Lec 17 - Nervous System V - Brain II

Question 1

What is the brain stem responsible for?

Answer 1

nerve fibers pass from the cerebral hemispheres to the spinal cord through the brain stem.

nuclei of the cranial nerves are located here

Question 2

what 3 parts does the brain stem consist of?

Answer 2

medulla oblongata, pons, midbrain

Question 3

what is the location and contents of the medulla oblongata?

Answer 3

location - foramen magnum

contents - cardiovascular and respiratory centers of blood. (blood pressure, heart rate) Motor and sensory crossovers.

Question 4

what is the location and contents of the pons?

Answer 4

location - superior to medulla

contents - part of respiratory center bridge to cerebellum cranial nerves

Question 5

what is the location and contents of the midbrain?

Answer 5

location - superior to pons

contents - auditory and visual reflex centers

Question 6

what does the diencephalon consist of?

Answer 6

1. thalamus

2. hypothalamus

Question 7

where is the thalamus located and what is its purpose?

Answer 7

location - superior to midbrain (beneath corpus callosum)

purpose - relay center for all sensations except smell

Question 8

function and location of hypothalamus?

Answer 8

location - superior to midbrain, inferior to thalamus
function - controls sleep/wake cycle, hunger/thirst

Question 9

what is the reticular activating center?

Answer 9

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

Question 10

what is the function of the cerebellum?

Answer 10

coordinates movement

controls flexor and extensor muscles

Question 11

what is the function of the basal ganglia

Answer 11

it initiates movements in an adult.

Question 12

what is substantia nigra?

Answer 12

it is part of the basal ganglia in the midbrain.

damage leads to parkinsons

Question 13

what is the limbic system responsible for?

Answer 13

sex drive, major memory center

damage leads to alzheimers

Question 14

what are tracts or pathways composed of?

Answer 14

ascending or descending bundles of fibers which conduct info between the brain and spinal cord.

Question 15

what is the ascending tract? give its origin, ,decussation, and destination

Answer 15

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

Question 16

which is the descending tract? give origin, decussation, destination

Answer 16

corticospinal tract - MOTOR

origin - area 4
decussation - medulla
destination - spinal cord

Question 17

what is the synapse in the sensory relay center called?

Answer 17

the thalamus

Question 18

which two neurons is the innervation of skeletal muscle dependent upon? where are they located

Answer 18

1. upper motor neurons - grey matter of cortex [precentral gyrus] axon synapses on a lower motor neuron
2. lower motor neurons - cell body in brain stem or spinal cord. axon synapses on skeletal muscle fibers.

Question 19

what does damage to the upper and lower motor neurons result in?

Answer 19

1. poliomyelitis - lower motor neuron lesion

2. cerebrovascular accident (CVA or stroke) - upper motor neuron lesion

Question 20

what does poliomyelitis result from? list 3 examples of poliomyelitis

Answer 20

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

Question 21

if damage occurs in the corticospinal tract, you might expect the following symptoms:

Answer 21

a. spastic paralysis (random movement)
b. reflex intact (exaggerated)
c. babinski response present when poking the foot with a pencil.

Question 22

if branches of the right middle cerebral artery that supply the precentral gyrus was damaged, what area of the body would be affected?

Answer 22

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