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ANATOMY OF THE ABDOMEN. BY DR. AHMAD KAMIL SHAHWAN PH.D. GENERAL SURGERY. THE ABDOMIN. The Abdomen is the region of the trunk that lies between the diaphragm above & the inlet of the pelvis below. The abdominal wall:
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ANATOMY OF THE ABDOMEN BY DR. AHMAD KAMIL SHAHWAN PH.D. GENERAL SURGERY
THE ABDOMIN • The Abdomen is the region of the trunk that lies between the diaphragm above & the inlet of the pelvis below. • The abdominal wall: • Superiorly , the abdominal wall is formed by the diaphragm ,which separates the abdominal cavity from the thoracic cavity . • Inferiorly the abdominal cavity is continuous with the pelvic cavity through the pelvic inlet. • Anteriorly ,the abdominal wall is formed by the lower part of thoracic cage & below by the rectus abdominus M ,,ext. oblique ,int. oblique & transverse abdominus M.& fasciae.
The abdominal wall • Posteriorly,the abdominal wall is formed in the midline by the 5 lumbar vertebrae & their intervertebra discs,laterally,by the 12th ribs ,upper part of bony pelvis ,the psoas M.,the quadratus lumborum M.,& the aponeuroses of origin of transversus abdominus M. The anterior abdominal wall is divided by 2 midclavicular lines longitudanally & subcostal & inter tubercular lines transeversly to 9 regions: right & left hypochondrium& epigastric area in between., right & left lumbar areas & umbilicus area in between & right & left iliac fossae(inguinal) & hypogastric area in between.
The abdominal wall The abdominal wall formed from 1- the skin : which supplied by the ant. Rami of the lower 6 thoracic & 1st lumber Nn. (which is the ilio-hypogastric & ilio-inguinal Nn.). T7 supply the skin of epigastric area,T10 supply the umbilicus&L1supply area above the inguinal lig.& the symphysis pubis. 2- The superficial fascia :which divided to superficial fatty layer & deep membranous layer.,the fatty layer changed in the scrotum to dartos M.
The abdominal wall 3- the deep fascia :it is a thin layer of aleolar tissue covering the mm. 4- the muscular layer : consist of 3 broad thin sheets that are aponeurotic in front (ext. oblique , int. oblique & trasversus abdominus )also there is a wide vertical M( the rectus abdominus M.) which enclosed by the sheet to form the rectus sheath . 5- The fascia transversalis :thin layer of fascia that lines the trasversus abdominus M.& extend down to form the femoral sheath.
The abdominal wall 6- the extra-peritoneal fat . 7- the parietal peritoneum THE INGUINAL CANAL : It is an oblique passage ( canal ) through the lower abdominal wall & it allows to pass structures to & from the testis to abdomen in male,& the round lig .of the uterus to labium majus in female.& it transmits the ilio-inguinal N. in both sexes. The canal is 4 cm long lies above & parallel to the inguinal lig. Extend from the deep inguinal ring (a hole in transversalis fascia) down ward & medially to superficial inguinal ring( a hole in the aponeurosis of the ext. oblique M.
THE INGUINAL CANAL The walls of inguinal canal : The ant. wall :apooneurosis of ext. oblique M. The post.wall :the fascia transversalis . The inf. wall (the floor) : the inguinal lig. The sup. wall (the roof ): the lowest Ff. of int. oblique & transversus abdominis Mm.
THE INGUINAL CANAL The spermatic cord : is a collection of strs. that pass through the inguinal canal to & from the testis , it is formed from : 1- The vas deferens . 2- the testicular artery . 3- The testicular veins (pampiniform plexus). 4- Testicular lymph nodes . 5- autonomic Nn. 6-processus vaginalis . 7- Cremasteric A. 8- Artery to vas deferens . 9- Genital br. Of genito-femoral N .
The spermatic cord The spermatic cord covered by 3 concentric layers of fascia derived from the layers of ant. Abdominal wall : 1- The external spermatic fascia derived from the ext. oblique aponeurosis. 2- Cremastric fascia derived from the int. oblique M. 3- Internal spermatic fascia derived from the fascia transversalis .
The scrotum It is an outpouching of the lower part of the ant. Abd. Wall . It contains the testes , the epididymides & the lower end of spermatic cord. The wall of the scrotum has the fallowing layers: the skin ,superficial fascia( dartos M. replace the fatty layer) , The external spermatic fascia , Cremastric fascia , Internal spermatic fascia & tunica vaginalis .
THE ABDOMINAL CAVITY The peritoneum It is a serous membrane lining the wall of the abdomen & the pelvic cavities (= parietal P.) & clothing the abdominal & pelvic viscera (=visceral P) , the space between them called the peritoneal cavity which contain small amount of fluid .Between the parietal P. & the fascia covering the abd. Is a layer of connective tissue called the extra-peritoneal tissue. The organs which are covered totally with visceral P. called intraperitoneal organs while those covered partially or lying behind the P. called retroperitoneal organs.
The omentum: is 2- layers folds of P. that connects the stomach to other viscus. The greater omentum connects the stomach to transverse colon ,The lesser omentum connect the stomach to liver. The mesentery is a 2-layers folds of P. connecting parts of intestine to the post. abd. wall. e.g. mesentery of small int., the transverse colon, The sigmoid colon. The Parietal P. is sensitive to pain,temp.,touch & pressure & supplied by lower 6 thoracic & 1st lumber Nn. while the visceral P. sensitive to strech& tearing& supplied by autonomic N.S.
The gastrointestinal tract The osophagus : is a muscular collapsible tube ,25 cm long, joins the pharynx to the stomach, its major part in the thorax, enters the abdomen through an opening in the right crus of the diaphragm &enter the stomach on its right side. The stomach :It is J-shape organ lies under cover of the lower ribs, has cardiac orifice above & pyloric orifice below,& has greater & lessercurvitures , & ant. & post. Surfaces. It devided to :fundus,body ,incisura angularis , antrum , pyloric canal & pyloric sphincter.
The Stomach The lesser curvature :forms the right border & extends from the cardiac orifice to the pylorus. It is suspended from the liver by the lesser omentum. The greater curvature :forms the left border, the greater omentum extends from the lower part to the transverse colon & the gastro-splenic omentum extend from the upper part to the spleen . The mucus membrane forms many folds called rugae that are longitudinal in direction. It has 3 muscular layers:longitudinal , circular & oblique. The stomach function is :storage of food ,mix the food with gastric secretions to form chyme, & the delivery of the chyme to the small intestine.
The small intestine It extends from the pylorus to the ileo-cecal valve & divided to duodenum , the jejunum & the ileum. The duodenum : is a C- shape tube ,25 cm long, joins the stomach to the jejunum . It receives the opening of the bile & pancreatic ducts & curves around the head of pancreas. It divided to 4 parts : 1st part is 5cm long, begins at pylorus & runs upward & backward on the right side of L1 vertebra.
The duodenum The 2nd part: is 8 cm long runs vertically downward in front of the right kidney & on right side of L1,2 vertebrae. Its medial border receives the bile duct & the main pancreatic ducts in major duodenal papilla & receive the accessory panc. Duct higher up in the minor duod. Papilla . The 3rd part: is 8 cm long ,runs horizontally to the left, in front of the vertebral column& the lower margin of the head of panc. The 4th part: is 5 cm long, runs upward & to the left to the duodeno-jejunal flexure. The mucus memb. Is formed in circular folds called Plicae circularis .
The Jejunum & The Ileum It is 6 m long. The jejunum is the upper 2/5th of this length start in duodeno-jejunal junction to merge with the ileum which end in the ileo-cecal junction. The coils of them are freely mobile & attached to the post. abd. wall by fan – shape fold of peritoneum called Mesentery of the small intestine. The jejunum has wider-bored, thicker-walled , redder & less fat than the ileum ,also the plicae circulares are larger ,more numerous & closely set.
The Large Intestine It extends from the end of the ileum to the anus. It divided to Cecum , Appendix ,ascending colon ,Transverse colon ,Descending colon ,Sigmoid colon , Rectum & Anal canal. Its function is absorption of water & electrolytes& the storage of undigested material until it can be expelled from the body as feces . The Cecum : It is a blind-ended pouch located in the right iliac fossa , attached to its postero-medial surface is the appendix. The longutudinal Mm. folded in 3 strips called the teniea coli which covered the base of the appendix.The ileum enter the large int. at the junction of the cecum with the ascending colon in the ileo-cecal valve.
The Large Intestine TheAppendix :is a narrow muscular tube contain large amount of lymphoid tissue ,its base lies below the ileo-cecal junction & attached by the meso-appendix to the mesentery of the small int.The tip lies in many positions like retrocecal, pelvic, paracecal, subhepatic & retro-ileal sites.
The Large Intestine The Ascending Colon :It is 13 cm long ,extend upward from the cecum to inf. surface of the liver where it turns to the left forming the hepatic flexure & become continuous with the transverse colon. The Transverse Colon : It is 40 cm long , begins at hepatic flexure extend across the abd. suspended by the transverse meseocolon, to the splenic flexure where turns downward to start the descending colon.
The Large Intestine The Descending Colon : It is 25 cm long , extend from the splenic flexure downward to pelvic brim to continue with sigmoid colon, The Sigmoid Colon :It is 35 cm long ,begins at the pelvic brim to continue with the rectum at S3 vertebra .Its attached to post. pelvic wall by sigmoid mesocolon where the left external iliac Vv. & the left ureter pass..
The Large Intestine The rectum :It is 13 cm long begins in front of S3 as continuation of sigmoid colon to pass downward fallowing the curve of the sacrum & coccyx to the tip of the coccyx where pierce the pelvic diaphragm & become continuous with the anal canal . The dialated lower part called the rectal ampulla. The Anal Canal :is 5 cm long extend from the pelvic diaphragm to the anus opening & surrounded by the anal sphincters.