Keyword Definitions
Anterior abdominal wall: multilayered structure formed by skin, fascia, muscles, vessels, and nerves protecting abdominal viscera.
External oblique: outermost flat abdominal muscle with fibers directed inferomedially.
Internal oblique: middle layer muscle with fibers running superomedially.
Transversus abdominis: innermost flat muscle, fibers run horizontally.
Rectus abdominis: paired vertical strap muscle enclosed in rectus sheath.
Neurovascular plane: potential space where segmental nerves and vessels run between muscle layers.
Segmental nerves: lower intercostal, subcostal, iliohypogastric, and ilioinguinal nerves supplying wall and skin.
Arcuate line: point below umbilicus where posterior rectus sheath ends; important in surgical incisions.
Linea alba: midline fibrous raphe formed by fusion of aponeuroses.
Transversalis fascia: fascia deep to transversus abdominis, continuous with extraperitoneal fat and peritoneum.
Chapter: Anatomy
Topic: Abdominal Wall
Subtopic: Neurovascular Plane
Lead Question – 2012
Neurovascular plane in anterior abdominal wall -
a) Between ext oblique and internal oblique
b) Between int. oblique and transversus abdominis
c) Below transversus abdominis
d) Above ext. oblique
Explanation: The neurovascular plane of the anterior abdominal wall lies between the internal oblique and transversus abdominis. Intercostal, subcostal, iliohypogastric, and ilioinguinal nerves course here with vessels, making this the safe plane for surgical splitting incisions. Correct answer: (b).
A surgeon makes a gridiron incision for appendectomy. Which muscular plane is split to access the appendix safely?
a) Between external oblique and internal oblique
b) Between internal oblique and transversus abdominis
c) Between rectus and transversalis fascia
d) Below peritoneum
Explanation: The gridiron incision exploits the neurovascular plane between internal oblique and transversus abdominis. This minimizes vascular injury, preserves nerves, and provides safe access. Correct answer: (b).
During laparotomy, injury to iliohypogastric nerve leads to which deficit?
a) Sensory loss over umbilicus
b) Weakness of external oblique
c) Numbness over suprapubic skin
d) Loss of cremaster reflex
Explanation: The iliohypogastric nerve (L1) runs in the neurovascular plane, supplying suprapubic skin. Injury causes sensory loss over suprapubic region. Correct answer: (c).
A patient undergoing lower abdominal surgery develops numbness in scrotum and medial thigh. Which nerve likely injured in the neurovascular plane?
a) Ilioinguinal nerve
b) Genitofemoral nerve
c) Obturator nerve
d) Lateral femoral cutaneous nerve
Explanation: The ilioinguinal nerve travels in the neurovascular plane and enters inguinal canal. Injury produces scrotal/labial and medial thigh numbness. Correct answer: (a).
Which muscle’s aponeurosis contributes to both anterior and posterior layers of rectus sheath above arcuate line?
a) External oblique
b) Internal oblique
c) Transversus abdominis
d) Pyramidalis
Explanation: Internal oblique aponeurosis splits to enclose rectus above arcuate line, forming both anterior and posterior sheath layers. Correct answer: (b).
Below arcuate line, which layer lies posterior to rectus abdominis?
a) External oblique aponeurosis
b) Internal oblique aponeurosis
c) Transversalis fascia
d) Posterior rectus sheath
Explanation: Below arcuate line, all aponeuroses pass anteriorly; only transversalis fascia remains posterior to rectus. Correct answer: (c).
During open hernia repair, which nerve is at risk near superficial inguinal ring?
a) Ilioinguinal nerve
b) Iliohypogastric nerve
c) Genitofemoral nerve
d) Femoral branch of genitofemoral
Explanation: The ilioinguinal nerve emerges from neurovascular plane and runs in inguinal canal, exiting superficial ring. Injury during hernia surgery causes scrotal/labial numbness. Correct answer: (a).
During Pfannenstiel incision, which vessel is at risk in neurovascular plane near lateral rectus?
a) Superior epigastric artery
b) Inferior epigastric artery
c) Deep circumflex iliac artery
d) External iliac vein
Explanation: The inferior epigastric artery runs in rectus sheath lateral border and is vulnerable in lower transverse incisions. Correct answer: (b).
A patient with penetrating trauma to abdominal wall has paralysis of lower rectus abdominis. Which nerve injured?
a) Intercostal T6
b) Intercostal T10
c) Subcostal T12
d) Iliohypogastric L1
Explanation: Rectus abdominis receives segmental innervation from T7–T12 nerves traveling in neurovascular plane. Paralysis of lower rectus implies injury to subcostal T12. Correct answer: (c).
Which landmark guides safe splitting of abdominal wall muscles during laparotomy?
a) Linea alba
b) Neurovascular plane between internal oblique and transversus abdominis
c) Transversalis fascia
d) Median umbilical ligament
Explanation: Muscle splitting incisions like McBurney’s rely on neurovascular plane between internal oblique and transversus abdominis to reduce bleeding and nerve injury. Correct answer: (b).
A 40-year-old male develops flank bulge after nephrectomy incision. Cause?
a) Damage to iliohypogastric/ilioinguinal nerves in neurovascular plane
b) Weakness of transversalis fascia
c) Injury to femoral nerve
d) Loss of rectus sheath integrity
Explanation: Flank bulge results from denervation of internal oblique and transversus due to iliohypogastric/ilioinguinal nerve injury in neurovascular plane during flank incision. Correct answer: (a).