Flashcards in USMLE Road Map - Pelvis And Perineum II Deck (44):
Course of the internal pudendal artery:
Reaches the perineum by exiting the pelvis through the greater sciatic foramen --> Crossing the ischial spine --> Passing through the lesser sciatic foramen.
The inferior rectal artery supplies the ...?
Anal canal below the pelvic diaphragm.
The perineal branch supplies muscles in the ...?
Superficial and deep perineal pouches and skin of the:
3. And scrotum.
The artery to the bulb and a deep artery of the penis and clitoris supply ...?
1. Erectile tissues.
2. The bulbourethral gland.
3. The greater vestibular gland.
The dorsal artery of the penis and clitoris supplies ...?
Erectile tissue and skin of the penis and clitoris, respectively.
Pelvic wall branches:
1. The iliolumbar artery.
2. The lateral sacral artery.
The iliolumbar artery ...?
Crosses the pelvic brim to supply the:
2. The psoas major/minor.
3. Quadratus lumborum muscles.
The lateral sacral artery supplies structures in the ...?
Walls of the lesser pelvis and sends branches into the sacral canal through the ventral sacral foramina.
Lower limb branches:
1. The superior gluteal artery.
2. The inferior gluteal artery.
3. The obturator artery.
The superior gluteal artery ...?
Exits the pelvis through the greater sciatic foramen and supplies the gluteus maximus + medius + minimus.
The inferior gluteal artery ...?
Exits the pelvis through the greater sciatic foramen and supplies the gluteus maximus muscle.
The obturator artery ...?
Exits the lesser pelvis with the obturator nerve through the obturator foramen and supplies the medial aspect of the thigh.
The pudendal nerve innervates ...?
1. Skeletal muscles in the pelvic diaphragm.
2. In both perineal pouches of the perineum.
3. The skin that overlies the perineum.
The pudendal nerve is formed by the ...?
Ventral rami of sacral spinal nerves from S2, S3, S4.
Pudendal nerve course ...?
Exits the pelvis superior to the pelvic diaphragm by passing through the greater sciatic foramen --> Crosses the ischial spine --> Enters the pudendal canal after passing through the lesser sciatic foramen.
3 main branches of the pudendal nerve:
1. Inferior rectal nerve.
2. Perineal nerve.
3. Dorsal nerve of the penis.
The inferior rectal nerve - Course:
Branches from the pudendal nerve at the entrance of the pudendal canal --> Crosses ischioanal fossa.
The inferior rectal nerve innervates ...?
1. External sphincter muscle.
2. Skin of the anal canal below the pectinate line.
3. Skin covering the anal triangle.
The perineal nerve has superficial branches, the ...?
Posterior scrotal nerves - Supply skin of the posterior scrotum and posterior labial nerves that supply the skin of the labia majora and vestibule.
The perineal nerve has also a deep branch that innervates ...?
Muscles of the superficial and deep perineal pouches, including:
1. Transverse perineus.
2. Sphincter urethrae.
The dorsal nerve of the penis and clitoris innervates ...?
Skin of the penis and clitoris, respectively.
The pudendal nerve contains ...?
General sensory fibers, including those that convey PAIN from structures in the perineum (the lower part of the vagina, urethra, anal canal below the pectinate line, external genitalia, and skin of the perineum).
The pudendal nerve conveys sensations of ...?
Pain during the 2nd stage of labor that results from stretching or tearing of the lower part of the vagina as the fetus passes through the pelivc and urogenital diaphragms.
A pudendal nerve block may be performed to ...?
Suppress labor pain by anesthetizing the pudendal nerve as it crosses the ischial spine.
The ischial spine may be palpated through the ...?
Lateral wall of the vagina.
Motor functions of the pudendal nerve:
1. Maintains voluntary urinary continence by facilitating contraction of the sphincter urethrae.
2. Maintains voluntary fecal continence by facilitating contraction of the external anal sphincter.
3. Supports pelvic viscera + prevents prolapse.
4. Helps maintain erection of the penis and clitoris.
5. Facilitates expulsion of urine from the penile urethra during micturition and sperm and seminal fluid during ejaculation.
What provides the SNS innervation to the smooth muscle and glands in the pelvis and perineum?
The lower thoracic and lumbar splanchnic nerves.
The lower thoracic and lumbar splanchnic nerves have severe motor functions:
1. Contraction of the sphincter vesicae.
2. Contraction of smooth muscle in the ductus deferens, prostate, and seminal vesicles.
3. Emptying of the secretory products of the bulbourethral and greater vestibular glands.
4. Contraction of the internal anal sphincter.
The internal pudendal artery supplies structures in the ...?
Lower thoracic and lumbar splanchnic nerves carry visceral pain from ...?
1. The fundus.
2. The body.
3. The cervix of the uterus.
4. The upper part of the vagina during the 1st stage of labor.
Lower thoracic and lumbar splanchnic nerves carry visceral pain ALSO from ...?
1. GI structures in the hindgut.
2. From pelvic viscera.
Covered by peritoneum including the bladder and most of the uterus.
Pelvic splanchnic nerves (or pelvic nerves) provide the ...?
PNS innervation to smooth muscle and glands in the pelvis and perineum.
Micturition is mediated by the ...?
The vesical reflex has 2 components:
1. A filling stage.
2. An emptying stage.
The filling stage of the vesical reflex:
During the filling stage --> Stretch receptors in the wall of the bladder that are innervated by sensory fibers in pelvic splanchnic nerves respond to the presence of urine in the bladder and the degree of stretch of the bladder wall.
When the bladder fills, a bladder storage center is activated in the CNS, which ...?
Stimulates SNS nerves to inhibit the detrusor --> Allow further bladder stretching without contraction.
As the bladder fills, the wall of the bladder ...?
Compresses the oblique entry points of the ureters --> Preventing reflux of urine into the ureters.
When does conscious perception of bladder fullness appreciated?
At or near a micturition threshold.
Pain fibers that are stimulated by bladder fullness course with thoracic and lower lumbar splanchnic nerves and refer pain over the ...?
T11 through L1 dermatomes in the lower anterior abdominal wall.
During the emptying stage ...?
The micturition threshold is reached, and a CNS micturition center is activated.
The ... muscle in the male contracts to expel urine from the penile urethra near the end of the micturition.
The nerves involved in the vesical reflex:
1. PNS and SNS fibers.
2. Pudendal nerves.
In surgical procedures involving the prostate, which nerves may be injured?
The cavernous nerves.