Definition - What does Cervical Canal mean?
The cervical canal is a passage inside the cervix through which the uterine cavity opens to the vagina. It acts as a gate that allows the passage of sperm into the uterus for fertilization, but prevents the fetus from being prematurely delivered, typically until 40 weeks of pregnancy is completed. Abnormalities of the cervical canal can cause infertility by blocking the passage of sperm for fertilization or by leading to miscarriages.
Cervical canal is also called the endocervical canal and the cavity of the cervix.
FertilitySmarts explains Cervical Canal
The cervix is considered the neck of the uterus. The cervical canal is a narrow tunnel inside the cervix that takes the shape of a spindle that is wider in the middle and gets narrower towards both ends.
The lower end of the cervical canal opens to the vagina through the external opening, also known as the external cervical os. Similarly, the upper end of the cervical canal is continuous with the cavity of the uterus through the internal os.
The cervical os changes in size during the menstrual cycle. During the fertile period of the cycle, estrogen opens the cervical os and the cervix produces fertile cervical mucus to aid the passage of sperm. During infertile days, or when the egg has been fertilized, progesterone takes over that closes the cervical os and produces thick mucus that blocks the cervical canal, preventing more sperm from entering the uterus.
The two openings are usually kept very tight. During childbirth, the tissue of the cervix becomes soft and stretched and makes the cervical canal sufficiently wide to allow the delivery of the head of the fetus. Maintaining this tightness in the cervical canal is very important during pregnancy. If the cervical canal widens early, a condition known as cervical incompetence, the fetus may be delivered before maturation leading to a miscarriage or premature birth.
The cervix also plays a major role in fertilization. Sperm that enters the vagina during intercourse should travel through the cervical canal to enter the uterine cavity, after which they have to find their way through the fallopian tubes to meet with an egg. The cervix produces cervical mucus to nourish and facilitate the passage of the sperm through the cervical canal. Structural abnormalities of the cervical canal leading to narrowing of the canal or complete blockage or abnormalities in cervical mucus production can limit the entry of sperm into the uterus causing infertility.