Anterior Abdominal Wall, Diaphragm, and Peritoneal Cavity Flashcards
What is the abdomen?
Part of the trunk between thorax and pelvis that houses the digestive organs and part of the urogenital system
Functions of the anterior abdominal wall
1) Supports and protects viscera
2) Trunk movements (posture and rotation/flexion)
3) Ambulation
4) Increase of intra-abdominal pressure by muscle contraction
5) Disease diagnosis
Borders of the anterior abdominal wall
Superior: Costal margins (6th to 12th ribs) and xiphoid process
Inferior: ASIS, inguinal ligament, pubic crest, pubic symphisis
Lateral: Vertical plane thru ASIS
Vertebral level of the umbilicus
Between L3 and L4 / T10 dermatome
Fetal precursor of umbilicus
Site of fetal connection to the placenta (via umbilical vein and artery)
Composition of the linea alba
Union of aponeuroses of flat muscles on either side
T or F: Inferior to the umbilicus, the linea alba is not indicated by a groove
T
The linea semilunaris serves as a marker for what?
The lateral margin of the rectus abdominis
The transverse attachments between the anterior rectus sheath and rectus abdominis
Tendinous intersections
The inguinal groove extends from the ASIS to?
Pubic tubercle
T or F: The inguinal groove is composed of the folded lateral edge of external abdominal aponeurosis
F (It is composed of the folded inferior edge)
Two planes that divide the abdomen into 4 quadrants
Median plane and transumbilical plane
Imaginary vertical line following the linea alba from the xiphoid process to pubic symphysis
Median plane
Imaginary horizontal line at the level of the umbilicus
Transumbilical plane (L3 to L4)
Planes that divide the abdomen into 9 regions
Horizontal: Transpyloric and transtubercular planes
Vertical: Right and left midclavicular planes
Level of the transpyloric plane
L1 to L2
Aside from passing thru the pylorus, the transpyloric plane traverses what structure?
Hilum of the kidney
Level of the transtubercular plane
L5
The midclavicular planes pass from the midpoint of the clavicles to the midpoint of what structure?
Inguinal ligament
T or F: The subcostal plane (L3) passes thru the lower border of the 9th costal cartilage on each side
F (It passes thru the lower border of the 10th costal cartilage)
Three lateral regions of the abdomen (from top to bottom)
Right and left hypochondriac, right and left lumbar, right and left inguinal/iliac
Three median regions of the abdomen (from top to bottom)
Epigastric, umbilical, suprapubic/hypogastric
Contents of the right hypochondriac region
Liver, gallbladder, hepatic flexure of colon
Contents of the epigastric region
Liver, transverse colon, abdominal aorta and IVC
Contents of the left hypochondriac region
Stomach, spleen, splenic flexure of colon
Contents of the right lumbar region
Ascending colon, kidney, small intestine
Contents of the umbilical region
Duodenum, pancreas, small intestine, abdominal aorta and IVC, iliac vessels
Contents of the left lumbar region
Jejunum, pancreas, descending colon, kidney
Contents of the right inguinal region
Ileum, caecum, appendix
Contents of the suprapubic region
Small intestine, rectum, bladder, uterus/spermatic cords, iliac vessels
Contents of the left inguinal region
Sigmoid colon, small intestine
Visceral pain often refers to this region
Umbilical
Pain from heartburn and ulcers refer to this region
Epigastric
Gas pain may refer to this region
Left lumbar
Layers of the anterior abdominal wall from superficial to deep
Skin, superficial fascia, deep fascia, muscles, transversalis fascia, extraperitoneal/preperitoneal/peritoneal fat, parietal peritoneum
Two layers of the superficial fascia
Camper’s fascia (superficial fatty layer) and Scarpa’s fascia (deep membranous layer)
T or F: The anterior abdominal wall is made up of 4 paired muscles
T (3 flat/horizontal muscles: External oblique, internal oblique, transversus abdominis; 1 vertical muscle: rectus abdominis)
Origin, insertion, and action of the external oblique
O: External surfaces of 5th to 12th ribs
I: Xiphoid process, linea alba, anterior half of iliac crest, pubic crest, pubic tubercle
A: Rotates, flexes, and laterally bends the trunk; compresses abdominal contents
The inferior border of the external oblique aponeurosis forms what structures?
Inguinal ligament, reflex inguinal ligament, lacunar ligament
Abdominal ligament that crosses the midline to attach to the opposite side
Reflex inguinal ligament
Innervation of the external oblique
T6 to T12, subcostal nerve (T12)
T or F: The external oblique participates in the formation of the superficial inguinal ring
T
What structures exit the superficial inguinal ring in males and females respectively?
Spermatic cord and round ligament
Direction of fibers of the internal oblique
Superomedial but becomes inferomedial towards the inguinal ligament
Attachments of the internal oblique
Thoracolumbar fascia, iliac crest, inguinal ligament
The internal oblique contributes to what structure medially?
Rectus sheath and linea alba
The internal oblique contributes to what structure inferiorly?
Conjoint tendon (with transversus abdominis)
Conjoint tendon arches over what structure?
Spermatic cord
Innermost flat abdominal muscle
Transversus abdominis
Direction of fibers of transversus abdominis
Horizontal
T or F: The transversus abdominis contributes medially to the conjoint tendon and inferomedially to the rectus sheath
F (Transversus abdominis contributes medially to the rectus sheath and inferomedially to the conjoint tendon)
Innervation of the transversus abdominis
T6 to T12 ventral rami
Origin of the transversus abdominis
Posteriorly from the thoracolumbar fascia
T or F: Rotation of the trunk to the left involves the contraction of the ipsilateral obliques
F (It involves the contralateral obliques)
T or F: When extending the spine, the flat abdominal muscles contract passively
T (To provide resistance to prevent the spine from snapping)
Direction of fibers of the rectus abdominis
Vertical
Contributions of the rectus abdominis medially and laterally
Linea alba and linea semilunaris respectively
Posterior margin of the rectus abdominis
Ends posteriorly as the arcuate line (inferior margin or border of the posterior rectus sheath) midway between the umbilicus and pubic symphysis
Arteries contained by the rectus abdominis
Superior and inferior epigastric a.
Innervation of the rectus abdominis
T6 to T12 ventral rami
Action of the rectus abdominis
Main trunk flexor and passive resistance against spine extension
Origin and insertion of the pyramidalis
O: Pubic crest and pubic symphysis
I: Linea alba
T or F: The pyramidalis is absent in 20% of people
T
Strong but incomplete fibrous compartment of the rectus abdominis and pyramidalis
Rectus sheath
Borders of the rectus sheath
Superior: Xiphoid process and 5th to 7th costal cartilages
Inferior: Pubic symphysis and pubic crest
Medial: Linea alba
Lateral: Linea semilunaris
Contents of the rectus sheath
Superior and inferior epigastric a. and v., lymph vessels, distal portions of the thoracoabodminal nerves (T7-T12)
Composition of the rectus sheath
Decussation and interweaving of the aponeuroses of the 3 flat muscles
Composition of the anterior rectus sheath
Aponeurosis of the external oblique and anterior lamina of superior 2/3 of internal oblique aponeurosis
Composition of the posterior rectus sheath
Aponeurosis of the transversus abdominis and posterior lamina of the superior 2/3 of the internal oblique
Inferior end of the posterior rectus sheath
Arcuate line or linea semicircularis
Clinical importance of the arcuate line
The arcuate line delineates the transversalis fasica below it, not an ideal place for stitches
Nerve supply of the anterior abdominal wall
T5 to T11 (including lateral cutaneous branches of T7-T9/T10), subcostal nerve (T12), 2 terminal branches of L1 (iliohypogastric and ilioinguinal)
Distal, abdominal parts of the ventral rami of the inferior 6 thoracic spinal nerves (T7 to T11)
Thoracoabdominal nerves
Distribution of the thoracoabdominal nerves
T7 to T9: superior to umbilicus
T10: level of umbilicus
T11 with subcostal (T12) and iliohypogastric and ilioinguinal nerves (L1): inferior to umbilicus
Innervates the suprapubic region
Iliohypogastric
Nerves that travel anteroinferiorly between the internal oblique and transversus abdominis
Thoracoabdominal, subcostal, iliohypogastric nerves
T or F: Iliohypogastric and ilioinguinal nerves pierce the internal oblique at the ASIS to travel superficial to it and deep to the external oblique
T
Primary blood vessels of the anterior abdominal wall
Internal thoracic, external iliac, femoral a., greater saphenous v.
Branches of the internal thoracic
Superior epigastric, musculophrenic
Branches of the external iliac
Inferior epigastric, deep circumflex iliac
Branch of the femoral a.
Superficial circumflex iliac
Branch of the greater saphenous v.
Superficial epigastric
T or F: The superior and inferior epigastric a. anastomose in the epigastric region
F (They anastomose in the umbilical region)
T or F: Venous drainage is via accompanying veins paired with their respective arteries
T
T or F: Blood drains towards the umbilicus
F (Blood drains away from the umbilicus)
Superficial epigastric v. (femoral v. tributary) and lateral thoracic v. (axillary v. tributary) anastomose thru what vein, uniting the veins of the superior and inferior halves of the body
Thoraco-epigastric v.
3 superficial inguinal v. end in what vein?
Greater saphenous v.
Importance of superficial and deep anastomoses of veins
Collateral circulation when either vena cava is occluded
Superficial lymphatic drainage of the abdomen
Superior to the umbilicus: To axillary or cervical nodes
Inferior to the umbilicus: To superficial inguinal nodes
Deep lymphatic drainage of the abdomen
Accompanying deep veins -> External iliac / common iliac / lumbar nodes -> cisterna chyli and thoracic duct
Inferior portion of the anterior abdominal wall, also known as the groin
Inguinal region
The inguinal region extends between what two structures?
ASIS and pubic tubercle
Anatomical significance of the inguinal region
Region where structures enter and exit the abdominal cavity
Clinical significance of the inguinal region
Entry/exit pathways serve as potential sites of herniation
Boundaries of Hesselbach’s Trigone / Inguinal Triangle
Medial: Lateral border of rectus abdominis
Lateral: Inferior epigastric vessels
Inferior: Inguinal ligament
Structural weakness of the inguinal triangle
Only peritoneum, endoabdominal fascia, and transversalis fascia form the wall (devoid of muscle insertion); deep inguinal ring lies internal to it while the superficial inguinal ring lies external to it
T or F: Direct inguinal hernias in the inguinal triangle are more common in females
F (More common in males)
Location of the inguinal canal
Parallel and superior to the medial half of the inguinal ligament
Borders of the inguinal canal
Roof: Internal oblique and transversus abdominis
Floor: Inguinal ligament
Anterior wall: External oblique
Posterior wall: Transversalis fascia
External exit of the inguinal canal thru the external oblique aponeurosis
Superficial inguinal ring
Location of the superficial inguinal ring
Superolateral to the pubic tubercle
Borders of the superficial inguinal ring
Roof: Arching fibers of the internal oblique and transversus abdominis
Floor: Inguinal ligament reinforced medially by lacunar ligament
Anterior wall: External oblique aponeuorsis
Posterior wall: Laterally - transversalis fascia, medially - internal oblique and conjoint tendon
Contents of superficial inguinal ring
Spermatic cord and round uterine ligament (males and females respectively), ilioinguinal nerve (L1, sensory to genital region, superior to spermatic cord), blood and lymphatic vessels, patent sac for scrotum (in babies)
Internal entrance to the inguinal canal thru the transversalis fascia
Deep inguinal ring
Location of the deep inguinal ring
1.25 cm superior to the midinguinal ligament, lateral to the epigastric vessels, medial to origin of transversus abdominis
T or F: The testes migrates thru the processus vaginalis
T
Patent processus vaginalis
May cause congenital herniation
Origin of the internal spermatic fascia
Transversalis fascia
Origin of the cremaster muscle
Internal oblique
Origin of the external spermatic fascia
External oblique
Contents of the spermatic cord
Pampiniform plexus, ductus deferens, cremasteric artery, testicular artery, artery of the ductus deferens, genital branch of the genito-femoral nerve, sympathetic nerve fibers, lymph vessels
T or F: While females do not have a spermatic cord, they have a cremaster muscle
F (Females also do not have a cremaster muscle)
5 peritoneal folds/ligaments of the posterior surface of the anterior abdominal wall
Median umbilical fold (1), medial umbilical folds (2), lateral umbilical folds (2)
Extent of the median umbilical fold
Midline from apex of bladder to umbilicus
The median umbilical ligament, contained in the median umbilical fold, covers the remnant of what embryonic structure which connects the fetal urinary bladder with the amniotic sac?
Urachus (Non-closure leads to chronic renal problems with urine coming out of the umbilicus)
Medial umbilical folds are remnants of what embryonic structure?
Umbilical arteries
Lateral umbilical folds go over which structures?
Inferior epigastric vessels
Fossae between median and medial folds
Supravesical fossae
Fossae between medial and lateral folds
Medial inguinal fossae
Fossae lateral to lateral folds
Lateral inguinal fossae
Fossa that is the site of the deep inguinal ring (under the peritoneum)
Lateral inguinal fossa
Extends between the liver and abdominal wall peritoneum above the umbilicus
Falciform ligament
The round ligament of the liver, also known as the ligamentum teres hepatis, is the remnant of what structure?
Umbilical vein
Clinical significance of round ligament
Blood may be cannulated here prior to the closure of the umbilical vein for babies in need of cannulation
Musculoaponeurotic partition forming the roof of the abdomen and floor of the thorax
Diaphragm
Functions of the diaphragm
1) Respiration
2) Assists in raising intra-abdominal pressure
3) Facilitates blood circulation (thru IVC)
Innervations of the diaphragm
1) Phrenic nerve (C3 to C5) - sensory and motor
2) Intercostal nerves (T5 to T11) - sensory of peripheral portion
3) Subcostal nerve (T12) - sensory of peripheral portion
Apertures on diaphragm surface
IVC (T8), esophageal hiatus (T10), aortic hiatus (T12 inferior border)
Components of the aponeurotic central part of the diaphragm
Clover-shaped leaves and central tendon
Size and location of clover-shaped leaves
Right lateral leaf - Largest; curves posteriorly
Anterior/middle leaf - Intermediate size; inferior to the heart
Left lateral leaf - Smallest
Characteristics of the central tendon of the diaphragm
Trifoliate aponeurotic portion whose superior aspect fuses with the inferior surface of the fibrous pericardium; Perforated by the caval/IVC foramen
Components of the muscular peripheral part of the diaphragm
Sternal portion, costal portion, lumbar portion
Attachment of the sternal portion of the diaphragm
Posterior part of xiphoid process
Characteristics of the costal portion of the diaphragm
Arise from the internal part of the ribs interdigitating with transversus abdominis; Forms right and left hemidiaphragms
Origin of the lumbar portion of the diaphragm
Upper lumbar vertebra
Ligaments of the lumbar portion of the diaphragm
Median arcuate ligament, medial arcuate ligaments, lateral arcuate ligaments
The median arcuate ligament, arching over the anterior aspect of the aorta and uniting the right and left crura of the diaphragm, forms what structure?
Aortic hiatus
Composition of medial arcuate ligaments
Condensation of psoas muscle fascia
Musculotendinous bands that arise from the anterior surfaces of L1 to L3 vertebra, ALL, and intervertebral discs
Crura of the diaphragm
Characteristics of the right crura of the diaphragm
Larger and longer than the left crus, arises from L1 to L3/L4, forms the esophageal hiatus
Characteristics of the left crura of the diaphragm
Arises from L1 to L2/L3
Arteries supplying the superior diaphragmatic surface
Superior phrenic a. (from thoracic aorta), musculophrenic a. and pericardiophrenic a. (from internal thoracic a.)
Arteries supplying the inferior diaphragmatic surface
Inferior phrenic a. (from abdominal aorta)
Veins draining the superior diaphragmatic surface
Superior phrenic v. (into IVC), musculophrenic v. and pericardiophrenic v. (into internal thoracic v.)
Veins draining the inferior diaphragmatic surface
Inferior phrenic v. (right into IVC, left anteriorly into IVC and posteriorly into left renal v.)
Lymphatic drainage of superior diaphragmatic surface
Diaphragmatic nodes -> phrenic nodes -> parasternal and posterior mediastinal nodes
Lymphatic drainage of inferior diaphragmatic surface
Superior lumbar lymph nodes
Characteristics of indirect hernia
Appears lateral to inferior epigastric vessels; usually congenital when the processus vaginalis fials to resorb upon birth
Characteristics of direct hernia
Appears medial to inferor epigastric vessels; commonly occurs among the elderly due to chronic cough and prostatic problems that increase intra-abdominal pressure
Thin potential space within the abdominal cavity that continues to the pelvic cavity
Peritoneal cavity
Lining of the peritoneal cavity
Continuous layer of simple squamous epithelium (mesothelium) that forms the parietal and visceral peritoneum
Contents of the peritoneal cavity
No organs, only a thin film of peritoneal fluid (composed of water, electrolytes, and other substances)
Function of peritoneal fluid
Lubricates peritoneal surfaces allowing smooth mobility of visceral organs
Two types of peritoneum
Parietal and visceral peritoneum
More external walls of the peritoneal cavity that lines the internal surface of the abdominopelvic wall
Parietal peritoneum
Characteristics of parietal peritoneum
Sensitive to pressure, pain, heat and cold, and laceration with well-localized pain; supplied by same blood and lymphatic vasculature and nerves as wall region it lines
More internal walls of the peritoneal cavity that invests visceral organs
Visceral peritoneum
Characteristics of visceral peritoneum
Insensitive to pressure, pain, heat and cold, and laceration with poorly localized pain; supplied by same blood and lymphatic vasculature and nerves as the organ it covers
Organs almost completely covered by visceral peritoneum
Intraperitoneal organs
Examples of intraperitoneal organs
Stomach, superior part of the duodenum, jejunum and ileum, transverse and sigmoid colon, superior rectum, liver and gallbladder, spleen
Organs exterior to the peritoneal cavity and posterior to the peritoneum
Retroperitoneal organs
Examples of retroperitoneal organs
Kidneys and ureters, abdominal aorta and IVC, part of the duodenum, part of the pancreas
Double layer of peritoneum derived from invaginations of peritoneum by an organ
Mesentery
Functions of the mesentery
Connects visceral organ to body wall constituting a continuity of parietal and visceral peritoneum; movement of organs; neurovascular communication
Double layer extension or peritoneal fold that passes from the stomach and proximal part of the duodenum to adjacent organs
Omentum
Large peritoneal fold that hangs from greater curvature of stomach and proximal part of duodenum, attaching to the transverse colon and its mesentery
Greater omentum
Parts of the greater omentum
1) Gastrophrenic lig.
2) Gastrosplenic lig.
3) Gastrocolic lig.
Smaller layer that connects lesser curvature of stomach and proximal part of duodenum to liver; more primitive ventral mesentery
Lesser omentum
Parts of the lesser omentum
1) Hepatogastric lig.
2) Hepatoduodenal lig. (contains liver portal triad)
Two main divisions of the peritoneal cavity
Greater sac and lesser sac
Divisions of the greater sac delineated by the transverse mesocolon
Supracolic and infracolic compartments
Organ contents of supracolic compartment
Stomach, duodenum, pancreas, liver, and spleen
Spaces of the supracolic compartment
Subphrenic recess, subhepatic recess, hepatorenal recess/Morrison’s pouch
Location and boundaries of hepatorenal recess/Morrison’s pouch
Located at right subhepatic space bounded by the right lobe of liver, right kidney, and duodenum
Most dependent portion of abdominal cavity when in supine position
Hepatorenal recess/Morrison’s pouch
Organ contents of the infracolic compartment
Jejunum and ileum, large intestine, sigmoid colon and rectum
What structure further divides the infracolic compartment into right and left infracolic spaces?
Mesentery of the small intestine
Spaces of the infracolic compartment
Rectovesical pouch, rectouterine pouch/pouch of Douglas
Characteristics of rectovesical pouch
Located between bladder and rectum, dependent portion in males
Characteristics of rectouterine pouch/pouch of Douglas
Between rectum and uterus, dependent portion in females
Clinical significance of rectouterine pouch/pouch of Douglas
Site where fluid accumaltes when there are ruptured cysts in the ovaries, uterus, or appendix
Divisions of the lesser sac/omental bursa
Superior recess and inferior recess
Location of the lesser sac
Posterior to the stomach and lesser omentum
Function of the lesser sac
Permits free movement of the stomach on structures posterior and inferior to it
Limits of the superior recess
Posteriorly by the diaphragm and posterior layers of the coronary ligament
Location of the inferior recess
Between superior parts of the greater omentum
Communication between greater and lesser sacs
Foramen of Winslow
Boundaries of the foramen of Winslow
Superior: Caudate lobe of liver
Inferior: Superior part of duodenum
Anterior: Portal triad
Posterior: IVC and crus of diaphragm
Clamping of the hepatoduodenal ligament to interrupt blood flow and prevent excessive bleeding
Pringle’s manuever
