Anterior abdominal wall

Question 1

Overview of abdominal cavity

Answer 1

-Boundary between thorax and abdomen = diaphragm
-Boundary between abdominal and pelvic cavity = pelvic inlet (imaginary)
-Abdominal cavity can extend superiorly up to 4th intercostal space
-Abdominal cavity is musculo-aponeurotic - providing protection, flexibility, distensibility

Question 2

Anatomical 9 regions of abdomen

Answer 2

-2 vertical midclavicular lines that pass from midpoint of clavicles to midinguinal points
-Superior subcostal plane that passes through inferior border of the 10th costal cartilage
-Inferior transtubercular plane that passes through iliac tubercles and body of L5 vertebra

Question 3

Clinical 9 regions of abdomen

Answer 3

-2 vertical semilunar lines that run parallel to lateral edges of rectus abdominus
-Superior transpyloric plane (transects pylorus of stomach)
-Inferior interspinous plane (transects anterior superior iliac spine)

Question 4

4 quadrants of abdomen

Answer 4

-Transumbilical plane passes through the umbilicus
-Vertical median plane passes longitudinally through the body

Question 5

Organ locations in abdominal cavity

Answer 5

-Bladder is pelvic organ when empty
-Bladder is abdominal organ when full

Question 6

Surface anatomy of anterior abdominal wall

Answer 6

Linea alba - visible in lean individuals as a vertical skin groove
Semilunar lines - slightly curved linear impressions in the skin parallel to the lateral edges of the rectus sheath
Inguinal ligament - extends between anterior superior iliac spine and the pubic tubercle

Question 7

Superficial anatomy of anterior abdominal wall

Answer 7

-Superior to the umbilicus, the subcutaneous tissue is consistent with that found in most regions
-Inferior to the umbilicus, the deepest part of the subcutaneous tissue (superficial fascia) is reinforced by many elastic and collagen fibres
-It has 2 layers: Superficial fatty (Camper’s layer) and Deep membranous (Scarpa’s layer)

Question 8

Intermediate anatomy of anterior abdominal wall

Answer 8

-Everyone has 6 or 8 packs because of the tendinous junction

Question 9

Deep anatomy of anterior abdominal wall

Answer 9

-Transversus abdominus (horizontal)
-Rectus abdominus (vertical)

Question 10

Layers of anterior abdominal wall

Answer 10

-Skin
-Superficial fascia - fatty superficial layer and membranous deep layer
-Muscles and aponeuroses covered by deep fascia
-Endoabdominal (transversalis) fascia - refers to portion of fascia which lines the internal surface of the transversus abdominis muscle and it aponeurosis
-Extraperitoneal fat
-Parietal peritoneum

Question 11

Features of the external oblique

Answer 11

Origin: External surfaces of 5-12th ribs
Insertion: Linea alba, Anterior half of iliac crest, Pubic tubercle
Action: Lateral flexion of trunk, Rotation of trunk, Stabilisation of pelvis, Compression of abdomen
Innervation: Intercostal nerves (T5-T11), Subcostal nerve (T12), Iliohypogastric nerve (L1)

Question 12

What does inguinal ligament run between?

Answer 12

-Anterior Superior Iliac Spine (ASIS)
-Pubic tubercle

Question 13

Features of internal oblique

Answer 13

Origin: Thoracolumbar fascia, Anterior 2/3 of iliac crest
Insertion: Inferior borders of 10-12th ribs, Linea alba
Action: Lateral flexion of trunk, Rotation of trunk, Stabilisation of pelvis, Compression of abdomen
Innervation: Intercostal nerves (T6-T11), Subcostal nerve (T12), Iliohypogastric nerve (L1), Ilioinguinal nerve (L1)

Question 14

Features of transverse abdominis

Answer 14

Origin: Internal surfaces of 7-12th costal cartilages, Thoracolumbar fascia, Iliac crest
Insertion: Linea alba, Pubic crest
Action: Stabilisation of pelvis, compression of abdomen
Innervation: Intercostal nerves (T6-T11), Subcostal nerve (T12), Iliohypogastric nerve (L1), Ilioinguinal nerve (L1)

Question 15

Thoracolumbar fascia

Answer 15

-Gives rise to transversus abdominis and internal oblique
-But not the external oblique

Question 16

Features of rectus abdominis

Answer 16

Origin: Pubic symphysis, Pubic crest
Insertion: Xiphoid process, 5-7th costal cartilages
Action: Flexion of the lumbar spine, Stabilisation of pelvis, Compression of abdomen
Innervation: Intercostal nerves (T5-T11), Subcostal nerve (T12)

Question 17

Features of pyramidalis

Answer 17

Origin: Pubic crest
Insertion: Linea alba
Action: Tenses the linea alba
Innervation: Subcostal nerve (T12)

Question 18

Movement of muscles

Answer 18

-Contralateral external and internal oblique muscles work together to rotate the trunk
-Ipsilateral external and internal obliques produce lateral flexion
-Rectus abdominis produce trunk flexion

Question 19

Features of rectus sheath

Answer 19

-Incomplete fibrous sheath that encloses rectus abdominis and pyramidalis muscles
-Also encloses superior and inferior epigastric arteries, veins, lymphatic vessels and distal portions of spinal nerves T7-T12
-Formed from aponeuroses of 3 abdominal muscles

Question 20

What is the arcuate line?

Answer 20

-Line between the aponeurotic posterior wall of rectus sheath (covering 3/4 of rectus abdominis) and transversalis fascia (covering 1/4)

Question 21

Above and below the arcuate line

Answer 21

-Bottom 2 pack is harder to obtain because 3 aponeuroses in the way instead of 1.5

Question 22

Nerves of anterior abdominal wall

Answer 22

T7-T12
-Distal anterior rami of the T7-T12 spinal nerves - they are the former intercostal nerves distal to the costal margin
-Run in the neurovascular plane between the internal oblique and transverse abdominis muscles to supply the skin and muscles of anterior abdominal wall

Question 23

Vessels of anterior abdominal wall

Answer 23

Anterolateral abdominal wall receives blood from:
-Superior epigastric artery - branch of the internal thoracic artery
-Inferior epigastric artery - branch of the external iliac artery
-External iliac artery continues as the femoral artery at the inguinal ligament
-Lateral region of abdominal wall supplied by 10th and 11th posterior intercostal arteries and the subcostal artery from descending aorta