Anatomy 4. Intestines Flashcards
(156 cards)
1
Q
Which parts of the small intestine are mobile?
A
Not the duodenum. The jejenum/ ileum are mobile.
2
Q
What are the peritoneal positions of the duodenum segments?
A
Proximal first segment is intraperitoneal. The rest is secondarily retroperitoneal.
3
Q
Why are the ascending and descending not mobile?
A
They are secondarily retroperitoneal.
4
Q
How is the caecum bound?
A
To the lateral abdominal wall by a fold of peritoneum.
5
Q
What is the transverse mesocolon?
A
The mesentery of the transverse colon.
6
Q
Where does the transverse mesocolon attach?
A
To the posterior wall of the omental bursa.
7
Q
How does the lumen size of the small and large intestine differ?
A
The small intestine has a smaller diameter than the large intestine.
8
Q
What is the longitudinal muscle of the small intestine like?
A
It is a continuous layer.
9
Q
What are the three bands of longitudinal muscle in the large intestine?
A
Teniae coli.
10
Q
What is the teniae coli?
A
The three bands of longitudinal muscle in the large intestine.
11
Q
Which parts of the intestine have fatty tags?
A
The small intestine has none, but the large intestine has them attached to its wall, appendices epioploicae.
12
Q
What is the wall of the small intestine like?
A
Smooth.
13
Q
What is the wall of the large intestine like?
A
Sacculated, forming haustra.
14
Q
What does sacculation of the large intestine wall form?
A
Haustra.
15
Q
What folds does the mucous membrane of the small intestine have?
A
Permanent folds, plicae circulares.
16
Q
What are plicae circulares?
A
The permanent folds of the mucous membrane of the small intestines.
17
Q
How does lymphoid tissue exist in the small intestine?
A
As Peyer’s patches.
18
Q
What is the size of the duodenum?
A
25cm long.
19
Q
What shape does the duodenum have?
A
A C-shape.
20
Q
What does the duodenum wrap around?
A
The head of the pancreas.
21
Q
Where does the duodenum begin and end?
A
Begins at the pylorus on the right side and ends at the duodenojejunal flexure on the left side.
22
Q
At what vertebral level are the duodenojejunal flexure exist?
A
L2 vertebra, 2-3cm left of the midline.
23
Q
How is the duodenum fixed?
A
By peritoneum to structures on the posterior abdominal wall.
24
Q
What are the four parts of the duodenum?
A
Superior, descending, inferior, and ascending.
25
How big is the superior part of the duodenum?
5cm.
26
Where does the superior part of the duodenum lie?
Anterolateral to the body of the L1 vertebra.
27
How big is the descending part of the duodenum?
7-10cm.
28
Where does the descending part of the duodenum descend?
Along the right sides of L1-L3 vertebra.
29
How big is the inferior part of the duodenum?
6-8cm.
30
Where does the inferior part of the duodenum cross?
The L3 vertebra.
31
How big is the ascending part of the duodenum?
5cm.
32
Where does the ascending part of the duodenum go from and to?
Begins at the left of L3 vertebra and rises superiorly to the superior border of the L2 vertebra.
33
What is the duodenal cap/ampulla?
The first 2cm of the superior part of the duodenum, immediately distal to the pylorus.
34
How does the ampulla differ from the rest of the duodenum?
It has mesentery and is mobile, the rest of the duodenum is retroperitoneal and immobile.
35
Why is the ampulla a common site of ulceration?
It is immediately distal to the pylorus.
36
How can erosion of a duodenal ulcer cause severe blood loss?
It can erode through the gastroduodenal artery.
37
Which parts of the superior part of the duodenum does peritoneum cover?
The anterior aspect, but not the posterior aspect.
38
Where does the hepatoduodenal ligament attach to the duodenum?
To the proximal part superiorly.
39
Where does the greater omentum attach to the duodenum?
To the proximal part inferiorly.
40
Where do the bile and main pancreatic ducts enter the duodenum?
The posteromedial wall of the descending part via the ampulla of vater.
41
What forms the transverse mesocolon?
The peritoneum of the anterior proximal side and distal thirds of the duodenum reflect in its middle third to form the double-layered mesentery of the transverse colon.
42
What does the inferior part of the duodenum pass over?
The inferior vena cava, aorta and L3 vertebra.
43
Why is the anterior surface of the inferior part of the duodenum not covered by peritoneum?
Where the superior mesenteric artery and vein, and the root of the mesentery of the jejunum and ileum cross the duodenum.
44
How is the posterior inferior part of the duodenum separated from the vertebral column?
By the right psoas major muscle, inferior vena cava, aorta, and right testicular/ovarian vessels.
45
What does the ligament of Treitz do?
Supports the duodenum as it joins the jejunum at the duodenojejunal flexure.
46
What does contraction of the ligament of Treitz do?
It widens the duodenojejunal flexure to facilitate movement.
47
What is the jejunum?
The second part of the small intestine.
48
What is the ileum?
The third part of the small intestine.
49
Where does the jejunum begin?
Begins at the duodenojejunal flexure.
50
Where does the ileum end?
At the ileocaecal junction.
51
How long are the jejunum and ileum collectively?
6-7m.
52
What proportion of the 6-7m length of the small intestine is jejunum, and what proportion is ileum?
The jejunum constitutes approximately two fifths and the ileum three fifths.
53
Where does the jejunum lie?
In the left upper quadrant of the infracolic compartment.
54
Where does the ileum lie?
In the right lower quadrant of the infracolic compartment.
55
Where does the terminal ileum lie?
In the pelvis usually.
56
Where does the terminal ileum end?
In the medial aspect of the caecum.
57
What does the mesentery attach?
The jejunum and ileum to the posterior abdominal wall.
58
What are between the two layers of small intestine mesentery?
Superior mesenteric vessels, lymph nodes, a variable amount of fat, and autonomic nerves.
59
What does the root of the mesentery cross?
The ascending and inferior parts of the duodenum, abdominal aorta, inferior vena cava, right ureter, right psoas major, and right testicular/ovarian vessels.
60
How do the colours of jejunum and ileum differ?
Jejunum is deeper red, ileum is paler pink.
61
How do the jejunum and ileum differ in terms of diameter?
Jejunum is larger - 2-4cm, ileum is narrower - 2-3cm.
62
How do the jejunum and ileum differ in terms of wall?
The jejunal wall is thick and heavy, whereas the wall of the ileum is thin and light.
63
How do the jejunum and ileum differ in terms of vascularity?
Jejunum has greater vascularity, ileum has less.
64
How do the jejunum and ileum differ in terms of vasa recta?
Longer in jejunum than ileum.
65
How do the jejunum and ileum differ in terms of arcades?
The jejunum has few large loops, the ileum has many short loops.
66
How do the jejunum and ileum differ in terms of fat in mesentery?
The jejunum has less than the ileum.
67
How do the jejunum and ileum differ in terms of circulae folds/ plicae circulares?
Large, tall and closely packed in jejunum but low and sparse in ileum, almost absent in the distal part.
68
How do the jejunum and ileum differ in terms of lymphoid nodules/ Peyer's patches?
There are few in the jejunum but many in the ileum.
69
How is the GI tract split into foregut, midgut, and hindgut?
Foregut is until the duodenum, proximal to the bile duct.
Midgut includes the duodenum (distal to the bile duct), jejunum/ileum, cecum/ascending colon, proximal 2/3 transverse colon.
Hindgut includes the distal 1/3 transverse colon, descending/sigmoid colon, rectum/upper anal canal.
70
What is the blood supply to the foregut?
Coeliac trunk.
71
What is the blood supply to the midgut?
Superior mesenteric artery and superior mesenteric vein.
72
What is the blood supply to the hindgut?
Inferior mesenteric artery and inferior mesenteric vein.
73
Which parts of the gut is the duodenum derived from?
Foregut and midgut.
74
What is the blood supply of the parts of the duodenum?
Proximal to the bile duct is from the coeliac trunk, via the superior pancreaticoduodenal branch of the gastroduodenal artery.
Distal to the bile duct is the inferior pancreaticoduodenal branch of the superior mesenteric artery.
75
Where do the pancreaticoduodenal arteries lie?
In the curve between the duodenum and the head of the pancreas.
76
What do the veins of the duodenum drain into?
Hepatic portal vein, directly or through the superior mesenteric and splenic veins.
77
What are the jejunum and ileum derived from?
The midgut.
78
What is the blood supply to the jejunum?
The jejunal artery from the superior mesenteric artery.
79
What is the blood supply to the ileum?
The ilial artery from the superior mesenteric artery.
80
Where does the superior mesenteric artery arise?
From the abdominal artery at the level of L1 vertebra, about 1cm inferior to the coeliac trunk.
81
Where does the superior mesenteric artery run?
Between the layer of mesentery. It sends 15-18 branches to the jejunum and ileum.
82
What forms arterial arcades?
Loops of the arteries branching from the superior mesenteric artery.
83
What gives rise to the vasa recta?
The arterial arcades.
84
What makes up the large intestine?
The caecum, appendix, ascending, transverse, descending, and sigmoid colon, rectum, and anal canal.
85
How is the large intestine distinguished from the small?
By the omental appendices, teniae coli, haustra, and diameter.
86
What are the omental appendices?
Small, fatty, omentum-like projections.
87
What are the teniae coli?
Three distinct longitudinal bands of muscle that begin at the appendix and run the length of the large intestine.
88
What happens to the teniae coli at the rectosigmoid junction?
The bands of muscle merge together into a continuous layer around the rectum.
89
What are haustra?
Sacculations of the wall of the colon between teniae.
90
What is the caecum?
The first part of the large intestine, it's a blind intestinal pouch -7.5cm x 7.5cm.
91
Where does the caecum lie?
In the iliac fossa of the right lower quadrant of the abdomen, inferior to the ileocaecal junction.
92
When may the caecum by palpable through the anterolateral abdominal wall?
If it is distended with faeces or gas.
93
Why can the caecum by displaced from the iliac fossa?
It is almost entirely enveloped by peritoneum so is mobile.
94
How is the caecum commonly bound to the lateral abdominal wall?
By one or more caecal folds of peritoneum.
95
What is the appendix?
A blind intestinal diverticulum that contains masses of lymphoid tissue.
96
What does the appendix arise from?
The posteromedial aspect of the caecum inferior to the ileocaecal junction.
97
What is the mesoappendix?
The short, triangular mesentery of the appendix.
98
What is the mesoappendix derived from?
The posterior side of the mesentery of the terminal ileum.
99
Where does the mesoappendix attach?
To the caecum and the proximal part of the appendix.
100
What is the derivation of the caecum?
It is midgut derived.
101
What is the blood supply of the caecum?
The ileocolic artery from superior mesenteric artery.
102
What is the derivation of the appendix?
It is midgut derived.
103
What is the blood supply to the appendix?
The appendicular artery, from the superior mesenteric artery.
104
What is the venous drainage from the caecum and appendix?
The ileocolic vein.
105
What are the four parts of the colon?
Ascending, transverse, descending, and sigmoid.
106
What is the path of the ascending colon?
It passes superiorly on the right of the abdominal cavity from the caecum to the right lobe of the liver. Here it turns to the left at the right colic flexture.
107
Where does the hepatic flexure lie?
Deep to the 9th and 10th ribs and is overlapped by the inferior part of the liver.
108
How does the ascending part of the colon differ from the caecum?
It is narrow and is secondarily retroperitoneal.
109
How is the ascending colon separated from the anterolateral abdominal wall?
By the greater omentum.
110
What is the right paracolic gutter?
A deep vertical groove lined with parietal peritoneum between the lateral aspect of the ascending colon and the adjacent abdominal wall.
111
What is the longest, and most mobile part of the large intestine?
The transverse colon.
112
Where does the transverse colon run from and to?
From the right colic flexure to the left.
113
Where is the left colic flexure?
Anterior to the inferior part of the left kidney.
114
How does the left colic flexure attach to the diaphragm?
Through the phrenicocolic ligament.
115
Where does the transverse colon and transverse mesocolon loop down to?
Inferior to the level of the iliac crests.
116
What is the root of the transverse mesocolon continuous with?
The parietal peritoneum posteriorly.
117
What is the position of the descending colon?
It is a secondarily retroperitoneal structure between the left colic flexure and left iliac fossa.
118
What is the left paracolic gutter?
The deep vertical groove lined with parietal peritoneum between the lateral aspect of the ascending colon and the adjacent abdominal wall.
119
What is the shape of the sigmoid colon?
S-shape of variable length.
120
What does the sigmoid colon link?
The descending colon and the rectum.
121
What makes the rectosigmoid junction?
The termination of teniae coli, 15cm from the anus.
122
What is the sigmoid mesocolon?
The long mesentery of the sigmoid colon that gives it considerable mobility.
123
Where does the left ureter and division of the left common iliac artery lie in relation to the sigmoid mesocolon?
Retroperitoneally, posterior to the apex of the root of the sigmoid mesocolon.
124
What is the derivation of the ascending colon and right colic flexure?
Midgut.
125
What is the blood supply to the ascending colon?
Ileocolic artery from the superior mesenteric artery.
126
What is the blood supply to the right colic flexure?
Right colic artery from the superior mesenteric artery.
127
What forms the marginal artery?
Anastomosis of the ileocolic, right colic, and right branch of the midline colic arteries.
128
What is the venous drainage of the ascending colon and right colic flexure?
The ileocolic and right colic veins, drain into the superior mesenteric veins and then the portal vein.
129
What are the derivations of the transverse colon?
Midgut and hindgut.
130
What is the blood supply of the transverse colon?
Mostly from the superior mesenteric artery via the middle colic artery. Some blood from the right colic (superior mesenteric root) and left colic (inferior mesenteric root) arteries via the marginal artery.
131
What is the venous drainage of the transverse colon?
Middle colic vein, drains into the superior mesenteric vein and then the portal vein.
132
What are the descending and sigmoid colon derived from?
The hindgut.
133
What is the blood supply to the descending and sigmoid colon?
The inferior mesenteric artery via the left colic and sigmoid arteries.
134
What is the venous drainage of the descending and sigmoid colon?
The left colic and sigmoid veins, drain into inferior mesenteric vein and then the splenic and portal veins.
135
What is the rectum?
The fixed, primarily retroperitoneal and subperitoneal, terminal part of the large intestine.
136
What are the parts of the rectum and how do their peritoneal coverings differ?
First third - peritoneum covers the anterior and lateral surfaces.
Second third - peritoneum covers anterior surface.
Final third - no covering, subperitoneal.
137
What is the derivation of the rectum?
From the hindgut.
138
What is the blood supply of the rectum?
Proximal rectum from the inferior mesenteric artery via the superior rectal arteries.
Distal rectum from branches of the internal iliac arteries - right and left middle rectal arteries. And branches of the interior pudendal arteries - right and left inferior rectal arteries.
139
What is the venous drainage of the rectum?
The superior, middle, and inferior rectal veins. Superior drains into inferior mesenteric vein, then splenic and portal vein. Middle and inferior drain into systemic system.
140
Why are the anastomoses between the portal and systemic venous systems in the anal canal clinically important?
They are important in portal hypertension.
141
What is the anal canal?
The terminal part of the large intestine and of the entire digestive canal.
142
Where does the anal canal begin and end?
Begins where the rectal ampulla narrows by the pubrectalis muscle, and ends at the anus.
143
What does the anal canal descend between?
Posteroinferiorly between the anococcygeal ligament and the perineal body.
144
What are the anal columns?
The series of longitudinal ridges in the superior half of the mucous membrane of the anal canal.
145
What is the anorectal junction?
Where the rectum joins the anal canal.
146
What are the inferior ends of the anal columns joined by?
Anal valves.
147
What is superior to the anal valves?
Anal sinuses.
148
What do anal sinuses do?
Exude mucus when compressed by faeces. This aids in evacuation of faeces from the anal canal.
149
What is the pectinate line?
An irregular line from the inferior comb-like shape of the anal valves.
150
How does the anal canal differ superior and inferior to the pectinate line?
In arterial supply, innervation, and lymphatic drainage.
151
What are the derivations of the anal canal?
Above the pectinate line - hingut.
| Below the pectinate line - endoderm.
152
What is the blood supply of the anal canal?
Above the pectinate line - inferior mesenteric artery via the superior rectal artery.
Below the pectinate line - inferior rectal arteries. Middle rectal arteries form anastomoses with superior and inferior rectal arteries.
153
What is the innervation of the anal canal?
Above pectinate line is visceral supply so sensitive to stretch. Below pectinate line is somatic supply from inferior anal nerves (branches of the pudendal nerve) so sensitive to pain, touch, and temperature.
154
What forms the floor of the rectovesical pouch in males?
After the second third of the rectum, the peritoneum reflects onto the posterior wall of the bladder.
155
What forms the floor of the rectovesical pouch in females?
After the second third of the rectum, the peritoneum reflects onto the posterior part of the fornix of the vagine.
156
What is the vesicouterine pouch?
The peritoneal reflection in females between the uterus and urinary bladder.
