Gross anatomy & histology of ileum, jejunum

1. Practical demonstration of gross anatomy & histology of Jejunum , Ileum,Appendix and Colon By Dr. Abdul Waheed Ansari Chairperson &Prof. Anatomy, RAKCOMS. RAKMHSU. 10/27/2014 1

2. Learning outcomes of the lab are:- 1. Identify the different segments of small intestines-Duodenum, Jejunum and Ileum. 2. Identify the gross features of large intestines-appendix, ascending colon, transverse colon, descending colon, sigmoid colon, rectum and anal canal. 3. Histological features of ileum, jejunum, appendix and colon. 10/27/2014 2

3. Features of duodenum It is the first part of small intestines, 25 cms long. It is retroperitoneal except first inch of first part of duodenum. It has four parts , C shaped . Second part has opening of CBD and pancreatic ducts, major duodenal papilla and minor duodenal papilla. 10/27/2014 3

4. The Jejunum is the second portion of small intestines It starts from duodenojejunal flexure to ileocaecal junction. The proximal 1/3 rd are the jejunum loops and distal 2/3 rd are the loops of ileum. The jejunum loops are more muscular and more vascular where as ileal loops are thin walled and less vascular, interior shows plicae circularis. Internally ileum have Payer’s patches. The plicae circularis are few in the ileum. 10/27/2014 4

5. The arterial supply of jejunum and ileum The superior mesenteric artery is the artery of midgut. It gives jejunal branches and ileal branches and terminates as ileocaecal artery. The accompanying vein joins the splenic vein to form the portal vein. 10/27/2014 5

6. Histology of Jejunum The mucosa of the small intestine is lined by simple columnar epithelium which evaginates into villi. The epithelium of villi is continuous with that of adjacent crypts. Lamina propria of the small intestine forms the core of villi and surrounds the crypts . The muscularis mucosa of the small intestine forms a thin layer. 10/27/2014 6

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8. Ileum The Peyers patches are found in the ileum. They are found at the antimesentreric border. Histology of Ileum is characterized by submucosa having lymphoid tissue-Peyer’s patches 10/27/2014 8

9. Appendix The human's appendix averages 11 cm in length but can range from 2 to 20 cm. The diameter of the appendix is usually between 7 and 8 mm It has no haustrations, no taenia coli and no plicae circularis and no Peyer’s patches and no appendices epiploicae. It has a mesentery of its own, carrying the artery to appendix. The tip of the appendix can have a variable position within the abdominal cavity : retro-caecal (65-70%) pelvic (25-30%) pre- or post-ileal (5%) Inflammation is called as appendicitis. Pain will be felt around umbilicus because of referred pain-T10 segment dermatome. The arterial supply- appendicular artery, a branch of the ileocolic artery which is a branch of the superior mesenteric artery. 10/27/2014 9

10. Normal appendix ultrasound image longitudinally 10/27/2014 10 Appendicitis –perforation detected by sonography

11. Sonography of swollen and inflamed appendix longitudinal section Appendicitis shows up as a tubular structure that does not push out of the way or compress, often with changes in the adjacent fat from the inflammation. This will often cause the patient to say, “Ouch, that is where it hurts.” 10/27/2014 11

12. Histology of appendix 10/27/2014 12

13. Colon histology The mucosa is having simple columnar epithelium with lots of mucus glands-goblet cells. Simple tubular intestinal glands. Submucosa having neurovascular bundles. Muscularis external having both circular and longitudinal fibers- taenia coli are longitudinal bundles 10/27/2014 13

14. The large intestines The caecum, appendix , ascending colon, transverse colon, descending colon, sigmoid colon, rectum and anal canal are parts of large intestines. It is supplied by branches from superior and inferior mesenteric arteries. At the anal canal there is anastomosis between systemic veins and portal veins, hence one of the sites for anal hemorrhoids formation. It shows haustrations, taenia coli, appendices epiploicae, all typical features of large intestines, except appendix rectum and anal canal. The anal canal has dual epithelial lining, upper part simple columnar and lower part stratified squamous non keratinized. The anal canal has two sphincters, external and internal. External anal sphincter is voluntary where as internal is involuntary. 10/27/2014 14

15. Large intestines external features 10/27/2014 15

16. The anal canal 10/27/2014 16

17. References http:// www.studyblue.com/notes/note/n/anal-triangle/deck/8502291 http:// ect.downstate.edu/courseware/haonline/labs/L39/130202.htm http:// histologyatlas.wisc.edu/slides/398 http://quizlet.com/17115737/27-digestive-system-flash-cards / http:// www.ultrasoundcases.info/Cases-Home.aspx 10/27/2014 17