Learning Objective
By the end of this topic, the learner should be able to identify key fetal circulatory and extraembryonic structures, describe their postnatal derivatives, and recognize important anatomic and clinical correlations.
Fetal–Postnatal Derivatives
Cardiovascular Shunts
- Ductus arteriosus
→ Ligamentum arteriosum
Located near the left recurrent laryngeal nerve - Foramen ovale
→ Fossa ovalis
Venous Structures
- Ductus venosus
→ Ligamentum venosum - Umbilical vein
→ Ligamentum teres hepatis (round ligament of the liver)
Contained within the falciform ligament
Umbilical and Extraembryonic Structures
- Umbilical arteries
→ Medial umbilical ligaments - Allantois (via the urachus)
→ Median umbilical ligament
The urachus represents the allantoic remnant between the bladder and the umbilicus
Exam Pearls
- Patent ductus arteriosus → failure of ductus arteriosus closure.
- Urachal anomalies → urine leakage from the umbilicus.
- Ligamentum arteriosum injury may affect the left recurrent laryngeal nerve
