THE UTERUS

UTERUS

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• ABOUT 60%of women uterus reaches adult stage by age 15 years.
• There is sudden increase in weight and height during adolescent phase of development.
• The body leans forward from the isthmus and bends over slightly at the junction with the cervix.
• Its adopt an anteverted and anteflexed position.

UTERUS CONT’D

• In about 10% of women, the uterus lean backwards instead of forward so it adopt retroverted and retroflexed position. This may cause painful coitus and infertility.
• SITUATION- It lies in the true pelvis.
• SHAPE- Resemble an English pear.
• SIZE- 7.5cm long, 5cm wide, 2.5cm thick. The weight is approximately 57g.

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GROSS STRUCTURE

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• THE CERVIX – It forms lower 1/3^rd
• ISTHMUS – Is the narrowed constriction about 7mm thick lying between the body of the uterus and the cervix.
• THE CORPUS /BODY- It forms the upper 2/3rds of the uterus and is that portion of the organ lying above the cervix.
• THE CORNUA- Area where fallopian tubes are inserted. The lumen of the tubes opens into the uterus.
• FUNDUS- The portion lying above and between the cornua.
• THE CAVITY- Is the triangular in shape potential hollow in the centre of the organ.

The walls of the cavity normally lie in an apposition.

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MICROSCOPIC STRUCTURE

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ENDOMETRIUM

• Mucus lining of the uterus made up of ciliated epithelium.

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• Its appearance varies with each day of the menstrual cycle because it is influenced by ovarian hormones.

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• During menstruation it is shed as far as the basal layer and renewed on average of every 28days from menarche to the menopause.

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MYOMETRIUM

• This is the muscle layer and forms the bulk of the uterus. It is more thicker in the upper part of the uterus.
• It has involuntary muscle fibres which are intermingled with areolar tissues, blood vessels, lymphatic vessels and nerves.
• It also has inner circular and outer longitudinal involuntary muscle fibres which are continuous with those of the fallopian tubes.

PERIMETRIUM

• It covers the uterus almost completely and is attached firmly to the uterus except for the anterior portion of the isthmus where it has loose attachment which allows the bladder to expand and forms uterovesical pouch.

RELATIONS

• ANTERIOR- Uterovesical pouch and bladder
• POSTERIOR- Rectouterine pouchof Douglads and rectum.
• LATERAL- Broad ligaments, uterine tubes and the ovaries
• SUPEROIR- Intestines
• INFERIOR- Vagina

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SUPPORT

1. Vagina.
2. The Broad ligaments.
3. Cardinal ligaments or Mackenrodt’s ligaments or the transverse cervical ligaments.
4. Pubocervical ligaments and uterosacral ligaments.
5. The Round ligaments.
6. The ovarian ligament.

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FUNCTIONS

• To prepare a bed for the fertilized ovum.
• To nourish the fertilized ovum for the gestation period.
• To expel the products of conception of full term.
• To involutes following childbirth.

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BLOOD SUPPLY

• Ovarian arteries
• Uterine arteries

• VENOUS DRAINAGE

Ovarian veins

• LYMPHATIC DRAINAGE

Into the internal iliac and the sacral glands.

• NERVE SUPPLY

Through sympathetic and parasympathetic nerves

�CHANGES IN THE UTERUS DURING PREGNANCY�

• Non pregnant uterus is pear shaped. The uterus becomes globular at the end of the 12weeks then changes to oval after the 5^th month until term.

ENDOMETRIUM

• During Pregnancy the endometrium changes to deciduas.
• Corpus luteum produce progesterone and oestrogen which causes the deciduas to become thicker, richer, tortuous and more vascular at the fundus where implantation usually and normally takes place.

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ENDOMETRIUM CONT’D

• The lower segment of the uterus becomes less thinner, less lighter and less vascular.
• The decidua produce glycogen-rich environment for the blastocyte until the trophoblastic cells begin to form the placenta.human chorionic Gonadotrophic hormone stop the production of the corpus lutuem once the placenta is formed.

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MYOMETRIUM

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• There is increase in size called hypertrophy and increase in number called hyperplasia.
• The uterus increase 10 times in length and 5 times in thickness. The weight increase from 60grams to 900grams or 1 kilogram. There is also increase in size from 7.5* 5*2.5 to 30*23*20.

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MYOMETRIUM CONT’D

• Progesterone causes relaxation of the muscles.
• At 8weeks of gestation the uterus generate small painless, waves of contractions which last for a 60 seconds called Braxton hicks contraction.
• circular muscle layer 

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THE END

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