Endoscopy identifies three normal constrictions of the esophagus. Measured from the upper incisor teeth, these constrictions lie approximately at:
- A 15 cm, 25 cm, 40 cm ✓
- B 10 cm, 20 cm, 30 cm
- C 20 cm, 30 cm, 45 cm
- D 15 cm, 30 cm, 50 cm
Correct answer: A. 15 cm, 25 cm, 40 cm
Explanation
The three narrowings are at about 15 cm (cricopharyngeus, C6), 25 cm (crossed by the aortic arch and left main bronchus, T4 to T5), and 40 cm (diaphragmatic hiatus, T10) from the incisors. These sites are where swallowed foreign bodies lodge, where strictures form after corrosive ingestion, and where squamous cell carcinoma shows a higher incidence. The 25 cm site corresponds to the level of the sternal angle.
Reference: Gray's Anatomy for Students, 4th ed.
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Written and medically reviewed by the StethoPrep medical team.