Lec 17 - Nervous System V - Brain II Flashcards
What is the brain stem responsible for?
nerve fibers pass from the cerebral hemispheres to the spinal cord through the brain stem.
nuclei of the cranial nerves are located here
what 3 parts does the brain stem consist of?
medulla oblongata, pons, midbrain
what is the location and contents of the medulla oblongata?
location - foramen magnum
contents - cardiovascular and respiratory centers of blood. (blood pressure, heart rate) Motor and sensory crossovers.
what is the location and contents of the pons?
location - superior to medulla
contents - part of respiratory center bridge to cerebellum cranial nerves
what is the location and contents of the midbrain?
location - superior to pons
contents - auditory and visual reflex centers
what does the diencephalon consist of?
- thalamus
2. hypothalamus
where is the thalamus located and what is its purpose?
location - superior to midbrain (beneath corpus callosum)
purpose - relay center for all sensations except smell
function and location of hypothalamus?
location - superior to midbrain, inferior to thalamus function - controls sleep/wake cycle, hunger/thirst
what is the reticular activating center?
it is a column of neurons that are located in the middle of the brain stem from the thalamus to the medulla.
these neurons maintain a conscious state, when dmged, = coma
what is the function of the cerebellum?
coordinates movement
controls flexor and extensor muscles
what is the function of the basal ganglia
it initiates movements in an adult.
what is substantia nigra?
it is part of the basal ganglia in the midbrain.
damage leads to parkinsons
what is the limbic system responsible for?
sex drive, major memory center
damage leads to alzheimers
what are tracts or pathways composed of?
ascending or descending bundles of fibers which conduct info between the brain and spinal cord.
what is the ascending tract? give its origin, ,decussation, and destination
fasciculus gracilis and cuneatus - SENSORY
origin: spinal cord
decussation: medulla. right side of body - left brain, left side of body - right brain
destination: area 3,1,2 in cerebral hemisphere
which is the descending tract? give origin, decussation, destination
corticospinal tract - MOTOR
origin - area 4
decussation - medulla
destination - spinal cord
what is the synapse in the sensory relay center called?
the thalamus
which two neurons is the innervation of skeletal muscle dependent upon? where are they located
- upper motor neurons - grey matter of cortex [precentral gyrus] axon synapses on a lower motor neuron
- lower motor neurons - cell body in brain stem or spinal cord. axon synapses on skeletal muscle fibers.
what does damage to the upper and lower motor neurons result in?
- poliomyelitis - lower motor neuron lesion
2. cerebrovascular accident (CVA or stroke) - upper motor neuron lesion
what does poliomyelitis result from? list 3 examples of poliomyelitis
this disorder results from a viral infection that damages the lower motor neurons located in the ventral gray horn of the spinal cord.
a. flaccid paralysis - no movement, laying there
b. reflexes absent
c. muscle atrophy - needs stimulus
if damage occurs in the corticospinal tract, you might expect the following symptoms:
a. spastic paralysis (random movement)
b. reflex intact (exaggerated)
c. babinski response present when poking the foot with a pencil.
if branches of the right middle cerebral artery that supply the precentral gyrus was damaged, what area of the body would be affected?
right = left
middle cerebral artery = lateral, upper limb
=> left upper limb, lateral
left = right part of body
anterior cerebral artery = lower limb
=> right lower limbs
