Vagina
The vagina not only is the female genital canal but also serves
as the excretory duct for the menstrual flow from the uterus and forms part of
the birth canal. This muscular tube extends upward and backward between the
vulva and the uterus (see Fig. 8.4). It measures about 3 in. (8 cm) long. The
cervix of the uterus pierces its anterior wall. The vaginal orifice in a virgin
possesses a thin mucosal fold, called the hymen, which is perforated at its
center. The upper half of the vagina lies above the pelvic floor within the
pelvis between the bladder anteriorly and the rectum posteriorly; the lower
half lies within the perineum between the urethra anteriorly and the anal canal
posteriorly
.
.
Supports
of the Vagina
■■
Upper third: Levatores ani muscles and transverse cervical, pubocervical, and
sacrocervical ligaments
■■
Middle third: Urogenital diaphragm
■■
Lower third: Perineal body
Blood
Supply
Arteries
The vaginal artery, a branch of the internal iliac artery,
and the vaginal branch of the uterine artery supply the vagina.
Vulva
The term vulva is the collective name for the female
external genitalia and includes the mons pubis, labia majora and minora, the
clitoris, the vestibule of the vagina, the vestibular bulb, and the greater vestibular
glands.
Blood Supply
Branches of the external and internal pudendal arteries on each
side.
The skin of the vulva is drained into the medial group of superficial
inguinal nodes.
Lymph Drainage
Medial group of superficial inguinal nodes
.
.
Nerve Supply
The anterior parts of the vulva are supplied by the
ilioinguinal nerves and the genital branch of the genitofemoral nerves. The
posterior parts of the vulva are supplied by the branches of the perineal
nerves and the posterior cutaneous nerves of the thigh.
Vulval
Infection
In the region of the vulva, the presence of numerous glands
and ducts opening onto the surface makes this area prone to infection. The
sebaceous glands of the labia majora, the ducts of the greater vestibular
glands, the vagina (with its indirect communication with the peritoneal
cavity), the urethra, and the paraurethral glands can all become infected. The
vagina itself has no glands and is lined with stratified squamous epithelium.
Provided that the pH of its interior is kept low, it is capable of resisting infection
to a remarkable degree.
The
Vulva and Pregnancy
An important sign in the diagnosis of pregnancy is the
appearance of a bluish discoloration of the vulva and vagina as a result of
venous congestion. It appears at the 8th to 12th week and increases as the
pregnancy progresses.
Urethral
Infection
The short length of the female urethra predisposes to
ascending infection; consequently, cystitis is more common in females
than in males.
Urethral
Injuries
Because of the short length of the urethra, injuries are
rare. In fractures of the pelvis, the urethra may be damaged by shearing forces
as it emerges from the fixed urogenital diaphragm.
Catheterization
Because the female urethra is shorter, wider, and more
dilatable, catheterization is much easier than in males. Moreover, the urethra
is straight, and only minor resistance is felt as the catheter passes through
the urethral sphincter.
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