Anatomy part 3 Flashcards
The perineum lies inferior to the … … and is the area between your … and …
pelvic diaphragm (pelvic floor)
anus and external genitalia
What external features are part of the
- male (4)
- female (4)
perineum
Male - penis, urethra, scrotum, anus
Females - vulva, urethra, vagina, anus
The perineum anatomically is diamond shaped and can be split into 2 triangles, with the base of each triangle being a transverse line that joins
the 2 ischial tuberosities
The perineum anatomically is diamond shaped and can be split into 2 triangles
Which triangle lies inferior to the pubic symphysis and which triangle is associated with the coccyx
Urogenital triangle
Posterior anal triangle
The anal opening is located centrally in the posterior anal triangle with what on either side
ischioanal fossae
The urogenital triangle contains many layers
One of the deeper layers is a layer of tough fascia that divides the triangle into a superficial and deep perineal pouch; it is perforated by the vagina + urethra in females and the uretraa and ducts of the bulbourethral glands in males
What is this layer called + what is its function
Perineal membrane - provide attachment for the muscles of the external genitalia
List the muscles of the perineum (6)
External anal sphincter External urethral sphincter Bulbospongiosus Ischiocavernosus Superficial transverse perineal Deep transverse perineal
What is the perineal body
A fibromuscular mass formed by all the perineal muscles attaching centrally where the urogenital and anal triangle meet
- external anal sphincter
- bulbospongiosus
- superficial and deep transverse perineal muscle
- levator ani
- external urinary sphincter
All the perineal muscles are innervated by
A branch of the pudendal nerve
External anal sphincter
- innervation
- function
Branch of pudendal nerve
Constrict anal canal to maintain continence
Bulbospongiosus
- innervation
- function (males/females)
Branch of pudendal nerve
Males - compresses bulb of penis to expel remaining urine from urethra after micturition
Females - constricts the vaginal opening
Ischiocavernosus
- innervation
- function
Branch of pudendal nerve
Maintains erection of penis/clitoris
Superficial + deep transverse perineal
- innervation
- function
Branch of pudendal nerve
Fix perineal body in the centre of the perineum to support the abdominopelvic organs
External urethral sphincter
- innervation
- function
Branch of pudendal nerve
Maintain urinary continence by constricting urethra
Clinical significance of the perineal body
Maintains the integrity of the pelvic floor, esp in females as its rupture during childbirth in females predisposes to prolapse of pelvic organs
The perineal body can rupture during childbirth
What can be done to prevent excessive tearing of the perineum and its muscles
Episiotomy
What are the layers of the urogenital triangle from deep to superficial
The external urethral sphincter is first found in which of these layers
Deep perineal pouch –> perineal membrane –> superficial perineal pouch –> perineal fascia
Deep perineal pouch then pierces the perineal membrane
Internal urethral sphincter
- innervation
- function
Sympathetic fibres from T10-L2
Constrict proximal urethra to maintain urinary continence
The ischioanal fosse mainly contain + function
fat + connective tissue
allow anal canal to expand during defaecation
Why may abscesses form in the ischioanal fossa
Pus from perianal abscesses can traverse through the external anal sphincter into the ischioanal fossa
A neurovascular bundle enters the ischioanal fossa on its lateral wall - what does this bundle consist of
Pudendal canal - pudendal nerve, internal pudendal a + v
What are the component parts of the penis
Foreskin (prepuce) Urethra Glans Corpus spongiosum Corpora cavernosa
Penis can be divided into 3 parts - root, body and glans
In the root, the erectile tissues are known as the left and right crura and the bulb of the penis
The crura continue into the body of the penis and become the … and the bulb becomes the …
Crura –> corpora cavernosa
Bulb –> corpus spongiosum
The urethra runs through what erectile tissue of the penis
Corpus spongiosum
Distally, the corpus spongiosum expands to form the
glans
Penis
- innervation
- arterial supply
Motor + sensory - pudendal nerve
Parasympathetic - cavernous nerves
Branches of internal pudendal artery
Lymphatic drainage of penis
Superficial inguinal nodes
Components of the female external genitalia (6)
Vulva - collective term for:
- mons pubis
- labia minora
- labia majora
- clitoris
- vestibule (area enclosed by the labia minora containing the vaginal and urethral orifice)
- greater vestibular (bartholin’s) glands
Where are the greater vestibular glands + function
On either side of the vaginal orifice
Secrete mucous to lubricate vagina
What are the 2 elongated masses of erectile tissue on either side of the vaginal opening called
Bulbs of the vestibule - equivalent to bulb of penis
