Antero-lateral abdominal wall and inguinal canal

Question 1

Learning outcomes

Answer 1

• Describe and identify the fasciae of the antero-lateral abdominal wall
• Describe and identify the cutaneous innervation, arterial supply, venous drainage and lymphatic drainage of the antero-lateral abdominal wall
• Identify the external oblique, internal oblique and transversusabdominis muscles
• Identify the rectus sheath and the rectus abdominis muscles
• Identify and describe the location and boundaries of the inguinal canal

Question 2

Anterior abdominal wall- layers and cutaneous innervation

Answer 2

Skin, superficial layers (fatty: camper’s fascia and membranous: scarpa’s), external (aponeurosis) and internal oblique muscle, transversus abdominus muscle, transversalis fascia
Anterior/lateral cutaneous branches- Thoraco-abdominal nerves (T7-T11)
Anterior/lateral cutaneous branches of subcostal nerve (T12)
Anterior superior iliac spine (ASIS)
Iliohypogastric nerve (L1)
Ilioinguinal nerve (L1) attached by inguinal ligament

Dermatomes- areas of skin innervated by single spinal nerve

Question 3

Arterial supply

Answer 3

Musculophrenic, superior epigastric, 10th posterior intercostal, 11th posterior intercostal, inferior epigastric, superficial epigastric, superficial circumflex iliac arteries

Question 4

Venous drainage

Answer 4

• The plexus/network of veins (made up by thoracoepigastric, peri-umbilical, superficial epigastric, femoral and axillary veins) is responsible for draining superficial structures of the abdominal wall of venous blood.
• Blood from within the plexus drains into the internal thoracic vein and lateral thoracic vein (superiorly) and into the superficial and inferior epigastric veins (inferiorly).

Question 5

Lymphatic drainage

Answer 5

Superifical drainage- Superficial lymphatic vessels accompany the subcutaneous veins; lymph from within these lymphatic vessels (above the level of the transumbilical plane) will drain into the axillary nodes.

Lymph within these superficial lymphatic vessels (below the level of the transumbilical plane) will drain into the superficial inguinal lymph nodes.

Question 6

Muscles of the abdominal cavity

Answer 6

see clinically oriented anatomy or pictures of lecture 2 y2m1
External/internal transverse oblique mm, rectus abdominus mm (divided by tendinous intersections)
Rectus sheath encloses each RA muscle along the length of the muscle
Arcuate line shows where posterior rectus sheath terminates

Question 7

Deep inguinal ring

Answer 7

The deep inguinal ring is located at the mid-point of the inguinal ligament – this ligament spans the distance between the pubic tubercle and the anterior superior iliac spine
• Structures passing through the deep inguinal ring:
• Vas deferens and testicular aa. and vv.
• Round ligament of the uterus

Question 8

Superficial inguinal ring

Answer 8

• The superficial inguinal ring (arrow) is located superior to the pubic tubercle.
• Structures passing through the superficial inguinal ring:
• The spermatic cord
• The round ligament of the uterus - not to be confused with the broad ligament of the uterus

The inguinal canal has boundaries formed of the roof, floor, anterior and posterior walls
Anterior wall: external oblique aponeurosis
Posterior wall: conjoint tendon medially; transversalis fascia laterally
Roof: fibres of internal oblique m. and transversus abdominis m.
Floor: lower edge of inguinal ligament