Perineum anal triangle

1. Perineum
Dr. Mohamed Elfiky
Professor of anatomy and embryology

2. Perineum
Dr. Mohamed Elfiky
Professor of anatomy and embryology
Ischio-rectal fossa , pelvic
floor and blood supply of
pelvis and perineum

3. Symphysis pubis
Tip of sacrum
Ischial tubersity Ischial tubersity
Urogenital Triangle
Anal Triangle
Anal Canal Ischio-rectal fossa
Urogenital
triangle
Anal
triangle
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4. Mohamed el fiky
LEVATOR ANI
PELVIC CAVITY
PERINEUM

5. Right
ischiorectal foss
Left
ischiorectal
foss
Ischio-rectal Fossa
Anal Triangle
Mohamed el fiky

6. Mohamed el fiky

7. Shape & position :
- It is a wedge - shaped space situated one on each side of the anal canal. - It has an apex (directed upwards) , base ( directed
downwards) & 4 walls (ant. , post., med. & lateral).
Ischio-rectal Fossa
Boundaries:
(1) The Base : directed downwards & formed by the
perineal skin and fascia on the side of the anal orifice.
(2) The Apex: directed upwards (forming the edge of the
wedge) it is formed by the meeting of the med & lat.
walls of the fossa i.e the origin of levator ani from the
obturator facia.
(3) Ant-wall: formed by the post. border of the perineal
membrane & the superficial & deep transversus perinei
muscles (superficial & deep to the membrane).
(4) Post-wall: formed by the sacrotuberus lig. and the
lower border of gluteus maximus m. (overlapping the lig)
(5) lat-wall: (vertical): formed by the obturator internus
m. & the obturator fascia covering it including the
pudendal canal.
(6) Medial wall: sloping, formed by : the levator ani m.
(in the upper 2/3) & the external anal sphincter ( in the
lower 1/3)
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8. Contents of the Ischio-rectal fossa
(1) Semiliquid pad of fat: allows distension of the anal canal
during defecation.
(2) Inferior rectal nerve:
• Arises from the pudendal n. in the post part of the pudendal
canal It traverses the fossa from lat. to med where it enters
the ext anal sphincter (supplying it).
(3) Inf. .rectal artery & vein:
Arise from the internal pduendal vessels in the pudendal
canal Accompany the inf. rectal n. across the fossa to
reach the anal canal & the skin around the anus.
(4) Scrotal (labial) nerve & vessels:
• Arise in the pudendal canal in the lat. wall of the fossa.
• They pass forwards in the ant. part of the fossa to reach the
superficial perineal pouch.
(5) perineal branch of S4 :
• pierces the coccygeus muscle to enter the post. part of the
ischiorectal fossa.
• It supplies the ext. anal sphincter & the skin behind the
anus.
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9. Dorsal nerve of penis or clitoris
Internal pudendal
vessels
Pudendal Nerve
Posterior scrotal
nerves
Origin: arises as one of the 2 terminal branches of the sacral plexus S.2, 3, 4.
Termination: ends in the pudendal canal by dividing into 2 terminal branches:
(1) Darsal n. of penis. (2) Perineal n.
Course & relations:
(1) It accompanies the internal pudendal artery as far as the pudandal canal
in the lat. wall of ischio-rectal fossa having the same course.
(2) It ends in the posterior part of the pudendal canal by dividing into its 2
terminal branches.
Branches of Pudendal n.:
(1) Inf. rectal n.: arises in the pudendal canal near its beginning & traverses
the ischio-rectal fossa from lat. to med. It supplies:
(a) Inf. surface of levator ani m. (b) External anal sphincter.
(2) Perineal n.: the larger of the 2 terminal branches of pudendal n. It divides
into:
(a) Scrotal (or labial) branches which run fowards to supply the skin of
scrotum or labium majus.
(b) Muscular branches: to all perineal muscles & sphircter urethrae.
(3) Dorsal n. of penis: (the smaller of the 2 berminal branches) : pierces the
ant. part of the perineal membrane to enter the superficial perineal pouch,
where it runs on the dorsum of the penis lat. to the dorsal a. It supplies
sensory fibers to the penis.

10. Dorsal Nerve of Penis
Pudendal Nerve
Posterior Scrotal Nerves
Inferior Rectal Nerve
Perineal Nerve
Pudendal Nerve
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11. Deep and dorsal arteries of penis
Internal pudendal artery
Origin : it arises inside the pelvis as one of the 2 terminal branches of the
ant. division of internal iliac artery.
Course & relations:
(1) It leaves the pelvis : through the greater sciatic foramen below
piriformis m., to reach the gluteal region.
(2) In the gluteal region: it crosses the back of the ischial spine between the
pudendal n. medially & n. to obturator internus laterally.
(3) It leaves the gluteal region & enters the lesser sciatic foramen to reach
the perineum accompanied by the pudendal n.
(4) It enters the pudendal canal (in the lat. wall of the ischio rectal fossa)
form its post. end then runs forwards.
(5) Then, it enters the deep perineal pouch where it ascends along the
side of the pubic arch.
Termination: it ends by piercing the perineal membrane a short distance
below the symphysis pubis & dividing into deep & dorsal arteries of penis.
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12. Posterior Scrotal Arteries
Perineal artery
Inferior rectal
artery
Dorsal artery of penis
Deep artery of penis
Artery of the bulb of penis
Urethral artery
Branches of Internal pudendal artery
(1) Inf. rectal a.: arises in the post. part of the
pudendal canal. It traverses the ischio-rectal
fossa from lat. to med. to reach the anal canal
(supplying it).
(2) Scrotal (or labial) arteries: run in the
superficial perineal pouch accompanying the
corresponding nerves to supply the scrotum (or
labium majus).
(3) Artery of bulb: arises in the deep perineal
pouch & pierces the perineal membrane to enter
the bulb of penis.
(4) Deep artery of penis: one of the 2 terminal
branches after piercing the perineal memb. It
enters the crus of the penis to supply it.
(5) Dorsal artery of penis : the other terminal br.
of pudendal a. . It runs along the dorsal surface
of the penis.
Mohamed el fiky

13. Definition:
It is a fascial tunnel in the lat. wall of the ischiorectal fossa transmitting the
pudendal n. & internal pudendal vessels.
Site & extent :
It lies just above the sacrotuberous lig. extending from the lesser sciatic foramen
to the post. border of the perineal membrane.
Formation:
It is formed by the splitting of the fascia covering the obturator internus m. below
the tendinous arch-into 2 layers that envelop the pudendal n. & int. pud. vessels .
Contents:
(1) pudendal n. : in the post. part of the canal, pudendal n. gives off the inf.
Rectal n. And then soon divides into a larger perineal n. & a smaller dorsal n. of
penis (or clitoris).
(2) Internal pudendal vessel: The int. pudendal a. gives off its inf. rectal branch
in the post-part of the canal. In the ant-part of the canal, the artery gives its
scrotal (or labial) branch.
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14. WALL OF PELVIC CAVITY
1) Anterior pelvic wall
2) Lateral pelvic wall
3) Posterior wall
4) Pelvic floorMohamed el fiky

15. PELVIC FLOOR
§ Pelvic floor is formed by pelvic
diaphragm which is composed of
Levator ani and Coccygeus
Origin: The muscle has a linear origin, which is
quite extensive and comprises of the following
structures:
Back of the body of pubis
Tendinous arch, which is formed by
thickening of fascia covering the
obturator internus muscle
Spine of ischium
LEVATOR ANI MUSCLE
Insertion:
From the extensive origin described above, the fibers sweep downward and medially to their insertion in three groups.
Anterior fibers :
The anterior fibers form the levator prostatae in males and sphincter vaginae in females. They form a sling around the
prostate or vagina respectively and are inserted the perineal body, in front of the anal canal.
The levator prostate, which is present in males supports the prostate gland and stabilizes the perineal body. The
sphincter vaginae, which is present in females, constricts the vagina and stabilizes the perineal body.
Mohamed el fiky

16. LEVATOR ANI MUSCLE
• Intermediate fibers: ( puborectalis and pubococcygeus )
These fibers form the puborectalis and pubococcygeus parts of the levator ani. Puborectalis is in the form of a sling lying around
the junction of rectum and anal canal. Pubococcygeus passes posteriorly towards the coccyx and is inserted into a small fibrous mass
called the anococcygeal body. The anococcygeal body lies between the tip of coccyx and anal canal.
• Posterior fibers (Iliococcygeus ) :
Posterior fibers form the iliococcygeus part of the muscle. It is inserted into the anococcygeal body and the coccyx
• Nerve supply:
• Levator ani muscle is innervated by the perineal branch of the fourth sacral nerve. It also receives nerve fibers from the perineal branch
of pudendal nerve.
• Action:
1. The levatores ani of the two sides collectively form an efficient muscular support for pelvic viscera and thus helps them stay in position.
2. The sling-like and sphincter-like portions of the muscle have important role in continence.
3. In addition, it also resists the rise in intra-pelvic pressure during the staining and expulsive efforts of the abdominal muscles.
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17. PELVIC BLOOD VESSLS

18. Internal Iliac Artery
External Iliac Artery
Common Iliac Artery
Aorta
anterior
posterior
A- Internal Iliac Artery
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19. Beginning: begins opposite the sacroiliac joint as one of terminal branches of the
common iliac artery. It is 4 cm long.
Termination: it ends at the upper margin of the greater sciatic foramen by dividing
into ant. & post. divisions.
Branches of Int. iliac artery
(A) Branches from the post. division : (Common in both sexes)
(1) Ilio lumar a.
(2) Lateral sacral arteries (all are parietal)
(3) Sup. gluteal a.
(1 ) Ilio-lumbar a. : Passes upwards & laterally in front of the sacro- iliac
joint, disappears deep to psoas major m., where it divides into 2 branches :
(a) Iliac br.: runs laterally deept to iliacus m. & divides into branches supplying this muscle.
(b) Lumbar br.: passes upwards between psoas major & quadratus lumborum supplying them.
(2) Lateral sacral arteries:
- These are 2 arteries which pass medially towards the ant. sacral foramina where each a.
divides into 2 branches.
- Each one of the resulting 4 arteries passes through an ant. sacral foramen to supply the
contents of the sacral canal.
- The terminal branches of these sacral arteries finally pass throught the post sacral foramina to
supply the muscles of the back.
Internal Iliac Artery
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20. (3) Superior gluteal a.:
• It is the continuation of the post division of int iliac a
•• It passes between the lumbo-sacral trunk & the first sacral n.
•• Then it leaves the pelvis by passing through the greater sciatic
•foramen above the piriformins muscle to reach the gluteal region (see lower limb) .
B- Branches of the ant. division of internal iliac a.
(I) Parietal branches
(1) Obturator a.
(2) Internal pudendal a.
(3) Inf. gluteal a.
(II) Visceral branches
(1) Umbilical a. & its sup. vesical branches
(2) Middle rectal a.
(3) Inf. vesical a. in the male (replaced by the vaginal a . in the female).
(4) Uterine a. in the female.
(1) Obturator a.: Run forwards on the lat. wall of the lesser pelvis below & behind
the obturatror n.
• Passes through the obturator canal to enter the thigh. Branches:
(a) Pubic branch: ascends behind the sup. pubic ramus to anastomose with the
pubic br. of inf. epigastric a.
N.B: abnormal obturator a. may replace that artery.
(b) Vesical branch to the urinary bladder.
(c) Ant. & post. terminal branches outside the pelvis (deep to obt. externus m. )

21. (2) Inferior gluteal a . :
• One of the 2 terminal branches of ant. division of internal iliac a.
• Leaves the pelvis through the greater sciatic foramen below
piriformis.
• Enters the gluteal region to supply the gluteal muscles & shares in the
formation of iliac, cruciate & trochanteric anastomoses.
(3) Internal pudendal a. :
•• It is the second terminal br. of ant. division of int. iliac a.
•• Course & relations: See perineum.
(4) Umbilical a:
It is the highest br . of ant. division of internal iliac a .
It passes forwards on the side wall of pelvis then ascends upwards on the back of
ant. abd. wall as far up as the umbilicus
Its proximal part (1-2 cm.) is patent & gives off the sup. vesical a. to supply the
upper surface of the urinary bladder.
Its distal part is obliterated & called the lat. umbilical lig.
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22. (5) Middle rectal a.:
• Runs medially to reach the middle part of the rectum.
• It supplies the rectum as well as the seminal vesicale & prostate.
• It anastomoses with the sup. & inf. rectal arteries.
(6) Inferior vesical a.:
• Supplies the base of the urinary bladder, seminal vesicle, lower part of the
ureter & prostate.
• It gives origin to the artery of vas deferens.
• In the female, this a. is replaced by the vaginal a.
(7)Vaginal a.:
Runs forwards & medially on levator ani then descends on the vagina. it also
sends branches to the inf. lat surface of the urinary bladder.
(8)Uterine a.: passes at first medially in the post attached border (root)
of the broad lig., crosses above the ureter ( 1 lat to the cervix) then
ascends in the med. border of the lig. & finally turns laterally in the
messosalpinx just below the fallopian tube. Mohamed el fiky

23. 1- Iliolumbar Artery
2- Lateral Sacral Arteries
3- Superior Gluteal Artery
S1
S2
Branches of Internal Iliac Artery
i- Branches of The Posterior Division
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24. 1- Obturator Artery
S1
S2
pubic branch
vesical branch
ii- Branches of The Anterior Division
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25. 2- Umbilical Artery
The Lateral Umbilical Ligament
The Umbilicus
Superior Vesical Artery
ii- Branches of The Anterior Division
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26. 3- Inferior Vesical Artery (males only)
S1
S2
4- Vaginal Artery (females only)
5- Middle Rectal
ii- Branches of The Anterior Division
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27. 6- Internal Pudendal Artery
Ischial Spine
Pudendal Nerve
7- Inferior Gluteal Artery
ii- Branches of The Anterior Division
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28. 8- Uterine Artery
Ureter
Root of Broad Ligament of the Uterus
Cervix
ii- Branches of The Anterior Division
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