Anatomy

Perineum

Rhomboid space at the lower end of 

abdomen which lies between two thigh

Boundaries

• Anteriorly bounded by 

pubic arch and 
Arcuate pubic 
ligament

• Posteriorly the tip of 

coccyx

• On each side 

ischiopubic rami, 
ischial tuberosity & 
sacrotuberous 
ligament

Division

• Divided into two 

regions by a line 
joining the anterior 
part of ischial 
tuberosity

• Urogenital region 

• Anal region

Urogenital region

• Placed between two 

ischiopubic rami

•

In male contains urethra 

enclosed by root of penis, 
scrotum

• In females contains 

urethral and vaginal 
orifice & female external 
genitalia 

• Three membranes 
• Two spaces 

Three membranes 
Two spaces 

• Part of pelvic fascia 

continuous laterally 
with the fascia over 
obturator internus & 
constitutes superior 
fascia of urogenital 
diaphragm 

• Second membrane is 

inferior fascia of the 
urogenital diaphragm 
(Perineum)

• Most superficial 

membrane is 
membranous layer of 
superficial fascia

• Between upper and 

middle layer is deep 
perineal space

• Between the middle 

and membranous 
layer is superficial 
perineal space

• Posteriorly all three 

membranes are attached 
to perineal body & to 
each other thus closing 
the perineal spaces 
behind

•

Anteriorly the upper & 

middle membrane fuse a 
little behind the pubic 
symphysis & form 
transverse ligament of 
the pubis

• Traced Anteriorly  the 

membranous layer is 
continues with the 
anterior abdominal wall

Structures piercing the perineal 

membrane in males

• Urethra 

• Duct of bulbourethral gland

• Artery & nerve to bulb, urethral artery,  

deep artery & dorsal artery of penis

• Posterior scrotal nerves & vessels

• Branches of perineal nerve to superficial 

perineal muscles

Structures piercing the perineal 

membrane in females

• Urethra 

• Vagina

• Artery & nerve to the bulb of the vestibule

• Deep & dorsal artery of clitoris

• Posterior labial arteries & nerves 

• Branches of perineal nerve to superficial 

perineal muscles

Urogenital diaphragm

Formed by

• Superficial fascia of 

urogenital diaphragm

• Deep perineal muscles                     

Sphincter urethrae,                  
Deep transverse perinei

• Inferior fascia of 

urogenital diaphragm 
(perineal membrane)

Superficial perineal space in the 

male

•

Contents

•

Root Of Penis 

Bulb 
Right & left crura

•

Muscles

Bulbospongiosus
Ischiocavernosus
Superficial transversus          

perinei

All muscles are supplied by 

perineal branch of pudendal 
nerve

Nerves

•Branches of perineal nerve- posterior 
scrotal, nerve to bulb & muscular 
•Long perineal nerve from posterior 
cutaneous nerve of thigh
•Vessels- branches of perineal artery 
namely posterior scrotal and transverse 
perineal
•Branches of artery of penis namely 
artery to bulb, urethral artery and deep 
&dorsal artery of penis

Superficial perineal space in the 

female  

• Female external genitalia

• Muscles 

Bulbospongiosus

Ischiocavernosus

Superficial 

transversus perinei

Nerve supply of muscles is 

by perineal branch of 
pudendal nerve

Female external genital organs

Muscles

Nerves

• Branches of perineal nerve- posterior labial, 

nerve to bulb & muscular 

• Long perineal nerve from posterior 

cutaneous nerve of thigh

Vessels- branches of perineal artery namely 

labial and transverse perineal

• Branches of artery of clitoris namely artery to 

bulb,deep &dorsal artery of clitoris

• greater vestibular gland in females

Deep perineal space

• Contents
• Membranous 

urethra

• Muscles- sphincter 

urethrae, deep 
transverse perinei

Nerves-
• Dorsal nerve of 

penis and muscular 
branches from 
perineal nerve

Vessels-
• Artery of penis
• Bulbourethral 

Gland In Males 

Applied 

• Membranous part of urethra is narrowest 

& least dilatable

• Extravasation of urine

• Proalpse of pelvic viscera due to perineal 

body rupture

ANAL REGION

• Triangular area 

between the 
posterior  margin of 
the urogenital 
diaphragm & the 
coccyx

• Transmits the anal 

canal   

• Anal canal is 

surrounded by external 
anal sphincter

• Anal canal is connected 

to the coccyx by 
anococcygeal ligament

• On either side of canal 

is a triangular space 
called ischiorectal fossa

• Perineal body (central 

tendon of perineum) is 
situated 1.25 cm 
anterior to anal canal  

Ischiorectal fossa

•

Wedge shaped space 
between obturator internus 
& levator ani

•

Base is formed by skin 

•

Widest & deepest 
Posteriorly, continues with 
the lesser sciatic foramen

•

Anteriorly continues with a 
narrow space filled with 
loose areolar tissue  

•

Lateral wall by fascia 
covering obturator internus 

•

superomedial wall formed 

by fascia covering levator 
ani & external anal sphincter

Contents of Ischiorectal fossa

• vessels & nerves 

that enter thru 
lesser sciatic 
foramen and run in 
pudendal canal 

• Perineal branch of 

the fourth sacral 
nerve  

• Perforating 

cutaneous 
branches of S2 &3

Recesses of Ischiorectal fossa

• Anterior recess

• Posterior recess

• Horseshoe recess

Applied anatomy

• Ischiorectal abscess

• Anorectal fistula and external sinus

• Prolapse of rectum

• Ischiorectal hernia

PUDENDAL CANAL

•

seen in the lateral wall of 

Ischiorectal fossa

• bounded laterally by 

obturator fascia 

• Medially by lunate fascia
• Begins Posteriorly near 

lesser sciatic foramen 

• Inferiorly related to 

sacrotuberous ligament

• Extends to the posterior 

border of perineal 
membrane

Contents

• Pudendal nerve S234

• Internal pudendal 

vessels

Pudendal nerve

• Chief nerve of 

perineum & external 
genitalia

• Derived from sacral 

plexus

• Branches

Inferior rectal nerve
Perineal nerve
Dorsal nerve of    

penis 

Applied – pudendal 

nerve block        

Internal pudendal artery

• Chief artery of 

perineum

• Terminal branch of 

anerior division of 
internal iliac artery

• Branches

• Inferior rectal artery

• Perineal atrery

• Artery of penis/clitoris