Cerebellum

The cerebellum sits at the base of the brain and has:

• 3 surfaces: anterior (petrosal), superior (tentorial), inferior (suboccipital)
• 2 hemispheres
• 1 median vermis

3 fissures:

1. primary (tentorial),
2. horizontal (petrosal),
3. prebiventral/prepyramidal (suboccipital)

Vermis

The vermis is divided in 9 lobules: (in a clockwise rotation, looking the pt sagittally from his left), and separated into groups by fissures

• lingula
• central lobule
• culmen: primary (tentorial) fissure
• declive
• folium: horizontal (petrosal) fissure
• tuber: prebiventral/prepyramidal (suboccipital) fissure
• pyramis
• uvula
• nodulus

Cerebellar hemisphere

Each of the 9 vermis lobules is associated in both sides with two cerebellar hemisphere lobules and, suitably, you will have 18 cerebellar hemisphere lobules:

• wing of lingula (lingula)
• wing of Central lobule (central lobule)
• quadrangular lobule (culmen): primary (tentorial) fissure
• simple lobule (declive)
• semilunar superior lobule (folium): horizontal (petrosal) fissure
• Semilunar superior lobule (tuber): prebiventral/prepyramidal (suboccipital) fissure
• biventral lobule (pyramis)
• yonsil (uvula)
• flocculus (nodulus)

Connections to brian stem

1. to midbrain = superior cerebellar peduncles (brachia conjunctiva)
2. to pons = middle cerebellar peduncles (brachia pontis)
3. to medulla = inferior cerebellar peduncles (restiform bodies)

CSF Cisterns

1. cerebellopontine angle cistern
2. cisterna magna
3. quadrigeminal plate cistern
4. superior cerebellar cistern

Blood supply

The cerebellum is essentially suplied by three vessles:

1. superior cerebellar artery (SCA) (branch of the distal basilar)
2. anterior inferior cerebellar (AICA) (branch of the proximal basilar)
3. posterior inferior cerebellar (PICA) (branch of the distal vertebrals)

Superior cerebellar (SCA)

The SCA supplies:

• whole superior surface of the cerebellar hemispheres down to the great horizontal fissure
• the superior vermis
• dentate nucleus.
• most of the cerebellar white matter

Anterior inferior cerebellar (AICA)

The amount of tissue supplied by the AICA is variable (PICA - AICA dominance) but usually includes:

• middle cerebellar peduncle
• infrolateral portion of the pons
• flocculus
• anteroinferior surface of the cerebellum

Posterior inferior cerebellar (PICA)

The PICA has a variable territory depending on the size of the AICA, but usually supplies:

• posteroinferior cerebellar hemispheres (up to the great horizontal fissure)
• inferior portion of the vermis.

• 18% arise extracranially, inferior to the foramen magnum
• 10% arise from the basilar rather than vertebral artery
• 2% bilaterally absent
• occasionally loops around the cerebellar tonsil.

It divides into lateral and medial branches that supply the inferior portion of the vermis and cerebellar hemispheres respectively.

NOTE: Occasionally a small vertebral will terminate into a common PICA / AICA trunk.