Pelvis Viscera - Perineum & Neurovascular Supply

what are the layers of the pelvic floor from deep to superficial?

peritoneum → endopelvic fascia → pelvic viscera → pelvic diaphragm → perineal membrane → superficial and external genital muscles (sphincters) → vulvar skin

what are the characteristics of the external sphincter muscles?

muscle type: striated muscle

control: voluntary

innervation: pudendal nerve

function: allows for conscious control over opening and release

what are the characteristics of the internal sphincter muscles?

muscle type: smooth muscle

control: involuntary

innervation: autonomic and enteric nervous systems

function: maintains resting tone and initial closure of the opening

what are the ureters?

muscular (smooth) tubes running from kidneys to bladder 25-30cm long

the tube that carries urine from the kidney to the bladder

what are the characteristics of the urinary bladder?

a hollow container surrounded by a strong smooth muscular wall

temporary reservoir for urine, a healthy bladder can hold about 500 ml of urine

the bladder wall has three main layers: the muscularis propria, serosa, and adventitia. the muscularis propria is a thick layer of smooth muscle that contracts to expel urine

trigone - a triangular area at the base of the bladder that’s formed by three openings: ureteric orifices, internal urethral opening

what are the characteristics of the male urethra?

the male urethra is a crucial component of the male genitourinary system

the male urethra can subdivide into four parts: pre-prostatic urethra, prostatic urethra, membranous urethra, spongy urethra

function of the male urethra is to allow passage of urine and semen

what are the characteristics of the female urethra?

the female urethra is a short tube that carries urine from the bladder out of the body

the female urethra is about 1.5 inches (3-4 cm) long

the urethra starts at the neck of the bladder, goes through the pelvic floor, and opens into the vestibule, the area between the labia minora. the urethral openings is in front of the vaginal opening and behind the clitoris

internal urethral sphincter is where urethra leaves bladder and external is in the pelvic floor

what are the ovaries?

a pair of female reproductive organs that produce hormones and store and release eggs

what is the uterus?

a hollow muscular organ located in the female pelvis between the bladder and rectum

what are the uterine (Fallopian) tubes?

one of two long, slender tubes that connect the ovaries to the uterus. eggs pass from the ovaries, through the fallopian tubes, to the uterus

what is the cervix?

the lower, narrow end of the uterus (womb) that connects the uterus to the vagina (birth canal)

what is the vagina?

the elastic, muscular reproductive organ of the female genital tract

what is the ductus deferens?

muscular tube in the male reproductive system that transports sperm from the epididymis to the urethra

what is the seminal vesicle?

glands that produce the fluids that will turn into semen

what is the ejaculatory duct?

two tubes in the male reproductive system that carry sperm and fluids into the urethra during ejaculation

what is the prostate gland?

male reproductive organ that produces fluid for semen and helps expel it during ejaculation

what are the bulbourethral glands?

a small, pea-sized gland in the male reproductive system that secretes a fluid to lubricate the urethra and neutralize urine

what are the arteries of the lesser pelvis in females?

6 main arteries enter:

paired internal iliac, paired ovarian, superior rectal, median sacral

what are the arteries of the lesser pelvis in males?

4 main arteries enter:

paired internal iliac, superior rectal, median sacral

what is the anterior division of the pelvic vasculature?

umbilical artery (ligament)

obturator artery

inferior vesical or vaginal artery

uterine artery

middle rectal artery

internal pudendal artery

inferior gluteal

what is the posterior division of the pelvic vasculature?

iliolumbar artery

lateral sacral artery

superior gluteal

what are the contents of the anal triangle?

the anus (posterior)

what are the contents of the urogenital triangle?

(anterior) contains the root of the scrotum and penis in males or the external genitalia in females

what is the perineal membrane?

it stretches between the two sides of the pubic arch and covers the anterior part of the outlet

what is the perineal body?

an irregular fibromuscular mass located between the anal canal and the perineal membrane

what is the perineum and its boundaries?

diamond shaped area - lies inferior to the pelvic outlet and is separated from the pelvic cavity by the pelvic diaphragm (levator ani and coccygeus muscles)

bounded by:

pubic symphysis (anterior), inferior pubic rami and ischial rami (anterolaterally), ischial tuberosity (lateral), sacrotuberous ligament (posterolaterally), sacrum and coccyx (inferior)

what is the origin, insertion, and innervation of bulbospongiosus?

male origin: perineal body, median penile raphe

female origin: perineal body

male insertion: perineal membrane, dorsal aspect of corpus spongiosum and corpora cavernosa, fascia of bulb of penis

female insertion: pubic arch, fascia of corpora cavernosa and clitoris

innervation: deep branch of perineal nerve (of pudendal nerve) (S2-4)

what is the origin, insertion, and innervation of ischiocavernosus?

origin: ischial tuberosity and ramus

insertion: crus of clitoris or penis

innervation: deep branch of perineal nerve (of pudendal nerve) (S2-4)

what is the origin, insertion, and innervation of superficial transverse perineal?

origin: ischial tuberosity and ramus of ischium

insertion: perineal body, the central tendon of the perineum

innervation: deep branch of perineal nerve (of pudendal nerve) (S2-4)

what are the posterior division nerves of the sacral plexus?

superior gluteal (L4, 5, S1)

inferior gluteal (L5, S1, 2)

common fibular (L4, 5, S1, 2) (aka peroneal)

what are the anterior division nerves of the sacral plexus?

tibial (L5, S1-3)

pudendal (S2-4)

what are the nerves of both divisions of the sacral plexus?

lumbar sacral trunk (L4, L5)

sciatic (L4-5, S1-3)

posterior femoral cutaneous (S1-3)

what are the small somatic nerves of the sacral plexus?

branch to quadratus femoris and inferior gemellus (L4-5, S1) (ant. divison)

branch to obturator internus and superior gemellus (L5, S1-2)

nerve to piriformis (S1-2) (posterior division)

pudendal nerve (S2-4)

what are the nerves of the coccygeal plexus?

from S4-5, Co1 ventral rami

nerve to levator ani

coccygeus

external sphincter muscles

anococcygeal nerve

pelvic splanchnic nerves

pudendal nerve

what are the characteristics of the pudendal nerve?

S2-S4 (somatic)

passes between the piriformis and coccygeus muscles

leaves pelvis via greater sciatic foramen

reenters via lesser sciatic foramen

gives off the inferior rectal nerves, the perineal nerve, and the dorsal nerve of the penis or clitoris

variations are possible, may come off sciatic nerve

subject to compression

what are the four routes of the pelvic autonomic nervous system?

sacral sympathetic trunks (lumbar)

periarterial plexuses

hypogastric plexuses

pelvic splanchnic nerves (parasympathetic)