Abdomen — MCQs

Abdomen Indian Medical PG Practice Questions and MCQs

Question 191: What is the criminal nerve of Grassi?

A. Anterior branch of the vagus nerve at the pylorus
B. Anterior branch of the vagus nerve at the cardia
C. Proximal branch of the posterior vagus nerve (Correct Answer)
D. Distal branch of the posterior vagus nerve

Explanation: The **Criminal Nerve of Grassi** is a high-yield anatomical landmark in gastrointestinal surgery, specifically during procedures for peptic ulcer disease. ### **Explanation of the Correct Answer** The correct answer is **C (Proximal branch of the posterior vagus nerve)**. The nerve of Grassi is the first (most proximal) branch of the **posterior vagal trunk**. It arises high up near the gastroesophageal junction and supplies the **gastric cardia and fundus**. In surgeries like **Highly Selective Vagotomy (HSV)**, the goal is to denervate the acid-secreting parietal cell mass while preserving the "crow’s foot" (nerve of Latarjet) to maintain antral motility [1]. If this specific proximal branch is missed (hence the name "criminal"), it continues to stimulate acid secretion in the fundus, leading to **recurrent peptic ulcers**. ### **Why the Other Options are Incorrect** * **Option A & B:** The nerve of Grassi is a branch of the **posterior** vagus, not the anterior vagus. The anterior vagus primarily gives off hepatic branches and the anterior nerve of Latarjet. * **Option D:** Distal branches of the posterior vagus (like the posterior nerve of Latarjet) are usually preserved in selective vagotomies to maintain pyloric emptying. ### **Clinical Pearls for NEET-PG** * **Origin:** Posterior Vagus (Right Vagus). * **Clinical Significance:** Most common cause of **recurrent ulceration** after a supposedly "complete" vagotomy. * **Surgical Landmark:** It is often found behind the esophagus or within the lesser omentum, requiring careful mobilization of the esophagus to identify and divide it [1]. * **Mnemonic:** "Post-Grass" — **Post**erior vagus gives the nerve of **Grass**i.

Question 192: In a left loin nephrectomy, which muscle is NOT cut?

A. Trapezius (Correct Answer)
B. Serratus inferior posterior
C. Latissimus dorsi
D. Internal oblique

Explanation: ### Explanation The standard surgical approach for a nephrectomy (loin or flank incision) involves an oblique incision between the 12th rib and the iliac crest. To reach the kidney, the surgeon must divide the layers of the posterolateral abdominal wall and the muscles overlying the renal fascia [1]. **Why Trapezius is the Correct Answer:** The **Trapezius** is a large, superficial muscle of the upper back and neck. Its lowermost fibers originate from the spinous processes of the thoracic vertebrae (up to T12) and insert into the spine of the scapula. It is located significantly **superior** to the lumbar region (loin). Therefore, it is never encountered or divided during a renal surgery. **Analysis of Incorrect Options:** * **Latissimus Dorsi:** This is the most superficial muscle of the lower back. It must be incised or retracted to access the deeper layers during a loin incision. * **Serratus Posterior Inferior:** This muscle lies deep to the latissimus dorsi, originating from T11-L2 and inserting into the lower four ribs. It is frequently encountered and divided when the incision is made near the 12th rib [1]. * **Internal Oblique:** Along with the External Oblique and Transversus Abdominis, the Internal Oblique forms the lateral abdominal wall [2]. These muscles must be divided to reach the retroperitoneal space where the kidney resides. **Clinical Pearls for NEET-PG:** * **Layers of Loin Incision (Superficial to Deep):** Skin → Superficial fascia → Latissimus dorsi and External oblique → Serratus posterior inferior → Internal oblique and Transversus abdominis → Fascia transversalis → Perirenal fat → Gerota’s fascia [1]. * **Nerve at Risk:** The **Subcostal nerve (T12)** and **Iliohypogastric nerve (L1)** are at high risk of injury during a loin incision, which can lead to postoperative bulging of the abdominal wall (pseudohernia). * **Positioning:** For this surgery, the patient is placed in the **lateral decubitus position** with a "kidney bridge" elevated to widen the space between the 12th rib and the iliac crest [1].

Question 193: Commonest location of Spigelian hernia is at which anatomical region?

A. Below the arcuate line
B. Above the arcuate line
C. Both above and below the arcuate line (Correct Answer)
D. None of the above

Explanation: A **Spigelian hernia** occurs through the Spigelian fascia, which is the aponeurotic layer between the lateral border of the rectus abdominis muscle and the semilunar line (linea semilunaris). **Why the correct answer is C:** The Spigelian fascia is widest and weakest in the area known as the **Spigelian hernia belt**, a transverse band located between the level of the umbilicus and the interspinal plane. Anatomically, the **arcuate line** (Line of Douglas) is situated within this belt [2]. While the fascia is inherently weak below the arcuate line due to the absence of the posterior rectus sheath, clinical studies and surgical data confirm that these hernias occur both **above and below the arcuate line** [1]. Therefore, the "commonest location" encompasses the entire Spigelian belt region spanning across the arcuate line. **Why incorrect options are wrong:** * **Option A & B:** Selecting only "above" or "below" is restrictive. While the area below the arcuate line is structurally weaker, a significant percentage of hernias are found cephalad to the line or directly at its level. **High-Yield Clinical Pearls for NEET-PG:** * **"Interstitial Hernia":** It is often called an interstitial hernia because the hernial sac typically lies *deep* to the external oblique aponeurosis, making it difficult to diagnose on physical exam (no visible bulge). * **Clinical Presentation:** Patients usually present with localized pain and a "reducible" mass that disappears on lying down. * **Diagnosis:** Ultrasound or CT scan is the gold standard for diagnosis. * **Treatment:** Due to a high risk of strangulation (narrow neck), surgical repair is always indicated.

Question 194: Which of the following is not a constituent of the mesorectum?

A. Pararectal lymph nodes
B. Inferior rectal artery (Correct Answer)
C. Middle rectal vein
D. Inferior mesenteric plexus

Explanation: The **mesorectum** is a fatty connective tissue sheath surrounding the rectum, enclosed by the visceral layer of pelvic fascia (mesorectal fascia). It is a critical anatomical landmark in "Total Mesorectal Excision" (TME) for rectal cancer surgery [1]. ### **Why the Inferior Rectal Artery is the Correct Answer** The **inferior rectal artery** is a branch of the **internal pudendal artery**, which originates in the Alcock’s canal (pudendal canal) within the ischioanal fossa [1]. It supplies the lower anal canal and the external anal sphincter. Because it arises outside the pelvic fascia and enters the anal canal below the levator ani, it is **not** contained within the mesorectal envelope [1]. ### **Analysis of Other Options (Constituents of Mesorectum)** * **Pararectal Lymph Nodes:** These are the primary nodes draining the rectum and are embedded within the mesorectal fat. Their removal via TME is vital to prevent local recurrence. * **Middle Rectal Vein:** Along with the middle rectal artery (from the internal iliac), these vessels traverse the lateral ligaments of the rectum and are found within the mesorectal tissue. * **Inferior Mesenteric Plexus:** Autonomic nerves (sympathetic fibers from the inferior mesenteric plexus and parasympathetic fibers from the pelvic splanchnic nerves) travel within the mesorectum to supply the rectal wall. ### **High-Yield Clinical Pearls for NEET-PG** * **Superior Rectal Artery:** This is the direct continuation of the Inferior Mesenteric Artery and is the **primary** arterial constituent of the mesorectum. * **Surgical Plane:** In TME, the surgeon operates in the "holy plane" (a relatively avascular plane) between the visceral mesorectal fascia and the parietal presacral fascia to ensure complete tumor removal and nerve preservation. * **Lymphatic Drainage:** The upper and middle rectum drain into the pararectal nodes (within the mesorectum), while the lower rectum can also drain to the internal iliac nodes.

Question 195: A tumor of the uncinate process of the pancreas affects which of the following vessels?

A. Superior mesenteric artery (Correct Answer)
B. Portal vein
C. Common hepatic artery
D. Inferior mesenteric artery

Explanation: **Explanation:** The **uncinate process** is a hook-like projection from the lower part of the head of the pancreas. Its anatomical significance lies in its relationship with the **Superior Mesenteric Vessels**. **1. Why Option A is Correct:** The uncinate process extends medially and posteriorly to the superior mesenteric vessels. Specifically, the **Superior Mesenteric Artery (SMA)** and the **Superior Mesenteric Vein (SMV)** pass directly **anterior** to the uncinate process (and posterior to the neck of the pancreas). Therefore, a tumor in the uncinate process can easily compress or invade the SMA, leading to vascular complications or making the tumor surgically unresectable. **2. Why the Other Options are Incorrect:** * **B. Portal Vein:** The portal vein is formed behind the **neck** of the pancreas by the union of the splenic vein and SMV. While close, the SMA is the primary vessel related to the uncinate process itself. * **C. Common Hepatic Artery:** This artery runs along the **upper border** of the pancreas (above the body and head) to reach the lesser omentum. It is not in direct contact with the uncinate process. * **D. Inferior Mesenteric Artery:** This vessel arises from the aorta much lower (at the level of L3) and supplies the hindgut. It has no direct anatomical relationship with the pancreas. **High-Yield Clinical Pearls for NEET-PG:** * **Development:** The uncinate process and the lower part of the head develop from the **ventral pancreatic bud**, while the rest of the pancreas develops from the dorsal bud. * **Nutcracker Syndrome:** The SMA and the Abdominal Aorta form a "clamp" where the **Left Renal Vein** and the **3rd part of the Duodenum** can be compressed. * **Surgical Landmark:** During a Whipple procedure, the relationship between the uncinate process and the SMA is the most critical step for determining resectability. (Note: No relevant references provided directly support the anatomical relationship between the uncinate process and the superior mesenteric vessels specifically for pancreatic head tumors.)

Question 196: Which artery supplies the hindgut?

A. Descending colon
B. Superior mesenteric artery
C. Inferior mesenteric artery (Correct Answer)
D. Coeliac trunk

Explanation: **Explanation:** The development of the gastrointestinal tract is divided into three segments based on embryological origin and arterial supply. [3] The **Inferior Mesenteric Artery (IMA)** is the dedicated artery of the **hindgut**. [1] 1. **Why Option C is correct:** The hindgut extends from the distal one-third of the transverse colon to the upper part of the anal canal (above the pectinate line). The IMA, arising from the abdominal aorta at the level of **L3**, supplies these structures via its branches: the left colic, sigmoid, and superior rectal arteries. [1] 2. **Why other options are incorrect:** * **Option A (Descending colon):** This is an anatomical structure *supplied by* the artery, not the artery itself. * **Option B (Superior mesenteric artery):** This is the artery of the **midgut** (from the second part of the duodenum to the proximal two-thirds of the transverse colon). [1] * **Option D (Coeliac trunk):** This is the artery of the **foregut** (from the esophagus to the second part of the duodenum, including the liver, pancreas, and spleen). [3] **High-Yield Clinical Pearls for NEET-PG:** * **Water-shed area:** The **splenic flexure** (Griffith’s point) is the junction between the SMA and IMA territories. It is the most common site for ischemic colitis. [1] * **Marginal Artery of Drummond:** An important anastomosis along the inner border of the colon that connects the SMA and IMA, providing collateral circulation. [1] * **Venous Drainage:** The hindgut drains into the **Inferior Mesenteric Vein**, which typically joins the splenic vein before entering the portal system. [2]

Question 197: Which vessel is at risk during a Maylard incision on the anterior abdominal wall?

A. Superficial epigastric artery
B. Inferior epigastric artery (Correct Answer)
C. Superficial circumflex iliac artery
D. Deep circumflex iliac artery

Explanation: ### Explanation The **Maylard incision** is a transverse muscle-cutting incision used in pelvic surgeries to provide wider exposure than the Pfannenstiel incision. It involves the horizontal transection of the **rectus abdominis muscles**. **1. Why the Inferior Epigastric Artery (IEA) is the correct answer:** The IEA arises from the external iliac artery and ascends superiorly and medially. It enters the rectus sheath at the level of the arcuate line and runs along the **posterior surface** of the rectus abdominis muscle [2]. Because the Maylard incision requires the complete transverse division of the rectus abdominis fibers, the IEA is directly in the surgical path. To prevent significant hemorrhage, these vessels must be identified and ligated laterally before the muscle is cut. **2. Why the incorrect options are wrong:** * **A & C (Superficial Epigastric and Superficial Circumflex Iliac):** These are branches of the femoral artery located in the **superficial fascia** (Camper’s fascia) [1]. While they may be encountered during the initial skin incision, they are not the primary deep structures at risk during the muscle-cutting phase of a Maylard incision. * **D (Deep Circumflex Iliac):** This artery runs laterally along the iliac crest between the transversus abdominis and internal oblique muscles [2]. It is located too laterally and deeply to be the primary vessel at risk during a midline-focused rectus transection. ### High-Yield Clinical Pearls for NEET-PG: * **Pfannenstiel vs. Maylard:** Pfannenstiel is a muscle-**splitting** incision (rectus muscles are retracted laterally); Maylard is a muscle-**cutting** incision. * **Arcuate Line (Line of Douglas):** Below this level, the posterior rectus sheath is absent. The IEA enters the sheath at this landmark [2]. * **Hesselbach’s Triangle:** The IEA forms the **lateral boundary** of this triangle, making it a crucial landmark for distinguishing between direct and indirect inguinal hernias [3].

Question 198: Majority of the afferent blood supply to the liver is from which vessel?

A. Hepatic vein
B. Hepatic artery
C. Inferior vena cava
D. Portal vein (Correct Answer)

Explanation: **Explanation:** The liver has a unique dual blood supply, receiving blood from both the portal vein and the hepatic artery. **1. Why the Portal Vein is Correct:** The **Portal Vein** provides the majority (**75–80%**) of the total afferent blood volume to the liver [1], [3]. This blood is deoxygenated but rich in nutrients absorbed from the gastrointestinal tract. Despite being venous blood, it supplies about 50% to 70% of the liver's oxygen requirements due to its high flow rate [1]. **2. Why the Incorrect Options are Wrong:** * **Hepatic Artery (Option B):** While it carries highly oxygenated blood, it only contributes approximately **20–25%** of the total hepatic blood flow [1]. * **Hepatic Vein (Option A):** These are **efferent** vessels [4]. They drain deoxygenated blood from the liver sinusoids into the Inferior Vena Cava (IVC) [2]. * **Inferior Vena Cava (Option C):** The IVC receives blood *from* the liver via the hepatic veins; it does not supply afferent blood to the liver. **Clinical Pearls & High-Yield Facts for NEET-PG:** * **Portal Triad:** Consists of the Portal Vein, Hepatic Artery, and Bile Duct, all enclosed within the hepatoduodenal ligament (Glisson’s capsule) [1], [2]. * **Pringle Maneuver:** A surgical technique where the hepatoduodenal ligament is clamped to control bleeding from the hepatic artery and portal vein. * **Nutrient Processing:** The portal supply ensures that the liver is the first organ to process nutrients and toxins absorbed from the gut (First-pass metabolism) [3]. * **Pressure Dynamics:** The portal vein is a low-pressure system (5–10 mmHg) compared to the hepatic artery [1]. Obstruction leads to **Portal Hypertension**, manifesting as varices and splenomegaly.

Question 199: Which of the following is NOT among the relations of the left ureter?

A. Quadratus lumborum (Correct Answer)
B. Psoas major
C. Left gonadal vessels
D. External iliac artery

Explanation: The ureter is a muscular tube that descends retroperitoneally from the renal pelvis to the urinary bladder. Understanding its posterior and anterior relations is high-yield for NEET-PG. ### **Why Quadratus Lumborum is the Correct Answer** The ureters descend vertically on the **anterior surface of the Psoas major muscle** [2]. The Quadratus lumborum lies lateral and posterior to the Psoas major. Because the ureter follows the medial border of the Psoas major (near the tips of the lumbar transverse processes), it does not come into direct contact with the Quadratus lumborum. ### **Analysis of Incorrect Options** * **Psoas major:** This is the primary posterior relation. The ureter "rides" the Psoas major throughout its abdominal course, separated from it only by the genitofemoral nerve [2]. * **Left gonadal vessels:** These are key **anterior** relations. The testicular or ovarian vessels cross *anterior* to the ureter (remember the mnemonic: "Water under the bridge," where water is the ureter and the bridge represents the vessels) [2]. * **External iliac artery:** At the pelvic brim, the left ureter crosses the **commencement of the external iliac artery** (or the end of the common iliac) to enter the true pelvis [1], [3]. ### **High-Yield Clinical Pearls for NEET-PG** 1. **Constrictions:** The ureter has three physiological constrictions where stones (calculi) often lodge: (1) Pelvi-ureteric junction, (2) Pelvic brim/Iliac artery crossing, and (3) Vesico-ureteric junction (narrowest part) [1]. 2. **Blood Supply:** The ureter receives segmental supply. In the abdomen, the supply comes from the **medial** side (Renal, Gonadal arteries); in the pelvis, it comes from the **lateral** side (Internal iliac branches). 3. **Crossings:** In females, the **uterine artery** crosses *superior* to the ureter near the cervix—a critical landmark during hysterectomy [3].

Question 200: Which membrane is encountered when attempting to reach the lesser peritoneal sac and the head of the pancreas after penetrating the greater peritoneal sac?

A. Falciform ligament
B. Gastrohepatic ligament (Correct Answer)
C. Gastrosplenic ligament
D. Hepatoduodenal ligament

Explanation: To access the **lesser sac (omental bursa)** from the greater sac, one must traverse the **lesser omentum**. The lesser omentum is composed of two parts: the **gastrohepatic ligament** (connecting the lesser curvature of the stomach to the liver) and the **hepatoduodenal ligament** [1]. ### Why Option B is Correct: The **gastrohepatic ligament** forms the thin, membranous portion of the lesser omentum. Incising this membrane provides direct surgical access to the lesser sac, allowing visualization of the posterior wall of the stomach and the **head and body of the pancreas**, which lie in the retroperitoneum forming the bed of the lesser sac [1]. ### Why Other Options are Incorrect: * **A. Falciform ligament:** This attaches the liver to the anterior abdominal wall and diaphragm; it does not lead to the lesser sac. * **C. Gastrosplenic ligament:** This forms the left lateral boundary of the lesser sac [3]. While it relates to the sac, it is not the primary membrane penetrated to reach the head of the pancreas from an anterior approach. * **D. Hepatoduodenal ligament:** This is the thickened right free margin of the lesser omentum [2]. While it leads to the lesser sac via the epiploic foramen, it contains the **portal triad** (portal vein, hepatic artery, common bile duct) and is generally not incised to gain access due to the risk of major hemorrhage. ### NEET-PG High-Yield Pearls: * **Boundaries of the Epiploic Foramen (Winslow):** Anterior (Hepatoduodenal ligament), Posterior (IVC), Superior (Caudate lobe of liver), Inferior (1st part of duodenum). * **Pringle Maneuver:** Compression of the hepatoduodenal ligament to control bleeding from the hepatic artery or portal vein. * **Stomach Bed:** The pancreas (head/body), left kidney, left suprarenal gland, splenic artery, and transverse mesocolon form the posterior boundary of the lesser sac [3].

Practice by Chapter

Anterior Abdominal Wall

Practice Questions

Peritoneum and Peritoneal Cavity

Practice Questions

Stomach and Intestines

Practice Questions

Liver, Gallbladder and Biliary Tract

Practice Questions

Pancreas and Spleen

Practice Questions

Kidneys and Suprarenal Glands

Practice Questions

Abdominal Vasculature

Practice Questions

Posterior Abdominal Wall

Practice Questions

Innervation of Abdominal Viscera

Practice Questions

Applied Anatomy and Clinical Correlations

Practice Questions

Want unlimited practice?

Get full access to all questions, explanations, and performance tracking.

Start For Free

Abdomen — MCQs

Abdomen — MCQs

On this page

Practice by Chapter

Want unlimited practice?