uterus - Development, Pathology, Terminology, Additional images

A pear-shaped, thick-walled muscular organ of females which projects upwards and forwards above the bladder from the upper part of the vagina; also known as the womb. It consists of a fundus (the region of the body above the level of entrance of the uterine tubes), a body, and the cervix (separated from the body by a slight narrowing). The lower end of the cervix is surrounded by and opens into the upper part of the vagina. At birth the uterus is mainly an abdominal organ, the cervix being relatively large and not distinct from the body. It grows slowly until just before puberty, when its growth is rapid for a time. In old age the uterine wall becomes harder and more fibrous than in the younger woman. The pregnant uterus increases rapidly in size and weight as it rises into the abdomen. In the human female, the nonpregnant uterus is c.7·5 cm/3 in in length and weighs 40 g/1·4 oz. During pregnancy it increases in size to become c.30 cm/12 in in length and can weigh as much as 1 kg/2·2 lb by the eighth month. Immediately after childbirth it contracts, so that by the end of the eighth week it is back to its normal size (this process is known as involution). The epithelial lining (endometrium) is influenced by oestrogens and progestagens produced by the ovary. If implantation does not follow ovulation, the superficial layers of the endometrium are shed in response to hormonal changes, causing the menstrual flow.

Regions

From outside to inside, the path to the uterus is as follows:

Vagina Cervix uteri - "neck of uterus" External orifice of the uterus Canal of the cervix Internal orifice of the uterus corpus uteri - "Body of uterus" Cavity of the body of the uterus Fundus (uterus)

Layers

The layers, from innermost to outermost, are as follows:

Layer	Description
endometrium	The lining of the uterine cavity is called the "endometrium".
myometrium	The uterus mostly consists of smooth muscle, known as "myometrium".
perimetrium	The loose surrounding tissue is called the "perimetrium".
peritoneum	The uterus is surrounded by "peritoneum".

Ligaments

It is held in place by the following ligaments:

Name	Number	Description
anterior	one	vesicouterine fold of peritoneum
posterior	one	rectovaginal fold of peritoneum
lateral or broad ligament of the uterus (mesometrium)	two	part of peritoneum that extends from the sides of the uterus
uterosacral ligaments	two	rectouterine folds
round ligament of uterus	two	from lateral angle of the uterus to labium majus
ovarian ligaments	two	connect uterus to ovaries

Position

Under normal circumstances the uterus is both "anteflexed" and "anteverted". The meaning of these terms are described below:

Distinction	More common	Less common
Position tipped	"anteverted": tipped forward	"retroverted": tipped backwards
Position of fundus	"anteflexed": the fundus is pointing forward relative to the cervix	"retroflexed": the fundus is pointing backwards

Development

The bilateral Müllerian ducts form during early fetal life.

Pathology

Some pathological states include:

Prolapse of the uterus Carcinoma of the cervix - malignant neoplasm Carcinoma of the uterus - malignant neoplasm Ectopic pregnancy Fibroids - benign neoplasms Adenomyosis - ectopic growth of endometrial tissue within the myometrium Pyometra - infection of the uterus, most commonly seen in dogs

Terminology

The term uterus is commonly used within the medical and related professions, whilst the term womb is in more common usage.

Additional images

Schematic frontal view of female anatomy

Uterus and uterine tubes.