Cerebellum

Question 1

what is the function of the cerebellum? (2)

Answer 1

1. coordinate movement by regulating rate, range, and force of movement in an inhibitory fashion (unconscious proprioception)
2. also contributes to equilibrium/vestibular function (special proprioception)

Question 2

what is the embryological origin of the cerebellum?

Answer 2

the rhombencephalon (most caudal vesicle of neural tube);

thombencephalon includes the metencephalon (cerebellum and pons) and the myelencephalon (medulla oblongata)

Question 3

what are the 2 gross anatomical divisions of the cerebellum?

Answer 3

cortex and medulla

Question 4

what are the 3 cerebellar peduncles? what is their purpose?

Answer 4

rostral, middle, caudal; project from the spinal cord to the cerebellum

Question 5

what takes the afferent path to the cerebellum? (3)

Answer 5

1. prosencephalon
2. brainstem
3. spinal cord

to the cerebellar cortex

Question 6

what takes the efferent path from the cerebellum? (2)

Answer 6

1. cerebellar nuclei
2. brain stem nuclei (UMN to prosencephalon and spinal cord)

Question 7

how is the cerebellum related to the vestibular system? describe how this is messed up with a lesion

Answer 7

receives input from central vestibular system to coordinate movement accordingly; a lesion decreases the firing rate of one side and makes cerebellum and the rest of the brain think that the body is moving in the direction with the now falsely greater firing force

Question 8

how does inhibiting one half of the cerebellum lead to vestibular disease?

Answer 8

take away cerebellar inhibition (by lesion) of one side will increase the firing rate of the other side, causing vestibular dysfunction, meaning that you increase firing rate ipsilateral (no inhibition ipsilateral) and “decrease” firing rate contralateral (not actually decreased but appears decreased because other side not inhibited

Question 9

what are the clinical signs of cerebellar lesion (5)

Answer 9

1. rate, range, and force of motion lack inhibition
2. abnormal motor function (dysmetria, hyper/hypometria, ataxia, tremors)
3. no paresis/strength preserved
4. if unilateral, signs are ipsilateral!
5. NORMAL mentation!

Question 10

describe gait/stride with cerebellar ataxia (5)

Answer 10

1. dysmetria
2. no paresis/strength preserved
3. base wide stance
4. sway/fall to one side, front and backwards (truncal sway/titubation)
5. intention tremors of the head: head bobbing with intentional movement (like when trying to get to food bowl)

Question 11

describe how to evaluate postural reactions with a cerebellar lesion (4) and what will be observed (2)

Answer 11

1. hopping/hemi-walking
2. wheelbarrowing
3. extensor postural thrust
4. proprioceptive positioning/knuckling

will see these be INTACT but slightly uncoordinated so be slightly delayed with an exaggerated followthrough

Question 12

describe cranial nerves with a cerebellar lesions

Answer 12

loss of menace; but normal vision and normal facial nerve because pathway implies cerebral function (II in, through cerebellum for VII out)

Question 13

describe decerebellate rigidity; contrast with decerebrate rigidity

Answer 13

decerebellate
1. severe, acute cerebellar abnormality etiology due to removal of cerebellar control/extensor inhibition
2. opisthotonus (arch head, neck, spine)
3. rigid extension of thoracic limbs
4. pelvic limbs flexed under body due to hypertonia of hip flexors
5. normal consciousness

whereas decerebrate removes prosencephalic UMN control of brainstem but maintain UMN function of brainstem (facilitates extensors) so results in rigid extension of ALL limbs AND ALTERED MENTATION