Veterinary Abdominal Viscera (Animal)

 Abdominal Viscera

Alimentary Canal  (esophagus, stomach, intestine)

A.  Esophagus — cervical,  thoracic,  abdominal regions

                           (all striated in dog;  proximal 2/3’s striated in cat )

B.  Stomach:

                      Sphincters: 1) Cardiac (at cardia) and

                                         2) Pyloric (at pylorus)

                        Region:   a) Cardiac (surrounding cardia)

                                         b) Fundic (fundus = blind end)

                                         c) Body

                                         d) Pyloric (antrum & canal)

also, lesser curvature — LESSER OMENTUM

greater curvature —  GREATER OMENTUM

C. Small Intestine:

1)   Duodenum  — MESODUODENUM

regions: a) Cranial flexure

               b) Descending duodenum

               c) Caudal flexure

               d) Ascending duodenum

                e) Duodenal-jejunal flexure

2) Jejunum — MESOJEJUNUM      ----->MESENTERY

3) Ileum   — MESOILEUM      ----->  MESENTERY

                      antimesenteric vessel; ileocecal fold ileal (ileocolic)      

                      orifice

D. Large Intestine:

1) Cecum (blind end; no appendix)

                   cecocolic orifice; ileocecal fold

2) Colon  — MESOCOLON

                       Regions: a) Ascending colon

                                       b) Right colic flexure

                                       c) Transverse colon

                                       d) Left colic flexure

                                        e) Descending colon

3) Rectum  — MESORECTUM

4) Anal canal  (retroperitoneal)

                Anus = external opening

                Sphincters — a) Internal anal sphincter (smooth m.),

                                       b) External anal sphincter (striated m.);

Liver —

                  Secretes bile salts which emulsify ingested fat; bile is        

                  tored in the gallbladder develops in ventral 

                  mesogastrium:

                 (Diaphragm / LIGAMENTS / LIVER / LESSER  

                  OMENTUM / stomach)

Six lobes:

                Rright lateral lobe

                Right medial lobe

                Gallbladder

                Quadrate lobe

                 Left medial lobe

                 Left lateral lobe

                 Caudate lobe —

                                           Papillary process

                                      Caudate process

Pancreas —

                     Secretes proteolytic enzymes into duodenum;

                           also, endocrine secretions (insulin, etc.)

Structure:

                left lobe + body + right lobe;

                located in GREATER OMENTUM &   

                MESODUODENUM

Ducts:

                Pancreatic duct (smaller) empties with bile duct —>   

                major duodenal papilla.

              Accessory pancreatic duct (larger) empties —>  minor  

              duodenal papilla.

Kidney:

                — removes waste products from blood (urine);

—   regulates fluid/salt balance (blood osmotic pressure)

Topography —

                        Right kidney is more cranial than the left;

                       Cranial pole of right kidney is cupped by liver;

                       Left kidney is more loosely attached;

                       Feline kidneys are positioned more caudally.

Surface features —

                                cranial / caudal poles

                                dorsal / ventral surfaces

                                medial / lateral borders:

 medial border has a hilus (where vesselsand the ureter enter) that leads to aspace (renal sinus) where the renal pelvis is located.

Kidney structure —

                                    A fibrous capsule surrounds the kidney (capsular veins are prominent in the cat)

renal cortex = superficial tissue that contains vascular glomeruli

renal medulla =  deep tissue (an outer part and a less vascular inner part can be distinguished)

renal pyramid = the medulla between interlobar vessels (belonging to a renal lobe)

renal papilla = the free tip of a renal pyramid (not present as such in carnivores)

renal crest = median ridge produced by fusion of renal papillae in the carnivore

Ureter — (forms branches and calyces in multilobar kidneys)

                     conveys urine from kidney to urinary bladder.

renal pelvis = expanded proximal end of ureter ( located within renal sinus of unilobar kidney)

pelvic recess = lateral expansion of renal pelvis between interlobar vessels.

Spleen:

Structure

               — develops in dorsal mesogastrium;

               — becomes enlarged when capsular & trabecular smooth      

                     muscle relax (e.g., under barbiturate anesthesia)

Function

                — serves as a reservoir for blood cells (blood storage)

—   filters particles from blood, particularly over-aged

erythrocytes.

 Abdominal  Vessels

 Aorta:

A.  Branches to the abdominal wall:

1) lumbar aa. —  supply vertebral column, spinal cord, epaxial m., & skin over the back.

2) common trunk (previously, phrenicoabdominal a.) — supplies abdominal wall &  adrenal gland via cranial abdominal a. and diaphragm

3) deep circumflex iliac aa. — supply abdominal wall (caudally)

B.  Branches to paired organs:

1) renal a. — supplies kidney

2) ovarian a. or testicular a. — supplies gonad

C. Branches to unpaired organs (digestive system & spleen):

1) celiac a.

              — supplies cranial abdominal viscera (esophagus,

                    stomach, duodenum, liver & gall bladder,pancreas,

                      spleen)

               — the stomach has a quadrant blood supply(right/left &

                    gastric/gastroepiploic aa.)

2) cranial mesenteric a.

                                 — supplies duodenum to descending colon

                                      also pancreas

3) caudal mesenteric a.

                                  — supplies descending colon & rectum

D. Terminal branches of the aorta:    (within pelvic cavity)

1) external iliac a. (paired) — pelvic limbs

2) internal iliac a. (paired) — pelvis (wall & viscera)

3) median sacral a. (unpaired)

                                       — becomes median caudal a. of the tail

Portal Vein:

The portal vein conveys blood between two capillary beds (between alimentary tract capillaries and liver sinusoids).

Cranial and caudal mesenteric veins anastomose to from the portal vein which receives a splenic vein (left side) and the gastroduodenal vein (right side) before entering the liver.

The circulation sequence is . . .

Celiac and cranial and caudal mesenteric arteries and their branches

—> alimentary, etc. capillaries

—> satellite veins

—> portal vein

—> hepatic sinusoids

—> hepatic veins

—> caudal vena cava

Lymphatics:

Mesenteric lymph ducts converge to form a lymph "lake" (cysterna chyla)