

Answer 3

Digestive
- Mechanical and chemical breakdown of food
- Absorption of digested products from GI tract into blood and lymph
Lymphatic
- Transport of proteins, lipids and fluid to blood
Urinary
- Produces, stores and eliminates wastes and regulates volume and chemical composition of blood
Reproductive
- Production of gametes
Hormone release for regulation of reproduction

Question 4

Quadrants of the abdominopelvic region:

Answer 4

• One of two methods of categorizing the abdominopelvic region (the other divides into 9 segments)
  
  • Theoretical divisions used to help clinicians to localize, identify and diagnose patient symptoms
  • Four quadrants divided by theoretical anatomical lines
  • A vertical line that follows the linea alba from the xiphoid process of the sternum down to the pubic symphysis of the pelvis
  • Divides the abdominopelvic into left and right halves
  • A horizonal line that runs at the level of the umbilicus
    Divides the abdominopelvic cavity into an upper and lower hal

Question 5

Organs of the Abdominopelvic quadrant: Right upper Quadrant

STRRAP GLD

Answer 5

Liver (right lobe), stomach (pylorus), transverse colon (right half), ascending colon (superior portion), duodenum, gallbladder, pancreas, right kidney, right adrenal gland

Question 6

Left upper quadrant:

JILL PLSTD

Answer 6

Liver (left lobe), stomach, transverse colon (left half), Descending colon (superior portion), Jejunum, Illeum, pancreas (body and tail), left kidney, left adrenal gland, spleen

Question 7

Right lower quadrant:

BAIRCARURU

Answer 7

Ascending colon (inferior portion), right ureter, bladder, cecum, Ileum appendix, right ovary and uterine tube (F), right ductus deferens (M), uterus (F)

Question 8

Left Lower Quadrant:

(B)LUDSLULU

Answer 8

Descending colon (inferior portion), left ureter, bladder (when full), sigmoid colon, left ovary and uterine tube (females only), left ductus deferens (males only), Uterus (F)

Question 9

The Peritoneum:

Answer 9

• A serous membrane that functions to support and protect the abdominopelvic organs
  Contains two layers
  
  • Outer parietal peritoneum adheres to the anterior and posterior abdominal walls
  • Inner visceral peritoneum lines the surface of the abdominopelvic organs
  • Technically they are continuous with each other
  • The space between the two layers is called the peritoneal cavity
    Filled with lubricating fluid to reduce friction between layers during movement

Question 10

Intraperitoneal and retroperitoneal organs:

Answer 10

• Organs within the abdominopelvic cavity are either located intraperitoneally or retroperitoneally
  
  • Intraperitoneal organs are almost surrounded by visceral peritoneum
    Retroperitoneal organs are located behind/posterior to the peritoneum (retro=behind)

Question 11

Intraperitoneal organs:
SALT PRSSS

Answer 11

S: Stomach
A: Appendix
L: Liver
T: Transverse colon

P: Pancreas
R: Rectum (superior portion)
S: Small intestine (proximal portion of duodenum, jejunum, ileum)
S: Sigmoid colon
S: Spleen

Question 12

Retroperitoneal organs:
SAD PUCKER

Answer 12

S: Suprarenal (adrenal) glands
A: Aorta
D: Duodenum (distal portion)

P: Pancreas (except the tail)
U: Ureters
C: Colon (ascending and descending only)
K: Kidneys
E: (O) Esophagus
R: Rectum (inferior portion)

Question 13

The Mesentery:

Answer 13

• A double layered fold of peritoneum that wraps around and suspends visceral organs from the posterior wall
  
  • Plays a major role in supporting the abdominopelvic organs by anchoring them to the posterior abdominal wall
  • A store of fat for energy
  • Allows organs to move more relative to one another
    Contains the blood vessels, nerves and lymphatic supply of the abdominopelvic visceral organs

Question 14

The Omenta:

Answer 14

• The omenta are also folds of peritoneum that serve to support organs, store fat and play a role in immune defense
  
  • They are double-layered: Made up of two layers of visceral peritoneum
  • They arise from the stomach (and proximal duodenum) and extend to neighboring organs
  • There are two subdivision of the omentum depending on whether they extend from the greater or lesser curvature of the stomach
  • The lesser omentum
    The greater omentum

Question 15

Lesser Omenta

Answer 15

• Attaches from the hilum of the liver to the lesser curvature of the stomach
  Suspends the stomach from the inferior surface of the liver so that when the stomach fills, the force of gravity doesn’t cause the stomach to crush other visceral organs

Question 16

Greater Omentum:

Answer 16

• Descends from the greater curvature of the stomach and covers the anterior surface of the intraperitoneal organs
  Descends and then folds back on itself and ascends, forming a four-layered thick fold and attaches to the transverse colon

Question 17

Anterior Abdominal Muscles:

Answer 17

• Skin: Anterior
  
  • Lying deep is adipose tissue: Hyper dermis
  • Deeper than hyper dermis is skeletal muscle which forms anterior abdominal wall and lateral abdominal wall
  • Anterior skeletal muscles help to contain and protect abdominal visceral, they laterally flex and rotate vertebral column.
  • They produce force to remove contents from the body e.g. urination, defecation, child birth
  • Each external, internal oblique and transverse muscles contains tendons which are referred to aponeurosis: Include rectus abdominus muscle
    These meet in the midline to form a tough fibrous band extending from the xiphoid process to the pubic symphysis

Question 18

External oblique:

Answer 18

• Largest and most superficial of the anterolateral abdominal muscles
  
  • 5-12th ribs, inserts into linea alba and iliac crest
    The main function of this muscle is to compress the abdomen and flex vertebral column

Question 19

Internal obliques:

Answer 19

• Thin muscle sheet fanning out anteromedially
  
  • Fibers run perpendicular to external oblique
  • Origin is the iliac crest, inguinal ligament and the thoracolumbar fascia
  • Insertion is cartilage of ribs 7-10 and linea alba
    Key function: Compress abdomen and flex the vertebral column

Question 20

Transverse abdominis:

Answer 20

• Inner most of the three flat abdominal muscles and the fiber orientation are ideal for compressing the abdominal contents and increasing abdominal pressure and its origins are the iliac crests, the inguinal ligaments, lumbar fascia and the cartilages of ribs 5-10 with insertion in the xiphoid process, linea alba and pupas
  Main function: To compress the abdomen

Question 21

Rectus abdominis:

Answer 21

• Main vertical muscles of the anterior abdominal wall
  
  • The origins are the pubic crest and pubic symphysis and insertion is the cartilage of ribs 5-7 and xiphoid process
    Main function: Flex the vertebral column, compress abdomen to aid in expulsion from the body (defecation, urination, child birth)

Question 22

Abdominal aorta:

Answer 22

• Enters into abdominal cavity by piercing abdominal diaphragm
  
  • AA arises from the descending aorta is the major artery in the abdominal cavity and lies left of VC and against posterior body wall
  • It begins at aortic hiatus in diaphragm and ends at level of 4th lumbar vertebrae
  • Gives rise to visceral and parietal branches the unpaired visceral branches arise from the anterior surface of aorta and include the celiac trunk, superior mesenteric and inferior mesenteric arteries
  • These unpaired arteries supply the visceral organs of the digestive system
    Developmentally, these digestive system is divided into 3 sections: Fore gut, mid gut, hind gut. Give rise to organs of the digestive system

Question 23

Celiac trunk: SPLEDS

Answer 23

Supplies the foregut organs: Lower end of esophagus, stomach, duodenum, liver, pancreas, spleen

Question 24

Superior mesenteric artery: JICAAT

Answer 24

• Supplies the midgut
  Jejunum, ileum, caecum, appendix, ascending colon, proximal 2/3 of transverse colon

Question 25

Inferior mesenteric artery: RASDT

Answer 25

- Supplies the hindgut - Rectum, sigmoid colon, descending colon, distal 1/3 of transverse colon - Supplies proximal part of anus - Small intestine is not all derived from same embryological structure - 1st part: Duodenum from the foregut and supplies celiac trunk - The rest of the small intestine: Jejunum and ileum being derived from the midgut Being supplied by superior mesenteric artery

Question 26

Large intestine:

Answer 26

- Two embryological structures from both midgut and hind gut Therefore being supplied by both superior and inferior mesenteric artery

Question 27

Blood supply to upper organs of abdominopelvic cavity

Answer 27

- Inferior phrenic arteries: underside of the thoracic diaphragm and the adrenal glands - Suprarenal arteries: Suprarenal glands or adrenal glands - Large renal arteries: Kidneys - Gonadal arteries: Gonads-ovaries or testes Lumbar Arteries: posterior abdominal wall

Question 28

Blood drainage of abdomen: Portal Venous system:

Answer 28

- All blood from lower limbs, pelvis and abdomen needs to get back to the heart and is done by heaps of different branches that converge into the inferior vena cava - The inferior vena cava will leave the abdominal cavity through the thoracic diaphragm and take blood back to the heart - First though it needs to be taken to the liver for processing and sorting before going back into circulation - Inferior mesenteric vein: Drains blood from transverse colon, descending colon, sigmoid colon and rectum - Superior mesenteric vein: Drains blood from the Jejunum, ileum, the caecum and appendix, the ascending colon as well as most of the transverse colon - Large splenic vein: Spleen as well as receiving smaller veins draining blood from the duodenum, the gall bladder parts of the stomach and parts of the pancreas - Portal venous system drains into large Hepatic portal vein then to the liver and then to the inferior cava to the heart - Blood goes from liver to inferior vena cava which pierces the diaphragm to go back into the thoracic cavity and deliver blood to the heart

Question 29

Mesentery:

Answer 29

- Double sheet of peritoneum that helps suspend visceral organs - Support: Anchor viscera to abdominal wall e.g. small intestine (usually posterior) and allow movement of viscera, stores fat Plumbing and wiring: Conveys neurovascular structures to/from viscera

Question 30

Omenta:

Answer 30

- Double layers fold (apron) of peritoneum - Arise from stomach or proximal duodenum - Greater and lesser Omentum - Lesser attaches from the hilum of the liver to the lesser curvature of the stomach, it is a double fold of the peritoneum, one layer of visceral peritoneum squashed to another, suspends stomach from inferior surface of the liver so when the stomach fills with food the force of gravity doesn’t make the stomach drop and squash organs - Stores fat, contains macrophage deposits, isolates infections Greater: Larger of them both, double layer of peritoneum that descends from the greater curvature of stomach to form an apron anterior to the other intraabdominal organs, end up with four layers of peritoneum stuck together.

Question 31

Anterolateral abdominal wall

Answer 31

- The abdominal wall is made up of skeletal muscle and connective tissue, both of which are soft tissue - Skeletal muscles are important for increasing the pressure ding various physiological processes like respiration, defecation, micturition and changing the size of the stomach after feeding The flexibility of soft tissue walls allows for abdominal distension during pregnancy and obesity

Question 32

Posterior thoracic and abdominal walls:

Answer 32

- The posterior thoracic and abdominal walls are made up of spinal vertebrae and back muscles the largest group being the erector spinae The bones of the spine (hard tissues) provide stability and support for the trunk, while the skeletal muscles of the posterior thoracic and abdominal walls produce reinforce stability of the spine and facilitate movement

Question 33

In which quadrant of the abdominopelvic cavity do you find the gallbladder?

Answer 33

Right Upper

Question 34

What is the name of an abdominal structure that plays a role in the storage of fat around the visceral organs?

Answer 34

The Mesentary

Question 35

Which of the following visceral organs would be located behind the peritoneum?

Answer 35

Kidneys

Question 36

After cutting through the muscles to expose the appendix, what would you expect to have to cut through first?

Answer 36

The Peritoneum

Question 37

What artery would normally supply the region where the appendix is located?

Answer 37

The Superior Mesenteric Artery

Question 38

What are the acronyms for the blood supply, quadrants intraperitoneal/retroperitoneal?

Answer 38

Inferior mesenteric artery: RASDT Celiac trunk: SPLEDS Superior mesenteric artery: JICAAT Right upper Quadrant: STADG PRRL Right lower: BIARACURU Left upper quadrant: JILL PLSTD Left Lower Quadrant: (B)LUDSLULU Retroperitoneal: SAD PUCKER Intraperitoneal: SALT PRSS

Question 39

Which of the following options CORRECTLY identifies the (A) superior landmark, and (B) inferior landmark that, together, divide the abdominopelvic cavity into left and right halves?

Answer 39

Xiphoid process, pubic symphysis