Uterine isthmus

Uterine isthmus is a region in the female reproductive system that connects the body of the uterus to the cervix. It is a narrow passage that plays a crucial role in the process of reproduction, particularly during pregnancy and childbirth.

Anatomy

The uterine isthmus is located in the lower segment of the uterus, between the uterine body and the cervix. It is approximately 1-2 cm in length and is surrounded by the muscular wall of the uterus, known as the myometrium. The isthmus is lined by the endometrium, the innermost layer of the uterus, which undergoes cyclic changes during the menstrual cycle.

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Diagram of the human female reproductive system with the uterine isthmus labeled.

Function

The primary function of the uterine isthmus is to act as a conduit for sperm to travel from the cervix to the uterus during fertilization. It also plays a significant role during pregnancy, as it expands to form the lower segment of the uterus, providing space for the growing fetus. During childbirth, the isthmus dilates to allow the passage of the baby from the uterus to the birth canal.

Clinical significance

Abnormalities or disorders of the uterine isthmus can lead to various health issues, including infertility, ectopic pregnancy, and complications during childbirth. For instance, an isthmic pregnancy is a type of ectopic pregnancy where the fertilized egg implants in the isthmus instead of the uterine cavity. This condition is rare but can be life-threatening if not treated promptly.

See also

• Uterus
• Cervix
• Ectopic pregnancy
• Female reproductive system