Anterior abdominal wall and inguinal anatomy

Question 1

Describe the different muscles that make up the anterior abdo wall (where they are, which direction the muscle fibres run in etc.).

Answer 1

1. external oblique: most superficial layer of muscle
   - fibres run anterior to inferior (\\
2. internal oblique: middle layer
   - fibres run anterior to superior (///)
3. transversus abdominis: deepest layer
   - fibres run transverse (-)
4. Rectus abdominis: xiphoid process to pubic symphysis
   * muscles are enclosed by aponeurotic sheath

Question 2

Describe the position of the following muscle fibres ABOVE the arcuate line:

• external oblique
• internal oblique
• transversus abdominis

Answer 2

• external oblique: runs in front of rectus abdominis
• internal oblique: splits into two to run on either side (in front and behind rectus abdominis)
• transversus abdominis: run behind rectus abdominis

Question 3

Describe the position of the following muscle fibres BELOW the arcuate line:

• external oblique
• internal oblique
• transversus abdominis

Answer 3

aponeuroses of all muscles run behind the muscles

Question 4

Describe the blood supply to the abdomen.

Answer 4

1. internal thoracic artery –> superior epigastric to supply rectus abdominis
2. external iliac artery –> inferior epigastric to supply rectus abdominis
3. lower intercostal + lumbar arteries to supply the external, internal oblique and transversus abdominis

Question 5

What nerve roots are found at the level of:

• xiphoid
• umbilicus
• subcostal nerve
• iliohypogastric and ilioiguinal nerve

Answer 5

• xiphoid: T7
• umbilicus: T10
• subcostal nerve: T12
• iliohypogastric and ilioiguinal nerve: L1

Question 6

How is the inguinal ligament formed? What are its two connection/attachment points?

Answer 6

Inferior border of the external oblique’s aponeurosis rolls under itself to form the inguinal ligament

runs from the ASIS to the pubis

Question 7

What structures are contained within the spermatic cord?

Answer 7

• testicular artery
• ductus deferens
• pampiniform venous plexus
• genital branch of genitofemoral nerve
• ilioinguinal nerve

Question 8

What are the supporting structures (muscle, fascia etc) of the spermatic cord from external to internal?

Answer 8

External spermatic fascia
Cremaster muscle
Internal spermatic fascia

Question 9

What is the difference between deep inguinal ring and superficial inguinal ring?

Answer 9

deep inguinal ring: point at which the contents of the spermatic cord ENTER the abdominal wall
superficial inguinal ring: point at which the spermatic cord EMERGES from the abdominal wall

Question 10

Compare direct and indirect hernias.

Answer 10

Direct:

• acquired
• mostly males >40
• passes directly through abdominal wall (Hasselbach’s triangle)
• rarely enters scrotum
• medial to inferior epigastric vessels

Indirect:

• congenital (patent process vaginalis)
• more common (2/3)
• transverses canal within the processus vaginalis
• commonly enters scrotum
• lateral to inferior epigastric vessels

Question 11

What are the borders of Hasselbach’s triangle?

Answer 11

1. Inferior epigastric vessels
2. Inguinal ligament
3. Lateral border of rectus abdominis

Question 12

What are the other types of hernias (besides direct/indirect)?

Answer 12

1. incisional - following surgery, weakness in abdominal wall
2. inguinal - above and medial to pubic tubercle
3. umbilical - usually in babies - rectus abdominis not fully joined
4. femoral - femoral canal; most common in females

Question 13

Where is the femoral canal in relation to the inguinal ligament and the pubic tubercle?

Answer 13

inguinal ligament: canal beneath the ligament

pubic tubercle: canal is inferior and lateral