Exam 3 Lecture Material

3 body cavities

1. thoracic

2. abdominal

3. pelvic

Thoracic cavity

Thoracic inlet to thoracic outlet

Abdominal cavity

Throacic outlet to pelvic inlet

Pelvic cavity

pelvic inlet to pelvic outlet

Which body cavities are continuous with each other?

abdominal and pelvic

What lines the interior of the abdominal and pelvic cavities, and surfaces of organs within them?

peritoneum

Structure of peritoneum

simple epithelium [mesothelium]

Function of peritoneum

produces a small am.t of serous fluid to lubricate surfaces of organs within abdominal and pelvic cavities

Closed potential space formed by peritoneum

Peritoneal cavity

Is the peritoneal cavity under negative pressure?

NO

Portions of the peritoneal cavity extending into the pelvic cavity around pelvic viscera

Peritoneal pouches

Extra-abdominal extensions of peritoneum and peritoneal cavity through inguinal canals

vaginal processes

Peritoneal cavity that extends outside the abdomen through the inguinal canal

vaginal cavity

Peritoneum that leaves the abdominal cavity throuhg the inguinal canal

vaginal tunic

Parietal peritoneum

Forms outer walls of the peritoneal cavity and is firmly adherent to abdominal and pelvic walls via fascia

Visceral peritoneum

Peritoneum lining the surfaces of visceral organs (many)

Connecting peritoneum

Double-layer of peritoneum that connects parietal to visceral

Types of connecting peritoneum

• mesentery

• ligament

Mesentery

Connecting peritoneum containing blood vessel, lymphatic vessels, and nerves to and from the organ to which it connects

What is the prefix that typically begins named mesenteries?

meso-

Ligament

Connecting peritoneum typically devoid of vessels and nerves

Which vessel-containing mesenteries are named as ligaments?

Gastrosplenic lig.

Broad lig.

Gastrosplenic lig.

Mesentery which is a portion of the greater omentum

Broad lig.

Collective mesentery of the female repro. tract

How is peritoneum arranged in developing fetuses?

peritoneum lines the interior of the abdominal cavity and forms left and right peritoneal cavities with a midline area containing the primitive gut tube

Double layer of peritoneum from dorsal body wall to gut tube in the developing fetus

dorsal mesentery of the fetus

double layer of peritoneum from the ventral body wall to the gut tube in the developing fetus

ventral mesentery

What is contained within the ventral mesentery from the umbilicus caudally?

umbilical arteries

What is contained within the ventral mesentery from the umbilicus cranially?

umbilical vein

What happens to the dorsal mesentery during development?

Becomes the various mesenteries of the gut

What happens to the ventral mesentery during development?

Loses connection to the gut and becomes the falciform ligament and median ligament of the urinary bladder

What is the remnant of the ventral mesentery from the umbilicus cranially towards the liver?

falciform ligament

Which remnant of the ventral mesentery tends to fill with fat in adult dogs/cats?

falciform lig.

What is the remnant of the ventral mesentery from the umbilicus caudally towards the urinary bladder?

Median lig. of the urinary bladder

What umbilical vessel remnant does the falciform lig. contain?

Round lig. of the liver (umbilical vein remnant)

What umbilical vessel remnant does the median lig. of the urinary bladder contain?

Round ligg. of the urinary bladder (umbilical artery remnant)

Inguinal

Body region of the caudoventral abdomen between the thighs, where external genitalia is located in the male

Inguinal canal

Natural passageways through caudoventral most aspect of abdominal walls

What sex is the inguinal canal present in?

Both male and female

Function of inguinal canal

Route for male gonads to migrate out of abdominal cavity and into scrotum

Why do females have an inguinal canal?

During the time in fetal development when the abdominal musculature is forming, the fetus is sexually undifferentiated (i.e., doesn’t know if it’s male or female); thus, the fetus develops inguinal canals regardless of its genetic sex “just in case” it differentiates into a male

What passes through the inguinal canal?

• external pudendal a. & v.

• genitofemoral n.

• vaginal process and its contents

What is contained in the vaginal process in males?

testis and everything connected to it, forming the spermatic cord

What is contained in the vaginal process in females?

round lig. of the uterus

Round lig. of the uterus

remnant of the fetal gubernaculum

In what species does the vaginal process develop and grow through the inguinal canal?

Dogs only

2 openings of the inguinal canal

1. deep inguinal ring

2. superficial inguinal ring

Deep inguinal ring

Natural, triangular gap in caudoventral abdominal wall

What are the boundaries of the deep inguinal ring?

• caudal edge of internal abdominal oblique m. (cr)

• inguinal lig. (cd)

• lateral edge of rectus abdominis and its tendon (ventral/medial)

What is the tendon of the rectus abdominis called?

prepubic tendon

Superficial inguinal ring

ring-like slit in aponeurosis of the external abdominal oblique

What is the sole reason the inguinal canal is present?

To allow the vaginal process to grow through it so that the developing testis in the male can migrate down into the vaginal process

What name is given to the vaginal process once the testis and associated structures have passed into it?

spermatic cord

Regions of the stomach

1. Cardia

2. Fundus

3. Body

4. Pyloric part

5. Lesser and greater curvatures

What is the small area where the esophagus enters the stomach?

Cardia

Why is the cardia given this name?

Due to closer proximity to the heart

What is the blind-ended diverticulum/pouch of the stomach that protrudes left and somewhat dorsally?

Fundus

What is the large central region of the stomach?

Body

How much of the stomach is made up of the body?

~2/3

What is the terminal/distal 1/3 of the stomach?

pyloric part

What is the sphincter between the stomach and duodenum?

pylorus

What is the concave cranial and somewhat dorsal surface of the stomach?

Lesser curvature

What is the convex caudal and somewhat ventral surface of the stomach?

greater curvature

Where in the abdomen is the stomach situated?

transversely in the left and right cranial quadrants

In what direction are stomach contents carried?

Left to right

Position and shape of empty stomach

• Acute bend to lesser curvature (almost V-shaped)

• Nestled against caudal surface of liver

• Typically doesn’t extend past costal arch

Position and shape of full stomach

• More C-shaped

• Can extend as far caudally as the umbilicus

What arteries provide the arterial supply to the gut?

• Celiac

• Cranial mesenteric

• Caudal mesenteric

Describe the characteristics of the major arteries that supply the gut.

unpaired & come off of the abdominal aorta

What general areas does the celiac a. supply?

Most of cranialabdominal gut and associated organs

What specific organs does the celiac a. supply?

• spleen

• pancreas

• liver

• stomach

• proximal portion of descending duodenum

What structures does the cranial mesenteric a. supply?

• pancreas

• gut from distal descending duodenum to proximal descending colon

What structures does the caudal mesenteric a. supply?

Distal descending colon and part of rectum

Where does nearly all blood supply to the gut end up after draining from the organs?

Hepatic portal vein

What is the hallmark feature of the arterial supply to the gut?

collateral circulation

Are early branching patterns of the arterial supply to the gut clinical significant?

No (varies greatly)

3 major branches off the celiac a.

• splenic a.

• left gastric a.

• hepatic aa.

Where does the celiac a. typically arise from the aorta?

Just caudal to the aortic hiatus of the diaphragm

Path of splenic artery

Travels in greater omentum towards hilus of spleen and gives off branching with great variability in branching patterns

What aa. does the splenic a. give off?

left gastroepiploic a., multiple short gastric aa.

What does the splenic a. directly supply?

spleen (at the hilus)

What does the left gastroepiploic a. supply?

left side of greater curvature of stomach

Where do the short gastric aa. off the splenic a. course?

travel in gastrosplenic lig. (greater omentum) to the fundic area of the stomach

What must be taken into account when performing a splenectomy?

left gastroepiploic a. and short gastric aa. - must ligate only the branches of the splenic a. going to the spleen to preserve the blood flow of these aa. to the stomach

What are the aa. on the lesser curvature of the stomach called?

gastric aa.

Where does the left gastric a. branch from?

Direct branch of celiac a.

Where does the right gastric a. branch from?

terminal branch of hepatic a.

Course of gastric aa.

course along lesser curvature of stomach and anastomose with each other

What are the aa. of the greater curvature of the stomach called?

gastroepiploic aa.

Where does the left gastroepiploic a. branch from?

splenic a.

Where does the right gastroepiploic a. branch from?

indirect terminal branch of hepatic a. (specifically branches off gastroduodenal a.)

Path of the hepatic a.

Travels dorsal from celiac a. to the stomach towards the portal area of the liver

Make a 180 bend as it approaches liver

Continues towards pylorus & terminates into 2 branches

What structures does the hepatic a. supply?

• liver

• right side of stomach

• large portion of pancreas

• proximal descending duodenum

As the hepatic a. makes it’s 180 bend, what does it give off?

1-3 hepatic branches that go to the liver

What are the 2 terminal branches of the hepatic a.?

right gastric a.

gastroduodenal a.

Where does the gastroduodenal a. course?

caudally from hepatic a. dorsal to the pylorus

What are the 2 terminal branches of the gastroduodenal a.?

right gastroepiploic a.

cranial pancreaticoduodenal a.

Where does the cranial mesenteric a. typically arise from the aorta?

Immediately caudal to the celiac a.

What are most of the branches off the cranial mesenteric a.?

jejunal aa.

An early branch off the cranial mesenteric a., whose name is not important, supplies what structures?

ileum, cecum, & most of the colon