Peritoneum and Peritoneal Structures

Question 1

where is the pelvic cavity?

Answer 1

• smallest cavity at caudal end

Question 2

what is the peritoneum?

Answer 2

serous membrane lines abdominal, cranial part of pelvic, and scrotal cavities, reflects out and around organs within it
largest and longest membrane in body

Question 3

what are the functions of peritoneum?

Answer 3

• friction reduction
• free movement of mesentery
• fixation as by ligaments
• fat storage as in omentum

Question 4

what is a retroperitoneal organ?

Answer 4

• outside the cavity
• examples: kidneys, ureters (most of length), adrenal glands, aorta, Cd VC, lumbar lymph nodes

Question 5

what is a peritoneal organ?

Answer 5

• surrounded by peritoneum

Question 6

what gastrulation layer does the peritoneum come from?

Answer 6

• mesoderm

Question 7

what is the coleum?

Answer 7

peritoneal cavity

Question 8

what is clinically important about retroperitoneal organs?

Answer 8

• kidneys are covered by peritoneum on ventral surface only, trauma to kidney blood or urine may accumulate in space, fluids retained in this area cannot be diagnosed by palpation or abdominocentesis so can be harder and delayed in diagnosis

Question 9

what is clinically important to peritoneal cavity?

Answer 9

• if no serous fluid, peritonitis or rough handling may cause adhesions where layers stick and impair movement of organs thus impairing function
• peritoneal cavity has 2 openings in female for uterine tubes so peritonitis is more common

Question 10

what are the connecting peritoneums?

Answer 10

• dorsal mesentary
• ventral mesentary

Question 11

what is mesentary?

Answer 11

• a type of connecting peritoneum - wide and double layered
• connects: intestinal and reproductive tracts with abdominal wall
• contains blood vessels, lymphatics, and nerves

Question 12

how are the different lengths of mesentery formed?

Answer 12

• herniation –> rotation –> retraction of gut tube
• to begin gut tube growth exceeds that of body cavity and herniates through incomplete wall –> two rotations of gut loops –> body cavity enlarges –> return of gut
• return or retraction: begins at cranial and caudal most ends of tube (stomach, duodenum, colon) are first, then jejunum is last

Question 13

what is fixed viscera?

Answer 13

• early viscera packed tightly against body wall by the portions of gut that enter later, so mesenteries are partially fused with dorsal body wall
• stomach and duodenum cranially
• ileum, cecum, and all three parts colon caudally

Question 14

what is mobile viscera?

Answer 14

• regions of gut retracted late, mainly jejunum not crowded and retain long mesentery

Question 15

why is length of mesentery important?

Answer 15

• determines ease of access during surgery
• jejunum easily accessed - small incision
• stomach or colon would require larger incision

Question 16

what are the landmark mesenteries of fixed viscera?

Answer 16

• broad ligaments of uterus (right and left) - lateral most mesenteries and can be used to easily located uterine horns

Question 17

what are the short mesentary?

Answer 17

• descending duodenum (right)
• descending colon (left)

Question 18

where does the liver develop?

Answer 18

• ventral mesentery: lesser omentum and peritoneal ligaments of liver (falciform, coronary, triangular ligg.

Question 19

what is the root of mesentery?

Answer 19

• @ L2
• narrow attachment of long mesojejunum and mesoileum to dorsal body wall
• thick: contains cranial mesenteric a., intestinal lymphatics, autonomic n. plexus

Question 20

is ruminant mesentery short or long?

Answer 20

• short

Question 21

is horse mesentery long or short?

Answer 21

• long: common to have strangulation

Question 22

what is the omentum?

Answer 22

• passes from stomach to other organs or to abdominal wall
• lesser and greater (greater curve of stomach)

Question 23

what is lesser omentum?

Answer 23

• extends from liver to lesser curvature of stomach (hepatogastric lig.) and initial duodenum
• single sheet (2 layers) remnant of ventral mesogastrium
• covers papillary process of caudate lobe

Question 24

what is greater omentum?

Answer 24

• remnant of dorsal mesogastrium
• unattached at caudal border (can be lifted)
• has deep sheet and superficial sheet (each sheet has 2 layers)

Question 25

where is the superficial sheet of greater omentum and what is in it?

Answer 25

- next to ventral body wall - encloses spleen

Question 26

what is the deep sheet of greater omentum and what is in it?

Answer 26

- continues from bladder cranially, adjacent to abdominal organs, enclosed left lobe pancreas

Question 27

what is the omental bursa?

Answer 27

a subdivision of peritoneal cavity enclosed by greater and lesser omentum a potential space - collapsed in real life

Question 28

what is the epiploic foramen?

Answer 28

short passage between omental bursa and main peritoneal cavity found at base of caudate lobe of liver in all domestic animals

Question 29

what are the boundaries of epiploic foramen?

Answer 29

dorsally: caudal vena cava ventrally: portal vein caudally: hepatic a. in mesoduodenum

Question 30

what are the species differences of greater omentum?

Answer 30

carnivores: well-developed, peritoneum should be included in sutured layer ruminants: well-developed equine: poorly developed

Question 31

why is greater omentum clinically important?

Answer 31

- very mobile - surgeons tack bits on site of opened viscera - very vascular: used by surgeons to aid in re-vascularization - policeman of abdomen: limits spread of infection, has milky spots (macrophages) and omental adhesions (tissues stick) - can be removed, does not regenerate

Question 32

what are the remnants of ventral mesentary?

Answer 32

- ventral peritoneal folds carried umbilical arteries and vein in fetus - the falciform ligament: begins at umbilicus and passes to liver, attached to linea alba, in fetus carries umbilical vein (round ligament of liver in adult) - median ligament of bladder - lateral ligaments of bladder

Question 33

what is in the falciform ligament?

Answer 33

- adipose tissue that contains high conc of stem cells - attaches liver to ventral wall (linea alba)

Question 34

what is median ligament of bladder?

Answer 34

- attached ventral midline of bladder to abdomen caudal to umbilicus

Question 35

what are the lateral ligaments of bladder?

Answer 35

- lateral bladder to lateral abdominal walls

Question 36

what are ligaments?

Answer 36

- type of connection peritoneum, narrow and double layered - pass from wall to organ or form organ to organ - serves to fix organs more than as channels of vessels and nerves

Question 37

what is a fold?

Answer 37

- connecting peritoneum - less or no blood vessels - between 2 visceral organs - ex: cecocolic fold

Question 38

what nervous system supplies parietal peritoneum?

Answer 38

- somatic nn (because it covers walls of abdomen) - sensory innervation is by segmental spinal nn. (lumbar and thoracic nn.) - peritoneum on diaphragm receives sensory from phrenic n. - sensitive to irritation and cause localized pain

Question 39

what nervous system supplies visceral peritoneum?

Answer 39

- autonomic nn. (covers viscera) - sensory innervation of mesenteries, omenta, and ligaments proceeds from stretch not ordinary pain, temp, touch receptors - if excessive stretch or pressure avoided, viscera can be incised and sx manipulated without pain to animal

Question 40

what is vaginal process?

Answer 40

- blind ended portion of peritoneum protrudes through the inguinal canal and sits SQ - vaginal tunic (male) and vaginal process (female) - not in female cat