Anterior Abdominal Wall

Question 1

What are the two planes that divide the anterior abdominal wall into four quadrants?

Answer 1

Median Plane - vertical line drawn through the umbilicus

Transumbilical plane - horizontal line drawn through umbilicus at LIII/LIV

Question 2

What is the difference between the subcostal and transpyloric horizontal planes?

Answer 2

Subcostal - inferior to the costal margin

Transpyloric - line halfway between the xiphoid process and the umbilicus (passes through the pylorus of the stomach)

Question 3

Where is the transtubercular plane?

Answer 3

Inferior horizontal line that connects the tubercles of the iliac crests, passes through vertebrae LV

Question 4

What are the four main layers of the anterolateral abdominal wall (from external to internal)

Answer 4

Skin
Superficial fascia (camper’s and scarpa’s)
Muscles and associated fascia
Parietal peritoneum

Question 5

What is the difference in the superficial fascia above and below the umbilicus?

Answer 5

Above - single sheet of fascia

Below - has superficial fatty layer (camper’s), and deep membranous layer (scarpa’s)

Question 6

External Oblique Muscle

Answer 6

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

Question 7

Internal Oblique Muscle

Answer 7

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

Question 8

Transversus Abdominis

Answer 8

Origin - inguinal ligament, costal cartilages 7-12, iliac crest
Insertion - linea alba
Function - compress abdominal contents
Innervation - anterior rami of T7-L1 spinal nerves

Question 9

What is the transversalis fascia?

Answer 9

The endoabdominal fascia which lies deep to the transversus abdominis muscle

Question 10

Rectus Abdominis

Answer 10

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

Question 11

Pyramidalis

Answer 11

Origin - pubic crest and pubic symphysis
Insertion - linea alba
Function - tenses the linea alba
Innervation - anterior rami of T12

Question 12

What is the rectus sheath?

Answer 12

Sheath formed by the aponeuroses of the three flat muscles in the anterior abdominal wall

Question 13

Which muscles comprise the anterior and posterior wall of the rectus sheath?

At what point do these walls merge anteriorly?

Answer 13

Anterior wall - external oblique and half of internal oblique
Posterior wall - half of internal oblique and transversus abdominis

They merge at the arcuate line

Question 14

Describe the sensory innervation of the anterior abdominal wall

Answer 14

T7-T9 - from xiphoid process to umbilicus
T10 - around the umbilicus
T10-L1 - below the umbilicus

Question 15

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?

Answer 15

Ilio-inguinal nerve

Question 16

What are the wall boundaries of the inguinal canal?

Answer 16

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)

Question 17

Which muscles do the deep and superficial inguinal rings pass through?

Answer 17

Deep ring - transversalis fascia

Superficial ring - external oblique

Question 18

What is the difference between an indirect and direct inguinal hernia?

Answer 18

Indirect - protrusion through the deep inguinal ring

Direct - protrusion through the posterior wall of inguinal canal

Question 19

What is the superficial blood supply of the anterior abdominal wall?

Answer 19

Superior - musculophrenic (from internal thoracic)

Inferior (lateral) - superficial circumflex (from femoral)
Inferior (medial) - superficial epigastric (from femoral)

Question 20

What is the deep blood supply to the anterior abdominal wall?

Answer 20

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)

Question 21

What is the superficial lymphatic drainage of the anterior abdominal wall?

Answer 21

Above the umbilicus - drain into axillary nodes

Below the umbilicus - drain into superficial inguinal nodes

Question 22

What is the deep lymphatic drainage of the anterior abdominal wall?

Answer 22

Parasternal nodes - drain alongside internal thoracic

Lumbar nodes - drain alongside abdominal aorta

External iliac nodes - drain alongside external iliac

Question 23

The ilioinguinal and iliohypogastric nerves course through the lateral aspect of the anterior abdominal wall between which structures?

Answer 23

Between the transversus abdominus and internal Oblique muscles