ABDOMINAL WALL

Question 1

Planes that divide the regions of abdominal wall

Answer 1

Horizontal Plane
1. Transpyloric plane - between jugular notch and pubic symphysis, specifically at the level of L1 vertebra
2. Intertubecular plane - superior to the Right & Left iliac crest

Vertical Planes - midclavicular lines

Question 2

9 surface abdominal regions: Right to Left

Answer 2

1. Right hypochondrium
2. Epigastric
3. Left hypochondrium
4. Right flank
5. Umbilical
6. Left flank
7. Right groin
8. Pubic
9. Left groin

Question 3

Abdominal Quadrants: Right to Left

Answer 3

1. Right Upper Quadrant
2. Left Upper Quadrant
3. Right Lower Quadrant
4. Left Lower Quadrant

Question 4

Organs found in different abdominal quadrants:

Answer 4

Right Upper Quadrant (RUQ)
- Liver (right lobe)
- Gallbladder
- Pylorus (part of the stomach)
- Duodenum (first part of the small intestine)
- Head of the pancreas
- Right kidney and adrenal gland
- Hepatic flexure of the colon
- Parts of the ascending and transverse colon

Left Upper Quadrant (LUQ)
- Liver (left lobe)
- Stomach
- Spleen
- Pancreas (body and tail)
- Left kidney and adrenal gland
- Splenic flexure of the colon
- Parts of the transverse and descending colon

Right Lower Quadrant (RLQ)
- Cecum
- Appendix
- Ascending colon
- Small intestine (ileum)
- Right ureter
- Right ovary and fallopian tube (in females)
- Right spermatic cord (in males)

Left Lower Quadrant (LLQ)
- Small intestine
- Descending colon
- Sigmoid colon
- Left ureter
- Left ovary and fallopian tube (in females)
- Left spermatic cord (in males)

Question 5

Superficial Fascia

Answer 5

. Above the umbilicus
. Below the umbilicus
1. Fatty superficial layer (Camper’s fascia)
- continuous with fascia over thorax and thigh fatty layer
2. Membranous deep layer (Scarpa’s fascia)
- continuous into the peritoneum as Superficial perineal fascia (Colle’s fascia)

Question 6

Muscles of the anterolateral abdominal wall:

Answer 6

1. Flat muscles
   - lateral in the abdominal wall
2. Vertical muscles
   - located in the midline of abdominal wall

Question 7

Linea alba:

Answer 7

Aponeurosis of all the three flat muscles
From xiphoid process to pubic symphysis

Question 8

Flat muscles :

Answer 8

A. External oblique
- largest, most superficial; fibers run inferomedially

O: 5-12 ribs
I: Iliac crest & Pubic symphysis
A: contralateral rotation of torso
N: Thoracoabdominal nerves (T7-T12) ; Subcostal nerve (T12)

Question 9

Flat muscles:

Answer 9

B. Internal Oblique
-deep to external oblique, smaller & thinner ; fibers run superomedially

A: inguinal ligament, iliac crest & lumbodorsal fascia
I: 10-12 ribs
A: Bilateral contraction - compress abdomen ; Unilateral contraction - ipsilaterally rotates torso
N: Thoracoabdominal nerves
Subcostal nerve;
branch of lumbar plexus (Iliohypogastric & Ilioinguinal nerve)

Question 10

Flat Muscles:

Answer 10

C. Transversus Abdominis
- deepest; fibers runs transversely
- deep to this muscle is the transversalis fascia

O: inguinal ligament, 7-12 costal cartilages, iliac crest & thoracolumbar fascia
I: conjoint tendon, xiphoid process, linea alba & pubic crest
A: Compression of abdominal contents
N: Thoracoabdominal nerves
Subcostal nerve
Lumbar plexus

Question 11

Vertical muscles:

Answer 11

A. Rectus Abdominis
- long, paired muscle; split by linea alba
- lateral borders create surface markings the linea semilunaris
- intersected by fibrous strips - tendinous intersections

Note: Tendinous intersection & Linea alba give rise to the 6 pack

O: crest of the pubic bone
I: xiphoid process & costal cartilages of 5-7 ribs
A: assist flat muscles in compressing abdominal viscera; stabilize pelvis during walking ; depress the ribs
N: Thoracoabdominal nerves

Question 12

Vertical muscles:

Answer 12

B. Pyramidis
- small triangular muscle
- superficial to rectus abdominis
- located inferiorly: base - pubic bone ; apex - linea alba

O: pubic crest & pubic symphysis
I: linea alba
A: tenses linea alba
N: Subcostal nerve

Question 13

Rectus Sheath
- formed by aponeuroses of 3 flat muscles
- encloses the rectus abdominis & pyramidilis muscle

Anterior wall
- aponeuroses of external oblique & half of internal oblique

Posterior wall
- aponeuroses of half the internal oblique & transversus abdominis

Answer 13

Midway between umbilicus & pubic symphysis:
- all aponeuroses move to anterior wall of rectus sheath
- there is no posterior wall to the sheath
- rectus abdominis is in direct contact w/ transversalis fascia

Arcuate line - demarcation point where the posterior layer of rectus sheath ends

Question 14

Posterior Abdominal Wall

Answer 14

• Lumbar vertebrae
• Pelvic girdle
• Posterior abdominal muscles & associated fascias

Question 15

Posterior Abdominal Muscle:

Answer 15

A. Quadratus Lumborum
- lateral in posterior abdominal wall
- thick muscular sheet; quadrilateral
- posterior to the psoas major
- fibers runs superomedially

O: Iliac crest & iliolumbar ligament
I: L1-L4 transverse process & inferior border of 12th rib
A: extension & lateral flexion of vertebral column ; fixes 12th rib during inspiration
N: Anterior rami of T12-L4 nerves

Question 16

Posterior Abdominal Muscle:

Answer 16

B. Psoas major
- near midline of the posterior abdominal wall
-immediate lateral to lumbar vertebrae

O: transverse processes & T12-L5 vertebral bodies
I: lesser throchanter of the femur
A: flexion of thigh & lateral flexion of vertebral column
N: Anterior rami of L1-L3 nerves

Question 17

Posterior Abdominal Muscle:

Answer 17

C. Psoas minor
- present in only 60% population
- anterior to the Psoas major

O: T12-L1 vertebral bodies
I: Superior rami of the pubic (pectineal line)
A: flexion of vertebral column
N: Anterior rami of L1 spinal nerve

Question 18

Posterior Abdominal Muscle:

Answer 18

D. Iliacus
- fan shaped; inferiorly on the posterior abdominal wal
- combined w/ psoas major to form iliopsas - the major flexor of thigh

O: surface of iliac fossa & anterior inferior iliac spine
I: lesser throchanter of the femur
A: flexion & lateral rotation of the thigh & hip joint
N: Femoral nerve (L2-L4)

Question 19

Fascias of Posterior Abdominal Wall
- lies between parietal peritoneum & muscle of posterior abdominal wall
- this continuous w/ transversalis fascia of anterolateral abdominal wall

Answer 19

Psoas Fascia
- covers the psoas major muscle
- attached to:
Medially - lumbar vertebrae
Laterally - thoracolumbar fascia
Inferiorly - Iliac fascia

Thoracolumbar fascia
- consist of 3 layers: Posterior, middle, & anterior
Muscle enclosex between these layers:
1. Quadratus lumborum - between anterior & middle layers
2. Deep back muscles - between middle & posterior layers

Iliac fascia

Question 20

Posterior Layer
Posteriorly - between 12th rib & iliac crest
Laterally - meets the internal oblique & transversus abdominis muscle
These attachments covers the latissimus dorsi

Answer 20

Anterior layer
Anteriorly - transverse process of lumbar vertebrae, 12th rib & iliac crest
Laterally - continuous w/ aponeurotic origin of transversus abdominis muscle
Superiorly - thickens to become lateral acuate ligament
Inferiorly - joins w/ the iliolumbar ligaments