Penis
 The penis is composed of 2 parts:
o Root of the penis: it is the attached part and lies in the superficial
perineal pouch, on the lower surface of the perineal membrane. The
root consists of 2 crurae and a bulb.
o Body of the penis: it is the free part which consists of 2 corpora
cavernosa and one corpus spongiosum.
 Corpora Conversa:
o These are 2 elongated bodies lie side by side on the dorsum of the
penis.
o Each corpora continuous posterior with the crus of the penis which is
attached to the side of the pubic arch.
 Corporus spongiosum:
o It lies on the ventral surface of the penis .
o It is transversed throughout its whole length by the spongy urethra.
o It is continuous proximally with the bulb of the penis, and ends
distally by forming glans penis
o The glans penis is surrounded by a fold of skin called prepuse.
Muscles attached to the root of the penis:
o Ischio-cavernosus muscle : it extends between ischial tuberosity and
crus of the penis.
o Bulbo-spongiosusmuscle : it extends between bulb of the penis and
perineal membrane.
N.B:
 penis has 3 muscle attached to its root, 2 ischio-cavernosus muscles
and one bulbo-spongiosus muscle .
 All of these muscles supplied by muscular branches of the pudendal
nerve.
Arteries of the penis:
1. Dorsal arteries of the penis (2 on the dorsum of the penis)
2. Deep arteries of the penis (one on each crus)
3. Arteries of the bulb (2 in the bulb)
Veins of the penis:
1. Superficial dorsal vein of the penis: it runs in the middle of the
dorsum of the penis, superficial to the membranous fascia and ends on
superficial external pudendal veins.
2. Deep dorsal vein of the penis: it ends on the prostatic venous plexus of
veins which lies in prostatic sheath.
Perineum
Definition:
It is the region which overlies the outlet of the pelvis.
Boundaries: it is diamond-shaped and has the following boundries:
1. Anterior: pubic symphysis.
2. Posterior: tip of the coccyx
3. On each side:
o Side of the pubic arch.
o Ischial tuberosity.
o Sacro-tuberous ligament.
Divisions:
The perineum is divided by a transverse line passing between the 2 ischial
tuberosity into 2 triangles which are:
o Anal triangle ( GIT Block)
o Urogenital triangle.
Urogenital Triangle
 It is the anterior triangle of the perineum.
 It contains the external genital organs as well as 2 perineal
pouches which are:
o Superficial perineal pouch.
o Deep perineal pouch.
Boundaries of Urogenital Triangle:
Anterior
symphysis pubis.
Posterior
a line extends between 2 ischial tuberosity
Anteriolateral
pubic arch.
Urogenital
shows 2 opening in female:
Vagina
Urethra
Superficial perineal pouch
Definition:
It is the superficial fascia space present in the uro-genital triangle just beneath
the skin.
Boundaries:
1. Roof:
Perineal membrane
2. Floor:
Membranous layer of superficial fascia of the perineum.
3. Anterior:
The pouch is open where it is continuous with the space deep to
membranous layer of the superficial fascia of the anterior abdominal wall.
4. Posterior:
The pouch is closed by fusion of the roof and floor together along the
posterior border of the perineal membrane.
Contents:
1- root of the penis: the root of the penis consists of 2 crurae and a bulb. ( in
the female , it is replaced by 2 crurae of the clitoris and bulb of vestibule.)
2- Superficial perineal muscles:
a. Ischio-cavernous muscles
b. Bulbo-spongiosus muscle
c. Superficial transverse the perineal muscles
3- Nerves and vessels:
 Posterior scrotal nerves (or labial in female): they arise from the
pudendal nerve and supply skin of scrotum in male or vulva in female.
 Posterior scrotal vessels (or labial in female): they arise form internal
pudendal arteries and supply skin of the scrotum in male and vulva in
female.
 Dorsal nerve of the penis: it arises from the pudendal nerve.
 Terminal branches of the internal pudendal artery which are:
1- deep artery of the penis
2- dorsal artery of the penis
 Deep dorsal vein of the penis.
**Applied anatomy:
Rupture of the spongy urethra which is a content of the superficial pouch and
if ruptured by a trauma, the urine extravasates into the superficial perineal
pouch. The urine flows into the walls of the scrotum and penis and then
ascends into the lower part of the anterior abdominal wall.
Deep Perineal Pouch
It is a closed fascia space situated in the urogenital triangle deep to superficial
pouch.
Boundaries of the deep pouch:
 Roof: superior fascia of the uro-genital diaphragm which extends
between the 2 sides if the pubic arch.
 Floor: it is formed by inferior fascia of the urogenital diaphragm.
 On each side: the roof and floor fuse with the sides of the pubic arch.
 Anterior and posterior border: at these borders the roof and floor
fuse together, thus closing the deep fascia.
Contents of the deep perineal pouch:
 Membranous urethra
 Bulbo-urethral gland: these are 2 small glands situated on both sides
of the membranous urethra.
 Sphincter urethra: it is a voluntary muscle surrounds the
membranous urethra
 Deep transverse perineal muscles: which extends between ischial
tuberosity and perineal body.
 Nerves and vessels:
a- dorsal nerve to the penis
b- termination of the internal pudendal artery
Perineal Membrane
It is a strong triangular fibrous membrane which lies between the 2 sides of
the pubic arch.
Structures piercing the perineal membrane:
1.
2.
3.
4.
5.
6.
Membranous urethra
Ducts of bulbo-urethral glands
Dorsal artery and nerve of the penis (or clitoris in female)
Deep artery of the penis (or clitoris in female)
Posterior scrotal nerves and vessels (or labial in female)
Artery of the bulb (or artery of the vestibule in female)
N.B: Regarding the perineal membrane
It is less extensive than in male
It is splitted into right and left halves by vagina and urethra .