Equine Flashcards
How is the cecum anchored in the abdomen?
The cecal base is attached dorsally to the ventral surface of the right kidney, to the right lobe of the pancreas, and to a part of the abdominal wall caudal to these structures. The cecal base is attached medially to the transverse colon and the root of the mesentery, from which the vascular supply reaches the cecum.
How many bands does the cecum have? Which ones travel all the way to the apex?
4; dorsal and medial bands (the ventral band usually joins the medial band near the apex, and the lateral band may extend to the apex or fade out before reaching the apex)
The ileocecal fold runs from the antimesenteric border of the ileum to the _____ cecal band.
dorsal
The cecocolic fold (ligament) runs from the ________ cecal band to the _________ free band of the right _______ colon.
lateral; lateral; ventral
From where does the cecum derive its blood supply?
the cecal artery (a branch of the ileocecal artery)
Which cecal bands contain blood vessels?
the medial and lateral cecal bands contain the medial and lateral cecal arteries.
Which artery is the main source of blood supply to the cecal apex?
the medial cecal artery
In regard to cecal motility patterns, describe the directions of movement and the associated functions of each.
Pattern I: begins at the cecal apex and travels toward the base; mixing of cecal ingesta
Pattern II: begins at the caudal cecal base and travels to the apex; mixing of cecal ingesta
Pattern III: begins at the cranial cecal base and travels to the apex; mixing of cecal ingesta
Pattern IV: begins at the cecal apex and is conducted through the cecal base and cecocolic orifice and into the right ventral colon, progressive pattern that moves ingesta into the RVC.
Which drugs have been shown to depress progressive motility patterns, prolonging cecal emptying, and prolong the inhibition of spike bursts in the cecum when used in combination?
Xylazine and butorphanol
What drugs have been shown to increase the rate of cecal emptying?
Neostigmine methylsulfate, bethanechol chloride, and erythromycin lactobionate
How many bands (teniae) does the ventral colon have?
4; two ventral bands that are free, and two dorsal bands that are associated with the mesentery
Which colonic band is associated with vasculature?
the medial dorsal band
How many bands does the pelvic flexure have?
one
How many bands does the left dorsal colon have?
one
How many bands does the right dorsal colon have?
three
T/F: The teniae coli are composed of smooth muscle and collagen in varying proportions; The roles of the teniae coli are to provide mechanical support to the colon, to maintain orientation of the colon within the abdomen, and to allow distention and contraction of the intestinal segments depending on the degree of ongoing fermentation.
True; In the ventral colon, the site of bacterial fermentation, the teniae have a greater proportion of elastin than in the dorsal colon. In the right dorsal colon, the site of transport and regulation of ingesta through the transverse colon, smooth muscle cells are present in greater proportion.
From where is the blood supply to the ascending colon derived?
overall from the cranial mesenteric artery; the colic branch of the ileocecocolic artery supplies the ventral colon to the pelvic flexure, where it joins the right colic artery, another branch of the cranial mesenteric artery
From where is the blood supply to the transverse colon derived?
The middle colic artery, also a branch of the cranial mesenteric artery, provides blood supply to the transverse colon and to the initial part of the small colon
T/F: The principal mechanism for delay in transit is the retropulsive activity initiated in a pacemaker region near the pelvic flexure (approximately 30 cm (12 inches) aboral to the termination of the medial and lateral free teniae of the left ventral colon).
True; The coordinated contractions originating at the pelvic flexure pacemaker promote physical separation of small, well-digested particles, which are propelled aborally, and of coarser particles, which are propelled orally for further digestion.
How is the transverse colon anchored to the abdomen?
It is connected dorsally to the pancreas, to the dorsal aspect of the abdominal cavity, and by a short transverse mesocolon to the root of the mesentery.
T/F: The small colon is attached to the terminal duodenum by the duodenal colic fold
True
From where is the blood supply of the small colon derived?
The vascular supply to the small colon is derived from the caudal mesenteric artery with anastomoses cranially from the cranial mesenteric artery and caudally from the middle and caudal rectal arteries. The caudal mesenteric artery divides into two major branches, the left colic artery and the cranial rectal artery, with the left colic artery supplying the proximal three fourths of the descending colon and the cranial rectal, the distal one fourth.
T/F: In true hernias, the protrusion occurs through a normal aperture in the abdomen and contains a complete peritoneal sac (inguinal or scrotal hernia). These hernias are sometimes referred to as indirect hernias.
True
T/F: In false hernias, the protrusion does not arise through a normal aperture in the abdomen. False hernias do not initially contain a complete peritoneal sac and are usually created by trauma to the abdomen or develop after breakdown of a surgical entry (incisional hernias). These are also referred to as direct hernias.
True
From where is the blood supply to the small intestine derived?
the cranial mesenteric artery supplying the jejunal arteries and the ileocecal artery (supplies the ileum)
T/F: Digestion and absorption of nutrients take place predominantly in the lower half of the small intestine.
False; Digestion and absorption of nutrients take place predominantly in the upper half of the small intestine