Lab 4: Abdomen

Question 1

what are the 4 muscles and 2 sheets of strong fascia that, along with skin, make up the abdominal wall and support the heavy abdominal viscera?

Answer 1

1. external abdominal oblique
2. internal abdominal oblique
3. rectus abdominis
4. transversus abdominis

1 & 2: the external lamina of the rectus sheath made up of the aponeurotic tendons of the internal and external abdominal oblique muscles

Question 2

origin and insertion of the external abdominal obliques

Answer 2

origin: the ribs and thoracolumbar fascia
inserts: tuber coxae, linea alba and the iliac fascia

Question 3

what covers the external abdominal oblique?

Answer 3

abdominal tunic

Question 4

origin and insertion of the internal abdominal oblique

Answer 4

origin: tuber coxae and inguinal ligament
insertion: costal cartilages and the rib of T18

Question 5

what is located in the paralumbar fossa? (2 distinct structures)

Answer 5

1. branches of spinal nerves T18 - L2 running over the internal abdominal oblique
2. branches of the deep circumflex iliac artery running over the transversus abdominis

Question 6

what organs are seen on the right aspect of the horse? (5 organs)

Answer 6

1. cecum
2. dorsal ascending colon (aka dorsal large colon)
3. ventral ascending colon (aka ventral large colon)
4. right kidney
5. liver

Question 7

what organs are seen on the left aspect of the horse (4 organs)

Answer 7

1. spleen
2. stomach
3. left kidney
4. jejunum

Question 8

how is the descending duodenum secured in the abdomen?

Answer 8

it is suspended by the mesoduodenum

Question 9

what are the two types of coiled intestine on the left side and what are there descriptions?

Answer 9

1. jejunum - coiled, small diameter

2. descending (small) colon - thicker, with a whitish longitudinal band

Question 10

what are the 3 divisions that make up the cecum?

Answer 10

1. base - located dorsally
2. body - comma-shaped
3. apex

Question 11

how is the ileum differentiated from the jejunum?

Answer 11

the ileum is whitish and paler in color than the jejunum and has a firmer wall

Question 12

what connects the ileum to the cecum?

Answer 12

the ileocecal fold

Question 13

what connects the cecum to the right ventral colon?

Answer 13

the cecocolic fold

Question 14

what is another name for the ascending colon?

Answer 14

the large colon

Question 15

what are the 4 parts of the large colon?

Answer 15

1. the right ventral colon
2. the left ventral colon
3. the left dorsal colon
4. the right dorsal colon

Question 16

which part of the large colon is identified by its many sacculations?

Answer 16

the left and right ventral colon

Question 17

which part of the large colon is identified by its smooth surface?

Answer 17

the right and left dorsal colon

Question 18

what does the pelvic flexure connect? and what is its clinical significance?

Answer 18

the pelvic flexure connects the left ventral colon to the left dorsal colon.
it is a point of constriction which is a major cause of obstruction and subsequently colic.

Question 19

where is the transvere colon located within the abdomen?

Answer 19

midline just cranial to the root of the mesentary

Question 20

how is the descending colon (aka small colon) suspended in the abdomen?

Answer 20

it is suspended by the mesocolon

Question 21

when does the small colon become the rectum?

Answer 21

after it passes through the pelvic inlet the small colon becomes the rectum

Question 22

what connects the proximal end of the descending colon to the distal end of the duodenum?

Answer 22

the duodenocolic fold

Question 23

what is the significance of the duodenocolic fold?

Answer 23

it is important for proper identification of intestinal segments during surgery

Question 24

what structures can be palpated per rectum?

Answer 24

1. pelvic flexure
2. large colon
3. distal small colon
4. left kidney
5. root of the mesentary
6. cecum