perineums Flashcards
arterial supply of perineum
Via branches of the internal pudendal artery (a branch of the internal iliac)
Branches include:
- inferior rectal artery,
- perineal artery,
- artery of the bulb of the penis,
- deepartery of the penis,
- dorsal artery of the penis
It lies alongside the internal pudendal vein and the pudendal nerve in the pudendal canal at the
lower border of obturator internus muscle of the lateral pelvic/perineal wall
bulbospongiosus muscle
- The bulbospongiosus muscle can contract vigorously during orgasm and this allows ejaculation
to occur. - (These muscles also help to empty the urethra completely at the end of micturition in order to expel as much residual urine as possible)
- Innervated by pudendal S2-4
- surround corupus spongiosum (bulb)
- the central one (bulb)
muscle that surrounds corpora cavernosa
- ischiocavernosus
- covers the crura of penis (& clitoris)
corpora cavernosa
- Placed dorsally
- Attached to the pubic symphysis by the suspensory ligament
- The erectile tissue of the penis
- Invested proximally by the ischiocavernous muscles which restrict venous outflow from the
- penis during erection
- gets blood from deep arteries of penis & dorsal artery << both from INTERNAL PUDENDAL
- filling of the tissue compreses outlet veins> erection
glans
from corpus spongiosum
contains external urethral meatus
buck’s fascia
deep fascia of penis
condenses around pubic symphysis >> suspensory ligament of penis
tunica vaginalis
surrounds testes but defficient posteriorly
spermatic cord
- external spermatic fascia - from e_xternl oblique aponeurosis_
- cremasteric fascia + muscle - from internal oblique
- internal spermatic fascia - from transversalis fascia
- 3 arteries: testicular, cremasteric, vas
- 3 veins accompanying arteries
- 3 nerves: ilioinguinal, genitofemoral, sympathetics T10,11
- 3 otehrs: lympathics, vas, procesus vaginalis remnant (fibrous cord)
testicular veins
form pampiniform plexus around the testicular artery
>> countercurrent heat exchange
drain into testicular vein
right testicualr veins goes to IVC at L2
left testicular vein goes to left renal vein
bulbourethral glands
These glands are situated in the urogenital diaphragm
They secrete a substance into the urethra which prior to the arrival of the ejaculate which gives
it a rather viscous consistency >mucous for lubrication of urethra
venous drainage of prostate
Venous plexus between the true and false prostatic capsules which drains into the internal iliac
vein on either side
Some venous blood drains posteriorly around the rectum to the valve less vertebral veins. This
explains why prostatic carcinoma metastasizes early to the bones of the lumbar spine and pelvis
prostatic relations
Relations of the prostate:
Anteriorly – extraperitoneal fat lying deep to the pubic symphysis
Posteriorly – rectum separated by fascia
Superiorly – continuous with the neck of the bladder
Inferiorly – external urethral sphincter (within the deep perineal pouch)
Laterally – levator ani muscle
lymphatics male perineum
** superficial perineum (**lower anal cnaal, scrotal wall, penis) : SUPERFICIAL INGUINAL NODES
testes, epididymis, vas deferens >> PARA-AORTIC NODES AT L2
lobes of prostate
median lobe (central zone): between ejaculatory ducts and urethra
lateral lobes (right&left zones) main pass, separated by prostatic urethra
posterior lobe (peripheral zone): can be palpated through rectum (often cancer)
scrotal innnervation
anterior skin: L1,2
posterior skin: S3,4
erection
spinal cord reflex with higher control
sensory n of glans via pudendal n. travels to lvl of S3 of spinal cord
efferents are PNS S2-4 (pelvic splanchnics)
ejaculation
Ph1: contraction of smooth muscle in epididymis, vas by SNS L1,2; also c_loses internal urethral sphinctes_
Ph2: contraction of skeletal perineal muscles, propels semen down the urethra
seminal vesicles
alkaline secretion
rich in fructose, protein, yellow pigments
contains prostaglandins
60% semen volume
HCO3- rich
empties in ejacualtory ducts which form where vas deferens &seminal vesicles meet
each is a coiled blid sac, goes upward from prostate, lies between bladder and rectum
prostate secretions
adds 20% volume
rich in citric acid
has acid phosphatase
ductus deferens
OVER external iliac a
BEHIND inf epigastirc a.
OVER ureter
is a muscular tube lined with pseudostratified columnar epithelium
has stereocilia which are NOT motile but absorb fluids
3 layers:
outer Longitudinals, inner circular, outer Longitudinal
pudendal nerve
S2-4
via G sciatic f OUT, via L sciatic F IN
goes via pudendal canal with pudendal artery
has branches: inf. rectal, dorsal n. of penis, perineal
pouches
clitoris
Corresponds somewhat in structure to the penis
Contains 2 corpa cavernosa (erectile tissue) attached to the pubic rami
Its free extremity, the glans, is formed by the corpus spongiosum
ischiorectal(anal) fossae
These are the 2 fat‐filled spaces that lie on either side of the midline of the perineum, between
the anal canal and side wall of the pelvis
Medially – levator ani and external anal sphincter
Laterally – ischial tuberosity below and fascia over obturator internus
above
Anteriorly – perineal body and muscles of the urogenital diaphragm
Posteriorly – sacrotuberous ligament overlapped by gluteus maximus
The fossae do not communicate across the midline due to the presence of the anal canal and
sphincter.
However, they do communicate posteriorly through the retrosphincteric space.
This provides a horseshoe shaped path for the spread of infection from one fossa to the other
- The fossae contain (running along the lateral wall) the pudendal canal of Alcock which contains:
- Pudendal nerve – give branches to the anus, perineal skin and labial region
- Pudendal vessels – give branches to the anus, perineal skin and labial region
nerve supply to pelvic viscera
Pudendal nerve – supplies muscles of the pelvic diaphragm, muscle and skin of the perineum
and external genitalia
Sympathetic innervation – via the i_nferior hypogastric plexus_ which lies medial to the internal
iliac vessels
Parasympathetic innervations – from S2‐4
anterior trunk of internal iliac artery
- Obturator artery ‐ leaves pelvis through obturator canal
- Internal pudendal artery – leaves pelvis through greater sciatic foramen
- Inferior gluteal artery
- Superior vesical arteries
- Inferior vesical artery
- Artery to ductus deferens
- Middle rectal artery
- Vaginal artery
- Uterine artery
posterior trunk of internal iliac artery
- Iliolumbar artery
- Lateral sacral arteries
- Superior gluteal artery
cervical ligaments
The fascia of levator ani thickens in places and each of these thickenings anchors on to the
cervix of the uterus. These thickenings are known as the:
Pubocervical ligament
Transverse cervical ligament
Sacrocervical ligament
These ligaments are under the influence of oestrogen and after the menopause can become
slack which can lead to uterine prolapsed
fallopian tubes
Infundibulum – funnel‐shaped distal end from where the fimbriae project, its opening into the peritoneal cavity is called the abdominal ostium
Ampulla – largest and longest part, begins at the medial end of the infundibulum, it is tortuous and is the usual site of fertilization of the oocyte by the sperm
Isthmus – short narrow part
Intra‐mural/uterine – short segment that passes through the myometrium of
the uterus and opens via an ostium into the uterine cavity
ovaries
It is attached to the broad ligament by a fold of peritoneum called the mesovarium
From its superior pole extends the suspensory ligament of the ovary which is just an extension
of the broad ligament that carries the ovarian vessels in its free border
The ovary develops in the posterior abdominal wall and descends to the pelvis via the
gubernaculums,a fibrous cord connected to its lower pole.
The gubernaculum passes through the broad ligament of the uterus
The ovaries are supplied by the ovarian arteries which descend directly from the abdominal
aorta near the origin of development of the ovaries at the level of L2
Veins draining the ovaries form a plexus around the arteries and this plexus is called the
pampiniform plexus and from it arise the 2 ovarian veins. The right ovarian veins drains into the
IVC whereas the left ovarian vein drains into the left renal vein
