Exam IV: Abdomen I Flashcards
Abdomen: General Description
Anterior superior iliac spine (bumps on hips) abbv. ASIS
Pubic tubercles with pubic symphysis in between
Connection between ASIS and pubic tubercle = inguinal ligament
Iliac crest – helps to form the inferior posterior border until we reach the sacrum and vertebrae
Superiorly and anteriorly, the costal margin (bottom of the ribs) with xiphoid process
Internally and superiorly – diaphragm domes
Most of the walls are muscle and fat, whereas thorax is most bony structure boundaries
Inferior thoracic aperture= opening of the diaphragm that connects thorax and abdomen
Pelvic inlet= opening that connects the pelvis and abdomen
Peritoneum – lined by serous membrane filled with abdominal viscera
Abdominal Contents
Abdominal Viscera:
- Gastrointestinal system: esophagus, stomach, small and large intestines, liver, pancreas, and gallbladder
- Spleen
- Urinary system: kidneys and ureters
- Suprarenal glands
- Neurovascular
Most of the esophagus is in the thorax, but it also enters the abdominal cavity leading to the stomach
Large intestines: ascending, transverse, descending, sigmoid, and anal canal
Accessory organs: liver (size of a football), pancreas, gallbladder, spleen (near the stomach on the left)
Abdomen Functions
3 Main Functions:
- Houses the viscera and keeps it safe
- Involved in respiration
- Building of intra-abdominal pressure
Inspiration and expiration- dynamic abdomen because constantly moving associated with breathing
Pulling on the diaphragm downward creates a negative pressure so lungs can fill up with air
Contraction of abdominal muscles and build up pressure inside the abdominal to open an orifice (like coughing, vomiting, micturition (urination), childbirth, defecation, etc.)
Valsalva maneuver- opening of an orifice (coughing, sneezing, etc.)
Abdominal Boundaries
Bony Attachments/Landmarks
Lumbar Vertebrae
Pelvic Bones/Inlet
Inferior thoracic wall: costal margin, ribs XI and XII, and xiphoid process
Muscular Boundaries of the Abdomen
Muscular Wall:
Lateral to vertebrae: quadratus lumborum, psoas major, iliacus
Lateral wall: transversus abdominis, internal oblique, external oblique
Anterior wall: rectus abdominis
Abdominal Mesenteries and Peritoneum
Mesenteries: ventral (anterior) and dorsal (posterior)
Peritoneum: parietal, visceral, intraperitoneal, retroperitoneal
Developing embryo: forms a gut tube inside a tube aka GI tract tube inside the abdominal wall tube
GI tract: associated with mesenteries (ventral and dorsal)
Anterior is only associated with the proximal portion of the GI tract
Dorsal mesenteries is associated with the entire GI tract
Both anchor GI tract to wall
Rotation of the Gut
Rotate stomach to 90 degrees right, while also bringing everything it is attached to with it
Ex. duodenum and pancreas turned as well
When we push things to the back wall = covered by retroperitoneum
Going from intraperitoneal to retro = secondary retroperitoneal
If never intraperitoneal and always retro = primary retroperitoneal
Superior Aperture of the Abdomen
Inferior Thoracic Aperture=Superior Aperture of the Abdomen
Diaphragm attachments: along costal margins, ribs 11 and 12, posteriorly with vertebrae
Attachments: median arcuate ligament, medial arcuate ligament, lateral arcuate ligament
- Diaphragms must accommodate structures passing through like aorta via an opening = median arcuate ligament (medially located); associated with right and left crus meaning it attaches to L3
- Transverse process of L1 = medial arcuate ligament going over top of the psoas major
- Lateral arcuate ligament: goes from transverse process to rib 12; arching over the quadratus lumborum
These three ligaments formed a clean seal between the abdomen and thorax
Pelvic Inlet
Bony Landmarks:
Sacrum
Pubic symphysis
Lateral bony rim
Goes from pubic symphysis extending posteriorly to the sacrum border
Abdomen in Relation to Other Regions: Thorax
Relationship to abdomen to surrounding structures
Thorax: the dome of the diaphragm, so abdomen extends into thoracic wall
Diaphragm provides openings for structures to pass through
Abdomen in Relation to Other Regions: Pelvis
Pelvis: reproductive and urinary organs like uterus, uterine tubes, ligaments, ureters, bladder, ovaries
There is complete connectivity between the pelvis and the abdomen, therefore if there an infection it can easily spread from one cavity to another
Uterine tubes are a linkage to the outside environment
Pelvic structures extend into the abdomen like the bladder
When full the bladder extends upwards; inability to urinate with damage to urethra = suprapubic tube
Abdomen in Relation to Other Regions: Lower Limb
Lower limb and connectivity to abdomen
Blood vessels go through abdomen: aorta bifurcates at L4 to the right and left common iliac then both sides split into the external and internal iliac artery
When the external iliac passes underneath the inguinal ligament it becomes the femoral artery into the lower limbs
Many exit underneath inguinal ligament
Femoral triangle is where limbs empty; can get a femoral hernia due to weakness of the wall
Abdominal Blood Supply
Proximal segment: foregut with the stomach, esophagus, liver, gallbladder, pancreas derivatives, and segments 1 and 2 of duodenum; celiac artery that comes off the midline is associated that supplies all the foregut structures at L1
Midgut: 3 and 4 segments of duodenum, jejunum, ilium, colon/large intestine (2/3 transverse colon is transition from midgut to hindgut); midgut is all supplied by superior mesentery artery at L1
Hindgut: last 1/3 of transverse colon, descending, sigmoid, and top part of anal canal supplied by the inferior mesenteric artery at L3
Arrangement of the Viscera: Foregut
Rotation of the Gut
Foregut: Omental bursa/Lesser sac, Greater sac/Greater Omentum, and Omental foramen/Epiploic foramen
Foregut= stomach, remember 90 degree turn to the right and liver is turned with it and shoved into back wall
Ventral mesentery connects liver to stomach is covered by a membrane = omental bursa; lesser sac
Connection of greater to lesser sac = omental foramen
Development of connection and two spaces= important because passageway for infections to move
Arrangement of the Viscera: Midgut
Midgut: counterclockwise rotation
Midgut as it develops, likes to develop fast, and when it grows it runs out of space so it herniates/pushes the midgut to where the umbilicus will be; as we do this, superior mesenteric artery works as a midline for it, and a counter clockwise rotation occurs to signify where the midgut goes from small to large intestine (270 degree turn) and then draws back into the abdomen
Iliocecal junction: drawn into the top but then descends into the lower quadrant
The 270 degree turn allowed for large intestine to be flipped over the small intestine
Appendix associated with cecum, appendix gets tucked up because as descending it got put behind the cecum (retrocecal)
Innervation of the Anterior Wall
Dermatomes
T6 – Xiphoid
T10 – Umbilicus
L1 – Suprapubic
Musculature
T5 to T12- innervate the muscles they are associated with; if there is a muscle underneath the dermatome, it innervates it; one muscle is innervated by multiple dermatomes
T5-T6 – Upper external oblique
T7-L1 – Corresponding to abdominal wall
Groin in Anterior Wall
Descent of Gonads: starting position with gubernaculum pulling into the process vaginalis, which in females becomes the labium majorum and in males becomes the scrotum
Male: inguinal canal and spermatic cord
Inguinal canal: spermatic cord connection of testes/scrotum to abdomen
Female: gubernaculum develops into the round ligament of the uterus, which terminates in the labium majorum
Vertebra Level 1: Transpyloric Plane
Bony landmarks: from the jugular notch to sympysis pubis; costal margins
Pyloric opening: passage from stomach to first part of the duodenum
Pancreas body: comes out at L1
Kidneys: blood vessels and ureter are coming into the kidneys = hilum
Venous Shunts
Inferior vena cava in relation to vertebra:
- Left renal vein
- Left common iliac
- Lumbar veins
* must pass through midline because vena cava is on the right side and those above are on the left
All venous drainage from the GI system passes through the liver
Venous shunting: when looking at aorta, single arteries and paired arteries are branching out from it… veins are the same way (paired/single) if paired one may pass through the midline
Hepatic Portal System
Portal System: drains the GI tract from lower esophagus to upper anal canal along with draining the spleen and pancreas
Hepatic Portal Vein: digestive tract, pancreas, gallbladder, spleen all drain into first capillary bed, then the hepatic portal vein, then the capillaries within the liver for nutrient storage and distribution, and then the IVC to return to the heart
Hepatic Veins: drain to inferior vena cava (IVC)
Portacaval Antastomoses: General Description
Portacaval anastomoses: inferior esophagus, inferior rectum, umbilicus
Posterior wall: retroperitoneal areas of GI system, liver in contact with diaphragm (bare area), posterior of pancreas
There are times where portal system and caval systems combine
If we have portal hypertension, you can get high BP in veins via a blockage
Example: liver is blocked (possibly from cirrhosis) and blood gets backed up and get portal hypertension
As blood gets backed up into portal system and eventually gets back up where caval system is (vena cava) and so the systems dilate = get hemorrhoids
Valsalva maneuver can also cause hemorrhoids
Umbilicus: capitis medusa aka looks like snakes under the skin if vessels are dilated = get ascites and bloating of the abdomen
Prevertebral Plexus
Innervation:
1. Sympathetic: T5 to L2
above T5 is thorax
- Parasympathetic: Vagus nerve and S2 to S4
Vagus nerve innervates foregut and midgut structures; hindgut is innervated by S2-4
Four Quadrant Pattern
Two Planes:
1. Transumbilical plane- drawn through the umbilicus
2. Sagittal plane- separates right from left
These planes divide into 4 quadrants
These are patient’s directions aka patient’s left and right:
Upper Right: liver, diaphragm, right costal margin, gallbladder
Upper Left: spleen, stomach and left costal margin
Lower Right: McBurney’s point (sign for appendicitis), right anterior superior iliac spine (ASIS), appendix, right inguinal ligament, right pubic tubercle
Lower Left: descending colon, sigmoid colon, left anterior superior iliac spine, left inguinal ligament, left pubic tubercle
Nine Region Pattern
4 Dividing Planes:
- Subcostal plane- at bottom of ribs
- Tubercles on the crest of ilium = intertubercular plane (a bit above ASIS)
- Right Midclavicular line/edge of nipple/or goes through the nipple
- Left Midclavicular line/edge
Top Row:
right and left hypochondrium (think chondrocytes for cartilage and hypo as in below the cartilage) separated by the epigastric region
Middle Row:
right and left flank separated by the umbilical region
Bottom Row:
right and left groin separated by pubic region
Retroperitoneal: Primary vs. Secondary
Primary: thoracic esophagus, rectum, and anus
Secondary: pancreas, duodenum, ascending and descending colon
Portal-Caval Anastomoses: 4
- Inferior esophagus: left gastric esophageal branch anatosmoses with the azygos vein esophageal branch; esophageal varices if dilated
- Inferior rectum: IMA superior rectal branch’s middle rectal branch anastomoses with the IVC internal iliac vein rectal branches; hemorrhoids if dilated
- Umbilicus: hepatic portal vein’s paraumbilical branch anastomoses with the epigastric veins; caput medusa if dilated
- Posterior wall:
a. the veins of the duodenum, pancreas, liver, ascending, and descending colon anastomose with renal, lumbar, and phrenic veins and
b. anastomosis between portal veins channels in the liver and azygos system above the diaphragm across the bare area of the liver
