What are the three different types of fibers that enter the cerebellum and what is their function?
Superior cerebellar peduncle - connects the cerebellum and cerebrum
Pontocerebellar fibers (middle cerebellar peduncle) - connects the cerebellum and the pons
Infereior cerebellar peduncle (climbing fibers) - come from the inferior olivary nucleus of the medulla
"Climb the olive tree"
Name the 12 cranial nerves.
11. Accessory nerve (cranial root and spinal root)
12. Hypoglossal nerve
Where is the decussation of the pyramids?
What is another name for the corticospinal tract?
What is the lateral geniculate body involved in?
What is the medial geniculate body involved in?
What is the superior colliculus involved in?
What cranial nerve comes off dorsal to the brainstem?
Trochlear (CN IV)
What pathway does sight follow?
Rods and cones (layer 2) --> bipolar cells --> ganglion cells of the retina --> Optic nerve --> Optic chiasm --> optic tract --> lateral geniculate body --> Superior colliculus (visual motor functions) and calcarine cortex of occipital lobe (via the geniculocalcarine tract)
What pathway does hearing follow?
Spiral organ of corti --> CN VIII (cochlear nucleus) --> Lateral lemniscus (through trapezoid body) --> Inferior colliculus --> medial geniculate body --> temporal lobe of the cortex
LIME = Lateral, Inferior, Medial, Ear
Where are the Superior and inferior colliculi located?
What is the obex?
The fold at the bottom of the 4th ventricle
Where are the geniculate bodies located?
Lateral to the colliculi in the dorsal mesencephalon
What is the main function of the pons?
To relay fibers going to the cerebellum (pontocerebellar fibers via the Middle cerebellar peduncle)
Where is the pons located?
Superior to the medulla oblongata
Ventral to the cerebellum
Inferior to the midbrain
Where is the medulla oblongata located?
Caudal to the pons
What two important structures does the medulla oblongata contain?
Olives and the pyramids
What is the main function of the basal ganglia?
Background muscle tone
What 4 structures are in the basal ganglia?
What makes up the lentiform nucleus?
Where do fibers from the globus pallidus terminate?
What does a lesion of the basal ganglia cause?
Parkinson's disease (Paralysis agitans)
What does a lesion in the basal ganglia result in?
No dopamine in substantia nigra
What are the symptoms of Parkinson's?
What is another name for the anterior pituitary? What is it derived from?
Rathke's Pouch (oral ectoderm)
What is the link between the CNS and the Adenohypophysis?
Hypophyseal Portal system (blood)
What is another name for the Posterior pituitary? What type of tissue is it?
Where are oxytocin and ADH (Vasopressin) formed? Where are they released?
Formed in hypothalamus
Released by posterior pituitary
What is the thalamus?
The major sensory integration center, it recives all senses except smell prior to the cortex
Sensory fibers ascend through the thalamus to where?
the sensory cortex via the Internal capsule
What part of the thalamus recieves input from the cerebellum?
What part of the thalamus is a synaptic region for ascending spinal sensory pathways?
What part of the thalamus projects to sensory areas of the parietal and temporal lobes?
What are the main functions of the thalamus?
Temperature regulation, thirst, hunger, defensive reactions
What parts of dorsal column/ML pathway are ipsilateral? Contralateral?
Lower limb unconscious proprioception, whole limbs is ipsilateral (crosses over twice)
Lower limb unconscious proprioception, individual muscles and all others are contralateral
What is the function of the dorsal columns?
Conscious and unconscous proprioception, vibration, 2 point discrimination
What is the function of the posterior spinocerebellar tract?
Unconscious proprioception to the cerebellum from lower limbs
What is the function of the anterior spinocerebellar?
stretch from spindle cells of lower limbs
What is the spinocerebellar pathway?
DRG --> nucleus of clark C8 to L3 --> inferior cerebellar peduncle --> cerebrum
What causes Fredeicks ataxia?
damage to the spinocerebellar pathway
What does the lateral spinothalamic pathway carry?
pain and temperature
What does the anterior spinothalamic pathway carry?
Light touch and pressure
What is the spinothalamic pathway?
First order neuron to DRG (2nd order synapse) --> crosses over --> 2nd order neuron to medulla then midbrain then thalamus (3rd order synapse) --> 3rd order neuron to somesthetic area of cortex (post central gyrus)
Where is the 2nd order synapse for the spinothalamic tract?
Lamina 4,5,6 (nucleus proprius)
What type of fibers are the anterior spinothalamic 1st order neurons?
A beta fibers
What type of fibers are the lateral spinothalamic 1st order neurons?
A delta and C fibers
What does the spinotectal pathway carry?
Tactile stimulation causing visual reflexes
What is the spinotectal pathway?
DRG --> crosses over --> tectum (superior colliculus)
What does the spinoreticular pathway carry?
What is the spinoreticular pathway? What is another name for it?
Same as spinothalamic except it also synapses in the reticular formation and hypothalamus as well as the thalamus
What are the pyramidal tracts?
Lateral and anterior corticospinal tracts
What is the function of the corticospinal tract?
Conscious, voluntary motor movements form the cerebral cortex of Giant cells (betz cells) especially fine movements of the hands
What will a lesion in the corticospinal tract cause?
What is the lateral corticospinal pathway?
Motor cortex --> contralateral pyramid (lower medulla - dexussation of pyramids) --> spinal cord anterior horn
What is the anterior corticospinal pathway?
Motor cortex --> ipsilateral medulla --> contralateral spinal cord anterior horn (crosses at level of muscle)
What % of the corticospinal tract is lateral? anterior?
What descending tracts are extra pyramidal tracts?