Male External Genital Organs
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genital organs | Main
Anatomy Index | The lymphatic
Last updated 30 March 2006
Male External Genital Organs
- The scrotum develops from an out-pouching of the skin
of the anterior abdominal wall.
- The scrotum is a loose cutaneous fibromuscular sac that
is situated posteroinferior to the penis
and inferior to the pubic symphysis.
- Its bilateral formation is indicated by the midline scrotal raphe.
- This continues on the ventral surface of the penis as the penile raphe and
posteriorly along the median line of the perineum to the anus as the perineal raphe.
- The scrotum is composed of skin and dartos
- The dartos muscle is firmly attached to the skin and
consists largely of smooth muscle fibres that contract under the influence of cold,
exercise, and sexual stimulation.
- Under these conditions the wall of the scrotum becomes contracted and firm.
- Its skin becomes rugose.
- Contraction of the dartos and cremasteric
muscles causes the testes to be drawn up against the body.
- In hot weather the scrotum relaxes and allows the
testes to hang freely away from the body.
- This provides a larger skin surface for the dissipation of heat.
- These reflexes of the scrotum in response to temperature help to maintain a stable temperature, an important function because spermatogenesis is impaired by extremes of heat or cold.
- In older men the dartos muscle
loses its tone and the scrotum tends to be smoother and to hang down further.
Arterial Supply of the
- The external pudendal arteries supply the anterior aspect of the scrotum.
- The internal pudendal arteries supply its posterior aspect.
- It also receives branches from the testicular
and cremasteric arteries.
Venous Drainage of the
- The scrotal veins accompany the arteries
and join the external pudendal
Innervation of the Scrotum
- Its anterior part is supplied by the ilioinguinal
- Its posterior part is supplied by the medial and lateral scrotal branches
of the perineal nerve and the perineal
branch of the posterior femoral cutaneous nerve.
Lymphatic Drainage of
- The lymph vessels from the scrotum drain into the superficial
inguinal lymph nodes.
- This is the male organ of copulation.
- It is the common outlet for urine and semen.
- It is composed of 3 cylindrical bodies (L. corpora) of erectile cavernous tissue that are enclosed by a dense white fibrous capsule, the tunica
- Superficial to this layer is the deep fascia of the penis,
which forms a common covering for the two corpora
cavernosa and the corpus spongiosum.
- The skin of the penis is very thin,
dark in colour, and loose.
- Two of the three erectile bodies, the corpora cavernosa penis,
are arranged side by side in the dorsal
part of the penis.
- The corpus spongiosum penis lies ventrally
and contains the spongy urethra.
- The corpora cavernosa are fused
with each other in the median plane.
- Posteriorly they separate to form 2 crura (L. legs).
- The crura are attached on each side to the ischiopubic ramus.
- They support the corpus spongiosum penis, lying between
and inferior to the ischiopubic ramus.
- The penis consists of a root and a body
- The dorsal surface of the penis faces
posteriorly when the penis is erect, and anteriorly when it is in the flaccid
- The dorsum the penis is continuous with the anterior abdominal wall.
- The other aspect is referred to as the ventral surface.
The Root of the Penis
- This is its attached portion (radix).
- It is located in the superficial
perineal space between the perineal membrane
superiorly the superficial perineal fascia inferiorly.
- The root consists of crura, bulb,
and associated muscles (bulbospongiosus).
The Bulb of the Penis
The Body of the Penis
- This is the free part, which is pendulous
in the flaccid condition.
- Except for few fibres of the bulbospongiosus near the root, the body of the penis has no muscles.
- It consists of the corpora cavernosa and corpus spongiosum and is covered by skin.
- The spongy urethra is
within the corpus spongiosum.
The Glans Penis
- Distally, the corpus spongiosum
penis expands to form the conical glans penis.
- This is the concavity of that covers the free blunt ends
of the corpora cavernosa.
- The glans has a higher concentration of sensory nerve endings than the rest of the body of the penis.
- It is particularly sensitive to physical
- The prominent margin of the glans penis is the corona (L. crown).
- This projects beyond the ends of the corpora
- It overhangs an obliquely grooved
constriction called the neck of the penis.
- The slit-like opening of the spongy urethra is near the tip of the glans penis.
- It is called the external urethral orifice (meatus).
The Prepuce or Foreskin of the Penis
- This is where the skin and fasciae
of the penis are prolonged as a free fold of skin (L. praeputium,
- This covers the glans penis
to a variable extent.
- The frenulum of the prepuce, which is a median fold,
passes from the deep layer of the prepuce to a point just
inferior to the external urethra
The Fundiform Ligament
- The weight of the body of the penis is supported by 2 ligaments that are continuous
with the fasciae of the penis.
- The fundiform ligament arises from the membranous layer of subcutaneous tissue
of the lower abdomen (Scarpa's fascia).
The Suspensory Ligament
- This is a condensation of deep fascia in the form of a thick, triangular, fibroelastic band.
- It arises from the anterior surface of the pubic symphysis and passes inferiorly.
- It splits to form a sling,
which is attached to the deep fascia of the penis at the
junction of its fixed and mobile
Arterial Supply of the Penis
- The arteries to the penis are:
- The dorsal arteries, which run in the interval between
the corpora cavernosa on each side of the deep dorsal vein;
- The deep arteries, which pierce
the crura and run within the corpora cavernosa;
- And the artery to the bulb, which enters on each side.
- The dorsal and deep arteries
are branches of the internal
- The deep arteries are the principal
vessels that supply the cavernous spaces
(erectile tissue) in the three corpora.
- They give off numerous branches that open
directly into these spaces.
- When the penis is flaccid, these arterial branches are coiled; hence, they are called helicine
arteries (G. helix, a coil).
Venous Drainage of the Penis
- Blood from the cavernous spaces is drained by a venous plexus that joins the deep dorsal
vein located in the deep fascia.
- Blood from the superficial coverings of the penis drain
into the superficial dorsal vein and then into the superficial external pudendal vein.
Lymphatic Drainage of the
- From most of the penis, lymph drains into the superficial inguinal
- Vessels from the glans penis drain into the deep inguinal lymph nodes.
Innervation of the Penis
- The dorsal nerve of the penis is one of the two terminal branches of the pudendal
- The dorsal nerve arises in the pudendal
canal and passes anteriorly into the deep perineal space.
- It then runs to the dorsum of the penis where it passes
lateral to the arteries.
- It supplies both the skin
and glans penis.
- The penis is richly innervated with sensory
nerve endings, especially the glans.
- The cavernous nerves from the inferior
hypogastric plexus pass through the urogenital
diaphragm to reach the penis.
- The skin covering the root of the penis is supplied by the ilioinguinal nerve and the
posterior scrotal branches of the perineal nerve.