Pelvis and Perineum Practice Questions

Q: All of the following muscles contribute to the urogenital sphincter complex except?

Bladder base detrusor muscle. The **urogenital sphincter complex** is a specialized group of striated muscles located in the deep perineal pouch that surrounds the urethra. In females, this complex is particularly well-developed to provide urinary continence. **Why Option D is Correct:** The **Bladder base detrusor muscle** is a smooth muscle that forms the wall of the urinary bladder [1]. It is under autonomic (parasympathetic) control and its primary function is to contract during micturition to empty the bladder [2]. It is **not** part of the striated urogenital sphincter complex, which is under voluntary (somatic) control via the pudendal nerve. **Why the other options are incorrect:** * **Sphincter urethrae (Option B):** This is the primary component of the external urethral sphincter that encircles the urethra. * **Compressor urethrae (Option A):** Found in females, these muscle fibers originate from the ischiopubic rami and arch over the anterior aspect of the urethra. * **Urethrovaginal sphincter (Option C):** Also specific to females, these fibers encircle both the urethra and the vagina, acting as a functional unit to maintain continence. **NEET-PG High-Yield Pearls:** * **Innervation:** The urogenital sphincter complex is composed of **striated (skeletal) muscle** and is innervated by the **perineal branch of the pudendal nerve (S2-S4)**. * **Gender Difference:** In males, the complex is simpler, consisting primarily of the sphincter urethrae. In females, it is a tripartite complex (Sphincter urethrae + Compressor urethrae + Urethrovaginal sphincter). * **Location:** These muscles are located within the **deep perineal pouch** [1]. * **Clinical Significance:** Damage to these muscles or the pudendal nerve during pelvic surgery or childbirth can lead to **stress urinary incontinence**.

Q: Which branches of the lumbar plexus supply the urinary bladder?

L1 and L2. The autonomic nerve supply to the urinary bladder is derived from the **vesical plexus**, which contains both sympathetic and parasympathetic fibers. **1. Why L1 and L2 is correct:** The **sympathetic supply** to the bladder originates from the lateral horn cells of the **T11 to L2** spinal segments. These preganglionic fibers pass through the lumbar splanchnic nerves to the superior hypogastric plexus and then via the hypogastric nerves to the vesical plexus. In the context of the lumbar plexus branches, **L1 and L2** are the primary contributors to the sympathetic outflow that governs bladder filling (by causing relaxation of the detrusor muscle and contraction of the internal urethral sphincter). **2. Why the other options are incorrect:** * **L2, L3, and L4:** These segments primarily form the **Femoral** and **Obturator** nerves. While the obturator nerve (L2-L4) passes through the pelvis, it supplies the medial compartment of the thigh and does not provide autonomic innervation to the bladder. * **L3 and L4:** These segments are too low for the sympathetic outflow (which ends at L2) and too high for the parasympathetic outflow (which begins at S2). **Clinical Pearls for NEET-PG:** * **Parasympathetic Supply:** Arises from **S2, S3, and S4** (Pelvic Splanchnic Nerves). It is responsible for bladder emptying (contraction of the detrusor and relaxation of the internal sphincter). * **Pain Sensations:** Pain from the bladder (due to overdistension or spasm) travels with the **sympathetic** fibers to T11-L2, whereas pain from the bladder neck/trigone travels with the **parasympathetic** fibers to S2-S4. * **Micturition Center:** Located in the **Pons** (Barrington’s nucleus).

Q: Which of the following arteries gives rise to the uterine artery?

Internal iliac artery. **Explanation:** The **Internal Iliac Artery** is the primary artery of the pelvis, supplying the pelvic viscera, perineum, and gluteal region. It divides into anterior and posterior divisions. The **uterine artery** is a major branch of the **anterior division** of the internal iliac artery [1]. It travels medially in the base of the broad ligament (parametrium) to reach the junction of the cervix and the body of the uterus. **Analysis of Options:** * **A. Aorta:** The abdominal aorta terminates by dividing into the common iliac arteries at the L4 level. While it is the ultimate source, it does not give rise to the uterine artery directly. (Note: The *ovarian* artery arises directly from the aorta). * **B. Common iliac artery:** This artery divides into the internal and external iliac arteries at the level of the pelvic brim; it has no visceral branches of its own. * **D. External iliac artery:** This artery primarily supplies the lower limb and becomes the femoral artery after passing under the inguinal ligament. **High-Yield NEET-PG Pearls:** 1. **Water Under the Bridge:** The uterine artery crosses **superior** to the **ureter** near the lateral fornix of the vagina [1]. This is a critical landmark during a hysterectomy to avoid accidental ureteric ligation. 2. **Homologue:** The uterine artery in females is homologous to the **artery to ductus deferens** in males. 3. **Spiral Arteries:** The uterine artery eventually gives rise to spiral arteries, which supply the stratum functionalis of the endometrium and are shed during menstruation [1].

Q: What is the typical subpubic angle?

85 degrees. The **subpubic angle** (or pubic arch) is the angle formed by the convergence of the inferior rami of the ischium and pubis on either side at the pubic symphysis [1]. This measurement is a critical parameter in sexual dimorphism of the human pelvis. ### **Explanation of the Correct Answer** * **Option C (85 degrees):** In the **female (gynecoid) pelvis**, the subpubic angle [1] is typically wide, ranging between **80–90 degrees** (averaging around 85 degrees). This wider angle, along with a broader pelvic outlet and a rectangular pubic bone, is an evolutionary adaptation to facilitate childbirth by providing a larger space for the fetal head to pass. ### **Analysis of Incorrect Options** * **Option A & B (Less than 75 degrees):** These values are characteristic of the **male (android) pelvis**. In males, the subpubic angle is acute and narrow, typically measuring between **60–70 degrees** [1]. An angle less than 75 degrees in a clinical setting suggests a narrow pelvic outlet, which in females could lead to obstructed labor (cephalopelvic disproportion). * **Option D (110–120 degrees):** This is excessively wide and does not represent standard human pelvic anatomy. While the Platypelloid (flat) pelvis has a wide subpubic angle, it rarely reaches these extremes. ### **High-Yield Clinical Pearls for NEET-PG** * **The Rule of Thumbs:** A quick clinical way to estimate the angle is using the fingers. If the angle fits the spread of the **thumb and index finger**, it is likely a female pelvis (~90°); if it fits the spread of the **middle and index finger**, it is likely a male pelvis (~70°). * **Obstetric Significance:** The subpubic angle determines the "waste space" under the pubic symphysis. A narrow angle forces the fetal head posteriorly, increasing the risk of perineal tears. * **Other Female Pelvic Features:** Wide greater sciatic notch (>75°), oval/rounded pelvic brim, and a shorter, wider sacrum [1].

Q: Regarding the anorectal angle, which statement is true?

It plays an important role in the continence mechanism.. The **anorectal angle** is a critical anatomical landmark formed at the junction of the rectum and the anal canal [1]. ### **Explanation of the Correct Answer** **Option A is correct** because the anorectal angle is a fundamental component of the **fecal continence mechanism** [1]. It acts as a physical "kink" or valve that prevents the downward pressure of feces from entering the anal canal. This angle is maintained by the **puborectalis muscle** (a part of the levator ani), which loops around the junction like a sling, pulling it anteriorly toward the pubic bone [1]. ### **Analysis of Incorrect Options** * **Option B:** The angle is formed by the **puborectalis muscle** (striated muscle of the pelvic floor), not the external anal sphincter. The external sphincter surrounds the anal canal but does not create the angulation [1]. * **Option C:** At rest, the anorectal angle is typically between **80 to 100 degrees** (averaging around 90°). An angle of 30° would be pathologically acute [2]. * **Option D:** During defecation, the puborectalis muscle **relaxes**, allowing the anorectal angle to **increase** (become more obtuse/straighten to about 130-140°) [1], [2]. This straightening facilitates the smooth passage of stool. ### **NEET-PG High-Yield Pearls** * **The "Sling" Concept:** Think of the puborectalis as a "U-shaped" sling. Contraction sharpens the angle (continence); relaxation straightens the angle (voiding) [1]. * **Nerve Supply:** The puborectalis is supplied by the **nerve to levator ani (S3, S4)** and the inferior rectal nerve. * **Clinical Correlation:** Damage to the puborectalis or the pelvic floor nerves (often during childbirth) can lead to **fecal incontinence** due to the loss of this angle [1].

Q: A 24-year-old female is examined by an obstetrician in a delivery room. The obstetrician injects lidocaine near the tip of the ischial spine. Which nerve is blocked by the drug?

Pudendal nerve. ### Explanation **Correct Answer: B. Pudendal Nerve** The **pudendal nerve (S2–S4)** is the primary nerve blocked during a pudendal nerve block, a common procedure used in the second stage of labor for vaginal deliveries or minor perineal surgeries. **Anatomical Basis:** The pudendal nerve exits the pelvis through the greater sciatic foramen, passes behind the **sacrospinous ligament**, and re-enters through the lesser sciatic foramen. The **ischial spine** serves as the key clinical landmark for this block. When an anesthetic (like lidocaine) is injected transvaginally or transperineally near the tip of the ischial spine, it anesthetizes the nerve as it crosses the sacrospinous ligament. This provides sensory loss to the perineum and the lower third of the vagina. --- ### Analysis of Incorrect Options: * **A. Genitofemoral nerve (L1, L2):** Its femoral branch provides sensation to the upper anterior thigh, while the genital branch supplies the labia majora/scrotum and the cremasteric muscle. It does not pass near the ischial spine. * **C. Obturator nerve (L2–L4):** This nerve passes through the obturator canal to supply the adductor muscles of the thigh and the skin of the medial thigh. * **D. Iliohypogastric nerve (T12, L1):** This nerve supplies the skin over the hypogastric region and the lateral gluteal area. --- ### High-Yield Clinical Pearls for NEET-PG: 1. **Landmark:** The **ischial spine** is the most important palpable landmark for a pudendal block. 2. **Nerve Roots:** Pudendal nerve originates from the anterior rami of **S2, S3, and S4**. 3. **Limitations:** A pudendal block provides perineal anesthesia but **does not** abolish the pain of uterine contractions (which is mediated by T10–L1 sympathetic fibers). 4. **Complication:** Accidental intravascular injection into the **internal pudendal artery** (which runs adjacent to the nerve) is a potential risk.

Q: Fertilization occurs in which part of the fallopian tube?

Ampulla. **Explanation:** **1. Why Ampulla is Correct:** The **Ampulla** is the widest and longest part of the fallopian tube, making it the most common site for fertilization. It possesses a highly folded mucosal lining (plicae) and a rich supply of ciliated cells. These features create an ideal environment for the sperm and ovum to meet. Fertilization typically occurs here within 12–24 hours after ovulation. **2. Analysis of Incorrect Options:** * **Fimbriae (A):** These are finger-like projections at the distal end of the tube that "sweep" the ovum from the ovary into the infundibulum. They facilitate capture but are not the site of fertilization. * **Isthmus (B):** This is the narrow, thick-walled segment medial to the ampulla. While sperm undergo final maturation (capacitation) here, it is generally too narrow for the primary fertilization event. * **Interstitial/Intramural (D):** This is the segment that traverses the uterine wall. It is the narrowest part of the tube (0.7 mm) and is a rare but dangerous site for ectopic pregnancies. **3. NEET-PG High-Yield Pearls:** * **Ectopic Pregnancy:** The **Ampulla** is also the most common site for ectopic pregnancy (approx. 70-80%). * **Ciliary Action:** The movement of the ovum toward the uterus is mediated by ciliary beat and peristalsis, whereas sperm move primarily via their own motility and uterine contractions. * **Time Window:** The secondary oocyte remains viable for 12–24 hours, while sperm can survive in the female reproductive tract for 48–72 hours. * **Narrowest Part:** The **Interstitial** portion is the narrowest part of the fallopian tube, while the **Isthmus** is the narrowest part of the extra-uterine tube.

Question 1

Which of the following parts of the uterus is not covered with peritoneum?

Accepted Answer

Right & Left lateral borders

Answer

Fundus

Answer

Anterior surface of body

Answer

Posterior surface of body to posterior fornix of vagina

Question 2

All of the following muscles contribute to the urogenital sphincter complex except?

Accepted Answer

Bladder base detrusor muscle

Answer

Compressor urethrae

Answer

Sphincter urethrae

Answer

Urethrovaginal sphincter

Question 3

Which branches of the lumbar plexus supply the urinary bladder?

Accepted Answer

L1 and L2

Answer

L2 and L3

Answer

L3 and L4

Answer

L2, L3, and L4

Question 4

Which of the following arteries gives rise to the uterine artery?

Accepted Answer

Internal iliac artery

Answer

Aorta

Answer

Common iliac artery

Answer

External iliac artery

Question 5

What is the typical subpubic angle?

Accepted Answer

85 degrees

Answer

Less than 65 degrees

Answer

65-75 degrees

Answer

110-120 degrees

Question 6

Referred pain from which of the following conditions may be felt along the inner side of the right thigh?

Accepted Answer

Pelvic abscess

Answer

Inflamed pelvic appendix

Answer

Inflamed ovaries

Answer

Stone in pelvic ureter

Question 7

Regarding the anorectal angle, which statement is true?

Accepted Answer

It plays an important role in the continence mechanism.

Answer

It is due to the pull of the external anal sphincter.

Answer

It is around 30 degrees at rest.

Answer

The angle decreases during defecation.

Question 8

A 24-year-old female is examined by an obstetrician in a delivery room. The obstetrician injects lidocaine near the tip of the ischial spine. Which nerve is blocked by the drug?

Accepted Answer

Pudendal nerve

Answer

Genitofemoral nerve

Answer

Obturator nerve

Answer

Iliohypogastric nerve

Question 9

Fertilization occurs in which part of the fallopian tube?

Accepted Answer

Ampulla

Answer

Fimbrial

Answer

Isthmus

Answer

Interstitial

Question 10

A 17-year-old girl presents with severe abdominal pain and fever. Laboratory examination reveals an elevated white blood cell count, and a pregnancy test is positive. She reports attempting to terminate her pregnancy by inserting a sharp object into her vagina, which penetrated the posterior fornix. Into what region did the sharp object penetrate?

Accepted Answer

Rectouterine space

Answer

Deep perineal pouch

Answer

Ischioanal space

Answer

Rectovesical space

Pelvis and Perineum — MCQs

Pelvis and Perineum — MCQs

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