Biology Quiz: The Anatomy Of The Perineum

1. A 59-year-old woman comes to a local hospital for uterine cancer surgery. As the uterine artery passes from the internal iliac artery to the uterus, it crosses superior to which of the following structures that are sometimes mistakenly ligated during such surgery?

Ovarian artery

Ovarian ligament

Uterine tube

Ureter

Round ligament of the uterus

The ureter runs under the uterine artery near the cervix; thus, the ureter is
sometimes mistakenly ligated during pelvic surgery. The other structures mentioned are not
closely related to the uterine artery near the uterine cervix.

Explanation

The ureter runs under the uterine artery near the cervix; thus, the ureter is
sometimes mistakenly ligated during pelvic surgery. The other structures mentioned are not
closely related to the uterine artery near the uterine cervix.

2. A young couple is having difficulty conceiving a child. Their physician at a reproduction and fertility clinic explains to them that:

The ovary lies within the broad ligament

The glans clitoris is formed from the corpus spongiosum

Erection of the penis is a sympathetic response

Ejaculation follows parasympathetic stimulation

Fertilization occurs in the infundibulum or ampulla of the uterine tube.

Fertilization takes place in the infundibulum or ampulla of the uterine tube. The
glans clitoris is derived from the corpora cavernosa, whereas the glans penis is the expanded terminal
part of the corpus spongiosum. Erection of the penis is caused by parasympathetic stimulation,
whereas ejaculation is mediated via the sympathetic nerve. The ovaries are not enclosed in the broad
ligament, but their anterior surface is attached to the posterior surface of the broad ligament.

Explanation

Fertilization takes place in the infundibulum or ampulla of the uterine tube. The
glans clitoris is derived from the corpora cavernosa, whereas the glans penis is the expanded terminal
part of the corpus spongiosum. Erection of the penis is caused by parasympathetic stimulation,
whereas ejaculation is mediated via the sympathetic nerve. The ovaries are not enclosed in the broad
ligament, but their anterior surface is attached to the posterior surface of the broad ligament.

3. A 29-year-old woman is admitted to a hospital because the birth of her child is several days overdue. Tearing of the pelvic diaphragm during childbirth leads to paralysis of which of the following muscles?

Piriformis

Sphincter urethrae

Obturator internus

Levator ani

Sphincter ani externus

The pelvic diaphragm is formed by the levator ani and coccygeus, whereas
the urogenital diaphragm consists of the sphincter urethrae and deep transverse perinei muscles.
The piriformis passes through the greater sciatic notch and inserts on the greater trochanter of
the femur. The obturator internus forms the lateral wall of the ischiorectal fossa. The sphincter
ani externus is composed of three layers, including the subcutaneous (corrugator cutis ani), superficial,
and deep portions and maintains a voluntary tonic contracture.

Explanation

The pelvic diaphragm is formed by the levator ani and coccygeus, whereas
the urogenital diaphragm consists of the sphincter urethrae and deep transverse perinei muscles.
The piriformis passes through the greater sciatic notch and inserts on the greater trochanter of
the femur. The obturator internus forms the lateral wall of the ischiorectal fossa. The sphincter
ani externus is composed of three layers, including the subcutaneous (corrugator cutis ani), superficial,
and deep portions and maintains a voluntary tonic contracture.

4. An elderly man with benign enlargement of his prostate experiences difficulty in urination, urinary frequency, and urgency. Which of the following lobes of the prostate gland is commonly involved in benign hypertrophy that obstructs the prostatic urethra?

Anterior lobe

Middle lobe

Right lateral lobe

Left lateral lobe

Posterior lobe

The middle lobe of the prostate gland is commonly involved in benign prostatic hypertrophy, resulting in obstruction of the prostatic urethra, whereas the posterior lobe is commonly involved in the carcinomatous transformation. The anterior lobe contains little glandular tissue, and the two lateral lobes on either side of the urethra form the major part of the gland.

Explanation

The middle lobe of the prostate gland is commonly involved in benign prostatic hypertrophy, resulting in obstruction of the prostatic urethra, whereas the posterior lobe is commonly involved in the carcinomatous transformation. The anterior lobe contains little glandular tissue, and the two lateral lobes on either side of the urethra form the major part of the gland.

5. A 68-year-old woman with uterine carcinoma undergoes surgical resection. This cancer can spread directly to the labia majora in lymphatics that follow which of the following structures?

Pubic arcuate ligament

Suspensory ligament of the ovary

Cardinal (transverse cervical) ligament

Suspensory ligament of the clitoris

Round ligament of the uterus

The round ligament of the uterus runs laterally from the uterus through the deep inguinal ring, inguinal canal, and superficial inguinal ring and becomes lost in the subcutaneous tissues of the labium majus. Thus, carcinoma of the uterus can spread directly to the labium majus by traveling in lymphatics that follow the ligament. The pubic arcuate ligament attaches across the inferior aspect of the pubic symphysis and attaches to the medial borders of the inferior pubic rami. The suspensory ligament of the ovary runs from the ovary to the pelvic wall and transmits the ovarian vessels. The cardinal (transverse cervical) ligament runs from the cervix and the vagina to the pelvic walls. The suspensory ligament of the clitoris runs from the pubic symphysis and the arcuate pubic ligament to the deep fascia of the body of the clitoris.

Explanation

The round ligament of the uterus runs laterally from the uterus through the deep inguinal ring, inguinal canal, and superficial inguinal ring and becomes lost in the subcutaneous tissues of the labium majus. Thus, carcinoma of the uterus can spread directly to the labium majus by traveling in lymphatics that follow the ligament. The pubic arcuate ligament attaches across the inferior aspect of the pubic symphysis and attaches to the medial borders of the inferior pubic rami. The suspensory ligament of the ovary runs from the ovary to the pelvic wall and transmits the ovarian vessels. The cardinal (transverse cervical) ligament runs from the cervix and the vagina to the pelvic walls. The suspensory ligament of the clitoris runs from the pubic symphysis and the arcuate pubic ligament to the deep fascia of the body of the clitoris.

6. A 22-year-old woman receives a deep cut in the inguinal canal 1 inch lateral to the pubic tubercle. Which of the following ligaments is lacerated within the inguinal canal?

Suspensory ligament of the ovary

Ovarian ligament

Mesosalpinx

Round ligament of the uterus

Rectouterine ligament

The round ligament of the uterus is found in the inguinal canal along its course. Other ligaments are not passing through the inguinal canal.

Explanation

The round ligament of the uterus is found in the inguinal canal along its course. Other ligaments are not passing through the inguinal canal.

7. A 29-year-old woman with a ruptured ectopic pregnancy is admitted to a hospital for culdocentesis. A long needle on the syringe is most efficiently inserted through which of the following structures?

Anterior fornix of the vagina

Posterior fornix of the vagina

Anterior wall of the rectum

Posterior wall of the uterine body

Posterior wall of the bladder

A needle should be inserted through the posterior fornix, just below the posterior lip of the cervix while the patient is in the supine position, to aspirate abnormal fluid in the cul-de-sac of Douglas (rectouterine pouch). Rectouterine excavation is not most efficiently aspirated by puncture of other structures

Explanation

A needle should be inserted through the posterior fornix, just below the posterior lip of the cervix while the patient is in the supine position, to aspirate abnormal fluid in the cul-de-sac of Douglas (rectouterine pouch). Rectouterine excavation is not most efficiently aspirated by puncture of other structures

8. A 29-year-old carpenter sustains severe injuries of the pelvic splanchnic nerve by a deep puncture wound, which has become contaminated. The injured parasympathetic preganglionic fibers in the splanchnic nerve are most likely to synapse in which of the following ganglia?

Ganglia in or near the viscera or pelvic plexus

Sympathetic chain ganglia

Collateral ganglia

Dorsal root ganglia

Ganglion impar

The pelvic splanchnic nerves carry preganglionic parasympathetic general visceral efferent (GVE) fibers that synapse in the ganglia of the inferior hypogastric plexus and in terminal ganglia in the muscular walls of the pelvic organs. The sympathetic preganglionic fibers synapse in the sympathetic chain (paravertebral) ganglia or in the collateral (prevertebral) ganglia. The dorsal root ganglia contain cell bodies of general somatic afferent (GSA) and general visceral afferent (GVA) fibers and have no synapsis. The two sympathetic trunks unite and terminate in the ganglion impar (coccygeal ganglion), which is the most inferior, unpaired ganglion located in front of the coccyx.

Explanation

The pelvic splanchnic nerves carry preganglionic parasympathetic general visceral efferent (GVE) fibers that synapse in the ganglia of the inferior hypogastric plexus and in terminal ganglia in the muscular walls of the pelvic organs. The sympathetic preganglionic fibers synapse in the sympathetic chain (paravertebral) ganglia or in the collateral (prevertebral) ganglia. The dorsal root ganglia contain cell bodies of general somatic afferent (GSA) and general visceral afferent (GVA) fibers and have no synapsis. The two sympathetic trunks unite and terminate in the ganglion impar (coccygeal ganglion), which is the most inferior, unpaired ganglion located in front of the coccyx.

9. A 17-year-old boy suffers a traumatic groin injury during a soccer match. The urologist notices tenderness and swelling of the boy's left testicle that may be produced by thrombosis in which of the following veins?

Left internal pudendal vein

Left renal vein

Inferior vena cava

Left inferior epigastric vein

Left external pudendal vein

A tender swollen left testis may be produced by thrombosis in the left renal vein because the left testicular vein drains into the left renal vein. The right testicular vein drains into the inferior vena cava. The left internal pudendal vein empties into the left internal iliac vein. The left inferior epigastric drains into the left external iliac vein and the left external pudendal vein empties into the femoral vein.

Explanation

A tender swollen left testis may be produced by thrombosis in the left renal vein because the left testicular vein drains into the left renal vein. The right testicular vein drains into the inferior vena cava. The left internal pudendal vein empties into the left internal iliac vein. The left inferior epigastric drains into the left external iliac vein and the left external pudendal vein empties into the femoral vein.

10. On a busy Saturday night in Chicago, a 16- year-old boy presents to the emergency room with a stab wound from a knife that enters the pelvis above the piriformis muscle. Which of the following structures is most likely to be damaged?

Sciatic nerve

Internal pudendal artery

Superior gluteal nerve

Inferior gluteal artery

Posterior femoral cutaneous nerve

The superior gluteal nerve leaves the pelvis through the greater sciatic foramen, above the piriformis. The sciatic nerve, internal pudendal vessels, inferior gluteal vessels and nerve, and posterior femoral cutaneous nerve leave the pelvis below the piriformis.

Explanation

The superior gluteal nerve leaves the pelvis through the greater sciatic foramen, above the piriformis. The sciatic nerve, internal pudendal vessels, inferior gluteal vessels and nerve, and posterior femoral cutaneous nerve leave the pelvis below the piriformis.

11. A 37-year-old man is suffering from carcinoma of the skin of the glans penis. Cancer cells are likely to metastasize directly to which of the following lymph nodes?

External iliac nodes

Internal iliac nodes

Superficial inguinal nodes

Aortic (lumbar) nodes

Common iliac nodes

NOTICE THE QUESTION SAYS -SKIN-, the glans would drain to the deep inguinal nodes The superficial inguinal nodes receive lymph from the penis, scrotum, buttocks, labium majus, and the lower parts of the vagina and anal canal. These nodes have efferent vessels that drain primarily into the external iliac and common iliac nodes and ultimately to the lumbar (aortic) nodes. The internal iliac nodes receive lymph from the upper part of the rectum, vagina, uterus, and other pelvic organs, and they drain into the common iliac and then to the lumbar (aortic) nodes.

Explanation

NOTICE THE QUESTION SAYS -SKIN-, the glans would drain to the deep inguinal nodes The superficial inguinal nodes receive lymph from the penis, scrotum, buttocks, labium majus, and the lower parts of the vagina and anal canal. These nodes have efferent vessels that drain primarily into the external iliac and common iliac nodes and ultimately to the lumbar (aortic) nodes. The internal iliac nodes receive lymph from the upper part of the rectum, vagina, uterus, and other pelvic organs, and they drain into the common iliac and then to the lumbar (aortic) nodes.

12. A 58-year-old man is diagnosed as having a slowly growing tumor in the deep perineal space. Which of the following structures would most likely be injured?

Bulbourethral glands

Crus of penis

Bulb of vestibule

Spongy urethra

Great vestibular gland

The deep perineal space contains the bulbourethral (Cowper's) glands. The crus of the penis, bulb of the vestibule, spongy urethra, and great vestibular gland are found in the superficial perineal space.

Explanation

The deep perineal space contains the bulbourethral (Cowper's) glands. The crus of the penis, bulb of the vestibule, spongy urethra, and great vestibular gland are found in the superficial perineal space.

13. A 39-year-old man is unable to expel the last drops of urine from the urethra at the end of micturition because of paralysis of the external urethral sphincter and bulbospongiosus muscles. This condition may occur as a result of injury to which of the following nervous structures?

Pelvic plexus

Prostatic plexus

Pudendal nerve

Pelvic splanchnic nerve

Sacral splanchnic nerve

The perineal branch of the pudendal nerve supplies the external urethral sphincter and bulbospongiosus muscles in the male. All other nervous structures do not supply skeletal muscles but supply smooth muscles in the perineal and pelvic organs. The pelvic and prostatic plexuses contain both sympathetic and parasympathetic nerve fibers. The pelvic splanchnic nerve carries preganglionic parasympathetic fibers, whereas the sacral splanchnic nerve transmits preganglionic sympathetic fibers.

Explanation

The perineal branch of the pudendal nerve supplies the external urethral sphincter and bulbospongiosus muscles in the male. All other nervous structures do not supply skeletal muscles but supply smooth muscles in the perineal and pelvic organs. The pelvic and prostatic plexuses contain both sympathetic and parasympathetic nerve fibers. The pelvic splanchnic nerve carries preganglionic parasympathetic fibers, whereas the sacral splanchnic nerve transmits preganglionic sympathetic fibers.

14. A 59-year-old man is diagnosed with prostate cancer following a digital rectal examination. For the resection of prostate cancer, it is important to know that the prostatic ducts open into or on which of the following structures?

Membranous part of the urethra

Seminal colliculus

Spongy urethra

Prostatic sinus

Prostatic utricle

Ducts from the prostate gland open into the prostatic sinus, which is a groove on either side of the urethral crest. The prostate gland receives the ejaculatory duct, which opens into the prostatic urethra on the seminal colliculus (a prominent elevation of the urethral crest) just lateral to the prostatic utricle, which is a small blind pouch. The bulbourethral gland lies on the lateral side of the membranous urethra within the deep perineal space, but its duct opens into the bulbous portion of the spongy (penile) urethra.

Explanation

Ducts from the prostate gland open into the prostatic sinus, which is a groove on either side of the urethral crest. The prostate gland receives the ejaculatory duct, which opens into the prostatic urethra on the seminal colliculus (a prominent elevation of the urethral crest) just lateral to the prostatic utricle, which is a small blind pouch. The bulbourethral gland lies on the lateral side of the membranous urethra within the deep perineal space, but its duct opens into the bulbous portion of the spongy (penile) urethra.

15. A 46-year-old woman has a history of infection in her perineal region. A comprehensive examination reveals a tear of the superior boundary of the superficial perineal space. Which of the following structures would most likely be injured?

Pelvic diaphragm

Colles' fascia

Superficial perineal fascia

Deep perineal fascia

Perineal membrane

The superior (deep) boundary of the superficial perineal space is the perineal membrane (inferior fascia of the urogenital diaphragm). Colles' fascia is the deep membranous layer of the superficial perineal fascia. The deep perineal fascia essentially divides the superficial perineal space into a superficial and deep compartment. The pelvic diaphragm consists of the levator ani and coccygeus muscles

Explanation

The superior (deep) boundary of the superficial perineal space is the perineal membrane (inferior fascia of the urogenital diaphragm). Colles' fascia is the deep membranous layer of the superficial perineal fascia. The deep perineal fascia essentially divides the superficial perineal space into a superficial and deep compartment. The pelvic diaphragm consists of the levator ani and coccygeus muscles

16. An obstetrician performs a median episiotomy on a woman before parturition to prevent uncontrolled tearing. If the perineal body is damaged, the function of which of the following muscles might be impaired?

Ischiocavernosus and sphincter urethrae

Deep transverse perineal and obturator internus

Bulbospongiosus and superficial transverse perineal

External anal sphincter and sphincter urethrae

Bulbospongiosus and ischiocavernosus

The perineal body (central tendon of the perineum) is a fibromuscular node at the center of the perineum. It provides attachment for the bulbospongiosus, the superficial and deep transverse perineal muscles, and the sphincter ani externus muscles. Other muscles (ischiocavernosus, sphincter urethrae, and obturator internus) are not attached to the perineal body.

Explanation

The perineal body (central tendon of the perineum) is a fibromuscular node at the center of the perineum. It provides attachment for the bulbospongiosus, the superficial and deep transverse perineal muscles, and the sphincter ani externus muscles. Other muscles (ischiocavernosus, sphincter urethrae, and obturator internus) are not attached to the perineal body.

17. A 37-year-old small business manager receives a gunshot wound in the pelvic cavity, resulting in a lesion of the sacral splanchnic nerves. Which of the following nerve fibers would primarily be damaged?

Postganglionic parasympathetic fibers

Postganglionic sympathetic fibers

Preganglionic sympathetic fibers

Preganglionic parasympathetic fibers

Postganglionic sympathetic and parasympathetic fibers

The sacral splanchnic nerves consist primarily of preganglionic sympathetic neurons and also contain general visceral afferent (GVA) fibers. None of the other fibers listed are contained in these nerves.

Explanation

The sacral splanchnic nerves consist primarily of preganglionic sympathetic neurons and also contain general visceral afferent (GVA) fibers. None of the other fibers listed are contained in these nerves.

18. A 43-year-old man has a benign tumor located near a gap between the arcuate pubic ligament and the transverse perineal ligament. Which of the following structures is most likely compressed by this tumor?

Perineal nerve

Deep dorsal vein of the penis

Superficial dorsal vein

Posterior scrotal nerve

Deep artery of the penis

http://upload.wikimedia.org/wikipedia/commons/5/51/Gray321.pngThe deep dorsal vein, dorsal artery, and dorsal nerve of the penis pass through a gap between the arcuate pubic ligament and the transverse perineal ligament. The perineal nerve divides into a deep branch, which supplies all of the perineal muscles, and superficial branches as posterior scrotal nerves that supply the scrotum. The superficial dorsal vein of the penis empties into the greater saphenous vein. The deep artery of the penis runs in the corpus cavernosum penis.

Explanation

http://upload.wikimedia.org/wikipedia/commons/5/51/Gray321.pngThe deep dorsal vein, dorsal artery, and dorsal nerve of the penis pass through a gap between the arcuate pubic ligament and the transverse perineal ligament. The perineal nerve divides into a deep branch, which supplies all of the perineal muscles, and superficial branches as posterior scrotal nerves that supply the scrotum. The superficial dorsal vein of the penis empties into the greater saphenous vein. The deep artery of the penis runs in the corpus cavernosum penis.

19. A 42-year-old woman who has had six children develops weakness of the urogenital diaphragm. Paralysis of which of the following muscles would cause such a symptom?

Sphincter urethrae

Coccygeus

Superficial transversus perinei

Levator ani

Obturator internus

The urogenital diaphragm consists of the sphincter urethrae and deep
transverse perineal muscles. Weakness of the muscles, ligaments, and fasciae of the pelvic floor
such as the pelvic diaphragm, urogenital diaphragm, and cardinal (transverse cervical) ligaments
occurs as result of multiple child delivery, advancing age, and menopause. The pelvic diaphragm
is composed of the levator ani and coccygeus muscles. The superficial transverses perinei is one
of the superficial perineal muscles and the obturator internus forms the lateral wall of the ischiorectal
fossa.

Explanation

The urogenital diaphragm consists of the sphincter urethrae and deep
transverse perineal muscles. Weakness of the muscles, ligaments, and fasciae of the pelvic floor
such as the pelvic diaphragm, urogenital diaphragm, and cardinal (transverse cervical) ligaments
occurs as result of multiple child delivery, advancing age, and menopause. The pelvic diaphragm
is composed of the levator ani and coccygeus muscles. The superficial transverses perinei is one
of the superficial perineal muscles and the obturator internus forms the lateral wall of the ischiorectal
fossa.

20. A 22-year-old man has a gonorrheal infection that has infiltrated the space between the inferior fascia of the urogenital diaphragm and the superficial perineal fascia. Which of the following structures might be inflamed?

Greater vestibular gland

Bulbourethral gland

Membranous part of the male urethra

Deep transverse perineal muscle

Sphincter urethrae

The greater vestibular gland is located in the superficial perineal space between the inferior fascia of the urogenital diaphragm and the membranous layer of the superficial perineal fascia (Colles' fascia). All of the other structures are found in the deep perineal pouch.

Explanation

The greater vestibular gland is located in the superficial perineal space between the inferior fascia of the urogenital diaphragm and the membranous layer of the superficial perineal fascia (Colles' fascia). All of the other structures are found in the deep perineal pouch.