Lesson 7

Question 1

Brain Stem (contains what?)

Answer 1

1. Medulla oblongata
2. Pons
3. Midbrain
   Reticular formation

Question 2

Medulla oblongata

Answer 2

• starts at the foramen magnum and goes to pons
• made up of sensory (ascending) tracts and motor (descending) tracts
• Contain Pyramids and ducussation of pyramids

Question 3

Medulla contains

Answer 3

1. Pyramids and decussation of pyramids
2. olive
3. Gracile nucleus & cuneate nucleus
4. Gustatory nucleus
5. Cochlear nucleus
6. Vestibular nucleus

Question 4

pyramids

Answer 4

• bulges of white matter on the anterior part of the medulla
• formed by the corticospinal tracts

Question 5

decussation of pyramids

Answer 5

• crossing of axons in pyramids
• 90% of axons cross here
• explains why each side of brain controls the opposite side of body

Question 6

Nuclei in the Medulla

Answer 6

• Cardiovascular center
• Medullary rhythmicity area of the respiratory center
• Vomiting center
• Deglutition center

Question 7

Cardiovascular center

Answer 7

• regulates the rate and force of the heartbeat & the diameter of blood vessels

Question 8

Medullary rhythmicity area of the respiratory center

Answer 8

• adjusts the basic rhythm of breathing (along with areas in the pons)

Question 9

Vomiting center
Deglutition center

Answer 9

• causes vomiting
• causes swallowing

Question 10

olive

Answer 10

• just lateral to each pyramid
• oval-shaped swelling

Question 11

inferior olivary nucleus

Answer 11

• within the olive
• receives input from:
  cerebral cortex, red nucleus (midbrain),spinal cord
• its neurons extend into cerebellum, where they regulate the activity of cerebellar neurons
• it provides instructions that the cerebellum uses to make adjustments to muscle activity as you learn new motor skills

Question 12

Gracile nucleus & cuneate nucleus

Answer 12

are associated with sensations of touch, pressure, vibration and conscious proprioception

Question 13

Gustatory nucleus

Answer 13

• from tongue to brain
• receives gustatory input from taste buds of tongue

Question 14

Cochlear nucleus

Answer 14

• part of the auditory pathway from inner ear to brain
• receives auditory input from cochlea of the inner ear

Question 15

Vestibular nucleus

Answer 15

• equilibrium pathway from inner ear to brain

Question 16

Injury to medulla

Answer 16

• by hard blow to back of head/upper neck
• can be fatal
• damage to medullary rhythmicity area is really bad
• alcohol overdose also suppresses the medullaryrhythmicity area and may result in death

Question 17

Pons

Answer 17

• consists of nuclei and tracts
• is a bridge that connects parts of the brain with each other

Question 18

Pons contains

Answer 18

1. pontine nucleus
2. pneumotaxic area
3. apneustic area

Question 19

Pontine nucleus

Answer 19

• relays signals for voluntary movements from cerebral cortex to cerebellum

Question 20

Pneumotaxic area

Answer 20

Rhythm of breathing

Question 21

Apneustic area

Answer 21

Inhale/exhale

Question 22

Midbrain contains

Answer 22

1. Cerebral peduncles
2. Tectum
3. Substantia nigra
4. Red nuclei

Question 23

Cerebral peduncles

Answer 23

• paired bundles of axons

1. axons from corticospinal tracts:
   -motor area in cerebral
   cortex to the SC
2. corticobulbar tracts:
   -motor areas in cerebral
   cortex to medulla
3. corticopontine tracts:
   -motor areas in cerebral
   cortex to pons

Question 24

tectum

Answer 24

-posterior part
-contains 4 rounded elevations:
superior colliculi
inferior colliculi

Question 25

superior colliculi

Answer 25

* nuclei in 2 superior elevations * coordinates mvts of head, eyes, trunk in response to visual stim

Question 26

inferior colliculi

Answer 26

* nuclei in 2 inferior elevations * coordinates mvts of head, eyes, trunk in response to auditory stim startle reflex- sudden mvts of head, eyes, trunk that occur when surprised by a loud noise

Question 27

Substantia nigra

Answer 27

* neurons release dopamine and help control subconscious muscle activities * loss of these neurons is associated with Parkinson’sdisease

Question 28

Red nuclei

Answer 28

* involved in voluntary muscle movements * rich blood supply * iron-containing pigment

Question 29

Reticular formation

Answer 29

* is found throughout the brain stem * it’s a net-like arrangement of grey and white matter * grey matter – clusters of cell bodies * white matter – small bundles of myelinated axons

Question 30

Reticular activating system

Answer 30

* within reticular formation * consists of sensory axons that project to the cerebral cortex * can be activated by visual stimuli: * auditory stimuli * mental activities * pain, touch, pressure stimuli * proprioceptive receptors

Question 31

RAS Involved in? Active during?

Answer 31

* involved in consciousness consciousness – state of wakefulness in which an individual is fully alert, aware and oriented - active during arousal (awakening from sleep)

Question 32

Reticular activating system functions

Answer 32

* helps maintain attention and alertness * prevents sensory overload by filtering out insignificant information so that it does not reach consciousness * inactivation of the RAS produces sleep sleep – a state of partial consciousness from which an individual can be aroused

Question 33

Damage to RAS

Answer 33

* damage to the RAS results in coma * coma: a state of unconsciousness from which an individual cannot be aroused * in the lightest stages of coma, people still have brain stem and spinal cord reflexes * in deepest states, those reflexes are lost * drugs such as melatonin affect RAS by helping to induce sleep * anesthetics turn off consciousness via the RAS

Question 34

RAS motor axons do what?

Answer 34

* consists of motor axons that connect to the cerebellum and spinal cord to help regulate muscle tone * muscle tone: the slight degree of involuntary contraction in normal resting skeletal muscles * also involved in regulation of heart rate, BP, respiratory rate * RAS does not receive input from olfaction so even strong odors won’t wake people up