3. Anterior Abdominal Wall and Inguinal Region Flashcards
Label the yellow, blue and red structures.
Yellow = innermost intercostal
Blue = internal intercostal
Red = external intercostal (finishes mid-clavicular)
What are the 3 layers of muscle in the lateral abdominal wall? (List them from out to in)
What muscle is found anteriorly?
External oblique (fibres run in same direction as external intercostal) -> internal oblique -> transversus abdominis
Rectus abdominis
What is external oblique attached to superiorly and inferiorly?
What is the white fibrous tissue on the specimen?
What is the internal oblique attached to superiorly and inferiorly?
What direction does its fibres run in?
Where does it become aponeurotic?
Superiorly = ribs, inferiorly = iliac crest (NB: free inferior border when get to ASIS = inguinal ligament, creates space - pic on L).
Aponeurosis – thin, flat sheet of tendon, L and R knit together = fibrous line in middle
Same as external oblique
Anterior-superior
Mid-clavicular line (pic on R)
What direction do transversus abdominis fibres run in?
Where does rectus abdominis run to superiorly and inferiorly?
Describe rectus abdominis. What runs down the middle?
What is the rectus sheath?
Transverse around abdomen. Aponeurotic at mid-clavicular line.
Superiorly: xiphoid process Inferiorly: pubic symphysis
Tendinous intersections along the length of the muscle = compartmentalises muscle into different functional regions. Linea alba = fibrous line runs down middle.
Aponeurotic sheath enclosing the rectus abdominis, derived from the aponeuroses of external and internal oblique and transversus abdominis.
Describe how the muscles run in the rectus sheath.
What is the arcuate line? Is the structure of the rectus sheath the same here?
External oblique: laterally, Internal oblique: aponeurosis splits to anterior and posterior, Transversus abdominis: behind rectus abdominis, Transversalis fascia: lines internal aspect of abdominal wall.
1/3 of the way between umbilicus and pubic symphysis. Below it the structure of the rectus sheath changes: everything runs anteriorly to rectus abdominis, so weaker than above arcuate line.
Describe the arteries of the abdomen?
Internal thoracic either side of sternum, passes to diaphragm to supply rectus abdominis and becomes superior epigastric artery. Inferior epigastric artery comes from external iliac, usually larger than SEA. Lower intercostal and lumbar arteries wrap around lateral aspect
NB: internal thoracic sometimes used for CABG and one SE is wasting of abdominal muscles
Label A-F (nerve supply to abdomen).
What are the dermatome landmarks of the nerve supply to the abdomen?
A: subcostal
B: iliohypogastric
C: ilioinguinal
D: Obturator
E: Femoral
F: genitofemoral
T7 - xiphoid, T10 - umbillicus, T12 - subcostal nerve, L1 - iliohypogastric and ilioinguinal nerves (both part of lumbar plexus).
What creates the inguinal ligament?
What structures are found under the inguinal ligament?
What passes through the inguinal canal in a man or woman?
The inferior border of exteral oblique’s aponeurosis rolles under itself, creating the inguinal canal
Femoral nerve, artery, vein
Man: spermatic cord Woman: round ligament of the uterus
Label A-E
A: rectus abdominis
B: linea alba
C: ASIS
D: inguinal ligament
E: tendinous intersection
What does the spermatic cord do?
What is found within it?
What surrounds the spermatic cord?
Contains structures running to and from the testes (and plevis), and suspends testes within scrotum
Testicular artery, ductus deferens (continuous with epididymis), pampiniform venuos plexus, genital branch of genitofemoral nerve, ilioinguinal nerve (runs with cord)
3 layers derived from the layers of the abdominal wall: external spermatic fascia, cremaster muscle, internal spermatic fascia.
Label A-E of the spermatic cord
A: genital branch of genitofemoral nerve
B: testicular artery
C: ductus deferens
D: pampiniform venous plexus
E: ilioinguinal nerve
Describe testes development.
What is the superficial inguinal ring?
Develop on posterior abdominal wall and desend through inguinal canal to reach around 9th month (common for boys to be born with only 1 testis descended)
Point at which the spermatic cord emerges from the abdominal wall (pic -red ring)
How do the 3 layers of abdominal muscle cover the inguinal canal?
External oblique: aponeurosis surrounds spermatic cord (external spermatic fascia derived from EO so the 2 are continuous). Internal oblique: muscle fibres cover spermatic cord = contributes muscular fibres. Transversus abdominis: absent (ends too superiorly)
Where does the testes develop?
Describe the descent of the testes.
Testis develops in abdomen between peritoneum and abdominal wall.
As testis starts to enter inguinal canal, peritoneum sticks to the back of it and goes with it. It enters inguinal canal and pushes through transversalis fascia which eventually becomes the internal spermatic fascia. It passes through transversis abdominis but it’s deficient at that point so takes nothing from it. It pushes through internal oblique and takes a few muscle fibres from it = cremaster muscle. Then it goes through external oblique which is aponeurotic at that point, so get aponeurotic layer = external spermatic fascia.
The peritoneum is deeply infolded now = processus vaginalis. It’s sealed off superiorly and fibroses so left with little pouch of peritoneal in scrotum so testis can move freely in scrotum.
What does the cremaster muscle do, and what innervates it?
What are the deep and superficial inguial rings?
Moves scrotum up/down in response to temperature, innervated by genitofemoral nerve.
Deep: entrance to inguinal canal Superficial: exit to inguinal canal (all SC structures leave via)
Label A-D
A: ductus deferens
B: testicular vessels
C: genitofemoral nerve
D: ilioinguinal nerve
Label A-G
A: internal spermatic fascia
B: cremaster muscle
C: external spermatic fascia
D: transverse fascia
E: transverse abdominis
F: internal oblique
G: external oblique
What is a hernia?
Describe the 2 types.
Protrusion of fat/peritoneum/viscera (more of a prob b/c contains BVs) such as a small intestine through an opening or weakness. Inguinal hernias account for 75% of abdominal hernias. Hernias are usually harmless but potential risk of having blood supply cut off = medical and surgical emergency! The passageway through muscles of abdominal wall = weakness!
1) Direct: acquired, males >40yo common, hernia enters deep ring, may reach superficial, rarely enters scrotum. Next to spermatic cord, not inside.
2) Indirect: congenital (patent process vaginalis, more common (2/3), transverses canal within the PV, commonly enters scrotum)
What is Hasselbach’s Triangle?
Direct hernias occur due to a weakness in the anterior abdominal wall = Hasselbach’s triangle.
