What is the vagina and what are its key anatomical relations?

The vagina is a muscular canal that serves as the lower part of the birth canal and the female copulatory organ. It lies between the bladder and urethra anteriorly, and the rectum and anal canal posteriorly.

What are the dimensions and shape of the vagina?

The vagina varies in size and shape along its length. The anterior wall is 7.5 cm long, and the posterior wall is 9 cm long. Width increases upward from 2.5 cm at the lower end to 5 cm at the upper end, with the lumen cross-section being H-shaped in the lower third, transverse slit in the middle third, and round in the upper third.

What are the fornices of the vagina?

The fornices are recesses formed where the upper vagina surrounds the cervix. They include the anterior fornix, posterior fornix (which is the deepest, about 2 cm deeper than the anterior), and the right and left lateral fornices.

How is the vagina structured internally?

The vaginal wall has three layers: the adventitia (outer connective tissue with vessels and nerves), the muscular layer (smooth muscle with outer longitudinal and inner circular fibers), and the mucosa (stratified squamous non-keratinized epithelium, rich in glycogen, with an acidic pH maintained by lactic acid from Döderlein’s bacilli).

What is the hymen and what is its clinical significance?

The hymen is an incomplete mucous membrane fold near the vaginal orifice, with shapes like annular or crescentic. It typically ruptures during first intercourse, leaving tags called carunculae. An imperforate hymen can cause hematocolpos in menstruating girls.

How is the vagina supplied with blood, lymph, and nerves?

Supply varies by region. Blood comes from vaginal, uterine, internal pudendal, middle rectal, and inferior vesical arteries. Lymph drains from the upper third to internal and external iliac nodes, middle third to internal iliac nodes, and lower third to superficial inguinal nodes. Nerves include stretch-sensitive autonomic innervation in the upper two-thirds and highly sensitive touch innervation via the pudendal nerve in the lower third.

What are some common clinical conditions related to the vagina?

Common conditions include vaginitis (rare in adults due to acidic pH, more common in children and postmenopausal women), prolapse (which can lead to cystocele, urethrocele, or rectocele), and culdocentesis (a procedure via the posterior fornix to drain fluid or retrieve oocytes).

Vagina – Anatomy, Relations, Fornices & Exam

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