A sex organ, the uterus (womb) is found within the female’s pelvis. In the young adult woman it measures about 7.5 cm long, 5 cm wide, 3 cm thick and weighs about 70 g – it is pear shaped. At the end of pregnancy the uterus weighs approximately 1 kg.
From inside to outside, the uterus is composed of 3 layers. The endometrium which is the innermost layer is shed monthly during menstruation; if pregnancy occurs, the developing human implants into the endometrium. The middle layer, the myometrium is composed of smooth muscle which contracts involuntarily periodically during the menstrual cycle (causes menstrual cramping), during orgasm (apex of sexual stimulation) as well as during childbirth. The outermost uterine layer consists of loose supporting tissue, the perimetrium.
Monga A, (ed.), 2006, Gynaecology by Ten Teachers, 18th edition, Hodder Arnold, London, page 11. Go to reference
Internal female reproductive organs viewed from the front and side