Lecture 10: Anterior Abdominal Wall & Inguinal Region

Question 1

What are the layers of the antero lateral abdominal wall?

Answer 1

Parietal peritoneum
Extraperitoneal fascia
Transversalis fascia
Transversus abdominis muscle 
Internal oblique muscle
External oblique muscle
Scarpa's fascia
Camper's fascia
Skin

Question 2

What is the linea alba?

Answer 2

Where the muscles interdigitate along the midline

Question 3

What is the bony framework (muscle attachments) of the abdomen?

Answer 3

Costal margin
Iliac crest
ASIS
Pubic tubercle

Question 4

What is the most superficial anterior abdominal wall muscle?

Answer 4

External oblique “front pockets”
Overlaps the costal margin, pec major, serratus anterior and ribs anterolaterally
Has a free inferior edge = inguinal ligament
Extends ASIS to pubic tubercle with an opening (superficial/external inguinal ring)

Question 5

What is the intermediate anterior abdominal wall muscle?

Answer 5

Internal oblique “back pockets”
Lowermost fibres arise from lateral 2/3 of inguinal ligament
Arch up, over and down to insert into public crest
Attaches:
Costal margin - lateral/above
Thoracolumbar fascia - behind
Linea alba - middle

Question 6

What is the deepest anterior abdominal wall muscle?

Answer 6

Transversus abdominus
Horizontally orientated fibres
Continuous with the muscular diaphragm, under lapping internal costal margin
Lowermost fibres arise from lateral 1/3 of inguinal ligament, arching to insert into the pubic crest via conjoined tendon with internal oblique

Question 7

Where does rectus abdominis attach?

Answer 7

5, 6, 7, costal cartilage
Three tendinitis intersections
Gets wider as it goes up and overlaps costal margin

Question 8

What is the formation of the abdominal muscles in the upper rectus sheath?

Answer 8

External oblique (in front of rectus abdominis)
Internal oblique (splits around rectus abdominis, half in front/half behind)
Transversus abdominis (behind rectus abdominis)
Transversalis fascia
Parietal peritoneum

Question 9

What is the formation of the abdominal muscles in the lower rectus sheath?

Answer 9

External and internal obliques (in front of rectus abdominis)
Transversus abdominis (behind rectus abdominis)
Transversalis fascia
Parietal peritoneum

Question 10

What are the arteries of the anterior abdominal wall?

Answer 10

Internal thoracic -> gives off Superior epigastric and musculophrenic artery
External iliac -> gives off Inferior epigastric
Superficial epigastric runs in subcutaneous tissue

Question 11

Where do the superior and inferior epigastric arteries anastomose?

Answer 11

Both run in the rectus sheath, deep to the rectus abdominis

Anastomose in rectus abdominis

Question 12

What is the arcuate line?

Answer 12

A horizontal line that demarcates the lower limit of the back layer of the rectus sheath.
Where the inferior epigastric vessels perforate the rectus abdominis.
Occurs about 1/3 of the distance from the umbilicus to the pubic crest (variable)

Question 13

What layer of muscle are the nerves of the anterior abdominal wall found?

Answer 13

Between the intermediate and deep layers

Between internal oblique and transversus abdominals

Question 14

What is the venous drainage from the anterior abdominal wall?

Answer 14

Superficial veins in fascia
Deep veins follow arteries 
Dual venous drainage:
IVC - systemic
Portal 
Overlap , can go to either

Question 15

What is the pectineal ligament?

Answer 15

Linear extension along the pectineal

Question 16

What is the lacunar ligament?

Answer 16

Medial extension of the inguinal ligament

Reflects onto pectineal line of the pubic bone

Question 17

What is the deep inguinal ring?

Answer 17

Hole/deficiency half way between the ASIS and pubic tubercle

Mid point of the inguinal ligament

Question 18

What are the boundaries of the inguinal canal?

Answer 18

Floor: inguinal
Roof: arching fibres of internal oblique and transversus abdominus
Anterior wall: external oblique aponeurosis and internal oblique muscle (lat)
Posterior wall: transversalis fascia and conjoint tendon (medial)

Question 19

What are the 3 layers surrounding the spermatic cord?

Answer 19

Internal spermatic fascia
Cremasteric muscle fibres (fascia) -cold water
External spermatic fascia (external oblique)

Question 20

What is an abdominal wall hernia?

Answer 20

Protrusion of abdominal contents through abdominal wall

Question 21

Where are the areas of weakness where an abdominal wall hernia can occur?

Answer 21

Linea alba
Umbilical
Linear semilunaris

Question 22

What is the inguinal ligament?

Answer 22

Folded inferiori border of external oblique aponeurosis extending between ASIS and pubic tubercle

Question 23

What is the superficial inguinal ring?

Answer 23

Medial opening in the external oblique aponeurosis

Question 24

What is a bilateral indirect inguinal hernia?

Answer 24

Protrusion through the deep ring into the inguinal canal

Into scrotum

Question 25

What does an indirect hernia arise from?

Answer 25

Incomplete closure of the processus vaginalis, weak arching fibres of transversus abdominal & internal oblique, ilioguinal nerve L1, hence the herniated peritoneal contents extend into the scrotum (or labia)
Pulls peritoneum with it

Question 26

What is a bilateral direct inguinal herniae?

Answer 26

A protrusion forwards into the inguinal canal through an area of weakness in its posterior wall 
Bulges only, doesn't transverse 
Exploits inguinal (hesselbach's) triangle