Download MBBS (Bachelor of Medicine and Bachelor of Surgery) Latest Perineum Lecture PPT
General Boundaries
? Where is it?
? The perineum lies inferior to the pelvic outlet.
? It is physically separated from the pelvic cavity by the pelvic
diaphragm.
? In the anatomical position, it is the narrow region between
the proximal thighs.
? In the lithotomy position, its a diamond shaped area.
? It is a diamond-shaped area extending from
? The mons pubis anteriorly,
? The medial surfaces (insides) of the thighs laterally,
? The gluteal folds and superior end of the intergluteal
(natal) cleft posteriorly .
Definitions
The perineum is the specific portion of the pelvic region that contains
the external genitalia and the anal opening.
The perineum (perineal compartment) is bounded by the pelvic outlet
and is separated from the pelvic cavity by the pelvic diaphragm, which is
formed by the levator ani and coccygeus muscles.
The perinieum consists of structures that fill inferior aperture of pelvis.
The pelvic outlet is diamond-shaped and can be divided into 2 triangles:
The anal triangle and the urogenital triangle.
The superficial part of this region is called the perineum including the
external genitalia ( in the urogenital triangle) and the anus ( in the anal
triangle). It is also called the pudendal region, being supplied by the
pudendal nerves and vessels.
Specific Deep Boundaries/Fibrosseous
Landmarks that can be palpated: 4
angles & 4 sides
Anterior angle: Pubic Symphysis,
arcuate pubic ligament.
?Note the acute angle in male
?Note wider angle in females causing
more flaring of ischial tuberosities
Anterolateral sides: Ischiopubic rami.
Lateral angles : Two Ischial
tuberosities
Posterolateral sides: Sacrotuberous
ligaments on the right and left.
Posterior angle: Tip of coccyx - serving
as a point of attachment for
pubococcygeus muscle.
Divisions of the Superficial Perineal Region
? A line joining the two ischial tuberosities divides the perineum into:
? Urogenital Triangle - the anterior area
?Anal Triangle - the posterior area
? In the anatomical position, these two triangles are positioned at an
angle to each other.
Urogenital triangle(Anterium Perineum)
? Laterally by the
ischiopubic rami.
? Posteriorly by an
imaginary line between
the ischial tuberosities.
? Anteriorly by the inferior
margin of the pubic
symphysis
Membranes in Urogenital Triangle
3 membranes in this region
stretching across the rami.
From above downwards
1. Superior fascia of UGD. i.e.
part of pelvic fascia
2. Inferior fascia of UGD.
i.e.perineal membrane.
3. The most superficial
membrane is membranous
layer of superficial fascia. i.e.
colle's fascia.
Perineal Fasciae
? The perineal fascia consists of superficial and deep layers.
? The subcutaneous tissue of the perineum, or superficial perineal
fascia, like that of the inferior anterior abdominal wall, consists of
? Superficial fatty layer and Deep membranous layer (Colles fascia).
? In females, the fatty layer makes up the substance of the labia
majora and mons pubis and is continuous anteriorly and superiorly with
the fatty layer of subcutaneous tissue of the abdomen (Camper fascia).
? In males, the fatty layer is greatly diminished in the urogenital triangle,
being replaced altogether in the penis and scrotum with smooth
(dartos) muscle. It is continuous between the penis or scrotum and
thighs with the fatty layer of subcutaneous tissue of the abdomen.
? In both sexes, the fatty layer of subcutaneous tissue of the perineum
is continuous posteriorly with the ischioanal fat pad in the anal region.
Membranes in UrogenitalTriangle
? Between upper & middle is deep perineal space.
? Between middle & lower is superficial perineal space.
? Posteriorly all 3 membranes are attached to each other &
perineal body;thus closing superficial & deep spaces behind.
? Anteriorly superior & inferior fasciae of UGD fuse a little
behind pubic symphysis & form transverse ligament of
pubis=arcuate pubic ligament.
Dissection in the urogenital
triangle region reveals following
layers from superficial to deep:
1. Skin
2. Fatty layer of superficial fascia
3. Membranous layer of
superficial fascia (Colles facia)
4. Contents of superficial
perineal space
5. Perineal membrane (inf. Layer
of urogenital diaphragm)
6. Contents of deep perineal
space
7. Endopelvic facia (Superior
fascia of urogenital diaphragm)
Skin:
In male: midline raphe continuous with raphe of scrotum.
In female: perineal raphe leading to midline cleft called vestibule b/w
labia minora.
Raphe indicates development from fusion of two symmetrical halves.
Fatty layer of superficial fascia: continuous with the fatty
layer of superficial fascia in lower abdomen - fascia of camper
Colles fascia:
Membranous layer of
superficial fascia.
Forms lower limit of superficial
perineal pouch.
Attachments:
lateral: lower margin of
ischiopubic rami
posterior: attached to
posterior margin of perineal
membrane
Anterior: continuous with
dartos muscle of scrotum,
superficial fascia of penis and
Scarpa's fascia of lower
abdomen.
Superficial perineal
space/pouch:
Interfascial space below
perineal membrane
Boundaries
superior: perineal
membrane
inferior: Colles fascia
lateral: ischiopubic ramus
posterior: closed by fusion
of perineal membrane and
colles fascia
anterior: open with deep to
Dartos muscle and
superficial fascia of penis
and ant. abdominal wall
between fascia Scarpa and
External oblique
aponeurosis.
Contents:
A. Muscles:
Ischiocavernosus: cover
crus penis or crus
clitoridis.
Transversus perinei
superficialis.
Bulbospongiosus: cover
bulb of penis or bulb of
vestibule.
B. Blood vessels
Posterior scrotal/labial arteries - branch of perineal or internal
pudendal artery
Transverse perineal artery- branch of perineal artery.
C. Nerves
Posterior scrotal/ labial
nerves: branches of
superficial perineal
nerve.
Perineal branch of
posterior femoral
cutaneous nerve.
D. Other structures:
Crus penis/ crus
clitoridis.
Bulb of penis with
urethra traversing it.
Bulb of vestibule
with greater
vestibular gland.
Perineal membrane
Inferior fascia of
urogenital
diaphragm.
Triangular; apex
directed in the
front.
Stretched
between
pubic arch
Attachments
lateral: inner surface of ischiopubic ramus
anterior: thickened to form transverse perineal ligament.
posterior: perineal body in midline but laterally has free
margin.
Structures piercing the perineal membrane
1. Posterior scrotal/labial nerves and vessels
2. Deep artery of penis /clitoris
3. Dorsal artery of penis or clitoris
4. Urethra
5. In male: duct of bulbo-urethral glands and artery to the bulb of penis
6. In female: vagina
SUMMARY
? The superficial perineal pouch (compartment) is a
potential space between:
? The membranous layer of subcutaneous tissue
(colle's fascia).
? The perineal membrane (superiorly).
? The ischiopubic rami (laterally).
? Closed posteriorly and continuous anteriorly
with the space between the membranous layer of
superficial fascia and external oblique
Contents of superficial perineal pouch
Vessels & nerves of the superficial perineal pouch
Urogenital Diaphragm or
Triangular Ligament
? This consists of two muscles,
1. The sphincter urethrae in
which lies the membranous
part of the urethra (3/4 in.
long), and
2. The deep transverse
perineus.
? These muscles are enveloped
in two layers of fascia, the
fasciae superior and inferior of
the urogenital diaphragm
(upper and lower layers of the
triangular ligament), forming
the deep perineal pouch.
Deep perineal Space/pouch:
Closed interfacial space
inside the urogenital
diaphragm.
Boundaries
?superior: superior facia of
urogenital diaphragm
?inferior: perineal membrane
(inferior fascia)
?anterior: transverse
perineal ligament
?posterior: fused superior
and inferior fascia of
urogenital diaphragm
?lateral: inner surface of
ischiopubic rami
Contents:
A. Muscles
?Sphincter urethrae: surround membranous urethra.
?Deep Transverse perinei.
B. Blood vessels:
?Internal pudendal
artery and its
terminal branches
?Deep artery of
penis/ clitoris
?Dorsal artery of
penis/ clitoris
?Artery to the bulb
of penis/ bulb of
vestibule
C. Nerves
Dorsal nerve of penis/
clitoris
D. Other structures
Membranous urethra
Bulbo-urethral glands
in male
Vagina in female
CONTENTS OF DEEP PERINEAL POUCH
In Males
In Females
? Intermediate part of the
? Proximal part of the
urethra
urethra
? External urethral sphincter
? External urethral sphincter
muscles
muscles
? Bulbourethral glands
. Deep transverse perineal
? Deep transverse perineal
muscles
muscles
? Related vessels and nerves
? Related vessels and nerves
APPLIED ANATOMY
Urethral rupture: commonest site is rupture of proximal spongy
urethra below perineal membrane.
Mode of injury : perineal structure crushed between inferior pubic
ramus and any hard object like crossbar of bicycle
A. In superficial extravasation of urine,Urine escapes through the
rupture into the superficial perineal pouch, descends into the
scrotum, around penis and upto the anterior abdominal wall.
May even reach axilla but never enter thigh due to fusion of fascia
scarpa and fascia lata just below inguinal ligament.
PERINEAL BODY
? The midpoint of the line joining the ischial tuberosities is the central point of the
perineum.
. This is the location of the perineal body, which is an irregular mass, variable in size
and consistency and containing collagenous and elastic fibers and both skeletal and
smooth muscle.
? The perineal body lies deep to the skin, with relatively little overlying subcutaneous
tissue, posterior to the vestibule or bulb of the penis and anterior to the anus and anal
canal.
PERINEAL BODY
? The perineal body is the site of
convergence and interlacing of
fibers of several muscles,
including the:
? Bulbospongiosus.
? External anal sphincter.
? Superficial and deep transverse
perineal muscles.
? Smooth and voluntary slips of
muscle from the external anal
sphincter, levator ani, and
muscular coats of the rectum.
? Anteriorly, the perineal body
blends with the posterior border
of the perineal membrane and
superiorly with the rectovesical or
rectovaginal septum
In Males
In Females
Disruption of the Perineal Body
? The perineal body is an especially important structure in
women because it is the final support of the pelvic viscera,
linking muscles that extend across the pelvic outlet, like
crossing beams supporting the overlying pelvic diaphragm.
? Stretching or tearing the attachments of perineal muscles
from the perineal body can occur during childbirth, removing
support from the pelvic floor.
? As a result, prolapse of pelvic viscera, including prolapse of
the bladder (through the urethra) and prolapse of the uterus
and/or vagina (through thevaginal orifice) may occur.
APPLIED ANATOMY
Perineal tear:
Commonly during parturition of nullipara wome
Perineal tear if not repaired cause prolapse
Prevented by using Episiotomy.
Anal triangle(Posterior Perineum)
Posterior part of
perineum
Boundaries:
Anteriorly: imaginary
line joining two ischial
Tuberosities.
POSTEROLATERALLY:
sacrotuberous
ligament
Ischioanal (ischiorectal) fossa:
A perineal space on both side of anal canal.
Wedge shaped with apex directed upwards.
Lateral wall vertical and medial wall sloping downward and medially.
Fat filled: allows expansion of rectum and anal canal during
defecation.
Ischioanal (ischiorectal) fossa:
Measurements:
Vertical- 5cm
Anteroposterior- 5cm
Transverse- 2.5cm
Ischioanal (ischiorectal) fossa:
Boundaries
Laterally : obturator internus
and its fascia & ischial
tuberosity
Medially: levator ani covered by
anal fascia & external anal
sphincter
Anteriorly: superficial and deep
transverse perineal muscles.
Posteriorly: sacrotuberous
ligament covered by Gluteus
Maximus
Apex: fusion of obturator and
anal fascia
Base: skin and superficial fascia
Ischioanal (ischiorectal) fossa:
Recesses:
Anterior recess:
anterior extension
above the
urogenital
diaphragm.
Posterior recess:
posterior extension
between
sacrotuberous and
sacrospinous
ligament
Ischioanal (ischiorectal) fossa:
Lunate fascia:
Arched fascia in ischiorectal
fossa.
Starts from the periosteum
of ischial tuberosity makes
medial wall of pudendal
canal, lines obturator fascia
goes towards apex and
lines anal fascia blends with
it at the level of white line of
Hilton.
Summit of this facia called
tegmentum.
Ischioanal (ischiorectal) fossa:
Pudendal or Alcock's
canal:
Fascial tunnel in lateral
wall of ischiorectal fossa
2.5cm above ischial
tuberosity.
Formed either by
splitting of obturator
fascia or by separation
between lunate and
obturator fascia or by
splitting of perianal
fascia.
This post was last modified on 30 November 2021