Anatomy of the Perineum 4 Flashcards
Identify the parts of the male and female genitalia, their blood supply and innervations, and how they relate to the two diaphragms. Describe the ligaments of the uterus and ovaries and the basic supporting structures for all pelvic/perineal viscera.
1
Q
Describe the branches of the pudendal nerve and their functions.
A
- Ventral rami from spinal nerve segments S2,3,4
- Has typical spinal nerve components
- somatomotor
- general sensory
- post-synaptic sympathetics
-
Three branches
-
inferior rectal
- somatomotor to the external anal sphincter and levator ani
- sensory to skin around anus
-
perineal
- supplies skeletal muscles of UG diaphragm
- sensory to the posterior scrotum or labia
- dorsal nerve of the penis or clitorus (general sensory)
-
inferior rectal
- Parasympathetics for erection are from the pelvic plexus and, not the pudendal nerve
2
Q
What vessels do the pudendal vessels come from? What are the exceptions?
A
- Come from the internal illiac vessels (systemic/caval)
-
Exceptions
- gonads - testicular or ovarian arteries from aorta)
- upper rectum - superior rectal artery is the termination of the inferior mesenteric and vein is one of the three main portal system veins
- penis/clitoris
-
Exceptions
- Deep dorsal veins of penis/clitoris drain under the pubic symphysis into the prostatic or vesicular plexuses in the pelvis first before draining into the internal iliac
3
Q
What makes up the scrotum?
A
- Superficial perinal (Colle’s) fascia
- Dartos (smooth) muscle
- No fat
4
Q
What is the erectile tissues of the penis made up of?
A
- Left and right corpora cavernosa continuous with crura
-
Corpus spongiosum continuous with the bulb of the penis posteriorly and glans penis anteriorly
- Contains the urethra
- Deep penile fascia surrounds and binds together the corpora cavernosum and corpus spongiosum
5
Q
What is the route of sperm during ejaculation (from sympathetic stimulation)?
A
- Testes
- Epididymus
- where sperm are stored
- Vas (ductus) deferens
- Through spermatic cord and inguinal canal
- Joins seminal vesicle ducts to form ejactulatory duct in prostate gland
- Prostatic urethra
- Membranous urethra in UG diaphragm
- Penile urethra
- Navicular fossa in glans penis
6
Q
What are some major structures of the uterus? What are their boundaries?
A
-
Consists of:
- fundus
- ody
- cervix
- Structures found in broad ligament of the uterus (mesometrium)
- upper margin is the mesosalpinx
- mesentery of the uterine tubes
- posterior fold of hte broad ligament is the mesovarium
- mesentery of the ovaries and ovarian ligament
- upper margin is the mesosalpinx
7
Q
Define anteflexion and anteversion.
A
- Anteflexion - angle between the cervix and boy of the uterus
- Anteversion - angle between the uterus and vagina
8
Q
What are the major ligaments in the female reproductive tract? What are their attachments?
A
-
Ovarian ligament
- fibrous cord continuous with the round ligament of the uterus
- passes through the inguinal canal
- both are remnants of the embryonic gubernaculum
- fibrous cord continuous with the round ligament of the uterus
-
Cardinal ligaments
- lateral thickenings of perivascular pelvic fascia
- runs from the ischium to the cervix, vagina, bladder, and rectum
-
Pubovesicular ligament
- dense cord tightly anchoring the bladder (“vesicle”) to the pubic bone
- equivalent to the puboprostatic ligament in the male
9
Q
Where does the ovarian artery derive from?
A
- Direct branch of the aorta
- Anastamoses with the uterine artery
- Branch of the internal iliac
10
Q
Describe the make up and important structures of the vagina.
A
- Smooth muscle sheath with no glands or general sensory innervation
- Top of the vagina forms recesses around cervix of uterus called fornices
-
Posterior fornix is adjacent to rectouterine pout of peritneum
- convenient approach to obtain a sample of peritoneal fluid
11
Q
Where is the vestibule and what are vestibular bulbs?
A
-
Vestibule - space between labia minora and contains opening of:
- urethra
- vagina
- paraurethral glands
- greater vestibular glands
-
Vestibular bulbs
- erectile tissues on either side of the vestibule
- equivalent to male bulb of the penis and corpus spongiosum
- within the bulbospongeosus muscle
- swell during sexual arousal to project the labia minora to help dilate the vestibule
- erectile tissues on either side of the vestibule
12
Q
Compare the clitoris to the male penis.
A
- Similar but consists of one piece with two crura, a body, and aglans clitoris
- Consists of erectile tissue and is equivalent to the male corpus cavernosum
13
Q
What are the labia majora and minora?
A
-
Labia majora
- outermost large fold of superficial body wall
-
Labia minora
- smaller hairless folds devoid of fat
- forms wall of the vestibule inferiorly
- joints to cover the clitoris as its prepuce
14
Q
Describe the three major concepts described in class regarding the sensory innervation of the female genital organs.
A
-
Concept 1
- the more superior the organ, the higher the spinal segment supplying sensation
-
Concept 2
- autonomic vs. somatic routes for sensory fibers
- organs above the pelvic diaphragm are supplied via the pelvic (inferior hypogastric) plexus, which is autonomic
- pelvic diaphragm and everything inferior to it get somatic innervation via the pudendal nerve
-
Concept 3
- only routes for sensory fibers to get into the pelvic plexus are:
- lumbar splanchnic nerves form above - travel with sympathetic fibers
- pelvic splanchnic nerves - travel with parasympathetic fibers
- only routes for sensory fibers to get into the pelvic plexus are:
15
Q
What is the nerve supply of the fundus and body of the uterus?
A
- Highest organs in the pelvis
- sensations of uterine cramping would follow this route
- Sensory fibers are from lower thoracic and lumber spinal segments
- travel mostly with lumber splanchnic nerves that enter the plexus via the superior hypogastric plexus and left and right hypogastric nerves from above
