Pelvic Floor Week 14 Outline

• The pelvic floor and perineum have structures that need description
• The pelvic floor has functions that need description
• Pelvic walls need description
• Pelvic reproductive organs need identification, along with their function within the body
• Vascular supply and venous drainage of the perineum need description
• Innervation of the perineum needs description
• Structures within the urogenital and anal triangles of the male and female pelvis need description
• Structures of the male and female external genitalia need description
• Muscles forming the pelvic floor, their functions and their innervation need description
• Perineal muscles, their functions, and their innervation need description
• Sexual response in the male and female pelvis needs description
• Integration of the anatomy with clinical conditions of the pelvis and pelvic floor is important

Pelvic Walls

• Anteriorly: Bodies & Rami of Pubis, and the Pubic Symphysis are present
• Laterally: Obturator Foramen & Membrane, Obturator Internus, and the Tendinous Arch of Levator Ani are present
• Posteriorly: Sacrum & Coccyx, Ligaments of SI joint, and Piriformis are present

Floor

• Separates the pelvic cavity from the perineum
• Superficial Perineal Pouch exists between the perineal membrane and the skin of the perineum
• The perineal membrane is a thick, triangular fascia attached to the pubic arch with a free posterior border
• Deep Perineal Pouch is a triangular region between the pelvic diaphragm and perineal membrane

Muscular Pelvic Diaphragm

• Levator Ani consists of: Pubococcygeus, Iliococcygeus, Puborectalis
• Levator Ani Origin: Body of pubis, tendinous arch of levator ani, and the ischial spine
• Levator Ani Insertion: Perineal body, coccyx, walls of prostate or vagina, rectum, and the anal canal
• Levator Ani Innervation: N. to Levator Ani and Pudendal N.
• Levator Ani Action: Supports pelvic viscera, resists increased pressure, maintains anorectal angle, and reinforces external anal sphincter
• Coccygeus Origin: Ischial Spine
• Coccygeus Insertion: Inferior end of sacrum and coccyx
• Coccygeus Innervation: Ventral rami of S4 and S5
• Coccygeus Action: Supports pelvic viscera, pulls coccyx forward after defecation

Functions of the Pelvic Diaphragm:

• Supports the abdominopelvic organs
• Sphincteric functions for micturition and defecation
• Stabilizes posture and respiration
• Sexual functions

Male Reproductive Viscera:

• Penis is an external organ that surrounds the urethra and is the common outlet for urine and semen
• The body contains 3 columns of tissue
• There are 2 columns of erectile tissue called the Corpus Cavernosa
• There is 1 column of tissue that surrounds the urethra called the Corpus Spongiosum
• The root is the attached portion
• The bulb is a dilated root of corpus spongiosum, surrounded by the bulbospongiosus muscle
• Crus (2) are roots of corpus cavernosa, surrounded by ischiocavernosus muscle
• Prepuce is skin over the glans penis
• Testes produce sperm
• The Epididymis stores sperm and passes it to the Vas Deferens
• The Ductus (Vas) Deferens carries sperm to the ejaculatory duct in the prostate gland
• Ejaculatory ducts empty into the Prostatic Urethra
• Formed by the union of the Vas Deferens and Seminal Vesicles
• Seminal Vesicles secrete fluid to compose semen
• Prostate gland produces thin, milky fluid to compose semen
• Bulbourethral glands are beneath the prostate and add fluid to semen to lubricate the spongy urethra

Female Reproductive Viscera:

• The Uterus includes the body, cervix, and layers
• Round superior end of the uterus = Fundus
• Narrow, inferior region of the uterus = Isthmus
• The implantation of a blastocyst normally occurs in the uterus
• The uterus angles forward over the bladder (anteverted)
• The cervix is the inferior portion of the uterus.
• The end of the cervix bulges into the vagina
• The external Os is the opening to hallowed internal region
• Perimetrium - outer layer of the uterus
• Myometrium - the uterine musculature
• Endometrium - the uterine mucosal lining
• Round ligament supports the uterus in the midline
• Broad Ligament is a double layer of peritoneum and acts like a mesentery for the uterus and keeps uterus centered
• Transverse Cervical Ligaments run from the cervix and lateral fornix of the vagina to lateral pelvic walls
• Uterosacral Ligaments run from the superior and posterior cervix to the sacrum
• The fallopian tubes project laterally from the uterus
• Fallopian tubes connect the ovaries to the uterus
• Mature eggs are ovulated from the ovary and directed into the uterine tube
• Portions of the Fallopian Tubes include the Infundibulum, Ampulla, and Isthmus
• Infundibulum has fimbriae, which are finger-like projections

Ovaries

• Where eggs form and female hormones (estrogen and progesterone) are made
• Ovaries Develop in posterior abdominal wall and migrate to pelvic cavity

Vagina

• Muscular tube extending from the perineum through the pelvic floor and into the pelvic cavity
• Anterior to the Urinary bladder and urethra
• Lateral to the Levator ani and pelvic fascia and ureters
• Posterior to the Anal canal, rectum, and rectouterine pouch

Parts of the Vagina:

• Introitus: external opening
• Vaginal Vault: internal enlargement around the cervix
• Fornix: recess around the cervix; includes anterior, posterior, and lateral (2)

Clitoris

• External sexual organ
• Located in the labia minora
• Includes Root, Body, and Glans Clitoris (clitoral hood)
• Erectile tissue = corpora cavernosa

Perineum:

• Perineal Region and Perineum often used interchangeably in clinical settings
• Inferior to the pelvic aperture, separated from the pelvic cavity by the pelvic diaphragm
• The passage for reproductive tract, urinary tract and GI
• Separated in urogenital and anal triangles
• Urogenital Triangle is anterior between pubic symphysis and ischial tuberosities
• It is "closed" by the perineal membrane
• Urethra, vagina, and penis pass in the urogenital triangle
• Structures function to close the urethra and orifice, close the vagina and introitus, maintain erection, and propel urine and semen in the urethra of males
• The Anal Triangle is posterior between ischial tuberosities and the coccyx
• The anal triangle is the Passage of the anal canal
• Functions to close to the anal
• Perineal Body is the fibromuscular mass between the anal canal and perineal membrane of the urogenital triangle
• The Perineal Body is posterior to the vagina and bulb of the penis, anterior to the anus
• Convergence of several muscles on Perineal Body including bulbospongiosus, external anal sphincter, superficial and deep transverse perineal muscles and the external urethra sphincter and levator ani

Female Urogenital Triangle:

• External genitalia

External Genitalia

• Mons Pubis – fatty eminence anterior to pubic symphysis, pubic tubercle and superior pubic rami
• Labia Majora – prominent folds of skin, provide protection to urethral and vaginal orifices
• Labia Minora – folds of fat-free, hairless skin containing erectile tissue and neurovascular vessels
• Clitoris – erectile tissue
• Vestibule – space within the labia minora
• Urethral Opening (meatus)
• Vaginal Opening (introitus)
• Vestibular glands
• Greater (Bartholin's) – posterolateral to vaginal opening that secretes mucus into the vestibule during sexual arousal
• Lesser (Skene's) – open between the urethral and vaginal openings that secrete to moisten labia and vestibule
• Superficial perineal muscles
  • Superficial transverse perineal
  • Ischiocavernosus
  • Bulbospongiosus
• Deep Perineal Pouch
• Urethra
• External urethral sphincter
• Deep Transverse Perineal Muscle

Male Urogenital Triangle:

• External Genitalia
  • Penis
  • Scrotum - Fibromuscular sac for the testes and associated structures
• Superficial Perineal Pouch
  • Root of penis
  • Spongy urethra
• Superficial Perineal Muscles
  • Superficial Transverse Perineal
  • Ischiocavernosus
  • Bulbospongiosus
• Deep Perineal Pouch
  • Membranous urethra
  • External urethral sphincter
  • Deep transverse perineal muscles
  • Bulbourethral glands

Features of the Anal Triangle:

• Anal Canal & Anus are surrounded by internal and external anal sphincters
  • Internal anal sphincter – smooth muscle, autonomic control
  • External anal sphincter – skeletal muscle, somatic control
• Ischioanal Fossa contains: The anal canal and adipose tissue

Muscles of the Perineum

• Superficial
• External Anal Sphincter
• Origin: Skin and fascia surrounding the anus
• Insertion: Perineal body
• Innervation: Pudendal N. (S2-S4)
• Action: Constricts the anal canal, resisting defecation, supports perineal body and pelvic floor
• Bulbospongiousus
• Males
• Origin: Median raphe on ventral bulb of penis
• Insertion: Perineal membrane, dorsal aspect of corpus spongiosum and cavernosum
• Action: compresses bulb of penis to expel urine/semen, assist erection, supports perineal body and pelvic floor
• Females
• Origin: Perineal body
• Insertion: Pubic arch and fascia of corpus cavernosum of clitoris
• Action: "sphincter” of vagina, assists in clitoral erection, supports perineal body and pelvic floor
• Innervation: Pudendal N. (S2-S4)
• Ischiocavernosus
• Origin: internal surface of ischiopubic ramus and ischial tuberosity
• Insertion: Crus of the penis or clitoris and perineal membrane
• Innervation: Pudendal N. (S2-S4)
• Action: Maintains erection of penis and clitoris
• Superficial Transverse Perineal
• Origin: Internal surface of ischiopubic ramus and ischial tuberosity
• Insertion: passes along posterior perineal membrane toward perineal body
• Innervation: Pudendal N. (S2-S4)
• Action: Supports and fix the perineal body to support abdominopelvic viscera and resist increased pressure

Deep

• Deep Transverse Perineal
• Origin: Internal surface of ischiopubic ramus and ischial tuberosity
• Insertion: Passes along posterior perineal membrane to perineal body and external anal sphincter
• Innervation: Pudendal N. (S2-S4)
• Action: Supports and fix the perineal body to support abdominopelvic viscera and resist increased pressure
• External Urethra Sphincter
• Origin: Internal surface of ischiopubic ramus and ischial tuberosity
• Insertion: Surrounds urethra superior to perineal membrane
• Males - also ascends anterior to prostate
• Females - some fibers enclose the vagina (urethrovaginal spinchter)
• Innervation: Pudendal N. (S2-S4)
• Action: Compresses urethra to maintain urinary continence, relaxes during micturition
• Females – urethrovaginal portion compresses vagina

Perineum Vasculature:

• Supplied by branches of Internal Pudendal A.
• Branch of Internal Iliac A.
• Drained by Internal Pudendal V.
• Drains to Internal Iliac V.

Pelvic Innervation:

• Somatic
  • Lumbosacral plexus: ventral rami L1-S4
  • Branches supply the Lower Extremities
  • Branches supply the Pelvis & Perineum
  • Pudendal N. (S2-S4)
  • 3 Branches - Dorsal N. to the clitoris or penis - Perineal Branch - Inferior Rectal N. Sensory to most of the skin of the perineum, penis and clitoris Coccygeal Plexus: Ventral Rami of S4-CO
  • N.s to Levator Ani, Coccygeus, External Anal Sphincter
  • Sensory to the perianal skin

Sexual Response:

• Male
• Physical Stimulation of the genitals relayed by Pudendal N. (somatic) to CNS
• Pelvic Splanchnic Ns. (parasympathetic) causes vasodilation of deep penile arteries for erectile tissue of the penis and lubrication via bulbourethral glands
• Lumbar and Sacral Splanchnic Ns. (sympathetic) causes seminal fluid to mix with sperm for emission, and rhythmic contraction of smooth muscle along with Pudendal N. stimulating perineal muscles for ejaculation
• Internal urethra sphincter stimulated to contract to prevent reflux of semen into the bladder
• Female
• Physical stimulation of the genitals is relayed by the Pudendal N. (somatic) to the CNS
• Pelvic Splanchnic Ns. (parasympathetic) cause vasodilation for erectile tissue of the clitoris and stimulation of the vestibular glands for lubrication
• During orgasm, Lumbar & Sacral splanchnic Ns. (sympathetic) cause rhythmic contractions of genital organ smooth muscle and Pudendal N. causes rhythmic contraction of perineal muscles