Flashcards in The Perineum Deck (33):
What are the two triangles of the perineum called?
Urogenital triangle and anal triangle
Which structures form the borders of the perineum?
Anterior border = inferior border of pubic symphysis
Lateral border = ischial tuberosity
Posterior = tip of coccyx
Which triangle in the perineum consists of many layers of tissue?
What does the deep perineal pouch contain in females?
Proximal part of urethra, mass of smooth muscle, dorsal neurovasculature of clitoris
What does the superficial pouch in females contain?
Clitoris, ischiocavernosus muscle, bulbs of vestibule (bulbospongiosus), greater vestibular glands (Bartholin's gland), superficial transverse perineal muscle
Outline the order of layers in the urogenital triangle
Skin --> superficial perineal fascia (1. superficial fatty tissue Campers, 2. Colles' fascia which is membranous layer) --> deep perineal fascia and muscle (including superficial then deep pouches)
What are the anatomical borders of the anal triangle?
Coccyx, sacrotuberous ligament (laterally) and an imaginary line between the ischial tuberosities (to separate from urogenital triangle)
What are the anatomical borders of the urogenital triangle?
Pubic symphysis anteriorly, ischiopubic rami and sacrotubuerous ligaments laterally and imaginary line posteriorly between the ischial tuberosities.
Describe the blood supply to the perineum
Common carotid artery --> internal iliac artery then descends giving rise to the superior and then inferior gluteal arteries. The final branch of the interior iliac artery is the internal pudendal artery which then branches further to form the arteries of the perineum: inferior rectal, perineal and dorsal clitoral/penis
Describe the nervous supply to the perineum
Mainly from the pudendal nerve (S2,4 and 4 keeps the shit off the floor)
What structures does the anal triangle contain?
Contains the ischioanal fossa, which is lateral to the anal canal. On the lateral wall of this fossa is the obturator internus muscle which contains the pudendal canal (contains internal pudendal vessels and nerve).
Describe the contents of the superficial pouch in males
Root of penis, crura, ischiocavernous, bulbospongiosus, proximal part of spongy urethra and superficial transverse perineal muscles
Describe the contents of the deep pouch in males
external urethral sphincter, deep transverse perineal muscle, membranous portion of urethra, bulbourethral gland
In males, what causes the moistening of the external urethral orifice?
Stimulation of the Cowper's glands
Describe how nervous stimulation leads to the development of an erection
Parasympathetic outflow (S2-S4) goes to hypogastric plexus and causes the release of NO which leads to vasodilatation and engorgement. The pressure created is further accentuated by the ischiocavernosus and bulbospongiosus muscle action.
What is another name for the bulbourethral gland?
Which organs, in males, secrete fluids into the ejaculatory duct?
Seminal vesicles, prostate gland and bulbourethral glands
Describe how nervous stimulation leads to ejaculation
There is stimulation of sympathetic fibres to the smooth muscle of the ducts of the epididymis, vas deferens, seminal vesicles and prostate alongside rhythmic contractions of bulbospongiosus muscles (and bladder sphincter contracts involuntarily)
Describe the attachments of the crura in male anatomy
These are attached to the pubic arch and lie along the dorsum of the penis (form part of corpus cavernosum)
What is the prepuce?
Describe the attachments of the prepuce in male anatomy
The prepuce/foreskin covers the glans penis (head) and is connected to the glans by the frenulum
Describe the attachments of the bulb of the penis
Bulb of penis is attached to urogenital diaphragm (pelvic floor) and is transversed by urethra
Describe the attachments of the erectile tissue in males
There are 2 dorsal corpus cavernosa and 1 ventral corpus spongiosum (expands up to form glans penis)
What type of urethra is present in the penis shaft?
What are the 4 different names for parts of the urethra?
Pre-prostatic, prostatic, membranous and spongy
Describe the location of the pre-prostatic urethra
Vertical through the neck of the bladder
Describe the location of the prostatic urethra
Descends through anterior prostate
Describe the location of the membranous urethra
Descends through the deep perineal pouch
Describe the location of the spongy urethra
Courses through the corpus spongiosum
What is the role of the ischiocavernosus muscle?
It covers and compresses the crura in order to assist erection in women and men (penis or clitoris)
What is the function of the bulbospongiosus muscle?
Females: ejects clitoris and reduces size of vaginal orifice
Males: compresses urethra and dorsal vein, involved in ejaculation
What is the role of Bartholin's gland?
Secretes lubricating mucus at vaginal orifice through small ducts that pen in the posterior vestibule