Narrowest part of the fallopian tube is the :

Appeared in: RRB Staff Nurse Ahmedabad-2015

Explanation

The fallopian tube has four segments: interstitial, isthmus, ampulla, and infundibulum.
The interstitial portion, also known as the intramural part, is the segment that traverses the muscular wall of the uterus.
Due to its location within the thick myometrium, the interstitial portion has the smallest diameter, making it the narrowest part of the fallopian tube.

Option B: The isthmus is a narrow segment of the fallopian tube, but it is wider than the interstitial portion.
Option C: The infundibulum is the funnel-shaped, distal end of the fallopian tube and is significantly wider than the interstitial portion.
Option D: The ampulla is the widest and longest part of the fallopian tube, making it the opposite of the narrowest part.

Visual 1: Diagram - A labeled diagram of the female reproductive system, highlighting the four distinct parts of the fallopian tube (interstitial, isthmus, ampulla, infundibulum) to show their relative positions and sizes.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Anatomy of the fallopian tube as background academic context rather than a clinical decision trigger.
Understanding the anatomy of the fallopian tube is crucial for diagnosing and managing conditions like ectopic pregnancy. An interstitial pregnancy, though rare, is particularly dangerous because rupture can lead to massive hemorrhage due to the high vascularity of the surrounding myometrium.
The narrowness of the tubes, especially the isthmus and interstitial parts, makes them susceptible to blockage from infections (salpingitis) or adhesions, which is a leading cause of female infertility.
What if? - If a patient has a history of pelvic inflammatory disease (PID), the risk of tubal scarring and blockage increases significantly. This would make it harder for a fertilized egg to travel to the uterus, raising the risk of an ectopic pregnancy in the ampulla or isthmus.

How to Approach the Question

This is a factual recall question from anatomy.
First, identify the key terms in the question: 'Narrowest part' and 'fallopian tube'.
Mentally list or visualize the four segments of the fallopian tube in order from the uterus to the ovary: Interstitial (intramural), Isthmus, Ampulla, and Infundibulum.
Recall the defining characteristic of each part's diameter. The interstitial part passes through the uterine wall, making it the most constricted. The isthmus is narrow, the ampulla is wide, and the infundibulum is funnel-shaped.
Compare the options to your anatomical knowledge. The interstitial portion is correctly identified as the narrowest segment.

Concept Tested & Keywords

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Practise the full RRB Staff Nurse Ahmedabad-2015

Attempt every question from this paper in a timed mock, then review the full solution for each one.