18. Granule cell axons ascend to the molecular layer, bifurcate and form parallel fibers that run parallel to folia forming excitatory synapses on Purkinje cell dendrites. Cerebellar cortex also has several types of inhibitory interneurons: basket cells, Golgi cells, and stellate cells. Purkinje cell axon is only output of cerebellar cortex, is inhibitory and projects to the deep nuclei and vestibular nuclei. Deep nuclei axons are the most common outputs of the cerebellum (excitatory).
21. Cerebellar Output Pathways Lesions of lateral cerebellum affect distal limb coordination. Medial lesions affect mainly trunk control, posture, balance, and gait. Cerebellar deficits occur ipsilateral to the lesion because cerebellar outputs go to the contralateral side and then motor pathways decussate back to the original side (“double cross-over”). Vermis lesions do not cause unilateral deficits because medial muscle groups typically receive bilateral UMN inputs.
22. Static Equilibrium 1) keep the body in a desired position , Static equilibrium – The equilibrium is maintained in a FIXED POSITION , usually while stood on one foot. maintenance of body posture relative to gravity while the body is still.
23. Dynamic Equilibrium 2) move the body in a controlled way . Dynamic equilibrium The equilibrium must be maintained while performing a task which involves MOVEMENT e.g. Walking the beam. – maintenance of the body posture (mainly the head) in response to sudden movements. Tracking a moving object.
30. Static Equilibrium Inside the vestibule are two chambers : utricle and saccule . Regions of hair cells and supporting cells called maculae . Otoliths – “ear rocks”