Anterior Abdominal Wall Nerves

Question 1

Motor supply

Answer 1

1. Lower 5 intercostal
2. Subcostal nerves
3. Iliohypogastric nerve
4. Ilioinguinal nerve (branches of L1 and primary ramus)

Question 2

Sensory supply

Answer 2

1. Lateral and anterior cutaneous branches of lower 5 intercostal and subcostal nerves
2. Lateral cutaneous branch of iliohypogastric nerve
3. Cutaneous branches of ilioinguinal nerve

Question 3

Lower 5 intercostal and subcostal nerves course

Answer 3

1. Pass through abdominal wall neurovascular plane between internal oblique and transversus abdominis) supplying the 3 abdominal wall anterolateral muscles
2. Enter rectus sheath by piercing internal oblique aponeurosis deep lamina
3. Run between rectus abdominis and rectus sheath posterior wall
4. Pierces rectus abdominis after supplying it
5. Pierces rectus sheath anterior wall
6. End by becoming anterior cutaneous nerve lateral to linea alba

Question 4

Iliohypogastric and ilioinguinal nerves course

Answer 4

1. Emerge from under Psoas major lateral border
2. Descend laterally on quadratus lumborum behind kidney with Iliohypogastric lying at slightly higher level than ilioinguinal nerve
3. Above iliac crest, both pierce transversus abdominis to run in neurovascular plane between internal oblique and transversus supplying both
4. Reach ASIS level, where Iliohypogastric nerve pierces internal oblique and extends between it and external oblique aponeurosis
5. It pierces external oblique aponeurosis 2-3 cm above superficial Inguinal ring to supply skin above symphysis pubis
6. On the other hand, ilioinguinal nerve pierces internal oblique arched fibers
7. Reach Inguinal canal
8. Extends below spermatic cord
9. Emerge through superficial Inguinal ring supplying external genitalia skin and upper part of thigh medial side
10. Also supplies conjoint tendon

Question 5

Applied anatomy

Answer 5

Ilioinguinal nerve injury during appendicectomy leads to conjoint tendon weakness and predisposes to direct Inguinal hernia

Question 6

Horizontal bands of anterior abdominal wall skin are supplied by:

Answer 6

1. Skin at subcostal angle: by 7th thoracic nerve (T7)
2. 3 nerves (T7,8,9) to region above umbilicus
3. Skin at umbilicus level by 10th thoracic nerve (T10)
4. 3 nerves (T11,T12,L1) to region below umbilicus
5. Skin above symphysis pubis is supplied by Iliohypogastric nerve (L1)