cunninghams-manual-of-practical-anatomy-volume-2-72

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The corpus spongiosum has a finer mesh of 
erectile tissue and a more delicate fibrous capsule 
(the tunica albuginea). Thus, when the cavern-
ous tissue is filled with blood, it does not pre-
vent passage of fluid in the urethra. The arteries 
of the bulb [Figs. 9.8, 9.9] traverse the corpus 
spongiosum, inferior to the urethra. Thus each 
part of the penis has a separate blood supply.
See Clinical Applications 9.1 and 9.2 for the clin-
ical implications of the anatomy in this chapter.
dorsal vein lies deep to the deep fascia. It drains 
to the prostatic plexus of veins by passing below 
the pubic symphysis into the pelvis. The deep 
dorsal vein has a thick muscular wall, close to the 
pubis.
The paired dorsal arteries and nerves are the ter-
minal branches of the internal pudendal arteries 
and the pudendal nerves, which are described in 
Chapter 16. On the dorsum of the penis, the nerves 
are lateral to the arteries. Both supply the skin of 
the penis and the glans penis.
Dissection 9.6 examines the cut surface of the 
penis.
Structure of the penis
The corpora cavernosa are paired cylindrical 
bodies consisting of cavernous erectile tissue. 
They are enclosed in a dense sheath of white fi-
brous tissue—the tunica albuginea. Medially 
the tunicae albugineae fuse to form an incomplete 
median septum, through which the cavernous 
tissue of the two corpora are continuous. A deep 
artery of the penis lies near the centre of each cor-
pus cavernosum. When these arteries are dilated, 
the cavernous spaces are filled with blood under 
pressure, turning the corpora cavernosa into a rigid 
structure.
DISSECTION 9.6 Penis-2
Objective
I. To examine the cut section of the penis.
Instructions
1. Make a transverse section through the body of the 
penis, but leave the two parts connected by the 
skin of the urethral surface. Examine the cut sur-
face.
2. Identify the two corpora cavernosa, the corpus 
spongiosum, the tunica albuginea of the corpus 
cavernosum and spongiosum, the urethra, and the 
deep artery of the penis.
CLINICAL APPLICATION 9.1 Hydrocele
A 40-day-old infant is brought to the paediatric surgery 
department with history of a painless, right-sided swell-
ing in the scrotum that diminishes gradually when 
the child lies down. There is no history of trauma. On 
examination, the swelling is non-tender to touch and 
transilluminant (allows passage of light through it). The 
swelling surrounds the right testis and epididymis. A 
 diagnosis of hydrocele is made.
Study question 1: what is a hydrocele? (Answer: a 
 hydrocele is an abnormal collection of fluid between the 
parietal and visceral layers of the tunica vaginalis.)
Study question 2: what is a congenital hydrocele? 
 (Answer: under normal circumstances, most of the pro-
cessus vaginalis obliterates and the cavity of the tunica 
vaginalis is detached from the peritoneal cavity. If the 
processus vaginalis remains patent after birth, fluid from 
the peritoneal cavity fills the tunica vaginalis and forms 
a swelling around the testes. This is a congenital hydro-
cele.) A hydrocele can also be associated with inflamma-
tion of the testes and epididymis (epididymo-orchitis) or 
testicular tumours.
Study question 3: what is a haematocele? (Answer: 
a haematocele is a swelling around the testes due to 
haemorrhage into the tunica vaginalis, usually following 
trauma.)
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CLINICAL APPLICATION 9.2 Vasectomy
A 48-year-old man opted to undergo male steriliza-
tion, so that he and his wife would not have any more 
children. Male sterilization or vasectomy involves tying 
and cutting the vas deferens on both sides, as it lies in the 
spermatic cord. Under local anaesthesia, a skin incision is 
made on the front of the scrotum, above the epididymis, 
to access the structures in the spermatic cord. Review the 
coverings and contents of the spermatic cord.
Study question 1: what is the characteristic feature of 
the vas deferens which will enable the surgeon to dif-
ferentiate it from the other structures? (Answer: the vas 
deferens is firm and cord-like, and easily differentiated 
from the other structures by its feel.)
Study question 2: what is the blood supply to the vas 
deferens? Name the other important artery that lies in 
the spermatic cord and has to be preserved during the 
procedure. (Answer: the vas deferens is supplied by the 
artery to the vas. Care should be taken not to ligate the 
testicular artery, as it lies in the spermatic cord.)
Note: Potency, the ability of the male to have sexual 
intercourse, is based on hormones secreted by the testis 
and is not affected by vasectomy.