Vagina : Defination, Structure, Function, Diagram

VAGINA

Defination of vagina :-

• Vagina is a fibromuscular membranous sheath that is located between bladder and rectum. 
• Vagina runs obliquely upward and backward at the angle of 45°(horizontal) 
• The diameter of vaginal canal is 2.5cm that is widest in upper part and narrowest at its introitus(An entrance in the canal such as vagina). In adults anterior wall 7cm long and posterior wall 9cm long 
• Vagina is a communication channel(between cervix and vulva)that is formed by stratified squamous epithelium. 
• An abnormal opening between vagina and rectum called recto-vaginal fistula, which can be identify by culdoscopy. 

Fig. 1 midsagittal section of vagina 

Ph of vagina :-

• The acidic ph of vagina is 3.5 to 4.5 in reproductive age due to doderlein's bacilli (normal flora of vagina) which is a bacteria of lactobacilli species (due to conversion of glycogen into lactic acid). 
• The vaginal ph before reproductive age and after menopause is neutralize and alkaline. 

Reproductive age:-

• It is a period of getting menstrual period to menopause between the age of 15 to 45 year. 

Menopause :- 

• It is a period of women life when menstruation ceases typically between the 45 to 50 year of age. 

Structure of vagina :-

The vagina are look like H shaped on transverse action and it has three layer 

• Outer layer or adventitia composed of areolar tissue 
• Middle layer composed of smooth muscle
• Inner layer composed of stratified squamous epithelium. 

Fig.2 Layer of vagina

1.Outer layer :-

The outer layer of vagina is composed of areolar tissue and also known as adventitia that provides structural support to vagina and allows for expansion of the vagina during sexual intercourse and child birth. 

2.Middel layer :-

The middle layer of vagina is composed of smooth muscle and also called muscularis 

It provides supports to nerve bundle, control blood flow and contraction of vaginal tissues

3.Inner layer :-

Inner layer is composed of stratified squamous epithelium and also called mucosa that produce mucosa and have nutrients in rich amount that protects the skin inside vagina.

Relations of vagina :-

• Anterior :- The upper one-third part of the vagina is related to the base of bladder and lower two third part related to urethra 
• Posterior :- The upper one third part of vagina is related to the pouch of Douglas and middle third part of vagina related to the recto-vaginal septum. 
• Lateral walls :- The upper one-third part of vagina is related to the ureter and middle third part is related to the levator ani muscle

Functions of vagina :-

The vagina has three main functions 

• Sexual intercourse:- The vagina has a function of copulation by accepting penis and  provide a place for ejaculation.                              
• Child birth :- The vagina provides a way for delivery of new born from uterus by expands.  
• Menopause :- vagina also helps in uterine secretions and menstrual blood as a channel. 

Development of vagina :-

The development of vagina are occur in following steps 

• The fourth-fifth upper part of vagina developed from mullerian duct. 
• The lower one-fifth part of vagina developed from urogenital sinus. 
• External vaginal orifice is formed from the genital fold ectoderm after rupture of the urogenital membrane. 

Blood supply of vagina 

Arteries:-  

There are four arteries that supplies the vagina

• Cervicovaginal branch of the uterine artery
• Vaginal artery 
• Middle rectal artery 
• Internal pudendal artery 

Veins:-

• Internal iliac veins
• Internal pudendal veins

Vaginal Tests :-

Colposcopy :- 

• Colposcopy is used to fined a cancerous cells and abnormal cell by using an instrument called colposcope. 
• The colposcopy is also used for the diagnosis of vulva, vagina and cervix. 

Fig. 3 colposcope

Pelvic examination :-

• Pelvic examination is used for the examination of reproductive organs ( vulva, vagina and cervix) by using speculum. 

Fig. 4 speculum

• In this procedure your doctor will insert two lubricants gloved finger into the vagina by using one hand , the other hand used to press lower abdomen for check the size of your reproductive organs. 

Vaginal biopsy :-

• In this procedure a tissue sample is collect to diagnosis of cancer by using both way (needle and surgery). 

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I hope you all like our article on Vagina and it's all dimensions like ph, structure, function, relation, blood supply and tests of Vagina. If you have any query related to this topic then please comment. 

Thank you .