App 4 Flashcards
What changes occur during pregnancy
Uterus enlarged and stretches upwards into abdominal cavity
Cervix softens and increases in vascular IgG and forms a mucus plug
Divisions of perineum
Ischio anal triangle
Laterally bound by ischial tuberoscities,medically by anal canal and posterior by coccyx
Urogenital triangle
Anterior by pubic symphysis,laterally by ischiopubic rami inferiorly by tip of coccyx
Penis
Penis: Erectile tissue (corpora cavernosa and corpus spongiosum).
Neurovascular Supply: Dorsal nerves, arteries, and veins.
Scrotum testes epidydmis ductus deferens
Scrotum: Contains testes; richly innervated and vascularized.
Testis and Epididymis: Testis produces sperm; epididymis stores sperm.
Ductus Deferens: Transports sperm to the urethra.
Female external genetalia
Clitoris: Erectile tissue; homologous to the penis.
Vulva: External structures (labia, clitoris, vestibule).
Vagina: Muscular tube; richly vascularized.
Ovarian and testicular arteries
Origin: Abdominal aorta.
Course:
Testicular: Passes through the inguinal canal.
Ovarian: Travels in the suspensory ligament of the ovary.
Uterine and vagina arteries
Origin: Internal iliac artery.
Course:
Uterine artery: Travels in the cardinal ligament.
Vaginal artery: Supplies the vagina and vestibule.
Innervation of pelvic and perineal viscera
Autonomic Innervation:
Sympathetic: Hypogastric plexuses.
Parasympathetic: Pelvic splanchnic nerves.
Somatic Innervation: Pudendal nerve for perineal muscles and external sphincters.
Perineum
Anatomical region located inferiorly to main pelvic cavity and is separated by the pelvic diaphragm eg the levator ani and coccygeus muscle
Perineal body
Fibromuscular structure which is an anchoring point supporting integrity of pelvic floor
Attaches
Bulbospongiosus muscle.
Superficial transverse perineal muscle.
Deep transverse perineal muscle.
External anal sphincter.
Levator ani muscle (especially the puborectalis portion).
External urethral sphincter fibers (in some cases).
Where does the urethra pass through in males and females
In females it passes through deep perineal pouch,perineal membrane and superficial perineal pouch before opening in vagina
In males it travels through the penis
How is sperm prevented from moving in a retrograde direction
Internal urethral sphincter
Layers of fascia of urogenital triangle from deep to superficial
Deep perineal pouch- containing the deep transverse perineal muscles and the external urethral sphincter. It also contains the urethra, and the vagina (female) and bulbourethral glands (male).
Perineal membrane- provides attachment sites for the roots of the external genitalia
Superficial perineal pouch- containing the ischiocavernosus, bulbospongiosus and superficial transverse perineal muscles. It also contains the erectile tissue for the penis or clitoris, and the greater vestibular glands (female).
Perineal fascia (deep and superficial)
Skin (openings for the urethra and vagina)
Deep perineal pouch
First layer of perineum the urethra passes through
Main components are sphincters eg in women external urethral sphincter,spinchter urethrovaginalis,compressor urethrae and intrinsic factor antibodies male’s external urethral sphincter. Bulbourethal glands also present
It stabilises the perineal body
Innervated by pudendal nerves S2-S4
Perineal membrane
Separates deep and superficial perineal pouches
Attachment point for roots of external genetalia and muscles of superficial Perineal pouch
Supports pelvic floor
Superficial pouch
Below the perineal membrane is the superficial perineal pouch of the urogenital triangle. The superficial perineal pouch contains many structures including muscles and erectile tissue (penis or clitoris).
Erectile tissue in the superficial perineal pouch
The erectile tissues of the superficial perineal pouch are the penis and the clitoris and they consist of a core of expandable tissue surrounded by a connective tissue capsule. These two seemingly very different structures are actually very similar in make up
Clitoris
The 2 corpora cavernosa (crura) of the clitoris are the attached (to the bone) parts of the clitoris, they converge near to the pubic symphysis to form the body of the clitoris, which is not attached to the bone. Additionally, there are the 2 vestibular bulbs in the superficial perineal pouch, which are also erectile tissue, and they converge to form the glans of the clitoris. The glans of the clitoris is the only visible part of the clitoris in the perineum, however the body of the clitoris can be palpated under the skin. Additionally, there are the greater vestibular glands in the superficial perineal pouch, which secrete mucous into the vestibule of the vulva and around the opening of the vagina.
Penis
The penis is also formed by 2 corpora cavernosa as well as an additional corpus spongiosum (the equivalent to the vestibular bulbs and glans of the clitoris). The corpora cavernosa form the dorsal side, whilst the corpus spongiosum forms the ventral side of the penis. The corpus spongiosum is not erectile tissue as it contains the penile urethra (if this was erectile tissue it would compress the urethra inside it and prevent ejaculation). The corpus spongiosum expands distally to form the glans of the penis
Innervation for erection
The innervation of erection of the clitoris/penis comes from parasympathetic fibres of the pelvic splanchnic nerve
Blood flow from internal pudendal artery
Muscles in the superficial perineal pouch
Ischiocavernosus (associated with root of penis/clitoris)- moves blood from crura of penis/ clitoris into the body of the penis/ clitoris during erection
Bulbospongiosus (associated with root of penis/clitoris)- move blood into the glans of the clitoris or penis and assists with movement of residual urine/ semen from the penile urethra
Superficial transverse perineal muscle (associated with perineal body)- stabilise the perineal body
Perineal fascia
The perineal fascial layers are continuous with layers of abdominal fascia. The deep perineal fascia covers the muscles and erectile tissue of the superficial perineal pouch. The superficial perineal fascia is continuous with the superficial fascia of the anterior abdominal wall
Vulva and associated structures
The clitoris and vestibular bulbs along with connective tissue and skin folds form the vulva. The area where the urethra and vagina open is called the vestibule, and either side of this are two folds of (hairless) skin called the labia minora. The labia minora unite anteriorly around the body and glans of the clitoris to form the frenulum and prepuce of the clitoris. Posteriorly the labia minora unite to form the frenulum of the vagina. Lateral to the labia minora are the labia majora which are larger folds of skin (with hair). The labia majora unite anteriorly at the mons pubis, and they do not unite posteriorly forming the posterior commissure (a surface marking for the perineal body lying deep to this area).
Where do paraurethral and greater vestibular glands drain
Via ducts at urethral opening
Opening of vagina for latter
Scrotum
The scrotum is homologous to the labia majora in terms of their embryonic development, however during development the scrotum fuses in the midline to form a single scrotum into which the testes and their coverings and neurovasculature descend. The line of fusion in the scrotum forms the raphe in the midline extending from the anus, over the scrotal sac and to the inferior aspect of the penis.
Where is the external urethral orifice found
The external urethral orifice is located on the glans of the penis. The base of the glans forms a raised circular margin called the corona of the glans. The depression just below the corona is called the neck of the glans and it is from here a fold of skin usually arises which covers the glans, the prepuce of the glans (aka the foreskin).
Ischioanal fossa
Wedge shaped spaces that sit on either side of anal canal to expand during defecation (fat filled)
Pudendal nerve s2-s4 and internal pudendal nerve travel through here
