2017 Group Project 6

From Embryology
2017 Student Projects 


Mark Hill (talk) 16:16, 14 September 2017 (AEST) OK Feedback

Basic Anatomy of the Cerebellum




Cerebellum anatomical subdivisions.png






Neural Development

Diagram of a 2 Day Old Embryo Illustrating the Beginnings of Neural Development [8]



Cortical Layers


Purkinje/Pyramidal Cells


Granule Cells


Structure of the Cerebellum [10]

Deep Nuclei




Bergmann Glia



Oligodendrocytes are glia found primarily in the white matter of the cerebellum. These glial cells form the fatty myelin sheath that gives the white matter its color.

Early Brain Structure

z5114433 - primary - secondary - ventricles






Cerebellum Development

(find images of the visualiation of the foetal cerebellum)

As the neural tube folds, the anterior portion develops the three brain vesicles; prosencephalon, mesencephalon and rhombencephalon. The rhombencephalon then further divides into the mesencephalic and myelincephalic vesicles on embryonic day 9. The neural tube failure to close then creates a gap along the dorsal sides and this produces a mouth-like structure as the tube bends to establish the pontine flexure. The pontine flexure further deepens bringing the mesencephalon (midbrain) closer to the primordium of the cerebellum (metencephalon); anterior aspects of the myelincephalon (brain stem) fold underneath developing the cerebellum plate [12] Further development of the cerebellum begins between days 40 and 45 and it arises mostly from the metencephalon however the rhombic lips also contributes. The roof plate which is derived from the dorsal part of the alar plate thickens during development to become the cerebellum. The regulation of patterning involved when he primary fissure deepens by the end of the third month and divides the vermis shows to be particularly important for development. The two lateral bulges are separated into the cranial anterior lob and caudal middle lobe. As the lobes divide further into lobules, fissures are formed and this continues throughout embryonic, fetal and postnatal life, thus increasing the surface area of the cerebellar cortex. The most primitive part of the cerebellum to form is the flocculonodular lobe, which is derived from separation of the first transverse fissure and this functions to keep connections with the vestibular system and it is also concerned with subconsciously controlling equilibrium. The flocculonodular lobe is separated from another crucial part of the cerebellum, corpus cerebelli, by the posterolateral fissure.

The cerebellum has a very basic structure consisting 2 principal classes of neurons and 3 layers, the first is a single layer of inhibitory Purkinje cells which are sandwiched between a dense layer of excitatory granule cells, and another molecular layer of granular cell axons and purkinje cell dendritic fibres. The granule cells receive inputs from outside the cerebellum and project these inputs to purkinje cells where the majority of these inputs are further projected to a variety of cerebellar nuclei in the white matter [13]. The nuclei from the cerebellum are formed by a complex process of neurogenesis and neuronal migration. There are two types of grey matter in the cerebellum, the deep cerebellar nuclei and an external cerebellar cortex. There are 4 deep nuclei formed and the output of the cerebellar cortex are relayed through these nuclei, the ventricular layer produces 4 types of neurons that migrate to the cortex. The adjacent rhombic lips gives rise to cerebellar granule cells. [14]

z5018156 - https://www.ncbi.nlm.nih.gov/pubmed/21295689 [15]

Cerebellum Development Stages

Week 3
Early stage of neurulation
Late stages of neurulation
Week 4
Prosencephalon, mesencephalon and rhombencephalon is developed.
Week 5
week 6
Weeks 7-9
weeks 11-12
Weeks 15-16
Nodule and flocculus is developed. Several deep fissures are formed in the vermis which has increased in thickness similar to the hemispheres [18].



Dandy-Walker-Malformation (DWM) includes the incomplete development of the cerebellar vermis with cystic dilatation of the 4th ventricle and enlargement of the posterior fossa [19]. The cerebellar vermis (found at the medial, cortico-nuclear zone of the cerebellum [find reference]) may either be elevated or rotated upwards [19]. The communication of the 4th ventricle with the midline posterior fossa cyst is found on MRI scans of DWM [19]. Other characterisations include upward displacement of the tentorium and anterolateral shift of cerebellar hemispheres (reference DWM article).

Joubert syndrome (JS) is described as a rare inherited genetic disorder characterised by lack of muscle coordination, developmental delay, and either neonatal respiratory disturbances or abnormal eye movement [20]. On neuroimaging, the cerebellar vermis is identified to have gone through hypoplasia (underdevelopment) or dysplasia (abnormal development) [19].

Tecto-Cerebellar Dysraphism with Occipital Meningo-Encephalocele (TCD-OE) is a rare, infrequent abnormality defined by underdevelopment of the cerebellar vermis, tectal malformation, and occipital encephalocele [19]. TCD-OE patients also have development delay, lack of muscle coordination and irregular breathing like individuals with JS. However, those with TCD-OE also have episodic abnormal heavy breathing (tachypnea), low muscle strength, excess digits and a hole in the eye (opsoclonus), which can be seen as abnormal development. In neuroimaging, cerebellar midline defects are identifiable (such as a cleft of the cerebellar vermis), as well as elongation of the Superior Cerebellar Peduncle (SCP), dorsal midbrain deformity, displacement of the brainstem and vertical orientation of the cerebellar hemispheres [19].

Rhombencephalosynapsis is a rare, irregular cerebellar defect characterised by the failure to develop the vermis, dorsal fusion of the cerebellar hemispheres and fusion of dentate nuclei and SCP, which is seen as the keyhole-shape of the fourth ventricle in neuoroimaging [19].

Historic Images


  1. http://www.sciencedirect.com/science/article/pii/S1364661398012108
  3. https://commons.wikimedia.org/wiki/File:CerebellumDiv.png
  5. https://www.ncbi.nlm.nih.gov/books/NBK11042/
  6. https://www.ncbi.nlm.nih.gov/pubmed/2535662
  7. https://www.researchgate.net/publication/309323728_Arteries_and_Veins_of_the_Cerebellum
  10. <pubmed>25336734</pubmed>
  12. <pubmed>7605067</pubmed>
  13. <pubmed>25336734</pubmed>
  15. <pubmed>2775156</pubmed>
  16. <pubmed>21380713</pubmed>
  17. <pubmed>21380713</pubmed>
  18. <pubmed>21380713</pubmed>
  19. 19.0 19.1 19.2 19.3 19.4 19.5 19.6 <pubmed>22108217</pubmed>
  20. https://ac-els-cdn-com.wwwproxy1.library.unsw.edu.au/S0028384314604539/1-s2.0-S0028384314604539-main.pdf?_tid=61523f80-a72e-11e7-8612-00000aacb361&acdnat=1506920510_1adf2cde97720bd7909ebf0873992979