Anterior Abdominal Wall Flashcards
Boundaries
- Superior: diaphragm
- Anterolaterally: musculoaponeurotic walls
- Posterior: vertebral column
- Inferior: pelvic girdle
Abdominal wall fxns
- Protect viscera
- Maintain posture
- Provide mobility
- Assist resp
E. Pressure: dedication, micturation, and paruition
Umbilicus
L3-L4 disc level
1. T10 dermatome
Surface anatomy
- Umbilicus
- Linea alba: median fascial line
- Semilunar lines: from inferior costal margins to pubic tubercles
- Tendinous intersection: transverse lines between linea alba and semilunar lines
- Inguinal groove: inguinal ligament
A. Marks division of anterolateral wall and thigh
Fascial and muscular layers
- Skin and fat
- Subcutaneous fascia
- Potential space between subQ fascia and superficial investion fascia
- Muscular layers
- Endoabdominal (tranversalis) fascia
- Extraperitoneal fat
- Parietal peritoneum
Superficial fatty layer (Camper’s fascia)
- Continuous w/ superficial fascia of lower limb and thoracic wall
A. Cont. into labia
B. NOT in scrotum
Deep membranous layer (Scarpa’s fascia)
- Cont. w/ darto’s and colle’s fascia in scrotum and perineum
A. NOT thighs
External oblique
- Fxn: bilateral flexion and compress abdomen, unilat. Sidebend same side and rotate opp side
- Prox: ribs 5-12
- Distal: linea alba, iliac crest, pubis
- Innervation: thoracoabdominal n. (T7-T11) and subcostal n. (T12)
- Supply: musculophrenic, post intercostal, subcostal, sup an inf epigastric, superficial and deep circumflex iliac and post lumbar a.
Internal oblique
- Fxn: bilateral flexion and compress abdomen, unilat. Sidebend same side and rotate same side
- Prox: thoracolumbar fascia, iliac crest, ASIS, inguinal ligament
- Distal: ribs 10-12, linea alba, pectineal line
- Innervation: thoracoabdominal n. (T7-T11), iliohypogastric n. (L1), and ilioinguinal (L1), and subcostal n. (T12)
- Supply: musculophrenic, post intercostal, subcostal, sup an inf epigastric, superficial and deep circumflex iliac and post lumbar a.
Transversus abdominus
- Fxn: bilateral compress abdomen
- Prox: ribs 7-12, thoracolumbar fascia, iliac crest, ASIS, inguinal ligament
- Distal: linea alba, pectineal line
- Innervation: thoracoabdominal n. (T7-T11) and subcostal n. (T12)
- Supply: musculophrenic, post intercostal, subcostal, sup an inf epigastric, superficial and deep circumflex iliac and post lumbar a.
Rectus abdominus
- Fxn: flex trunk and compress abdomen
- Prox: pubic symphysis and crest
- Distal: costal cartilages rubes 5-7, xiphoid process
- Innervation: thoracoabdominal n (T6-T11) and subcostal (T12)
- Supply: post intercostal, subcostal, superior and inf epigastric a.
Pyramidalis
- Fxn: tenses linea alba
- Prox: pubis
- Distal: linea alba
- Innervation: subcostal (T12)
- Supply: inferior epigastric and circumflex iliac a.
Rectus sheath
- Aponeurotic fibers
A. Arcuate line: marks transition from sup to inf sheath
B. Sup to umbilicus: aponeurosis internal oblique splits- Ant in front of rectus abdominis
- Post behind rectus abdominis
C. Inf to umbilicus: aponeurosis from all 3 muscles fuse -> ant rectus abdominis
Falciform ligament
Sagittal peritoneal reflection between liver and sup wall
1. Encloses round ligament of liver an para-umbilical veins
Peritoneal folds
1. Median umbilical: median umbilical ligament A. Urachus: remnant of allantois 2. Medial umbilical: lateral median 3. Lateral umbilical: lateral medial A. Inf. Epigastric vessels B. Prone to bleeding
Peritoneal fossae
- Prone to herniation
- Supravesical: between median and medial umbilical folds
- Medial inguinal: between medial and lateral umbilical folds
A. “Hasselbach’s triangle”
B. Direct inguinal hernias - Lateral inguinal: lateral to lateral umbilical folds
A. Indirect inguinal hernias
Lumbar plexus
- Iliohypogastric
- Ilioinguinal
- Genitofemoral
Iliohypogastric n.
Ant. Rami L1
1. Innervates: skin supermedial thigh and inguinal region, internal oblique and transversus abdominis
Ilioinguinal n.
Ant. Rami L1
1. Innervates: skin supermedial thigh and scrotum/labia majora, internal oblique and transversus abdominis
- Passes thru sup inguinal ring
Genitofemoral n.
L1 and L2, pierces psoas major ->divides
- Femoral branch: supply roof femoral triangle
- Genital: external oblique -> cremaster muscles and mons pubis and labia majora
Incisional routes
- Longitudinal: exploratory surgery, access to organs
- Oblique: location and direction determined by muscle fiber orientation
A. Gridion (muscle-splitting): appendectomy, on McBurney in external oblique orientation
B. Subcostal: parallel subcostal margin- Gallbladder an biliary ducts right side and spleen left
- Avoids 7th and 8th spinal n.
- Transverse:
A. Suprapubic “bikini”: OB/GYN prodecures, linea alba and rectus abdominis retracted - High risk (nerve damage): Pararectus and inguinal
- Incisional hernia
- Endoscopic surgery (min. Invasive)
Abdominal hernias
Structures penetrate and pass thru abdominal wall in weaker areas (umbilical and epigastric)
- Congenital umbilical: weakness or incomplete closure due to inc. pressure
- Acquired umbilical: common in women and obese people
A. Due to surgery sometimes
B. Extrperitoneal fat protrudes area of weakness - Epigastric: via linea alba
A. Usually fat lobules
B. Painful (nerve compression) - Spegelian: via semilunar lines
A. Common in obese
Rectus sheath hematoma
Blood in rectus sheath
1. Tear in arterial supply of epigastric artery
Ventral body wall defect
Lateral folds don’t progress ventrally or abnormal fusion at midline
1. Gastroschisis: ventral body wall doesn’t close -> intestines herniate