Anatomy Review: Large Intestine and Rectum Histology
The presentation delves into the detailed morphology and histology of the large intestine and rectum, covering aspects often not emphasized in textbooks. It explores nuances such as the S-shaped structure of the rectum, the composition of the anal canal, the layers of epithelium, and the territorial origins of arteries. Additionally, it discusses the Riolan arcades and offers references for further reading on the subject.
Download Presentation
Please find below an Image/Link to download the presentation.
The content on the website is provided AS IS for your information and personal use only. It may not be sold, licensed, or shared on other websites without obtaining consent from the author. Download presentation by click this link. If you encounter any issues during the download, it is possible that the publisher has removed the file from their server.
E N D
Presentation Transcript
Klmn M: Morphology and histology of the large intestine and rectum To the lectures for EM 1-8 and 9-17 on March 21 and 22, 2019. Mainly the parts not emphasized in the textbook.
The main points: The rectum is not rectus i.e. straight, but S-shaped, the opening directed posteriorly rather than downward! The lower curvature contacts the prostate or the vaginal fornix. The anal canal has 3 parts below it: the pectinate line hemorrhoidal (venous plexus) below it: white line, and a shellow groove (note: at the border of the 2 subdivisions of ext. sphinter, see later) cutaneous epithelium intestinal (columnar: columnae and sinuses) intestinal epithalium epi-ectodermal border stratified squamous epithelium. keratinized stratified squamous The anal canal is below the floor of the pelvis (not yet lectured) The external voluntary sphincter onsists of 3 parts: deep, supeficial and subcutaneous. Tha last one is most important. The longitud. smooth has tendon-like elongations, which form connective tissue slings (conjoint fibromuscular layer) around the fascicles of the subcutaneous ext. sphincter) The territories of arteries correspond to the developmental origins: superior rectal (most part) hindgut derivative middle rectal (small, approx. the sinuses) - cloacal derivative inferior rectal - proctodeum derivative, ectodermal, below the pectinate line.
The Riolan arcades The term small or first Riolan arch (the anastomosis between the sup. and inf. Pancreaticoduodenal arteries is in use actually only in our institute; it is not applied in the textbooks. The mame arch of Riolan is most probably incorrectly applied on the marginal artery; it is the anastomosis or arch of Drummond. Which artery was described by Riolan it is already not clear; most probably it was the so-called meandering mesenteric artery, which also interconnects the middle and left colic arteries but in a more proximal and sinuous line. For literature, see the next page. Note: these and similar names of authors (eponymes) are not to be learned by students; we use them only as a homage to the elders.
Papers helping clarify thr Riolan question. Only for enthusianistic volunteers! Note: the first one was written by dr. gnes Nemesk ri and her co-workers from our institute. Szu k, Andr s; Hal sz, Vanda; G ti, Endre; Hars nyi, L szl ; Nemesk ri, gnes (2016) First Report on Arterial Anastomosis Between Transverse Pancreatic and Left Colic Arteries. Case Studies Journal Vol 5, Issue 2, Page 1 Lange, J.F., Komen, N., Akkerman, G., Nout, E., Horstmanshoff, H., Schlesinger, F., Bonjer, J., Kleinrensink, G.J., 2007. Riolan s arch: confusing, misnomer, and obsolete. A literature survey of the connection(s) between the superior and inferior mesenteric arteries. The American Journal of Surgery. 193, 742-748. Walter, T.G., 2009. Mesenteric Vasculature and Collateral Pathways. Semin. Intervent. Radiol. 26(3), 167-174. Fisher Df, Fry WJ. Collateral Mesenteric Circulation " Surgery, Gyencology and Obstetrics. 1987, 164(5):487-492 Gourley EJ, Gering SA. "The Meandering Mesenteric Artery: A Historic Review and Surgical Implications." Disease of the Colon & Rectum. Vol 48:5 (2005) pp 996- 1000 (the figure is taken from this paper). Douard R, Chevallier JM, Delmas V, Cugnenc PH Clinical interest of digestive arterial trunk anastomoses. Surg Radiol Anat. 2006 Jun;28(3):219-27.
