Uterus Diagram

Table of Content:

• What is Uterus?
• Well-labelled Diagram of the Uterus
• Uterus – Description
• Ligaments of Uterus
• Changes in Uterus
• Frequently Asked Questions

What is Uterus?

The uterus or womb lies between the urinary bladder and the rectum in the pelvic cavity. It is a thick-walled hollow muscular and pear-shaped organ that has a central cavity. The uterus opens into the vagina via the cervix. On the upper portion of its either side is the fallopian tube opening. These tubes help the uterus to communicate with the peritoneal cavity.

Here, let us learn more about the descriptive features of the uterus with a well-labelled diagram.

Well-labelled Diagram of the Uterus

Uterus – Description

• The uterus is a 7.5 cm long structure with a breadth of 5 cm. Its upper portion has a thickness of about 2.5 cm.
• Isthmus is a constriction present in the middle of the uterus.
• The uterus can be distinguished into – fundus, body and the cervix.
• The cervix is found below the isthmus, and the fundus is present above the entry points of the fallopian tube. Fundus is the round, uppermost portion of the uterus. The body or corpus of the uterus is present between the isthmus and the fundus.
• The lower constriction of the uterus is the cervix. It has a supravaginal (upper) portion that communicates with the uterus body through the orifice (internal os) of the cervix.
• The lower portion of the cervix projects into the anterior wall of the vagina and it communicates via another orifice (external os) of the cervix.
• The cervical canal is a flattened spindle-shaped canal of the cervix that forms the neck of the uterus.
• The uterine tube or fallopian tube is composed of 4 parts – the fimbriae (near ovary), infundibulum, isthmus and ampulla. Ampulla is the major portion and isthmus is the narrow portion of the tube.
• The point where the uterus and the fallopian tube meet is called the cornua or the uterine horn.
• Furthermore, this uterus structure is composed of three layers – serous layer, middle muscular or myometrium layer, and the inner mucus or endometrium layer.
• The outer serous is derived from the peritoneum, and it covers the anterior portion of the uterus completely. The posterior portion is covered only up to isthmus.
• The myometrium is the thickest layer that is made of smooth muscle fibres. These muscle fibres are arranged in 3 different layers. The external layer is made up of transversely arranged muscle fibres. The middle layer is made up of obliquely, transversely and longitudinally arranged muscle fibres. The innermost layer is made of circular muscle fibres. These muscular layers are interspersed with nerve fibres, blood vessels, areolar tissues and lymphatic vessels.
• The inner endometrium is soft, smooth and pale red in colour. It is composed of simple columnar epithelium. Its surface has tiny orifices via which the tubular follicles of the endometrium open.
• This endometrium also has connective tissue in which the uterine glands are present. These endometrial or uterine glands are the functional layers which are also lined by columnar epithelium.

Ligaments of Uterus

The uterus is properly held in place with a number of ligaments. Let’s have a look at some of those ligaments.

The broad ligament can be further distinguished into mesometrium (mesentery of uterus), mesosalpinx (mesentery of fallopian tubes) and mesovarium (mesentery of ovaries).

The ovarian artery is present in the suspensory ligament and it supplies oxygenated blood to the ovary.

Changes in the Uterus

The uterus changes its structure and function during different phases of life. Before menstruation, the uterus becomes enlarged and more vascular. The endometrial layer becomes thick with more blood supply. Later, this layer becomes desquamated during menstruation and then reforms after the menstrual period.

During pregnancy, the uterus becomes very large and after parturition, it comes back to its original size. But, the cavity still remains large. During old age, the uterus atrophies.

Further Reading:

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