Region 2 - Abdominal Walls Flashcards
Where is the trans-umbilical plane?
IV disc between L3 and L4
What are the 2 divisions of the abdominal superficial fascia below the umbilicus?
Superficial (fatty) - Camper’s fascia
Deep (membranous) - Scarpa’s fascia
What layer of abdominal fascia is continuous over the inguinal ligament and into the fascia of the thigh and perineum?
Camper’s (superficial fatty) fascia
How does Camper’s fascia contribute to the structure of the penis?
Loses fatty layer
Fuses with deeper layer (Scarpa’s fascia)
Becomes dartos fascia of scrotum
How does Camper’s fascia contribute to the female external genitalia?
Retains fatty layer
Contributes to fascia of labia majora
Where does the Scarpa’s fascia attach in the abdomen?
Pubic symphysis
Linea alba in midline
What does Scarpa’s fascia attach to in the perineum?
Posterior part of perineal membrane
- Superficial part ie Colles’ fascia
What does Scarpa’s fascia contribute to in the male external genitalia?
Fascia of penis
Dartos fascia of scrotum
Fundiform ligament of penis
What does Scarpa’s fascia contribute to in the female external genitalia?
Labia majora
What direction do the external oblique fibres run in?
Inferomedially (hands in pockets)
What is the origin of the external obliques?
Ribs 5-12
Where do the external obliques insert?
Iliac crest
Linea alba
Where does the external oblique aponeurosis run from and to?
From xiphoid
To pubic symphysis
What does the lower border of the external oblique aponeurosis form?
Inguinal ligament
What are the functions of the external obliques?
Flex trunk by using both
Turn to ipsilateral side by using one
What innervates the external obliques?
Anterior rami T7-T12 via:
- Thoracoabdominal nerves (T7-T11)
- Subcostal nerve (T12)
What direction do the fibres of the internal obliques run in?
Superomedially
What are the origins of the internal obliques?
Thoracolumbar fascia
Inguinal ligament
Iliac crest
What are the insertions of the internal obliques?
Ribs 9-12
Where does the aponeurosis of the internal obliques end?
Linea alba
Pectineal line
Pubic crest
What are the functions of the internal obliques?
Flex trunk by using both
Bend trunk to one side by using one
What innervates the internal obliques?
Anterior rami T7-L1 via:
- Thoracoabdominal nerves (T7-T11)
- Subcostal nerve (T12)
- Iliohypogastric and ilioinguinal nerves (L1)
What are the origins of the transversus abdominis?
Thoracolumbar fascia
Iliac crest
Inguinal ligament
Costal cartilages of ribs 7-12
What are the insertions of the transversus abdominis?
Linea alba
Pubic crest
Pectineal line
What innervates the transversus abdominis?
Anterior rami T7-L1 via:
- Thoracoabdominal nerves (T7-T11)
- Subcostal nerve (T12)
- Iliohypogastric and ilioinguinal nerves (L1)
What is the function of the transversus abdominis?
Support abdominal wall
What are the origins of the rectus abdominis?
Pubic tubercle
Pubic crest
Pubic symphysis
What are the insertions of the rectus abdominis?
Xiphoid process
Costal cartilages of ribs 5-7
What are the functions of the rectus abdominis?
Flexes trunk
Supports/Compresses abdominal wall
What innervates the rectus abdominis?
Anterior rami T7-T12 via:
- Thoracoabdominal nerves (T7-T11)
- Subcostal nerve (T12)
What is the origin of the pyramidalis?
Pubis
What is the insertion of the pyramidalis?
Linea alba
What is the function of the pyramidalis?
Tenses linea alba
What innervates the pyramidalis?
Anterior ramus T12 (subcostal nerve)
Where does the rectus sheath lie above the costal margin?
Directly on costal cartilage
Where is the arcuate line?
Half way between umbilicus and pubic bone
What is the structure of the rectus sheath above the arcuate line?
Aponeuroses of external oblique and half of internal oblique are anterior to rectus abdominis
Aponeuroses of half of internal oblique and transversus abdominis are posterior to rectus abdominis
What is the structure of the rectus sheath below the arcuate line?
All aponeuroses anterior to rectus abdominis
From superficial to deep, what are the layers of the abdominal wall?
Skin
Superficial (fatty) layer of superficial fascia (Camper’s)
Deep layer of superficial fascia (Scarpa’s)
Muscles and deep fascia
Transversalis fascia
Extraperitoneal fat
Parietal peritoneum
What is the median umbilical ligament?
Remnant of urachus
What are the medial umbilical ligaments?
Remnants of umbilical arteries
What do the lateral umbilical folds contain?
Inferior epigastric vessels
What nerves supply the anterior abdominal wall?
Lateral cutaneous branches of intercostal nerves 7-11 (T7-T11), subcostal nerve (T12) and iliohypogastric and ilioinguinal nerve (L1)
Anterior cutaneous branches of T7-T12
What is the arterial supply of the anterior abdominal wall?
Musculophrenic artery (from internal thoracic)
Femoral artery branches:
- Superficial epigastric
- Superficial circumflex iliac
What is the superficial lymphatic drainage of the anterior abdominal wall?
Superficial inguinal
Anterior axillary
Posterior axillary
What is the deep lymphatic drainage of the anterior abdominal wall?
Parasternal nodes (internal thoracic artery) Lumbar nodes (abdominal aorta) External iliac nodes
Where does the inguinal canal lie?
Superiorly to the medial half of the inguinal ligament
How long is the inguinal canal?
~4cm
What does the inguinal canal carry generally in males?
Structures to/from testis and abdomen
Ilioinguinal nerve
What does the inguinal canal carry generally in females?
Round ligament of uterus to labia majora
Ilioinguinal nerve
What is the superficial inguinal ring?
Triangular-shaped defect in external oblique aponeurosis
What forms the base of the superficial inguinal ring?
Pubic crest
What are the margins of the superficial inguinal ring attached to?
Lateral crus to pubic tubercle
Medial crus to pubic crest
What does the superficial inguinal ring give rise to?
External spermatic fascia
What forms the intercrural fibres of the superficial inguinal ring?
Superficial layer of deep fascia over external oblique
Where do the intercrural fibres lie in the superficial inguinal ring?
Superolaterally
What is the function of the intercrural fibres?
Support the superficial inguinal ring
What ligament can become fibrous and blend with the superficial inguinal ring?
Round ligament
What is the deep inguinal ring?
Oval opening in the transversalis fascia
Where is the deep inguinal ring located?
Halfway between ASIS and pubic symphysis (~1.3cm above inguinal ligament)
Where do the inferior epigastric vessels lie in relation to the deep inguinal ring?
Medially
What fascia does the deep inguinal ring give rise to?
Internal spermatic/round ligament
What forms the anterior wall of the inguinal canal?
External oblique aponeurosis
Internal oblique muscle fibres:
- In lateral third (weak area of deep ring in post. wall)
What forms the posterior wall of the inguinal canal?
Transversalis fascia
Conjoint tendon:
- In medial third (weak area of superfic. ring in ant. wall)
What is the conjoint tendon?
Common insertion of internal oblique and transversus abdominis
Where does the conjoint tendon insert?
Pubic crest
Pectineal line
What forms the roof of the inguinal canal?
Transversalis fascia laterally
Internal oblique and transversus abdominis muscle fibres centrally
What forms the floor of the inguinal canal?
Inguinal ligament Lacunar ligament (medial)
Where does the lacunar ligament originate and what direction does it move in?
Medial end of inguinal ligament
Superoposteriorly
Where does the lacunar ligament insert?
Pectineal line (superior pubic ramus) at pectineal ligament
What does the free edge of the lacunar ligament form?
Medial margin of femoral ring
How are the weak areas of the inguinal canal reinforced?
Oblique course
Compressed by internal oblique and transversus abdominis
Squatting (defaecation/childbirth) - Thighs protect wall
What is an indirect inguinal hernia?
Protrusion of tissue via deep inguinal ring
What is a direct inguinal hernia?
Protrusion of tissue by pushing through posterior wall into inguinal canal
Where does the spermatic cord begin and end?
Begin - Deep inguinal ring
End - Testis
What are the contents of the spermatic cord?
Ductus deferens (and artery)
Testicular artery and veins
Cremasteric artery (from inf. epigastric)
Genital branch of genitofemoral nerve
Lymph vessels
ANS nerves (SNS from renal/aortic plexuses)
What structures in the spermatic cord lie outside the internal spermatic fascia?
Cremasteric artery
Genital branch of genitofemoral nerve
What does the genital branch of the genitofemoral nerve supply?
Cremaster muscle
What are the coverings of the spermatic cord?
- Peritoneal diverticulum (processus vaginalis) from L1
- Internal spermatic fascia = Deep ring ie. transversalis fascia)
- Cremaster muscle (fascia) = Internal oblique
- External spermatic fascia = Superficial ring ie. external oblique
What is the function of the cremaster muscle?
Raises testes and scrotum for warmth and protection
What is the tunica vaginalis?
Closed off sac - a remnant if processus vaginalis
What cells form the gubernaculum?
Mesenchyme
Where does the gubernaculum descend through and to?
Through inguinal canal
To labiosacral swelling
At what point in development do the testes move through the inguinal canal?
7th-8th months
Why do the testes have the same coverings as the inguinal canal?
Follow gubernaculum
Why do the ovaries stay in the pelvis instead of descending?
Gubernaculum is stuck to uterus
What do the seminiferous tubules open into?
Rete testis
What temperature are the testes in relation to the abdomen?
3 degree celcius cooler
Where does lymph from the testes and epididymis drain to?
Para-aortic nodes at root of testicular artery (L2)
Where does lymph from the scrotal wall and fascia drain to?
Superficial inguinal nodes
What modalities is the parietal peritoneum sensitive to?
Pain
Touch
Temperature
Pressure
What is the anterolateral parietal peritoneum innervated by?
Lower 6 thoracic nerves (T7-T12)
What is the central part of the parietal peritoneum innervated by?
Phrenic nerve
What is the pelvic part of the parietal peritoneum innervated by?
Obturator nerve
What is the visceral peritoneum sensitive to?
Stretch (via ANS afferents)
What are the retroperitoneal organs?
Primary: - Kidneys - Suprarenal glands Secondary: - 2nd, 3rd and 4th parts duodenum - Ascending and descending colon - Pancreas - Upper 2/3rds rectum
What is a secondary retroperitoneal organ?
Were once mobile but now stuck to body wall
Where is the greater omentum suspended from?
Greater curvature of stomach and proximal duodenum
What does the greater omentum fold back to cover?
Anterior transverse colon
How is the greater omentum four-layered?
Each part is a double layer which folds back onto each other
What divides the greater sac?
Transverse colon
What is contained in the supracolic compartment of the greater sac?
Liver
Gallbladder
Stomach
What is contained in the infracolic compartment of the lesser sac?
Intestines
The blood vessels carried by the greater omentum supply what structures?
Itself:
- Via left and right gasto-omental (epiploic) vessels
Greater curvature of stomach
What is the other name for the lesser sac?
Omental bursa
Where is the lesser sac?
Portion of peritoneal cavity behind lesser omentum and stomach
Where does the lesser omentum originate?
Liver
Where does the lesser omentum attach and via what?
Lesser curvature of stomach (hepatogastric lig.) Proximal duodenum (hepatoduodenal lig.)
What collection of structures is contained in the hepatoduodenal ligament?
Portal triad:
- Hepatic artery (left ant.)
- Bile duct (right ant.)
- Portal vein (post.)
How do the greater and lesser sacs communicate?
Epiploic (omental) foramen
What is the function of the mesentery proper?
Carries vessels, nerves and lymphatics to/from most of small intestine (jejunum and ileum)
What vessels run in the mesentery proper?
Jejunal and ileal branches of superior mesenteric artery and vein
Other than the mesentery proper, what other ‘mesenteries’ exist?
Transverse mesocolon
Sigmoid mesocolon
Vermiform appendix mesocolon
What is the function of peritoneal fluid?
Lubrication
In what direction does peritoneal fluid flow and via what?
Superiorly
Via left and right paracolic gutters
Where does peritoneal fluid flow towards?
Subphrenic spaces
What are the paracolic gutters?
Grooves between:
- Ascending/Descending colon
- Posterolateral abdominal wall
What are the parts of the posterior abdominal wall fascia named after?
Muscles
What is the posterior abdominal wall fascia continuous with?
Pelvic fascia
Where does the femoral sheath lie?
Deep to inguinal ligament
What are the contents of the femoral sheath (from lateral to medial)?
Femoral artery
Femoral vein
Lymph vessels (in femoral canal)
What forms the anterior wall of the femoral sheath?
Transversalis fascia
What forms the posterior wall of the femoral sheath?
Iliopsoas fascia
What is the function of the femoral sheath?
Allows proximal femoral vessels to glide under inguinal canal during hip motion
From roughly superior to inferior, what are the nerves on the posterior abdominal wall?
Subcostal Iliohypogastric Ilioinguinal Genitofemoral Lateral femoral cutaneous Femoral Obturator Lumbosacral trunk
What vertebral levels does the right crus of the diaphragm extend from?
L1-L3
What vertebral levels does the left crus of the diaphragm extend from?
L1-L2
What is the origin of the quadratus lumborum muscle?
Iliac crest
What are the insertions of the quadratus lumborum muscles?
12th rib
L1-L4 transverse processes
What are the functions of the quadratus lumborum muscles?
One bends trunk to same side Both: - Pressure - Forced expiration - Support for 12th rib
What innervates the quadratus lumborum?
Anterior rami T12-L4
What fascia layers blend at the lateral border of the quadratus lumborum?
Middle layer of lumbar fascia with anterior layer
What does the anterior layer of the lumbar fascia form superiorly?
Lateral arcuate ligament
What is the origin of the iliacus?
Iliac fossa
What is the insertion of the iliacus?
Lessuer trochanter of femur
What is the function of the iliacus?
Flexion of hip
What is the innervation of the iliacus?
Femoral nerve (L2-L4)
What are the origins of the psoas?
T12-L4 vertebral bodies and IV discs (superficial)
L1-L5 (deep)
What is the insertion of the psoas?
Lesser trochanter of femur
What are the functions of the psoas?
Hip flexion
One = Bends trunk laterally
Both = Raise trunk from supine
What is the innervation of the psoas?
Direct lumbar plexus branches L2-L4
What is the long tendon anterior to psoas major called?
Psoas minor
What is the name of the lumbar fascia arch that passes over psoas major?
Medial arcuate ligament
At what level does the abdominal aorta bifurcate?
L4
Excluding lumbar arteries, what are the paired lateral branches off of the abdominal aorta?
Inferior phrenic arteries (T12) Suprarenal arteries (L1): - Superior - Middle Renal arteries (L1) Gonadal arteries (L2)
At what vertebral level is the IVC formed?
L5
Where do lumbar veins 1 and 2 drain to?
Ascending lumbar -> Azygos/Hemiazygos
Where do lumbar veins 3 and 4 drain to?
IVC
Where does the 5th lumbar vein drain to?
Iliolumbar vein -> Common iliac
Where does the right gonadal vein drain?
IVC
Where does the left gonadal vein drain to?
Left renal vein
What contributes SNS fibres to the coeliac plexus?
Coelic ganglia (greater splanchnic nerves) Aorticorenal ganglia (lesser splanchnic nerves)
What contributes PNS fibres to the coeliac plexus?
Fibres from posterior (and anterior) vagal trunks
Where is the coeliac plexus situated?
Around the coeliac trunk (prevertebral)
What does the coeliac plexus supply?
Foregut organs
What is the alternate name for the coeliac plexus?
Solar plexus
What contributes SNS fibres to the superior mesenteric plexus?
Superior mesenteric ganglion (gretaer and lesser splanchnic nerves)
What contributes PNS fibres to the superior mesenteric plexus?
Fibres from posterior (and anterior) vagal trunks
Where is the superior mesenteric plexus situated?
Around the superior mesenteric artery (prevertebral)
What does the inferior mesenteric plexus supply?
Hindgut up to the descending colon
What contributes SNS fibres to the inferior mesenteric plexus?
Inferior mesenteric ganglion (lumbar splanchnic nerves L1-L2)
What contributes PNS fibres to the inferior mesenteric plexus?
Pelvic splanchnic nerves S2-S4
What does the superior hypogastric plexus supply?
Ureteric and testicular plexuses
What contributes SNS fibres to the superior hypogastric plexus?
Lumbar splanchnic nerves L3-L4
What contributes PNS fibres to the superior hypogastric plexus?
Pelvic splanchnic nerves S2-S4
What does the inferior hypogastric plexus supply?
Sigmoid colon
Rectum
Bladder
(Via smaller plexuses)
What contributes SNS fibres to the inferior hypogastric plexus?
Hypogastric nerves (from sup. hypogastric plexus) - Pre- and postganglionic T10-T12 Sacral splanchnic nerves
What contributes PNS fibres to the inferior hypogastric plexus?
Pelvic splanchnic nerves
What does lymph join the intestinal trunk as? What vertebral level is this?
Cisterna chyli
At L1/2
What forms the lumbar plexus?
Anterior rami L1-L4
Where do the branches of the lumbar plexus form?
Within psoas muscle
What is the root value for the iliohypogastric and ilioinguinal nerves
Anterior rami L1
What is the sensory distribution of the iliohypogastric nerve?
Lateral gluteal skin
Pubic skin
What is the sensory distribution of the ilioinguinal nerve?
Medial thigh skin
Root of penis/scotrum OR mons pubis/labia majora
What is the motor distribution of the iliohypogastric and ilioinguinal nerves?
Internal obliques
Transversus abdominis
What is the root value for the genitofemoral nerve?
L1-L2
What is the sensory distribution of the genitofemoral nerve?
Scotrum/Mons pubis
Skin of upper anterior thigh
What is the motor distribution of the genitofemoral nerve?
Cremaster muscle
What are the root values for the lateral cutaneous nerve of thigh?
Anterior rami L2-L3
What is the sensory distribution of the lateral cutaneous nerve of thigh?
Anterior and lateral thigh
What are the root values of the femoral nerve?
L2-L4
What is the sensory distribution of the femoral nerve?
Skin of:
- Anterior thigh
- Medial leg
What is the motor distribution of the femoral nerve?
Pectineus
Iliacus
Anterior compartment of thigh
What are the root values of the obturator nerve?
L2-L4
What is the sensory distribution of the obturator nerve?
Skin of medial thigh
What is the motor distribution of the obturator nerve?
Obturator externus
Medial compartment of thigh
(May supply pectineus)