Lecture 17: Abdomen I Flashcards
What are the boundaries of the abdomen?
Superior: The diaphragm (fifth intercostal space)
Posterior: Lumbar vertebrae and quadratus lumborum muscles
Anterolateral: The muscles of abdominal wall
Inferior: The pelvic brim
See figure
What are the planes that divide the abdomen into quadrants?
Median plane (midline)
Transumbilical plane
See figure
What are the abdominal quadrants?
Right upper quadrant
Left upper quadrant
Right lower quadrant
Left lower quadrant
What are the planes that divide the abdomen into 9 parts?
Midclavicular planes
Subcostal planes
Transtubercular plane
See figure
What are the 9 abdominal regions?
Right hypochondriac region
Epigastric region
Left hypochondriac region
Right lumbar region
Umbilical region
Left lumbar region
Right iliac (inguinal) region
Hypogastric (pubic) region
Left iliac (inguinal) region
What are the layers of the anterolateral abdominal wall (superficial to deep)
skin
superficial fascia (fatty layer)
deep fascia (scrape fascia)
muscles
transversalis fascia,
extraperitoneal fat/fascia
peritoneum
See figure
Clinical significance of the scarpa fascia
Used to hold sutures when abdominal surgery is done, another layer of sutures in the skin
What happens if you move deep to the peritoneum?
In the abdominal cavity
What are the functions of the abdominal muscles?
- Protection of abdominal viscera
- Movement of the trunk
- Allow expansion of abdominal cavity
- Compressing the abdominal viscera
- Expelling abdominal contents (micturition, defecation, parturition, vomiting) – increase intra-abdominal pressure
What are the muscles of the anterolateral abdominal wall?
External oblique
Internal oblique
Transversus abdominis
Rectus abdominus
What is the outermost layer of abdominal muscles?
External oblique
How do the fibres of the external obliques run?
Down and toward the midline
“Hands in your pockets”
Actions of external oblique muscles
Flexion and rotation of trunk
Compression of viscera
Where are the internal obliques?
Middle layer of abdominal muscles
How do the fibres of the internal obliques run?
down and away from midline (perpendicular to external obliques)
Actions of internal obliques?
Flexion and rotation of trunk
Compression of viscera
Location of the transverses abdominus
Deepest and thinnest layer of abdominal muscle
How do the fibres of the transverses abdomens run?
Horizontally
Actions of transverses abdominus
Compression of viscera only!
No trunk movement (“suck it in”)
Appearance and location of rectus abdominus?
Pair of long, straplike muscles
extend vertically from the pelvis to the ribs
What separates the rectus abdominus muscles?
Linea alba (midline)
What are the rectus abdominus muscles enclosed within?
rectus sheath (aponeuroses of obliques)
How are divisions of rectus abdominus separated? How many divisions are there?
tendinous intersections
8 pack
Actions of rectus abdominus
Flexion of the trunk
Compression of viscera
Shape and origin of quadrates lumborum
Square-shapedmuscle originating on the pelvis
Action of quadrates lumborum
Powers lateral flexion of the lumbar spine
Stabilizes the 12th rib against the action of the diaphragm during inspiration
What does psoas major combine with?
Combineswithiliacus to form iliopsoas
Action of psoas major
Powers hip flexion and can also flex the trunk laterally
Innervation of psoas major
Femoral nerve
Abdominal muscles - cross section
See figure
Innervation of anterolateral abdominal wall
Mixed sensory and motor nerves
Anterior rami of spinal nerves T7 to L1
Includes intercostal nerves (T7-T11), subcostal nerve (T12), iliohypogastric and ilioinguinal nerves (L1)
See figure
What are the primary blood vessels of the anterolateral abdominal wall?
Superior epigastric vessels and branches of the musculophrenic vessels from the internal thoracic vessels.
Inferior epigastric and deep circumflex iliac vessels from the external iliac vessels.
See figure
What is the inguinal canal?
4 cm long tube-like space within the lower part of the anterior abdominal wall
Begins at the deep inguinal ring and ends at the superficial inguinal ring
What gender has the inguinal canal?
Present in males and females
Importance of inguinal canal in males
where the testis, which develop in the abdominal cavity, descend down into the scrotum
What are the boundaries of the inguinal canal?
Floor: inguinal ligament
Anterior wall: external oblique aponeurosis
Roof: formed by arched fibres of internal oblique and transversus abdominis muscles
Posterior wall: transversalis fascia (laterally) and conjoint tendon (medially)
Rings (openings) of the inguinal canal
Superficial inguinal ring: triangular opening in the external oblique aponeurosis
Deep inguinal ring: opening in the transversalis fascia.
Contents of the inguinal canal in males and females
Males: the spermatic cord and its coverings + the ilioinguinal nerve.
Spermatic cord contains: vas deferens, testicular artery and vein, genital branch of the genitofemoral nerve, lymphatic vessels
Females : the round ligament of the uterus + the ilioinguinal nerve.
See figure
What is the peritoneum?
Transparent membrane that covers most (BUT NOT ALL!) abdominal organs
See figure (white lines are peritoneum)
2 layers of peritoneum
Parietal – lines the abdominal wall
Visceral – covers the viscera
Role of peritoneum
Secretes peritoneal fluid that lubricates the organs and prevents friction
2 main divisions of peritoneal cavity
Greater sac (green): largest part of the cavity
Lesser sac (blue): smaller part, situated posterior to the stomach and liver
See figure
When are the divisions of the peritoneal cavity formed?
During embryonic development
Greater sac
See figure
What is the greater omentum?
Double layer of peritoneum, impregnated with fat and blood vessels
What does the greater momentum attach to?
stomach and transverse colon, inferior border is free
Hangs down like an apron, covering the abdominal viscera
Role of greater omentum
Prevents organs from sticking to the anterior abdominal wall
Mobility of greater omentum
Very mobile!
Can sense, migrate and wrap itself around an inflamed or infected organ!
Will also wrap itself any foreign object (clinical significance)
What are the parts of the greater omentum?
Gastrophrenic ligament
Gastroplenic ligmament
Gastrocolic ligament
See figure
Lesser sac
aka mental bursa
See figure
What is the lesser sac?
A pouch found posterior to the stomach
How does the lesser sac communicate with the greater sac?
Via the epiploic foramen (behind the stomach)
See figure
Clinical significance of lesser sac
The inferior recess of the lesser sac extends a considerable distance
Infectious material from abscesses can collect here!
Composition of lesser sac
Double layer of peritoneum
Made up of hepatoduodenal and hepatogastric ligaments
What does the hepatoduodenal ligament contain?
important blood and bile
vessels going to and from the liver
See figure (parts of greater omentum)
Composition of the peritoneal ligaments
Double layer of peritoneum
Role of the falciform ligament
Peritoneal ligament
Attaches the liver to anterior wall of abdomen
See figure
What is the mesentery?
Double layer of peritoneum that attaches organs to the posterior abdominal wall (mainly small intestine)
Now considered an organ itself!
What does the mesentery contain?
Blood/lymph vessels
Fat
Nerves
Role of mesentery
Makes the organs mobile
Suspends the small intestine
Carries nerves, lymph and blood vessels to small intestine
(see peritoneum figure)
Difference between intraperitoneal and retroperitoneal organs
Intraperitoneal organs are covered by visceral peritoneum
Retroperitoneal organs lie between the parietal peritoneum and the posterior abdominal wall
What are the intraperitoneal organs?
Stomach
Spleen
Liver and gallbladder
Small intestine (jejunum, ileum, and small part of duodenum)
Large intestine (transverse colon, sigmoid colon)
What are the retroperitoneal organs?
Kidneys and suprarenal glands
Pancreas
Most of duodenum
Large intestine (ascending and descending colon)
See figure (+peritoneum figure)
