Anatomy of Small and Large Intestines Flashcards
(95 cards)
1
Q
The small intestine is divided into?
A
- duodenum 2. jejunum 3. ileum
2
Q
Describe the duodenum?
A
- C-shaped 2. retroperitoneal - except near stomach
3
Q
What is the extent of the duodenum?
A
pyloric sphincter - duodenojejunal flexure
4
Q
The duodenum is characterised by?
A
tubular Brunners glands in submucosa that secrete mucous
5
Q
What is the primary function of the duodenum?
A
food digestion + absorption
6
Q
What are the parts of the duodenum?
A
- superior 2. descending 3. horizontal 4. ascending
7
Q
Describe the superior (first) part?
A
- related to the pylorus 2. intraperitoneal - found in the hepatoduodenal ligament : freely mobile
8
Q
What are the posterior relations of the first part?
A
- bile duct 2. gastrodudenal art 3. portal vein
9
Q
What condition is found mostly in the first part?
A
duodenal ulcers - 95%
10
Q
Describe the consequence of the perforation of ulcers?
A
- erode gastroduodenal art - haemorrhage 2. duodenal contents cause abdominal peritonitis
11
Q
Describe the descending (second) part?
A
- retroperitoneal 2. Bile duct and main pancreatic duct join to form hepatopancreatic ampulla on the posteromedial surface of the second part
12
Q
What is the major duodenal papilla (of Vater)?
A
a round projection in the duodenum into which the common bile duct and pancreatic duct drain - the primary mechanism for the secretion of bile and other enzymes that facilitate digestion
13
Q
Describe the relations of the second part of the duodenum?
A
- Fundus & body of gallbladder 2. right kidney 3. transverse colon 4. head of pancreas
14
Q
Describe the horizontal (third) part?
A
- Retroperitoneal 2. crosses vertebral column at L3
15
Q
The third part is related to?
A
- psoas major muscle 2. IVC and aorta 3. right ureter 4. gonadal vessels 5. superior mesenteric vessels
16
Q
Describe the ascending (fourth) part?
A
- Retroperitoneal 2. ascends to the level of L2 3. contains the duodenojejunal flexure
17
Q
What is the duodenojejunal flexure suported by?
A
suspensory ligament of Treitz
18
Q
What is the clinical importance of the ligament of Treitz?
A
- Lig of Treitz used to locate duodenojejunal flexure
- Clinical dividing line between upper and lower gastrointestinal tracts
- Most gastrointestinal hemorrhage is above the ligament of Treitz, coming from esophagus, stomach
19
Q
Describe the arterial supply of the duodenum?
A
- Supraduodenal art - can be used to identify the first part of the duodenum
- sup & inf pancreaticoduodenal arts with their ant & post branches that form arcades
- Right gastric art
- Gastroduodenal art
20
Q
Describe the venous drainage?
A
Duodenal veins draining into the portal vein
21
Q
Describe the lymphatic drainage of the duodenum?
A
- Ant lymphatic vessels drain into pancreaticoduodenal nodes, pyloric lymph nodes
- Post lymphatic vessels drain into sup mesenteric lymph nodes
- celiac lymph nodes
22
Q
Describe the innervation?
A
- vagus nerve 2. Celiac & sup mesenteric plexuses
23
Q
What is the extent of the jejunum?
A
duodenum - ileum
24
Q
Describe the jejunum?
A
- intraperitoneal
- Most of it lies in left upper quadrant
- Lumen slightly larger than ileum; wall thicker than ileum
- More mucosal folds than ileum - plicae circulare & villi
- Deeper red with greater vascularity
- Long straright arteries - vasa recta
25
Describe the ileum?
1. terminal portion of the small intestine 2. lies in right lowe quadrant 3. has shorter straight arteries than jejunum 4. has abundant lymph nodules - Peyers patches or Mesenteric patched : GALT
26
Describe the extent of the ileum?
ends at ileocecal junction and joins cecum medially through ileocecal valve
27
What is Meckels Diverticulum?
a remnant of the connection between gut tube & yolk sac that Projects from the ileum about 60cm from ileocaecal junction in about 2% of people
28
What may the Meckels Diverticulum contain?
pancreatic + gastric mucosa
29
Consequence of diverticulum mucosa ?
1. can erode intestinal mucosa causing bleeding 2. presents a pain distribution similar to that of appendicitis
30
Describe the mesentery associated withjejunum and ileum?
attached to posterior abdominal by mesentery
31
Describe the exent of the root of mesentery?
duodenojejunal junction - ileocolic junction
32
The root of the mesentery crosses?
1. ascending and horizontal duodenum 2. abdominal aorta and IVC 3. right ureter + right psoas major 4. right testicular or ovarian vessels
33
Describe the arterial supply of the jeunum and ileum?
Superior mesenteric artery (SMA) - arterial arcades that give rise to vasa recta (straight arts) - end arteries
34
Consequence of occlusion?
occlusion - ischemia of intestines
35
What is the origin of the SMA?
SMA origin – Transpyloric plane (L1) together with gall bladder (Murphy’s point); pylorus, renal hilum
36
Describe the venous drainage of jejunum and ileum?
superior mesenteric vein
37
Describe the lymphatic drainage of the ileum and jejunum?
Lacteals, sup mesenteric lymph nodes, ileocolic lymph nodes
38
Describe the innervation jejunum and ileum?
1. parasympathetic - vagus nerve 2. sympathetic - lesser splanchnic nerve 3. superior mesenteric plexus
39
What is the extent of the large intestine?
ileocecal junction - anus : about 1.5 m
40
What are the parts of the large intestine?
1. Cecum with attached vermiform appendix 2. Colon: ascending, transverse, descending, sigmoid 3. Rectum and anal canal
41
Describe ascending and descending colons?
1. held onto posterior abdomnial wall 2. in the retroperitoneal
42
Describe the transverse and sigmoid colons?
1. are suspended by mesenteries - mesocolon 2. are mobile
43
What are teniae coli?
three thickened bands of longitudinal muscle
44
What are haustra?
sacculations of its wall
45
What are omental (epiploic) appendages?
small pouches of omentum (peritoneum) filled with fat
46
What are diverticulae?
mucous membrane may herniate through perforations in muscle layer of colon made by blood vessels supplying epiploic appendages
47
What is diverticulitis?
causes abdominal pain
48
What are villi?
Mucosa has no villi but numerous mucus cells
49
Describe the cecum?
1. Blind sac invested in peritoneum 2. 8 cm W x 8 cm L, located in RIF
50
Where does the vermiform appendix attach?
posteromedial wall and taenia coli of the large intestine
51
Describe the lateral and medial attachments of the cecum?
attached by peritoneal cecal folds to iliac fossa and this produces a small sac of peritoneal cavity called retrocecal recess which lies posterior to cecum - It may extend sup, post to inferior end of ascending colon as retrocolic recess
52
The appendix lies where in 64% of people?
retrocolic recess
53
Describe the relations of the cecum?
1. posterior - lies on iliacus and psoas 2. anterior - small intestines and anterior abdominal
54
Describe the vermiform appendix?
1. About 8 cm long & worm-shaped 2. Joins cecum about 2.5 cm inf to ileocecal junction 3. Longer in children than in adults 4. Very mobile & its position is variable 5. Has a mesentery called mesoappendix which joins it to terminal ileum : Appendicular artery is within this fold - end artery 6. The 3 teniae coli of cecum converge at base of appendix
55
Describe how the vermiform appendix is related to Mc Burneys point?
the base of the vermiform appendix lies deep at Mc Burneys point - junction of lat & mid thirds of line joining ant sup iliac spine & umbilicus
56
Where are the incisions made?
made about 2.5 cm superomedial to ant. sup. iliac spine
57
What is appendicitis?
inflammation of the appendix - 1. It is obstructed by swelling of lymphoid tissue 2. Acute infection may cause thrombus in appendicular artery & rupture the appendix causing general peritonitis - increased abdominal pain
58
Describe the ascending colon?
1. about 15 cm long 2. ascends on the right side of the abdominal cavity 3. It usually has no mesentery - 25% of pple have a short mesentery 4. Lies retroperitoneally along right side of posterior abdominal wall
59
Describe the posterior relations of the ascending colon?
1. Back muscles: iliacus & quadratus lumborum + right kidney 2. Nerves of posterior abdominal wall: ilioinguinal & iliohypogastric
60
What are the anterior relations?
small intestines + greater omentum
61
What are the lateral relations?
covered by peritoneum, which attaches it to posterior abdominal wall
62
Describe the peritoneum of the ascending colon?
forms a trench or groove called right paracolic gutter
63
What is volvulus?
1. Abnormal mobility of cecum & proximal part of ascending colon because inferior part of ascending colon has a mesentery 2. It may cause obstruction of intestines resulting from twisting
64
What is cecopexy?
Anchoring procedure where tenia colia of cecum & ascending colon are sutured to abdominal wall to avoid volvulus
65
Describe the transverse colon?
1. 50 cm 2. largest and most mobile part of large intestine 3. has mesentery called transverse mesocolon 4. transverse colon is variable in position
66
What is the extent of the transverse colon?
right colic - left colic flexure
67
Describe the splenic flexure?
1. lies ant. to the inferior part of left kidney & is attached to the diaphragm by phrenicocolic ligament - shelf to support spleen 2. is more sup. & post. to right colic flexure 3. more acute & less mobile than hepatic flexure
68
Describe the descending colon?
1. 30 cm 2. smaller than ascending colon 3. It usually has no mesentery (33% of pple have) 4. has left paracolic gutter on lateral aspect
69
Describe the extent of the descending colon?
Left colic (splenic) flexure into left iliac fossa where it is continuous with sigmoid colon
70
Describe the relations of the descending colon?
1. superior - related to diaphragm & quadratus lumborum muscles 2. Passes ant. to lat. border of left kidney, transversus abdominis & quadratus lumborum muscles
71
Describe the sigmoid colon? (pelvic colon)
1. 40 cm 2. form S shaped loop 3. Has a long mesentery (sigmoid mesocolon) whose root has an inverted V - shaped attachment superiorly 4. Left ureter & a division of left common iliac artery are post to the apex of the mesentery 5. has long omental appendages 6. Rectosigmoid junction is about 15 cm from anus
72
What indicates the beginning of the rectum?
termination of teniae coli
73
What space does it occupy in males and females?
1. males - rectovesicle pouch 2. females - rectouterine pouch
74
Describe the relations of the sigmoid colon?
1. posterior - Left external iliac vessels & piriformis muscle
75
Describe the rectum?
12 cm
76
Describe the relations of rectum?
1. Superior - continuous with sigmoid colon at the level of S3 - rectosigmoid junction 2. Inferior - continuous with anal canal
77
What are the peritoneal relations of the rectum?
1. Sup 1/3 ant & lat peritoneal cover 2. Mid 1/3 ant peritoneal cover 3. Inf 1/3 no peritoneal cover
78
Describe the anal canal?
1. terminal part of the GIT - 4 cm 2. Has anal canals, anal columns & anal valves with anastomoses
79
What is the anus?
external opening of anal canal - 2 sphincters guard the anus
80
Descibe the sphincters of the anus?
1. External anal sphincter - composed of skeletal muscle 2. Internal anal sphincter - composed of smooth muscle fibers
81
What are hemorrhoids?
veins in the anal area
82
What is the arterial supply to the large intestine?
1. branches of SMA 2. branches of IMA
83
What are the branches of the superior mesenteric artery?
1. Middle colic art with its branches - R & L 2. Right colic with its branches - ascending & descending 3. Ileocolic with its branches - colic and ileal
84
What are the branches of the inferior mesenteric artery?
1. left colic artery 2. sigmoid artery
85
Describe the venous drainage?
1. superior mesenteric vein 2. inferior mesenteric vein 3. splenic vein 4. portal vein
86
Describe the lymphatic drainage?
preaortic lymph nodes - follow arteries
87
Describe the innervation?
1. parasympathetic 2. sympathetic
88
What is the parasympathic innervation?
1. vagus nerve 2. pelvic splanchnic nerves
89
What is the sympathetic innervation?
1. Superior mesenteric & aorticorenal ganglia 2. Lesser splanchnic nerves 3. Inferior mesenteric ganglia 4. Lumbar splanchnic nerves
90
What is a colonoscopy?
1. Procedure where the mucous membrane of the colon can be directly visualized through an endoscope 2. The interior of the large bowel can be observed from the anus to the cecum
91
What is a colonoscopy used for?
1. Photographs of suspicious areas, such as polyps, can be taken and biopsy specimens can be removed for pathologic examination 2. colorectal cancer
92
Describe the predisposition of the appendix to perforation?
Inflammatory edema of the appendicular wall compresses the blood supply to the appendix and often leads to thrombosis of the appendicular artery leading to necrosis and perforations
93
Describe the predisposition of the appendix to infection?
1. It is a long, narrow, blind-ended tube, which encourages stasis of large-bowel contents 2. It has a large amount of lymphoid tissue in its wall 3. The lumen has a tendency to become obstructed by hardened intestinal contents (enteroliths), which leads to further stagnation of its contents.
94
What is a cecostomy?
Procedures used to relieve large-bowel obstructions through a small opening in the anterior abdominal wall.
95
What is a colostomy?
Procedures used to relieve large-bowel obstructions through a small opening in the anterior abdominal wall.
