Pelvis and Perineum — MCQs

Pelvis and Perineum Indian Medical PG Practice Questions and MCQs

Question 561: Which of the following provides the MOST COMPLETE description of muscles attached to the perineal body?

A. Deep transverse perineal
B. Ischiocavernosum
C. Two unpaired : (i) External anal sphincter, (ii) Fibres of longitudinal muscle coat of anal canal.
D. Four paired muscles including bulbospongiosus, superficial transverse perineal, deep transverse perineal, and levator ani. In females, sphincter urethrovaginalis is also attached. (Correct Answer)

Explanation: Four paired muscles including bulbospongiosus, superficial transverse perineal, deep transverse perineal, and levator ani. In females, sphincter urethrovaginalis is also attached. [1] - The **perineal body** (or central tendon of the perineum) is a fibromuscular mass located in the midline of the perineum, serving as an important point of attachment for multiple muscles essential for pelvic floor integrity. - This option correctly identifies **four paired muscles** (bulbospongiosus, superficial transverse perineal, deep transverse perineal, and levator ani) and additionally mentions the **sphincter urethrovaginalis** in females, providing the most thorough description. [1] *Ischiocavernosus* - The **ischiocavernosus** muscle surrounds the crus of the penis or clitoris and attaches to the ischial tuberosity and pubic ramus. - While it contributes to perineal function, it does **not** directly attach to the perineal body, making this option incorrect. *Deep transverse perineal* - The **deep transverse perineal** muscle does attach to the perineal body and is part of the urogenital diaphragm. [1] - However, it is only one of several muscles, making this an incomplete description compared to the correct answer. *Two unpaired: (i) External anal sphincter, (ii) Fibres of longitudinal muscle coat of anal canal* - The **external anal sphincter** does indeed have fibers that connect to the perineal body, and the longitudinal muscle coat of the anal canal also contributes. [1] - However, this option *only* lists two unpaired structures and omits major paired muscles (bulbospongiosus, superficial transverse perineal, deep transverse perineal, and levator ani), making it an incomplete description of all attachments.

Question 562: What structure is primarily responsible for forming the anorectal angle?

A. Circular smooth muscle layer
B. Longitudinal smooth muscle layer
C. Puborectalis muscle (Correct Answer)
D. Internal anal sphincter muscle

Explanation: ***Puborectalis muscle*** - The **puborectalis muscle** is a U-shaped sling of skeletal muscle that originates from the pubis and loops around the posterior aspect of the anorectal junction, pulling the rectum anteriorly [1]. - This anterior traction creates the characteristic **anorectal angle**, which is crucial for maintaining fecal continence at rest [1], [2]. *Circular smooth muscle layer* - The **circular smooth muscle layer** is part of the involuntary muscular wall of the rectum and anal canal. - While it contributes to internal anal sphincter function, its primary role is not in forming the acute anorectal angle [2]. *Longitudinal smooth muscle layer* - The **longitudinal smooth muscle layer** runs along the entire gastrointestinal tract, including the rectum, and contributes to the overall structure and peristalsis. - It does not directly form the anorectal angle; that function is specific to the puborectalis muscle. *Internal anal sphincter muscle* - The **internal anal sphincter** is an involuntary smooth muscle thickening of the circular muscle layer, primarily responsible for resting anal tone [2]. - It plays a vital role in continence but does not contribute to the creation of the anorectal angle [2].

Question 563: What is the bispinous diameter?

A. 10.5 cm (Correct Answer)
B. 11.5 cm
C. 12 cm
D. 11 cm

Explanation: ***10.5 cm*** - The **bispinous (interspinous) diameter** is the transverse diameter of the midpelvis, measured between the two ischial spines. [1] - A measurement of **10.5 cm** is the average and normal length for this diameter. [1] - This is the **narrowest diameter of the pelvis** and represents a critical measurement during labor, as it is the narrowest point through which the fetal head must pass. [1] *11.5 cm* - This measurement is typically associated with the **obstetric conjugate** at the pelvic inlet, not the midpelvis. - The bispinous diameter, being the narrowest transverse diameter of the pelvis, is normally shorter than 11.5 cm. *12 cm* - A 12 cm measurement is too wide for the **bispinous diameter**. - The **transverse diameter of the pelvic inlet** is approximately 13 cm, and the **transverse diameter of the pelvic outlet** is about 11 cm, but neither of these is the bispinous diameter. *11 cm* - While 11 cm is close, it is slightly larger than the typical average for the **bispinous diameter** of 10.5 cm. - The **transverse diameter of the outlet** is approximately 11 cm [2], but this is a different measurement at a different level of the pelvis.

Question 564: Which of the following is NOT a component of the spermatic cord?

A. Poupart's ligament (Correct Answer)
B. Genito-femoral nerve
C. Vas deferens
D. Pampiniform plexus

Explanation: ***Poupart's ligament*** - **Poupart's ligament**, also known as the **inguinal ligament**, is a fibrous band extending from the anterior superior iliac spine to the pubic tubercle and forms the **inferior boundary of the inguinal canal**. - It is a boundary structure of the inguinal canal but is **not contained within the spermatic cord** itself [1]. *Genito-femoral nerve* - The **genital branch of the genitofemoral nerve** passes through the inguinal canal and supplies the **cremaster muscle** and scrotal skin [1]. - While it accompanies the spermatic cord through the canal, it is **not traditionally listed as a component of the spermatic cord** in standard anatomical classification, though some sources may include it [1]. *Vas deferens* - The **vas deferens** (ductus deferens) is a thick muscular tube that transports sperm from the epididymis to the ejaculatory duct. - It is a **primary structural component of the spermatic cord** and is the most prominent palpable structure within it. *Pampiniform plexus* - The **pampiniform plexus** is a network of 8-12 veins that surrounds the testicular artery within the spermatic cord. - This venous plexus provides a **countercurrent heat exchange mechanism** for thermoregulation of the testes and is a major component of the spermatic cord.

Question 565: Which of the following statements about seminal vesicles is FALSE?

A. Does not store sperm
B. Secretion of seminal vesicle gives a mucoid consistency to semen
C. Stores sperm (Correct Answer)
D. Contains large amount of fructose

Explanation: ***Stores sperm*** - This statement is **false** because the **seminal vesicles** produce fluid components of semen but **do not store sperm**. - Sperm are primarily stored in the **epididymis** until ejaculation [1]. *Contains large amount of fructose* - The seminal vesicles contribute **fructose** to the semen, which serves as the primary **energy source for sperm motility**. - A large amount of fructose is characteristic of seminal vesicle secretions. *Does not store sperm* - This statement is **true** because the primary function of seminal vesicles is to produce **seminal fluid**, not to store sperm [1]. - Sperm maturation and storage occur in the **epididymis**. *Secretion of seminal vesicle gives a mucoid consistency to semen* - The secretions from the seminal vesicles, including **fructose** and **fibrinogen**, contribute to the **gel-like, mucoid consistency** of semen upon ejaculation. - **Fibrinogen** aids in the coagulation of semen after ejaculation, forming a temporary clot.

Question 566: Which structure forms the lateral border of the ischiorectal fossa?

A. Perineal membrane
B. Obturator internus muscle (Correct Answer)
C. Gluteus maximus
D. Sacrotuberous ligament

Explanation: ***Obturator internus muscle*** - The **ischiorectal fossa** (also known as the **ischioanal fossa**) is a wedge-shaped space in the perineum, and its lateral wall is formed by the **obturator internus muscle** and its covering fascia [1]. - This muscle originates from the inner surface of the **obturator membrane** and the surrounding bone, descending through the lesser sciatic foramen to insert on the greater trochanter of the femur. *Perineal membrane* - The **perineal membrane** is a dense fibrous sheet that forms the inferior boundary of the **deep perineal pouch**. - It does not form a lateral border of the ischiorectal fossa but rather contributes to the floor of the **urogenital triangle**, anterior to the fossa. *Gluteus maximus* - The **gluteus maximus** is a large muscle of the buttock, primarily involved in extension and lateral rotation of the hip. - It lies superficial to the structures of the perineum and therefore does not form a boundary of the **ischiorectal fossa**. *Sacrotuberous ligament* - The **sacrotuberous ligament** is a strong fibrous band connecting the sacrum to the ischial tuberosity. - While it helps to define the boundaries of the **perineum** posteriorly and contributes to the stability of the **sacroiliac joint**, it does not form the lateral wall of the **ischiorectal fossa**.

Question 567: The uterine artery is a branch of which of the following?

A. Left common iliac artery
B. Internal iliac artery (Correct Answer)
C. Internal pudendal artery
D. Ovarian artery

Explanation: ***Internal iliac artery*** - The **uterine artery** is a direct branch of the **internal iliac artery**, specifically its anterior division, which supplies blood to the uterus [1]. - This artery is crucial for maintaining the vascular supply to the uterus, especially during pregnancy. *Left common iliac artery* - The **common iliac artery** bifurcates into the **internal iliac artery** and the **external iliac artery** [2]; it is not a direct source of the uterine artery. - The common iliac artery is a more proximal vessel in the arterial tree. *Internal pudendal artery* - The **internal pudendal artery** is also a branch of the **internal iliac artery**, but it primarily supplies the perineum and external genitalia, not the uterus. - It is often associated with structures such as the clitoris, labia, and structures of the anal triangle. *Ovarian artery* - The **ovarian artery** originates directly from the **abdominal aorta**, usually just below the renal arteries, and supplies the ovaries [2]. - Although it supplies the reproductive system, it is distinct from the uterine artery's origin and primary territory.

Question 568: Helicine arteries are branches of which artery?

A. None of the options
B. Femoral artery
C. External pudendal artery
D. Internal pudendal artery (Correct Answer)

Explanation: ***Internal pudendal artery*** - The **internal pudendal artery** is the primary arterial supply to the external genitalia, and its branches, including the **helicine arteries**, are crucial for erectile function. - In males, these arteries supply the **corpus cavernosa** of the penis, and in females, they supply the **clitoris**, playing a key role in sexual arousal. *Femoral artery* - The **femoral artery** is a large artery in the thigh that supplies blood to the lower limb, but it does not directly branch into the helicine arteries of the genitalia. - Its main branches include the **deep femoral artery** and the **superficial femoral artery**, which are involved in blood supply to the muscles and skin of the thigh. *External pudendal artery* - The **external pudendal artery** branches off the femoral artery and supplies the skin of the external genitalia and the perineum, but not the deeper erectile tissues via helicine arteries. - It primarily provides superficial blood supply, such as to the **scrotum** or **labia majora**, and is distinct from the internal pudendal artery's deeper distribution. *None of the options* - This option is incorrect because the **internal pudendal artery** is indeed the origin of the helicine arteries. - The other options provided are incorrect as they do not directly give rise to the helicine arteries.

Question 569: In the case of a penile injury, which of the following structures prevents the extravasation of blood?

A. Fascia of camper
B. Fascia transversalis
C. Buck's fascia (Correct Answer)
D. None of the options

Explanation: ***Buck's fascia*** - **Buck's fascia** is a strong, fibrous sheath that surrounds the **corpora cavernosa** and **corpus spongiosum**, acting as a confining layer. - In cases of **penile injury**, such as a penile fracture, rupture of the tunica albuginea leads to bleeding [1]. Buck's fascia contains this extravasated blood, preventing its spread beyond the penis and resulting in a characteristic **"eggplant" deformity** [1]. *Fascia of Camper* - The **fascia of Camper** is the superficial fatty layer of the anterior abdominal wall's superficial fascia. - It is continuous with the superficial perineal fascia but does not directly cover the erectile tissues of the penis. *Fascia transversalis* - The **fascia transversalis** is a deep fascia lining the inner aspect of the anterior abdominal wall, beneath the transversus abdominis muscle. - It plays a role in forming the posterior wall of the inguinal canal and is not directly involved in containing blood within the penis after an injury. *None of the options* - This option is incorrect because Buck's fascia specifically fulfills the function described, isolating blood within the penile shaft.

Question 570: In patients with penile or urethral injury, Colle's fascia prevents extravasation of urine from spreading into which anatomical space?

A. Superficial perineal space
B. None of the options
C. Ischiorectal fossa (Correct Answer)
D. Abdomen

Explanation: ***Ischiorectal fossa*** - Colle's fascia (superficial perineal fascia) is the membranous layer that defines the boundaries of the **superficial perineal space**. - When urethral injury occurs, urine extravasates into the superficial perineal space but is **prevented from spreading laterally and posteriorly** into the ischiorectal fossa because Colle's fascia fuses with the **ischiopubic rami** laterally and the **perineal membrane** posteriorly [1]. - The ischiorectal fossa is a space lateral to the **anal canal** that is separated from the superficial perineal space by these fascial attachments. *Superficial perineal space* - This is actually the space **into which** urine extravasates when penile or urethral injury occurs, not the space that is protected from extravasation [1]. - Colle's fascia forms the inferior boundary of this space, so urine collects here rather than being prevented from entering. *Abdomen* - Colle's fascia in the perineum is continuous with **Scarpa's fascia** of the anterior abdominal wall. - Due to this continuity, urine can actually **track superiorly** into the anterior abdominal wall along this fascial plane. - Therefore, Colle's fascia does NOT prevent spread to the abdomen. *None of the options* - This option is incorrect because Colle's fascia specifically prevents lateral and posterior spread into the ischiorectal fossa through its anatomical attachments.

Practice by Chapter

Pelvic Walls and Floor

Practice Questions

Pelvic Viscera

Practice Questions

Urogenital Organs

Practice Questions

Pelvic Vasculature

Practice Questions

Pelvic Innervation

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Male Perineum

Practice Questions

Female Perineum

Practice Questions

Pelvic Lymphatics

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Applied Anatomy and Clinical Correlations

Practice Questions

Gender Differences in Pelvic Anatomy

Practice Questions

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