Rhombencephalon

Dr Craig Hacking and Dr Matt A. Morgan et al.

The rhombencephalon, or hindbrain is a primary vesicle of the neural tube.

During the fifth week of embryological development the rhombencephalon further subdivides into the secondary brain vesicles, the metencephalon and the myelencephalon 1

The metencephalon goes on to form the pons, the majority of the cerebellum and the fourth ventricle. The myelencephalon becomes the medulla oblongata, and the central canal 1. The most rostral portion of the cerebellum receives contributions from the mesencephalon, and the floor of the fourth ventricle is derived in part, from the myelencephalon. 

At week 22, the typical shape of the brainstem is recognisable, however the cerebellum does not reach its final configuration until well after birth 2.

The most common structural disorder of hindbrain development is the Chiari malformation

The embryonic/fetal rhombencephalon is visible with endovaginal ultrasound at ~8-10 weeks as a hypoechoic region in the embryonic/fetal head. The hypoechoic region represents the developing rhombencephalon/hindbrain (medulla, pons, and cerebellum).

This is a normal structure, and is reportedly visible in all embryonic/fetal exams at 8-10 weeks 2. It becomes a normal fourth ventricle after the 11th week.

Ultrasound - obstetric
Neuroanatomy
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Article information

rID: 33060
Section: Anatomy
Synonyms or Alternate Spellings:
  • Fetal rhombencephalon
  • Fetal hindbrain
  • Embryonic rhombencephalon
  • Cystic rhombencephalon
  • Rhombencephalic vesicle

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    Case 1: fetal rhombencephalon
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    Case 2: fetal rhombencephalon (8w 4d)
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