Pelvis and Perineum Flashcards
What are the margins of the pelvic inlet?
Sacral promontory
Margin of ala
Sacroiliac joint
Arcuate line
Pectineal line (pecten pubis)
Pubic crest
Pubic symphysis
What are the parts of the linea terminalis?
Pubic crest
Pecten bupis
Arcuate line
What are the boundaries of the pelvic outlet?
Coccyx
Sacrotuberous ligament
Ischial tuberosity
Pubic arch
Pubic body
Pubic symphysis
What are the differences between male and female pelvis?
Hearth shaped inlet in males round in females
Obturator foramina face anteriorly in females
Pubic arch is larger in females (~120 degrees)
Pelvic inlet and outlet are wider in females than males.
Iliac crest is shorter and wider in females than in males.
What is the bulb of the penis/vestibule connected to?
The body of the pubis.
What are the 2 triangles formed when a horizontal line is drawn between ischial tuberosities?
Urogenital triangle (with vaginal opening or urethral opening in females and internal urethral sphincter of the penis)
Anal triangle (with coccyx)
What are the most superficial muscles of the pelvic floor and what do they do?
The ischiocavernosus (from ischial tuberosity to the crus of the clitoris) and the bulbospongiosus (from perineal body to the bulb of the vestibule and body of clitoris).
Ischiocavernosus allows blood to move from the crus of the clitoris to the bulb/glans of the clitoris.
What are the deep muscles of the pelvic floor?
Urogenital diaphragm (external urethral sphincter, and deep transverse perineal)
Pelvic diaphragm (Levator ani, external anal sphincter and coccygeus)
What is the nerve supply of the ischiocavernosus and Bulbospongiosus?
The pudendal nerve
Where does the external urethral sphincter originate and insert?
O - Ischiopubic rami
I - Encircles membranous part of the urethra
What provides the external urethral sphincter with its nerve supply?
Pudendal nerve and spinal nerve of S4
What does the external urethral sphincter do?
Compresses the membranous urethra and relaxed during micturition
What are the origin and insertion and action of levator ani?
O - Ischial spine and pubis
I - Coccyx, wall of urethra, vagina, and anus
A - Supports pelvic viscera and raises the pelvic floor.
What is the origin, insertion and action of coccygeus?
O - Spine of ischium
I - Coccyx and adjacent border of sacrum
A - Supports pelvic viscera and brings coccyx forward
What is the nerve supply of levator ani?
Pudendal nerve
Spinal nerve S4
What is the nerve supply of coccygeus?
Spinal nerve S4 - S5
What is the origin and insertion and action of the ischiocavernosus in males?
O - Ischial ramus and tuberosity
I - Crus of penis
A - Move blood from crura into body of erect penis
What is the origin and insertiona and action of bulbospongiosus?
O - Perineal body and median raphe
I - Perineal membrane and bulb of penis
A - Removal of residual urine from the urethra; Pulsatile ejaculation of semen
What nerve supplies both the bulbospongiosus and ischiocavernosus in males?
The pudendal nerve
What does the pudendal nerve do?
Motor: supplies skeletal muscles of perineum including the external urethral and anal sphincters as well as levator ani.
Sensory: Most skin of the perineum, penis and clitoris.
Where does the pudendal nerve originate and how does it travel?
Originates at sacral plexus at S2 - S4 and travels along the sacrospinous ligament then passes ischial spine (landmark for anaesthetics) and descends from there
