Abdomen Anatomy

Front 1

Right Upper Quadrant

Back 1

o Liver (right lobe)
o Gallbladder
o Pylorus (stomach)
o Duodenum (1st – 3rd parts)
o Head of pancreas
o Right suprarenal gland
o Right kidney
o Right colic/hepatic flexure
o Ascending colon (superior part)
o Transverse colon (right half)

Front 2

Left Upper Quadrant

Back 2

o Liver (left lobe)
o Pancreas (body and tail)
o Spleen
o Stomach
o Jejunum (proximal to ileum)
o Left suprarenal gland
o Left kidney
o Left colic/splenic flexure
o Descending colon ( superior part)
o Transverse colon (left half)

Front 3

Right Lower Quadrant

Back 3

o Most of ileum
o Cecum
o Appendix
o Ascending colon (inferior part)
o Right ovary
o Right uterine tube
o Right ureter (abdominal part)
o Right spermatic cord (abdominal part)
o Uterus (only when enlarged)
o Urinary bladder (only when full)

Front 4

Left Lower Quadrant

Back 4

o Sigmoid colon
o Descending colon (inferior part)
o Left ovary
o Left uterine tube
o Left ureter (abdominal part)
o Left spermatic cord (abdominal part)
o Uterus (only when enlarged)
o Urinary bladder (only when full)

Front 5

Abdominal wall boundaries

Back 5

Sup: diapragm
inf: pelvic inlet
antero-lat: llower part thoracic cage skin
post: vertebrae

Front 6

Qudrants

Back 6

• Vertical line or Median plane: follows the vertebral wall; starting from the epigastrium
• Horizontal line or Transumbilical plane: transects the umbilicus; between the IV disc of L3-L4 level

Front 7

Lateral Rectus/Semilunar Lines

Back 7

- Curve linear impressions parallel w/ the lateral edges of the rectus sheath
- From inferior costal margin (near the 9th costal cartilage) to pubic tubercle
- 5-8 cm from midline
- Enclose the rectus abdominis muscle
- Practical only in lean people who have distinct surface definition of the underlying muscle

Front 8

R/L Midclavicular Line

Back 8

- Represented by the vertical solid lines
- Runs from the MCL to the midinguinal points (midpoint of anterior superior iliac spine and symphysis pubis)
- 9 cm from midline

Front 9

Transpyloric Plane

Back 9

- Horizontal broken line running from the tip of the 9th costal cartilage to the fundus of the gallbladder, pylorus of the stomach, duodenojejunal junction, lower body of L1, neck of the pancreas to the hila of the kidneys; root of transverse mesocolon and origin of superior mesenteric a. and portal vein.
- At the junction of the linea semilunaris and costal margin

Front 10

Subcostal Plane

Back 10

-horizontal plane @ inf level of 10th Thoracic V, lower border 10th Costal cart

Front 11

Intertubercular/transtubercular plane

Back 11

horizontal plane crosses over iliac tubercle post to ASIS at lower border L5

Front 12

interspinous plane

Back 12

horizontal broken line that runs thru RIGHT ASIS to LEFT ASIS

Front 13

bony framework abdomen

Back 13

• Provides attachment of muscles
a. Costal Margin
- Formed by the cartilages of the 7th – 10th ribs
- Posterior side: 11th and 12th ribs
- Lowest level is at the level of L3
b. Xiphisternal junction – at the level of T9
c. Xiphoid process – at the level of T10
d. 5 Lumbar vertebrae and their corresponding IV discs
e. Iliac crest
- Highest point of the pelvis
- Found at the level of L4
- Landmark for lumbar tap

• The spinal cord ends at L1 (or L2); lumbar tap is done between L3-L4, L4- L5

Front 14

linea terminalis/pelvic BRIM

Back 14

- Bony edge/rim surrounding pelvic inlet
- Boundaries:
o Superior margin of pubic symphysis
o Post. border of pubic crest
o Pecten pubis/ pectineal line
o Arcuate line of ilium
o Ant. border of ala of sacrum
o Sacral promontory

Front 15

layers abdominal wall

Back 15

Skin Superficial Fascia Deep Fascia Muscles Transversalis Fascia Preperitoneal Peritoneum

Front 16

external oblique muscle

Back 16

• Largest and most superficial muscle
• Runs from 5th to 12th costal cartilages
• Inferiorly, it folds upon itself to form the Poupart/inguinal ligament (extends from ASIS to pubic tubercle)
• No attachment to posterior border; posteriormost fibers are free edged spanning between costal margin and iliac crest
• Runs infero-medially; ½ is aponeurotic, ½ fleshy
• Become aponuerotic medially at midclavicular line and inferiorly at spinoumbilical line
• Continues as external spermastic fascia that covers spermatic cord
• Forms a “digastrics muscle” w/ internal oblique (2-bellied muscle sharing a common tendon and working as a unit)

Front 17

deep fascia

Back 17

• Investing Fascia
• Thin layer of connective tissue directly beneath the superficial fascia; attached to muscles
• Continues to become the Buck’s fascia or deep penile fascia in the penile area
• Thickens to form the suspensory ligament that anchors the root of the penis to the symphysis pubis and arcuate line

• Potential spaces: between superficial and deep fascia or between Colle’s fascia and deep fascia

• site of urine extravasation when there is penile fracture

Front 18

scarpa's fasci

Back 18

• Deep membranous layer
• 1 – 2 fingerbreadths below the inguinal ligament then blends with the deep fascia lata of the thigh
• Becomes the Colles fascia/superficial perineal fascia in the perineal area at the margins of the pubic arch
• In the midline, it is not attached to the pubis but instead forms tubercular sheath for the penis or clitoris
• Thickening at the base and sides of the penis forms the fundiform ligament, suspends the penis dorsally and laterally

Front 19

camper's fascia

Back 19

• Fatty layer
• Continuous with superficial fat over the rest of the body; vary with nutritional status of individual
• Thick fascia in obese individuals
• From the thorax to the lower extremities
• Equivalent to the Dartos muscle of the perineum/scrotum

Front 20

superficial fascia

Back 20

• Also called Subcutaneous tissue/ Tela Subcutanea

Front 21

Internal Oblique Muscle

Back 21

• Has 3 origins: lumbar fascia, ant. 2/3 of iliac crest, lat. 2/3 of inguinal ligament
• Runs supero-medially or at right angles with the fibers of the external oblique muscle
• Fibers from the ASIS and lateral inguinal ligament run transversely
• Lower tendinous fibers with transversus abdominis form the conjoint tendon, attach medially to linea alba but has lateral free border

Front 22

Transversus Abdominis

Back 22

• Inserted into the linea alba, xiphoid process and symphysis pubis
• Like IOM, attach to posterior border via lumbar fascia
• From 7th to 12th costal cartilages
• Fibers run horizontally and forward (Transverse)

Front 23

Where is neurovascular plane located in chest wall?

Back 23

Between IOM and Tranversus Abdominis is a neurovascular plane which contains vessels that supply the abdominal wall

Front 24

Rectus Abdominis

Back 24

• Separated to left and right by a vertical ridge (linea alba)
• When contract; lateral margin forms a curved ridge called linea semilunaris which extends from tip of 9th costal cartilage to pubic tubercle.
• A long strap muscle that extends along the whole length of the anterior abdominal wall
• Broader above and lies close to the midline, being separated from its fellow by the linea alba; narrower inferiorly
• Has 3 tendinous intersections attached strongly to anterior rectus sheath
o Level of xiphoid process
o Umbilicus
o Halfway between the two

Front 25

Linea Alba

Back 25

transmit small vessels and nerves to skin
o Has umbilical ring: defect in linea alba through which fetal umbilical vessels passed to and from umbilical cord and placenta
o Found in the middle, underlying the umbilicus

Front 26

Pyramidalis

Back 26

• Absent in approximately 20% of the population
• Small triangular muscle which lies anterior to the inferiorpart of the rectus abdominis muscle

Front 27

All attached to linea alba except?

Back 27

rectus abdominis

Front 28

rectus sheath

Back 28

• Formed by the aponeuroses of the 3 anterolateral muscles
• Encloses the rectus abdominis muscle and the pyramidalis muscle
• The rectus abdominis is loosely attached to the posterior wall of the rectus sheath but closely adherent to the anterior wall
- Flexes and rotates the trunk, stabilize the pelvis
• The pyramidalis muscle maintains tautness of linea alba during trunk flexion and rotation
• Divided by linea alba, a fibrous band formed by the aponeuroses of the 2 lateral muscles; transmit small vessels to skin
- Extends from the xiphoid process to the symphysis pubis
• Transition between aponeurotic sheath covering the ¾ of rectus abdominis and transversalis fascia of the ¼ of inferior rectus abdominis
• Posterior wall: free and curved lower border
• Inferior epigastric vessels enter to rectus sheath to anatomose with superior epigastric vessels

Front 29

contents rectus sheath

Back 29

1. Anterior rami of lower 6 thoracic nerves (7th,8th, 9th,10th, and 11th) which forms the intercostals nerves and subcostal nerve
2. Superior ad inferior epigastric vessels
3. Lymphatic vessels

Front 30

disposition rectus sheath

Back 30

• Above the costal margin
- Ant. Wall: aponeurosis of external oblique
- Post wall: thoracic wall (5th – 7th costal cartilages and intercostals spaces)
• Between the costal margin and at the level of ASIS
- External oblique aponeurosis is in front of the rectus muscle
- Internal oblique aponeurosis split to enclose the rectus ms (superficial lamina)
- Transversus aponeurosis is behind the rectus muscle
• Below ASIS/between the ASIS and the pubis
- Ant. Wall: aponeuroses of the 3 muscles
- Post wall: Transversalis fascia

Front 31

median umbilical fold

Back 31

- Encloses the median umbilical ligament, a remnant of the urachus
- Urachus: formerly fetal allantois
- Extends from (or attaches) the apex of the bladder to the umbilicus

Front 32

medial umbilical folds

Back 32

2-
- Encloses the lateral umbilical ligaments, remnants of the (R) & (L) umbilical arteries

Front 33

lateral umbilica folds

Back 33

2-- Encloses inferior epigastric vessels (from external iliac vessels

Front 34

supravesical fossa

Back 34

- Between median umbilical folds and medial umbilical folds
- Rises and falls with filling and emptying of the bladder

Front 35

medial inguinal fossa

Back 35

- Between medial and lateral umbilical folds
- Also called the triangle of Hesselbach
- Potential site of less common type of hernia, direct inguinal hernia

Front 36

lateral inguinal fossa

Back 36

- Found in lateral of lateral umbilical folds
- |nclude the deep inguinal ring, a defect in transversalis fascia
- Potential site of indirect inguinal hernia, most common type of hernia in lower abdominal wall

Front 37

transversalis fascia

Back 37

• Thin layer of fascia that lines the transversus abdominis
• Continuous with a similar layer lining the iliacus muscle and diaphragm
• Space of bogros: a space between the transversalis fascia and preperitoneal layer

Front 38

deep inguinal canal

Back 38

- Oval opening or defect in the transversalis fascia

Front 39

peritoneal layer

Back 39

• Also called Extraperitoneal fat
• Thin layer of connective tissue that contains a variable amount of fat
• Lies between the fascia transversalis and the parietal peritoneum

Front 40

endoabdominal fascia

Back 40

internal aspect of abdominal wall with membranous sheet; essential in surgery, which has access to retroperitoneal cavity without entering the peritoneum.

Front 41

visceral peritoneum

Back 41

- Covers the visceral organs
- Insensitive to pressure, pain and temperature; sensitive to stretch and chemical irritation; pain here is poorly localized and usually felt at epigastric region.

Front 42

peritoneal cavity

Back 42

- Space bet. visceral and parietal peritoneum; contains no organs but peritoneal fluid (water, electrolytes, leukocytes and antibodies) for lubrication and movement without friction
- Closed cavity in males, but has exterior communication in females thru vagina, uterus, and uterine tube.

Front 43

peritoneal fluid

Back 43

- Normal: 50 mL
- Must reach about 1.5 L before clinically recognized as ascitis (excessive accumulation of fluid) in thin individual
- Around 3.5 Lin obese individuals before ascitis is clinically recognized

Front 44

paracentesis

Back 44

- Procedure in where peritoneal fluid is collected in subphrenic and hepatorenal recesses.
- Skin, Subcutaneous layer, deep investing layer, muscles, transversalis fascia, preperitoneal layer and parietal peritoneum are the structures being traverse during paracentesis.

Front 45

Greater Sac- main parts

Back 45

- Supracolic compartment
o Contains stomach liver and spleen
- Infracolic compartment
o Contains small intestine and colon
o Posterior to greater omentum;
o Has r and l infracolic spaces

Front 46

Lesser sac/omental bursa- smaller compartment post to stomach and lesser omentum

Back 46

- Superior recess – Superiorly limited by coronary ligament of liver and diaphragm
- Inferior recess – Between superior parts of greater omentum layers
- Function: Allows stomach to move freely on structure posterior and inferior to it

Front 47

omental foramen/epiploic foramen of winslow

Back 47

- Oval window where lesser and greater sacs communicate
- Boundaries
o Anteriorly: Hepatoduodenal ligament
o Posteriorly: IVC and right crus of diaphragm
o Superiorly: Liver
o Inferiorly: Duodenum (1st part)

Front 48

intraperitoneal organs

Back 48

Completely covered by visceral peritoneum such as spleen, stomach, liver etc.

Front 49

retroperitoneal/extraperitoneal organs

Back 49

Outside the visceral peritoneal or partially covered like kidney

Front 50

posterior abdominal wall

Back 50

• Midline: 5 lumbar vertebrae and their IV discs
• Lateral: 12th ribs, upper part of bony pelvis, the psoas ms, the quadratus lumborum ms, aponeuroses of origin of transversus abdominis muscles
• Fascia: Thoracolumbar fascia

Front 51

myopetctineal orifice

Back 51

Weak area and is common site for direct and indirect inguinal and femoral hernias

Front 52

iliopubic tract

Back 52

- Inferior continuation of transversalis fascia
- Deep to IL and Conjoint tendon

Front 53

reflected inguinal ligament

Back 53

- Fans upward and blends with external oblique aponeurosis
- Bypasses pubic tubercle and crosses linea alba

Front 54

pectineal ligament of cooper

Back 54

- Most lateral fiber of IL
- Runs along pecten pubis

Front 55

lacunar ligament of gimbernat

Back 55

- Forms medial boundary of subinguinal space
- They are deep fibers of IL passing posteriorly

Front 56

space of borgros/retroinguinal space

Back 56

Space between extraperitoneal fat and transversalis fascia; where prosthetic mesh is overlaid in hernia repairs

Front 57

inguinal canal

Back 57

site for indriect hernia
- A tunnel formed by deep and superficial inguinal rings
- Contains spermatic cord in males and round ligament of uterus/ligamentum teres uteri in females and ilioinguinal nerve (L1)

Front 58

deep inguinal ring

Back 58

- Entrance to inguinal canal
- Transversalis fascia covers innermost surface of canal and its structures

Front 59

superficial inguinal ring

Back 59

- Exit of inguinal canal structures
- Splits to form lateral (attach to pubic tubercle) and medial (attach to pubic crest) crura
- Intercrural fibers – Prevent crura from spreading

Front 60

inguinal canal boundaries

Back 60

• Ant. wall: Aponeurosis of Ext. and Int. Obl. Ms
• Post. wall: Transversalis fascia (Deep ring) and Conjoint tendon (Superficial ring)
• Roof: Musculoaponeurotic arches of transverses abdominis and Int. Obl. Ms
• Floor: Inguinal and Lacunar ligaments

Front 61

indirect inguinal hernia

Back 61

- Most common type of hernia
- May be strangulated and compromise the blood supply
- Congenital type of hernia

Front 62

direct inguinal hernia

Back 62

- Most common in elderly patients
- Seen in inguinal triangle
- Not as common as the indirect hernia

Front 63

femoral hernia

Back 63

- Common in females
- Enter femoral ring and femoral canal inferior to inguinal ligaments
- Neck of hernia sac: very narrow

Front 64

incisional hernia

Back 64

- Post-operative hernia
- Failure to close -> visceral will protrude out

Front 65

lumbar hernia

Back 65

- Occur in Petit’s Triangle at the posterior abdominal wall

Front 66

abdominal hernias

Back 66

a. Epigastric – Usually above the umbilicus
b. Umbilical – Congenital, AKA “Exomphalos or omphalocele; midgut fails to go back to intra-abdominal cavity from extraembryonic cavity
c. Semilunar – At the junction of arcuate line and linea semilunaris
d. Diaphragmatic

Front 67

arterial supply abdomen

Back 67

• The internal mammary or internal thoracic artery is a branch of the 1st part of subclavian artery. Its terminal branches are the superior epigastric a. and the musculophrenic a.

abdominal aorta

Front 68

abdominal aorta location

Back 68

• Abdominal aorta will begin at the aortic hiatus at T12 and ends at the level of L4 (Supracristal plane), which will branch into Right and Left Common Iliac A. that is further divided into External and Internal Iliac A. at the medial border of psoas muscles to pelvic brim

Front 69

branches abdominal aorta in 3 vascular planes

Back 69

- Anterior: unpaired visceral for Alimentary tract
o Celiac a.
o Superior mesenteric a.
o Inferior mesenteric a.
- Lateral: paired visceral for urogenital and endocrine organs
- Suprarenal
o Renal
o Gonadal
- Postero-lateral: paired parietal for diaphragm and body wall
o Subcostal
o Inferior phrenic
o Lumbar

Front 70

rest of abdominal aorta branches

Back 70

• External iliac: follows the ilio-psoas muscle -> Femoral a.
• Internal Iliac: enters the pelvic cavity

• Superior Epigastric a.
- Supplies upper central part of the abdominal wall
- Anastomoses with the inferior epigastric a.

• Inferior Epigastric a.
- Branch of the external iliac a.
- Supplies lower central part of the abdominal wall

• Deep Circumflex a.
- Branch of external iliac a.
- Supplies lower part of the lateral abdominal wall

• Lower 2 Posterior Intercostal a.
- Branch of descending aorta(thoracic)
- Supply lateral part of abdominal wall

• 4 Lumbar a.
- Branch of abdominal aorta
- Supply the lateral part of the abdominal wall
- The 5th pair of lumbar a. Will rise from medial sacral artery not from abdominal aorta

• Superficial epigastric and superficial circumflex iliac a.
- Branches of femoral artery

Front 71

venous drainage abdomen

Back 71

IVC, superificla veins, deep veins

Front 72

IVC

Back 72

o Forms from the union of common iliac veins at L5; 7cm longer than abdominal aorta
o All veins in posterior abdominal wall drains in IVC except Left testicular/ovarian vein which drain first to left renal vein before going to IVC

Front 73

superficial vein

Back 73

1. Lateral thoracic v.
- Above umbilicus
- Drains into the axillary vein
2. Superficial Epigastric v. and Great Saphenous v.
- Below umbilicus
- Drain into the femoral vein
3. Thoracoepigastric vein
- Anastomotic channel between lateral thoracic vein and superficial epigastric vein
4. Paraumbilical veins
- Connects the network through the umbilicus along the ligamentum teres to the portal vein
- Forms portal-systemic venous anastomoses

Front 74

deep veins

Back 74

1. Superior epigastric v., inferior epigastric v. and deep circumflex v.
- All drain into the internal and external thoracic veins
2. Posterior intercostals v.
- Drain into the azygos v
3. Lumbar veins
- Drain into the IVC

Front 75

porto-caval obstruction -portal vei

Back 75

- Obstruction of the portal vein causes distention of the paraumbilicus veins and the superficial veins around the umbilicus. Distended subcutaneous veins produce the caput medusa (varicose veins radiating from the umbilicus).

Front 76

porto-caval obstruction IVC/SVC

Back 76

- Obstruction of the IVC or SVC causes distention of the vessels running from the anterior chest wall to the thigh thus, the lateral thoracic vein anastomoses with the superficial epigastric v (a tributary of the great saphenous v.) producing a tortuous varicose vein extending from the axilla to the lower abdomen.

Front 77

retrograde flow due to SVC or IVC obstruction

Back 77

- IVC -> subclavian -> axillary -> lateral thoracic -> thoracoepigastric -> superficial epigastric -> femoral -> external iliac -> common iliac -> back to the IVC
- Commonly seen in liver cirrhosis

Front 78

superficial lymph drainage

Back 78

1. Axillary nodes (Anterior)
- Lymph from the anterior abdominal wall above the umbilicus
2. Superficial Inguinal nodes
- Lymph from below the umbilicus , below the iliac crest in posterior side
3. Axillary nodes (Posterior)
- Lymph from the skin of the back above the level of the iliac crest

Front 79

deep lymph drainage

Back 79

- All drain into the External iliac, Para-aortic, Lumbar, and Mediastinal nodes

Front 80

visceral and parietal peritoneum innervation

Back 80

Parietal peritoneum
- Innervated by the somatic nerves (lower 6 thoracic nerves, and 1st lumbar nerves)
- Sensitive to pain, temperature, touch and pressure

Visceral peritoneum
- Innervated by the ANS
- Only to stretch and tearing

Front 81

lower 6 thoracic nerves

Back 81

- Innervate the 3 anterolateral muscles plus the rectus abdominis muscle
- Found in between internal oblique and transverses abdominis muscles

Front 82

ilioinguinal nerve L1

Back 82

- Skin of scrotum or labium majus, mons pubis and adjacent medial aspect of the thigh ; internal oblique and transverse abdominal
- Enters through the inguinal canal
- Both iliohypogastric and ilioingunal nerve does not enter
the rectus sheath

Front 83

iliohypogastric nerve L1

Back 83

- Skin of hypogastric region and over the iliac crest; internal oblique and transverse abdominal muscles
- Pierces EOM above the superficial inguinal ring

Front 84

subcostal nerve T12

Back 84

- Lowest slip of external oblique muscle and skin over anterior superior iliac spine and hip
- Innervate the pyramidalis muscle

Front 85

thoracoabdominal nerve

Back 85

t7-t11
- Distributed over the anterior abdominal muscles overlying the skin ; periphery of diaphragm

Front 86

nerve suply of abdomen

Back 86

thoracoabdominal nerve, subcostal n, iliohypogastric n, ilioinguinal n, lower 6 thoracic n