Uterine pacemaker situated at:
A. Cornua of uterus
B. Isthmus
C. Cervix
D. Body of the temperature
Correct Answer: A. Cornua of uterus B
Explanation : The uterine pacemaker (the site where spontaneous uterine contractions normally originate) is located at the cornual region (also called the utero-tubal junction) near the insertion of the fallopian tubes, typically in the fundus of the uterus.
Key points:
• Most commonly, the dominant pacemaker is situated in the right cornual area (though it can be on either side or occasionally both).
• Electrical impulses generated here propagate downward through the myometrium toward the cervix, ensuring coordinated contractions during labor.
• This is why, in normal labor, contractions are strongest at the fundus and weaken toward the lower uterine segment (fundal dominance).
This anatomical and physiological fact is well-established in obstetrics and is the basis for understanding normal labor progression and conditions like incoordinate uterine action.
Other Options Details
Here are clear descriptions of all the options (which appear to be parts of the uterus and one incorrect option):
A. Cornua of uterus
• The cornua (singular: cornu) are the two upper “corners” or horns of the uterus where the fallopian tubes attach to the uterine cavity.
• They are the funnel-shaped lateral ends of the uterine fundus.
• This is where the interstitial (intramural) portion of each fallopian tube enters the uterus.
B. Isthmus
• The isthmus of the uterus is a short, narrow, constricted portion (about 1 cm long) between the body of the uterus (above) and the cervix (below).
• It is the lower part of the uterine body, just above the internal os of the cervix.
• During pregnancy, the isthmus elongates and becomes part of the lower uterine segment.
C. Cervix
• The cervix is the lower, cylindrical part of the uterus that projects into the vagina.
• Divided into:
• Supravaginal portion (above vagina)
• Vaginal portion (protrudes into vagina, also called portio vaginalis)
• Contains the cervical canal that connects the uterine cavity to the vagina through the external os and internal os.
• Produces cervical mucus and forms a barrier during pregnancy.
D. Body of the temperature
• This option is incorrect and does not exist in anatomy.
• It appears to be a distractor or typing error. There is no anatomical structure called “body of the temperature.”
• The correct term likely intended to confuse with “body of the uterus” or something unrelated.
Summary of actual parts of the uterus (from top to bottom):
1. Fundus → Cornua (where tubes attach)
2. Body (corpus)
3. Isthmus
4. Cervix
So correct anatomical options: A, B, C
Incorrect: D