Presentation on theme: "LARGE INTESTINE Dr. Zahiri In the name of God. The large intestine (or colon) the last part of the digestive system Absorb water, sodium and some fat."— Presentation transcript:
LARGE INTESTINE Dr. Zahiri In the name of God
The large intestine (or colon) the last part of the digestive system Absorb water, sodium and some fat soluble vitamins. The large intestine consists of : the cecum, appendix, colon, rectum, and anal canal. is about 4.9 feet (1.5 m) long Dr. Maria Zahiri
Characteristics of large intestine Taeniae coli: three bands of smooth muscle Haustra : bulges caused by contraction of taeniae coli Epiploic appendages (omental appendices ): are small pouches of the peritoneum filled with fat and situated along the colon. their function is unknown. Dr. Maria Zahiri
Taeniae coli Dr. Maria Zahiri
Epiploic appendages Dr. Maria Zahiri
Position: Lie in the right iliac fossa below the ileocaecal valve. Is a intraperitoneal organ (?) Posteriorly lies the retrocaecal recess which frequently contains the vermiform appendix. Size: Average 6-7 cm Caecum Dr. Maria Zahiri
Blood supply Dr. Maria Zahiri Vascular supply for caecum * Ileocolic artery Superior branch Inferior branch Ascending (colic) artery Anterior caecal artery Posterior caecal artery Appendicular artery Ileal artery
Dr. Maria Zahiri Superior branch Inferior branch Appendicular artery Ileal artery
Dr. Maria Zahiri
Veins: Dr. Maria Zahiri Superior mesenteric vein Ileocolic vein Superior branch Ascending colic veins Inferior branch Appendicular vein Anterior caecal vein Posterior caecal vein Ileal vein
Dr. Maria Zahiri Lymphatic drainage Anterior lymphatic vessels drain to: Anterior ileocolic nodes Posterior lymphatic vessels drains to: Posterior ileocolic nodes Inferior ileocolic nodes To: Superior mesenteric nodes
Innervation: Dr. Maria Zahiri sympathetic and parasympathetic nerves via the superior mesenteric plexus.
Dr. Maria Zahiri Vermiform appendix
The vermiform appendix Dr. Maria Zahiri is a narrow, vermian tube arises from the posteromedial caecal wall it varies from 5 to 20 cm in length, 2 cm below the end of the ileum.
The vermiform appendix Dr. Maria Zahiri It may occupy one of several positions: the commonest positions Retrocaecal (12 o’clock), retrocolic, pelvic or descending (4 o’clock) Other positions are occasionally seen especially when there is a long appendix mesentery allowing greater mobilit: subcaecal(6 o’clock) ; preilial(2 o’clock) ; postileal(2 o’clock).
McBurney’s point Dr. Maria Zahiri
The three taeniae coli on the ascending colon and caecum converge on the base of the appendix, and merge into its longitudinal muscle. The anterior caecal taenia is usually distinct and can be traced to the appendix. It is connected by a short mesoappendix to the lower part of the ileal mesentery.
Dr. Maria Zahiri The lumen of the appendix is small and opens into the caecum by an orifice lying below and slightly posterior to the ileocaecal opening. The orifice is sometimes guarded by a semi lunar mucosal fold forming a valve. The appendix usually contains numerous patches of lymphoid tissue although these tend to decrease in size from early adulthood.
Ileocolic artery Inferior branch Appendicular artery accessory arteries are common Dr. Maria Zahiri VASCULAR SUPPLY
Dr. Maria Zahiri one or more appendicular veins posterior caecal ileocolic vein Superior mesenteric vein
Lymphatic vessels Dr. Maria Zahiri are numerous but all end in the inferior and superior nodes of the ileocolic chain.
sympathetic and parasympathetic nerves from the superior mesenteric plexus. Dr. Maria Zahiri Innervation
colon the colon consists of four sections: the ascending colon, the transverse colon, the descending colon, and the sigmoid colon Dr. Maria Zahiri
Ascending colon Dr. Maria Zahiri narrower than the caecum- 15cm It ascends to the inferior surface of the right lobe of the liver, on which it makes a shallow depression, and then turns abruptly forwards and to the left, at the hepatic flexure. It is a retroperitoneal Told fascia
Dr. Maria Zahiri
TRANSVERS COLON The transverse colon is 50 cm long extends from the hepatic flexure in the right lumbar region across into the splenic flexure. The transverse colon is suspended from the anterior border of the body of the pancreas by the transverse mesocolon.
Dr. Maria Zahiri
SPLENIC FLEXURE forms the junction of the transverse and descending colon lies in the left hypochondriac region anteroinferior to the lower part of the spleen The left kidney lies behind to it
Dr. Maria Zahiri It lies more superiorly and posteriorly than the right hepatic flexure is attached to the diaphragm at the level of the tenth and eleventh ribs by the phrenicocolic ligament which lies below the anterolateral pole of the spleen.
Dr. Maria Zahiri DESCENDING COLON 25 cm It descends through the left hypochondriac and lumbar regions curves inferomedially to become the sigmoid colon at the inlet of the lesser pelvis. It is a retroperitoneal structure covered anteriorly and on both sides by peritoneum.
Dr. Maria Zahiri SIGMOID COLON begins at the pelvic inlet and ends at the rectum(S3) It is completely invested in peritoneum and is attached to the posterior pelvic wall and lower posterior abdominal walls by the fan-shaped mesosigmoid. The root of the sigmoid mesocolon has an inverted 'V‘ shape. The position and shape of the sigmoid colon vary greatly
Dr. Maria Zahiri Left paracolic gutter Left ureter
Superior mesenteric a. Inf. pancresticodudenal a. Jejunal and ileal a. Ileocolic a. Appendicular a. Right colic a. Middle colic a. Superior Mesenteric v. Dr. Maria Zahiri
Inferior mesenteric a. Left colic a. Sigmoid a. Superior rectal a. Inferior mesenteric v. Dr. Maria Zahiri
Colic marginal artery Dr. Maria Zahiri
The Sudeck's point (or Sudeck's critical point): refers to a specific location in the arterial supply of the rectosigmoid junction, namely the origin of the last sigmoid arterial branch from the inferior mesenteric artery (IMA). This arterial branch usually forms an anstomosis with a branch of the superior rectal artery. The anastomosis is small and often only singular. Dr. Maria Zahiri
The "critical point" of Sudeck is marked with an "X." Dr. Maria Zahiri
Rectum Dr. Maria Zahiri Rectum continuous with the sigmoid colon(S3) To upper end of the anal canal. Flexure: the sacral flexure & the perineal flexure three lateral curves : upper is convex to the right, the middle (the most prominent) bulges to the left, and the lower is convex to the right Both ends of the rectum are in the median plane
Dr. Maria Zahiri
: 2/3anterior and 1/3lateral covered by peritoneum. the rectovesical pouch : The peritoneum is reflected superiorly onto the urinary bladder in males recto-uterine pouch (pouch of Douglas): onto the posterior vaginal wall in females
Dr. Maria Zahiri
ARTERIES 1.superior rectal artery: upper third 2.middle rectal artery: middle third (from Int. Iliac) 3.inferior rectal artery: distal third ( from Int. pudendal)
Dr. Maria Zahiri veins 1.internal part: below the rectal and anal epithelium 2.external part: outside the muscular wall
Dr. Maria Zahiri veins External plexus : 1.inferior portion of the external plexus : is drained by the inferior rectal vein into the internal pudendal vein 2.middle portion : by a middle rectal vein into the internal iliac vein, 3.superior part : By a superior rectal vein, which is the start of the inferior mesenteric vein. Communication between portal and systemic venous systems is thus established in the rectal plexus.