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Flashcards in Exam IV: Abdomen I Deck (26):

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:
1. Gastrointestinal system: esophagus, stomach, small and large intestines, liver, pancreas, and gallbladder
2. Spleen
3. Urinary system: kidneys and ureters
4. Suprarenal glands
5. 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:
1. Houses the viscera and keeps it safe
2. Involved in respiration
3. 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

1. 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
2. Transverse process of L1 = medial arcuate ligament going over top of the psoas major
3. 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:
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

T6 – Xiphoid
T10 – Umbilicus
L1 – Suprapubic

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:
1. Left renal vein
2. Left common iliac
3. 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

1. Sympathetic: T5 to L2
above T5 is thorax

2. 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:
1. Subcostal plane- at bottom of ribs
2. Tubercles on the crest of ilium = intertubercular plane (a bit above ASIS)
3. Right Midclavicular line/edge of nipple/or goes through the nipple
4. 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

1. Inferior esophagus: left gastric esophageal branch anatosmoses with the azygos vein esophageal branch; esophageal varices if dilated

2. Inferior rectum: IMA superior rectal branch’s middle rectal branch anastomoses with the IVC internal iliac vein rectal branches; hemorrhoids if dilated

3. Umbilicus: hepatic portal vein’s paraumbilical branch anastomoses with the epigastric veins; caput medusa if dilated

4. 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