Download MBBS Perineum Lecture PPT

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? The perineum lies inferior to the pelvic outlet.

? It is physically separated from the pelvic cavity by the pelvic

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diaphragm.

? In the anatomical position, it is the narrow region between

the proximal thighs.

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? In the lithotomy position, its a diamond shaped area.

? It is a diamond-shaped area extending from

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? The mons pubis anteriorly,

? The medial surfaces (insides) of the thighs laterally,

? The gluteal folds and superior end of the intergluteal

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(natal) cleft posteriorly .

Definitions

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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

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and is separated from the pelvic cavity by the pelvic diaphragm, which is

formed by the levator ani and coccygeus muscles.

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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.

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The superficial part of this region is called the perineum including the

external genitalia ( in the urogenital triangle) and the anus ( in the anal

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triangle). It is also called the pudendal region, being supplied by the

pudendal nerves and vessels.

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Specific Deep Boundaries/Fibrosseous

Landmarks that can be palpated: 4

angles & 4 sides

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Anterior angle: Pubic Symphysis,

arcuate pubic ligament.

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?Note the acute angle in male

?Note wider angle in females causing

more flaring of ischial tuberosities

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Anterolateral sides: Ischiopubic rami.

Lateral angles : Two Ischial

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tuberosities

Posterolateral sides: Sacrotuberous

ligaments on the right and left.

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Posterior angle: Tip of coccyx - serving

as a point of attachment for

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pubococcygeus muscle.

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Divisions of the Superficial Perineal Region

? A line joining the two ischial tuberosities divides the perineum into:

? Urogenital Triangle - the anterior area

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?Anal Triangle - the posterior area

? In the anatomical position, these two triangles are positioned at an

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angle to each other.


Urogenital triangle(Anterium Perineum)

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? Laterally by the

ischiopubic rami.

? Posteriorly by an

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imaginary line between

the ischial tuberosities.

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? Anteriorly by the inferior

margin of the pubic

symphysis

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Membranes in Urogenital Triangle

3 membranes in this region

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stretching across the rami.

From above downwards

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1. Superior fascia of UGD. i.e.

part of pelvic fascia

2. Inferior fascia of UGD.

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i.e.perineal membrane.

3. The most superficial

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membrane is membranous

layer of superficial fascia. i.e.

colle's fascia.

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Perineal Fasciae

? The perineal fascia consists of superficial and deep layers.

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? 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).

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? In females, the fatty layer makes up the substance of the labia

majora and mons pubis and is continuous anteriorly and superiorly with

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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

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(dartos) muscle. It is continuous between the penis or scrotum and

thighs with the fatty layer of subcutaneous tissue of the abdomen.

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? 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

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? Between upper & middle is deep perineal space.

? Between middle & lower is superficial perineal space.

? Posteriorly all 3 membranes are attached to each other &

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perineal body;thus closing superficial & deep spaces behind.

? Anteriorly superior & inferior fasciae of UGD fuse a little

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behind pubic symphysis & form transverse ligament of

pubis=arcuate pubic ligament.

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Dissection in the urogenital

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triangle region reveals following

layers from superficial to deep:

1. Skin

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2. Fatty layer of superficial fascia

3. Membranous layer of

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superficial fascia (Colles facia)

4. Contents of superficial

perineal space

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5. Perineal membrane (inf. Layer

of urogenital diaphragm)

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6. Contents of deep perineal

space

7. Endopelvic facia (Superior

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fascia of urogenital diaphragm)

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Skin:

In male: midline raphe continuous with raphe of scrotum.

In female: perineal raphe leading to midline cleft called vestibule b/w

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labia minora.

Raphe indicates development from fusion of two symmetrical halves.

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Fatty layer of superficial fascia: continuous with the fatty

layer of superficial fascia in lower abdomen - fascia of camper

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Colles fascia:

Membranous layer of

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superficial fascia.

Forms lower limit of superficial

perineal pouch.

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Attachments:

lateral: lower margin of

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ischiopubic rami

posterior: attached to

posterior margin of perineal

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membrane

Anterior: continuous with

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dartos muscle of scrotum,

superficial fascia of penis and

Scarpa's fascia of lower

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abdomen.


Superficial perineal

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space/pouch:

Interfascial space below

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perineal membrane

Boundaries

superior: perineal

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membrane

inferior: Colles fascia

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lateral: ischiopubic ramus

posterior: closed by fusion

of perineal membrane and

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colles fascia

anterior: open with deep to

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Dartos muscle and

superficial fascia of penis

and ant. abdominal wall

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between fascia Scarpa and

External oblique

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aponeurosis.


Contents:

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A. Muscles:

Ischiocavernosus: cover

crus penis or crus

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clitoridis.

Transversus perinei

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superficialis.

Bulbospongiosus: cover

bulb of penis or bulb of

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vestibule.


B. Blood vessels

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Posterior scrotal/labial arteries - branch of perineal or internal

pudendal artery

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Transverse perineal artery- branch of perineal artery.


C. Nerves

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Posterior scrotal/ labial

nerves: branches of

superficial perineal

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nerve.

Perineal branch of

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posterior femoral

cutaneous nerve.

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D. Other structures:

Crus penis/ crus

clitoridis.

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Bulb of penis with

urethra traversing it.

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Bulb of vestibule

with greater

vestibular gland.

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Perineal membrane

Inferior fascia of

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urogenital

diaphragm.

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Triangular; apex

directed in the

front.

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Stretched

between

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pubic arch


Attachments

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lateral: inner surface of ischiopubic ramus

anterior: thickened to form transverse perineal ligament.

posterior: perineal body in midline but laterally has free

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margin.


Structures piercing the perineal membrane

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1. Posterior scrotal/labial nerves and vessels

2. Deep artery of penis /clitoris

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3. Dorsal artery of penis or clitoris

4. Urethra

5. In male: duct of bulbo-urethral glands and artery to the bulb of penis

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6. In female: vagina
SUMMARY

? The superficial perineal pouch (compartment) is a

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potential space between:

? The membranous layer of subcutaneous tissue

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(colle's fascia).

? The perineal membrane (superiorly).

? The ischiopubic rami (laterally).

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? Closed posteriorly and continuous anteriorly

with the space between the membranous layer of

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superficial fascia and external oblique


Contents of superficial perineal pouch

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Vessels & nerves of the superficial perineal pouch
Urogenital Diaphragm or

Triangular Ligament

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? This consists of two muscles,

1. The sphincter urethrae in

which lies the membranous

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part of the urethra (3/4 in.

long), and

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2. The deep transverse

perineus.

? These muscles are enveloped

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in two layers of fascia, the

fasciae superior and inferior of

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the urogenital diaphragm

(upper and lower layers of the

triangular ligament), forming

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the deep perineal pouch.


Deep perineal Space/pouch:

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Closed interfacial space

inside the urogenital

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diaphragm.

Boundaries

?superior: superior facia of

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urogenital diaphragm
?inferior: perineal membrane

(inferior fascia)

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?anterior: transverse

perineal ligament
?posterior: fused superior

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and inferior fascia of

urogenital diaphragm
?lateral: inner surface of

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ischiopubic rami


Contents:

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A. Muscles
?Sphincter urethrae: surround membranous urethra.

?Deep Transverse perinei.

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B. Blood vessels:

?Internal pudendal

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artery and its

terminal branches

?Deep artery of

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penis/ clitoris

?Dorsal artery of

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penis/ clitoris

?Artery to the bulb

of penis/ bulb of

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vestibule


C. Nerves

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Dorsal nerve of penis/

clitoris

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D. Other structures

Membranous urethra

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Bulbo-urethral glands

in male

Vagina in female

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CONTENTS OF DEEP PERINEAL POUCH

In Males

In Females

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? Intermediate part of the

? Proximal part of the

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urethra

urethra

? External urethral sphincter

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? External urethral sphincter

muscles

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muscles

? Bulbourethral glands

. Deep transverse perineal

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? Deep transverse perineal

muscles

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muscles

? Related vessels and nerves

? Related vessels and nerves

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APPLIED ANATOMY

Urethral rupture: commonest site is rupture of proximal spongy

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urethra below perineal membrane.

Mode of injury : perineal structure crushed between inferior pubic

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ramus and any hard object like crossbar of bicycle


A. In superficial extravasation of urine,Urine escapes through the

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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

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scarpa and fascia lata just below inguinal ligament.


PERINEAL BODY

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? The midpoint of the line joining the ischial tuberosities is the central point of the

perineum.

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. 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.

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? 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

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canal.


PERINEAL BODY

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? The perineal body is the site of

convergence and interlacing of

fibers of several muscles,

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including the:

? Bulbospongiosus.

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? External anal sphincter.

? Superficial and deep transverse

perineal muscles.

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? Smooth and voluntary slips of

muscle from the external anal

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sphincter, levator ani, and

muscular coats of the rectum.

? Anteriorly, the perineal body

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blends with the posterior border

of the perineal membrane and

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superiorly with the rectovesical or

rectovaginal septum

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In Males


In Females
Disruption of the Perineal Body

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? The perineal body is an especially important structure in

women because it is the final support of the pelvic viscera,

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linking muscles that extend across the pelvic outlet, like

crossing beams supporting the overlying pelvic diaphragm.

? Stretching or tearing the attachments of perineal muscles

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from the perineal body can occur during childbirth, removing

support from the pelvic floor.

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? 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.

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APPLIED ANATOMY

Perineal tear:

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Commonly during parturition of nullipara wome

Perineal tear if not repaired cause prolapse

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Prevented by using Episiotomy.


Anal triangle(Posterior Perineum)

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Posterior part of

perineum

Boundaries:

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Anteriorly: imaginary

line joining two ischial

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Tuberosities.

POSTEROLATERALLY:

sacrotuberous

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ligament


Ischioanal (ischiorectal) fossa:

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A perineal space on both side of anal canal.

Wedge shaped with apex directed upwards.

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Lateral wall vertical and medial wall sloping downward and medially.

Fat filled: allows expansion of rectum and anal canal during

defecation.

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Ischioanal (ischiorectal) fossa:

Measurements:

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Vertical- 5cm

Anteroposterior- 5cm

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Transverse- 2.5cm


Ischioanal (ischiorectal) fossa:

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Boundaries

Laterally : obturator internus

and its fascia & ischial

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tuberosity

Medially: levator ani covered by

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anal fascia & external anal

sphincter

Anteriorly: superficial and deep

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transverse perineal muscles.

Posteriorly: sacrotuberous

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ligament covered by Gluteus

Maximus

Apex: fusion of obturator and

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anal fascia

Base: skin and superficial fascia

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Ischioanal (ischiorectal) fossa:

Recesses:

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Anterior recess:

anterior extension

above the

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urogenital

diaphragm.

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Posterior recess:

posterior extension

between

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sacrotuberous and

sacrospinous

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ligament


Ischioanal (ischiorectal) fossa:

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Lunate fascia:

Arched fascia in ischiorectal

fossa.

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Starts from the periosteum

of ischial tuberosity makes

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medial wall of pudendal

canal, lines obturator fascia

goes towards apex and

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lines anal fascia blends with

it at the level of white line of

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Hilton.

Summit of this facia called

tegmentum.

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Ischioanal (ischiorectal) fossa:

Pudendal or Alcock's

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canal:

Fascial tunnel in lateral

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wall of ischiorectal fossa

2.5cm above ischial

tuberosity.

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Formed either by

splitting of obturator

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fascia or by separation

between lunate and

obturator fascia or by

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splitting of perianal

fascia.