Anterior Abdominal Wall Flashcards
What are the two planes that divide the anterior abdominal wall into four quadrants?
Median Plane - vertical line drawn through the umbilicus
Transumbilical plane - horizontal line drawn through umbilicus at LIII/LIV
What is the difference between the subcostal and transpyloric horizontal planes?
Subcostal - inferior to the costal margin
Transpyloric - line halfway between the xiphoid process and the umbilicus (passes through the pylorus of the stomach)
Where is the transtubercular plane?
Inferior horizontal line that connects the tubercles of the iliac crests, passes through vertebrae LV
What are the four main layers of the anterolateral abdominal wall (from external to internal)
Skin
Superficial fascia (camper’s and scarpa’s)
Muscles and associated fascia
Parietal peritoneum
What is the difference in the superficial fascia above and below the umbilicus?
Above - single sheet of fascia
Below - has superficial fatty layer (camper’s), and deep membranous layer (scarpa’s)
External Oblique Muscle
Origin - ribs 5-12
Insertion - iliac crest and pubic tubercle, ending at linea alba
Function - compression of abdominal contents, flexion of trunk
Innervation - anterior rami of T7-T12 spinal nerves
Internal Oblique Muscle
Origin - inguinal ligament, iliac crest, lumbodorsal fascia
Insertion - ribs 10-12
Function - compares abdominal contents, flex trunk
Innervation - anterior rami of T7-L1 spinal nerves
Transversus Abdominis
Origin - inguinal ligament, costal cartilages 7-12, iliac crest
Insertion - linea alba
Function - compress abdominal contents
Innervation - anterior rami of T7-L1 spinal nerves
What is the transversalis fascia?
The endoabdominal fascia which lies deep to the transversus abdominis muscle
Rectus Abdominis
Origin - pubic crest, pubic tubercle, pubic symphysis
Insertion - costal cartilages of ribs V to VII, and xiphoid process
Function - compress abdominal contents, flex vertebral columns, tense abdominal wall
Innervation - anterior rami of T7-T12 spinal nerves
Pyramidalis
Origin - pubic crest and pubic symphysis
Insertion - linea alba
Function - tenses the linea alba
Innervation - anterior rami of T12
What is the rectus sheath?
Sheath formed by the aponeuroses of the three flat muscles in the anterior abdominal wall
Which muscles comprise the anterior and posterior wall of the rectus sheath?
At what point do these walls merge anteriorly?
Anterior wall - external oblique and half of internal oblique
Posterior wall - half of internal oblique and transversus abdominis
They merge at the arcuate line
Describe the sensory innervation of the anterior abdominal wall
T7-T9 - from xiphoid process to umbilicus
T10 - around the umbilicus
T10-L1 - below the umbilicus
What is the nerve called which is a branch of L1 which supplies sensory innervation to the anterior surface of the scrotum or labia majora?
Ilio-inguinal nerve
What are the wall boundaries of the inguinal canal?
Anterior wall - external oblique, internal Oblique
Posterior wall - transversalis fascia and conjoint tendon
Superior wall - transversalis fascia, internal oblique, transversus abdominis
Inferior wall - inguinal ligament (thickening of external Oblique)
Which muscles do the deep and superficial inguinal rings pass through?
Deep ring - transversalis fascia
Superficial ring - external oblique
What is the difference between an indirect and direct inguinal hernia?
Indirect - protrusion through the deep inguinal ring
Direct - protrusion through the posterior wall of inguinal canal
What is the superficial blood supply of the anterior abdominal wall?
Superior - musculophrenic (from internal thoracic)
Inferior (lateral) - superficial circumflex (from femoral)
Inferior (medial) - superficial epigastric (from femoral)
What is the deep blood supply to the anterior abdominal wall?
Superior - superior epigastric (From internal thoracic)
Lateral - 10/11th intercostal and subcostal (from abdominal aorta)
Inferior lateral - deep circumflex (from external iliac)
Inferior medial - inferior epigastric (from external iliac)
What is the superficial lymphatic drainage of the anterior abdominal wall?
Above the umbilicus - drain into axillary nodes
Below the umbilicus - drain into superficial inguinal nodes
What is the deep lymphatic drainage of the anterior abdominal wall?
Parasternal nodes - drain alongside internal thoracic
Lumbar nodes - drain alongside abdominal aorta
External iliac nodes - drain alongside external iliac
The ilioinguinal and iliohypogastric nerves course through the lateral aspect of the anterior abdominal wall between which structures?
Between the transversus abdominus and internal Oblique muscles
