Pelvic And Perineal Myology Flashcards
What is the perineal body?
An irregular fibromuscular mass in the midline between the anal canal and the perineal membrane
Contains collagenous and elastic fibers
Is the attachment point for the bulbospongiosus, external anal sphincter, superficial transverse perineal and deep transverse perineal muscles
Sometimes classified as a central tendon of the pelvic and urogenital diaphragms
What are the superficial perineal muscles?
Superficial most muscles of the perineum
Includes superficial transverse, ischiocavernosus and bulbospongiosus muscles
What is the origin and insertion for the superficial transverse perineal muscles?
O: ischiopubic ramus and ischial tuberosity
I: perineal body
What is the action of the superficial transverse perineal M?
Support and fix perineal body, supports abdominopelvic viscera and resists increases in intraabdominal pressure
What are all superficial perineal muscles innervated by?
Deep perineal N
What is the origin and insertion for the ischiocavernosus muscle?
O: ischiopubic ramus and ischial tuberosity
I: medial aspect of the crus of the penis (male) or clitoris (female) and perineal membrane medial to the crura
What is the action of the ischiocavernosus M?
Maintain erection of penis or clitoris by compressing venous drainage, forcing blood from the crura into the body of the penis or clitoris
What is the origin of the bulbospongiosus M?
Median raphe, ventral bulb and perineal body (male), perineal body (female)
What is the insertion for the bulbospongiosus M?
Perineal membrane, fascia of bulb of penis and corpus spongiosum and corpora cavernosa of the penis (males)
Fascia of bulb of vestibule of vagina, pubic arch and fascia of the corpora cavernosa of the clitoris (female)
What is the action of the bulbospongiosus M?
Support and fix perineal body
Compress bulb of penis, assist erection by compressing venous drainage, forcing blood from the root of the penis to the body of the penis, expels final drops of urine/semen from the urethra (males)
Compresses vaginal orifice, assist in erection of bulbs of vestibule of vagina and compresses the greater vestibular glands (female)
What is the urogenital diaphragm?
Deep to and separated from the superficial perineal muscles by the perineal membrane however it may contain elements of the superficial perineal muscles and perineal membrane
Which muscles make up the urogenital diaphragm?
External urethral sphincter M including compressor urethrae and urethrovaginal sphincter M +
Deep transverse perineal M
What is the origin and insertion for the external urethral sphincter M?
Surrounds the urethra
What is the action of the external urethral sphincter?
Constrict urethra maintaining urinary continence
Which muscles are innervated by the dorsal N of the penis or clitoris?
External urethral sphincter M, compressor urethrae M
Dorsal N of clitoris only = urethrovaginal sphincter M
Which what is the origin and insertion for the compressor urethrae M?
Extends laterally from the external urethral sphincter
O: ischiopubic ramus and ischial tuberosity
I: median raphe and urethra via external urethral sphincter M
What is the action of the compressor urethrae M?
Constrict urethra maintaining urinary continence
What is the origin and insertion for the urethrovaginal sphincter M?
Slips of the external urethral sphincter M that also surrounds the vagina (in females)
O: ischiopubic ramus and ischial tuberosity
I: external wall of vagina
What is the action of the urethrovaginal sphincter M?
Compresses the vagina