Thalamocortex lesions

Intelligence, goal-directed behavior

Depressed mental status feat. head pressing, circling

Conscious proprioception ataxia with motor cortex lesions

BEHAVIOR IS CONTRALATERAL. Thalamic or parietal cortical lesions can lead to a lack of avoidance behavior in the contralateral nostril or earhole. (REFLEXES ARE IPSILATERAL, EXCEPT CROSSED-EXTENSOR REFLEX, WHICH HAS THAT NAME B/C IT IS UNIQUE)


Brainstem lesions

The bulk of the brainstem is made up of the RAS, responsible for arousal of the cerebrum

The parasympathetic nucleus of the brainstem

Vestibular nuclei

Depressed mental status but aware of surroundings

Abnormal posture: head tilt

Circling left, nystagmous fast phase to the right = left side vestibular problem

(Nystagmus slow phase is towards affected side. Why we describe using fast phase???)


CN lesions

The optic nerve decussates in the optic tract (according to Dr K)

The parasympathetic nucleus (midbrain) of the oculomotor nerve (pupil constriction)

  • The optic nerve (in) decussates twice

  • Damage to the oculomotor nerve itself or the parasympathetic nucleus in the brainstem leads to ipsilateral pupillary dilatation

  • “With unilateral oculomotor nerve dysfunction the contralateral pupil will constrict when the eye on the affected side is stimulated.”


Cerebellum lesions

Abnormal posture; intention tremor

Unconscious proprioception ataxia


Nonspecific “intracranial” lesions

Abnormal posture: Opisthotonos (UMN neck; rigid dorsal extension)




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