Ch. 84 and 85 Diaphragmatic Hernias

Question 1

How much of the diaphragm is made up by the Y shaped central tendon?

Answer 1

21%

Question 2

What layers does the central tendon have in the diaphragm?

Answer 2

two layers of fibers and around the foramen vena cava, the fibers have strong concentric arrangement

Question 3

What are the parts of the diaphragm (3)?

Answer 3

central tendon
pars lumbalis dorsally
pars sternalis ventrally

Question 4

what makes up the crus of the diaphragm

Answer 4

paired lumbar muscles form the diaphragmatic crura with the right crus being larger than the left
each crus has a bifurcate tendon from the 3rd and 4th lumbar vertebrae

Question 5

what is the sternal muscle

Answer 5

an unpaired medial muscle continuous with the left and right costal muscles

Question 6

what are the three openings of the diaphragm

Answer 6

esophageal
caval
aortic

Question 7

what runs through the caval foramen

Answer 7

just vena cava - and it is tight!

the adventitia literally fuses with the foramen

Question 8

what runs through the esophageal hiatus

Answer 8

esophagus and dorsal and ventral vagal trunks along with the esophageal blood supply

Question 9

what runs through the aortic foramen

Answer 9

aorta, azygos, hemiazygos, and the lumbar cistern of the thoracic duct

Question 10

what are the foramina of Morgagni

Answer 10

aka the sternocostal triangles
they are situated between the costal and sternal attachments of the thoracic diaphragm and allow egress of the cranial epigastric arteries (termination of the internal thoracic arteries)
herniations can occur and then they are called retrosternal or morgagni hernia!

Question 11

what is the blood supply to the diaphragm

Answer 11

main phrenic arteries

they arise from the paired phrenicoabdominal arteries and extend forward to ramify subperitoneally on the crura of the diaphragm –> pass medial to the dorsal extensions of the tendinous center –> divide over the tendinous part –> redivide farther in the peripheral musculature
Terminal branches will follow the costal muscle and anastomose with the prhenic branches of the 10th/11th/12th intercostal arteries

Question 12

what drains the blood of the diaphragm

Answer 12

cranial phrenic vein - empties into the cauda vena cava
caudal phrenic vein - joins the cranial abdominal vein to become the common phrenicoabdominal trunk, which empties into the cava near the ipsilateral renal vein

Question 13

what is the motor innervation to the diaphragm

Answer 13

the phrenic nerves - arise from the 5th/6th/7th in dogs (sometimes a twig of 4) and 4th/5th/6th in cats
cranial to the diaphragm, the phrenic nerves are invested by the plica venae cavae and mediastinum and each left and right divides into three branches to innervate all three diaphragmatic muscles

Question 14

what innervates the costal muscles

Answer 14

supplied by axons derived partly from the 4th nerve but mainly the 5th

Question 15

what innervates the crural musculature

Answer 15

axons supplied mainly from the sixth and partly from the fifth cervical nerves

Question 16

What is the role of the transverse septum in the diaphragm

Answer 16

in the embryo, the transverse septum originates in the region of the cervical vertebrae and then migrates caudally where it becomes the central tendon

*this is why the innervation to the diaphragm comes from all the way at C5/6/7 in the dog and C4/5/6 in the cat!

Question 17

What forms the diaphragmatic crura from the embryologic anatomy?

Answer 17

the esophageal mesentery forms the diaphragmatic crura and is dorsal to the transverse septum

Question 18

what is the fate of the embryologic pleuroperitoneal folds?

Answer 18

they develop along the lateral body walls and migrate medially where they close the pleuroperitoneal canals by fusion with the esophageal mesentery and dorsal portion of the transverse septum

Question 19

what will result from contraction of the diaphragm?

Answer 19

the diaphragm contracts during inspiration and pushes caudally on the viscera, which displaces the abdominal wall outward -> this will produce expansion of the caudal rib cage

there is only a net effect on caudal rib cage dimensions when the abdominal cavity is open

Question 20

What muscles are responsible for inspiratory dorsal displacement of the sternum

Answer 20

parasternal intercostal muscles

Question 21

what does the term peritonealization mean

Answer 21

traumatic or incisional hernias do not have hernia sacs but with time, they will develop peritoneum over them and make a new sac

Question 22

what is the term for when a rib inside the body fractures and creates a hernia?

Answer 22

auto penetrating hernia

Question 23

What makes up the linea alba. What will it become caudally?

Answer 23

fibers of the tendinous aponeuroses of the external abdominal oblique, internal abdominal oblique and transversus abdominus. It will narrow as it travels caudally and is called the prepubic tendon or sometimes called the cranial pubic tendon

Question 24

Where does the external abdominal oblique sheath run in relation to the rectus abdominus sheath?

Answer 24

ALWAYS superficial

Question 25

From the umbilicus to more caudal, where does the internal abdominal oblique fibers run in relation to the rectus abdominus?

Answer 25

the internal abdominal oblique fibers are superficial to the rectus caudally. Cranially, they run deep and superficial

Question 26

Where do the transverse abdominal muscle fascial fibers run in relation to the rectus abdominus?

Answer 26

in the cranial two thirds, the transverse abdominal sheath are deep to the rectus but in the caudal third, they are superficial

Question 27

what is the arcuate line

Answer 27

denotes the cranial most aspect where the aponeurosis of the internal abdominal oblique and the transverse abdominal muscles first transition to a location superficial to the rectus abdominis

Question 28

Where does the external abdominal oblique muscles originate from

Answer 28

4th or 5th to 12th rib and from the last rib and thoracodorsal fascia

Question 29

where do the fibers of the internal abdominal oblique arise?

Answer 29

from the thoracolumbar fascia caudal to the last rib and from the tuber coxae

Question 30

where does the transverse abdominal muscle originate from

Answer 30

the lumbar portion arises from the transverse processes of the lumbar vertebrae and thoracolumbar fascia and the costal portion arises from the medial sides of the 12th and 13th ribs and from the 8-11 costal cartilaegs

Question 31

what are epigastric hernias

Answer 31

aka cranial ventral midline hernias

most often congenital and include umbilical and substernal hernias

Question 32

What kind of abdominal wall defects are most at risk of incarceration and strangulation

Answer 32

defects with small inelastic hernial rings

Question 33

how does strangulation of abdominal contents occurring a hernia

Answer 33

constriction of blood supply at the hernia ring
torsion of the vascular pedicle because of increased organ mobility within the hernia

*incarceration of a hollow viscus organ favors strangulation because the intraluminal pressure increases and that obstructs venous outflow