Lecture 12: CNS Part 1

Question 1

Describe the process of brain development

Answer 1

1. Neural plate forms from surface ectoderm
2. Neural plate invaginates, forming the neural groove, flanked by neural folds
3. Neural fold cell migrate to form neural crest , which will form the PNS and other structures
4. The neural groove becomes the neural tube, which will form CNS structures

Question 2

Name the 3 primary brain vesicles

Answer 2

Prosencephalon (forebrain)
Mesencephalon (midbrain)
Rhombencephalon (hindbrain)

Question 3

The three primary vesicles give rise to 5 secondary vesicles. What are they?

Answer 3

Tell Dian me met my
Telencephalon 
Diencephalon
Mesencephalon 
Metencephalon
Myelencephalon

Question 4

Why is found in the telencephalon brain vesicle?

Answer 4

Cerebrum: cerebral hemispheres (cortex, white matter, basal nuclei)
Here the lateral ventricles are found

Question 5

What is found in the Diencephalon brain vesicle?

Answer 5

Thalamus, hypothalamus, epithalamus

Also the third ventricles are found here

Question 6

What is found in the mesencephalon

Answer 6

Brain stem, mid brain. The cerebral aqueduct

Question 7

What is found in the Metencephalon brain vesicle?

Answer 7

Brain stem, pons, cerebellum, fourth ventricle

Question 8

What is found in the myencephalon?

Answer 8

Brain stem, medulla oblongata, fourth ventricle

Question 9

Name the major regions of the adult brain?

Answer 9

1. Cerebral hemispheres: right and left
2. Diencephalon: thalamus and hypothalamus
3. Brain stem: midbrain, pons, and medulla
4. Cerebellum
   Refer to slide 14 of picture

Question 10

Regions and organization of CNS.
What is inside the grey matter?
What is inside the white matter?

Answer 10

Grey matter: is found in the cortex (outside layer) of cerebrum and cerebellum. Nuclei in cerebellum and cerebrum
Cell bodies.
White matter: myelinated axons

Question 11

Surface of the brain markings:
What are the 5 lobes of the cerebrum
1. Frontal, parietal, temporal, occipital, insula
What is the name of the fissure separating the two hemispheres?

Answer 11

1. Frontal, parietal, temporal, occipital, insula

2. Longitudinal fissure

Question 12

What is that line which separates the cerebellum from the cortex?

Answer 12

Transverse cerebral fissure

Question 13

Cerebral cortex.

What happens in the cerebral cortex?

Answer 13

It is the site of the conscious mind: awareness, sensory, perception, voluntary motor initiation, communication, memory storage, understanding. Each hemisphere connects to the contra lateral side of the body
Makes up 40% of total brain mass.
There are three types of functional areas: motor, sensory, association

Question 14

Motor areas. What is the area responsible for?

Answer 14

-have long axons
-allows conscious control of precise, skilled, voluntary movements, controls learned motor skills.
Brocas area: present in one hemisphere, and is a motor speech area which directs muscles of tongue, active when we speak

Question 15

Sensory area.
What is the sensory area responsible for?
Ie name each of the sensory functions and their roles in receiving sensory information.
Refer to slide 23 for good image

Answer 15

-visual areas: on occipital lobe, receives visual info from retinas
-auditory areas: temporal lobes, interprets information from inner ear as pitch, loudness, and location
-olfactory cortex: medial aspect of temporal lobes, region of conscious awareness of odors
-gustatory cortex: involved in perception of taste
-vestibular cortex: responsible for conscious awareness of balance (positions of head in space)
Visceral sensory area: conscious perception of visceral sensation eg upset stomach, or full bladder

Question 16

Somatosensory cortex:

What is it responsible for?

Answer 16

• receives sensory information from the skin,nskeletal muscles, and joints
• capable of identifying body regions being stimulated
• determines size, texture, and relationship of objects being touched

Question 17

What is the prefrontal cortex function as?

Answer 17

• most complicated cortical region
• involved with intellect, cognition, recall, and personality
• contains working memory needed for judgement, reasoning, persistence and conscience
• development depends on feedback from social environment

Question 18

What does the limbic system function as?

Answer 18

Provides emotional impact that helps establish memories

Question 19

What is Basal ganglia (nuclei). What is its functions?

Answer 19

Basal ganglia are areas of grey matter within the white matter.
Functions:
-influence muscular control
-help regulate attention and cognition
-regulate intensity of slow or stereotyped movements
-inhibit antagonistic and unnecessary movements
Refer to slide 32 for picture

Question 20

Diencephalon: has three structures. What are they were are they located?

Answer 20

1. Thalamus
2. Hypothalamus: has a stalk called the infundibulum which connects it to the pituitary
3. Pineal gland: extends from the posterior boarder and secretes melatonin: helps regulated sleep/ wake cycles

Question 21

What is the function of the hypothalamus?

Answer 21

• the autonomic control centre for many visceral functions (eg blood pressure, rate and force of heart beat, digestive tract motility
• centre for emotional response
• regulates body temperature, food intake, water balance, and thirst
• Regulates sleep and wake cycle
• controls release of hormones by the pituitary
• produces posterior pituitary hormones

Question 22

What are the functions of the thalamus

Answer 22

• the ‘relay’ station of the brain. It is the gateway to the cerebral cortex. It sorts, edits and relays information such as:
• afferent impulses from all senses and all parts of the body
• impulses from the hypothalamus for regulation of emotion and visceral functions
• impulses from the cerebellum and basal nuclei to help direct the motor cortices
• mediates sensation, motor activities, cortical arousal, learning and memory

It’s is 80% of the Diencephalon
Superolateral walls of the third ventricle
-nuclei project and receive fibres from the cerebral cortex

Question 23

Draw the peripheral nervous system pathway

Answer 23

Do it!

Question 24

What the 6 classification types of stimulus? Explain

Answer 24

Mechanoreceptors: responds to touch, pressure, vibration, stretch, itch
Thermoreceptors: sensitive to changes in temperature
Photoreceptors: respond to light energy eg retina
Chemoreceptors: responds to chemicals eg smell, taste, changes in blood chemistry
Nociceptors: sensitive to pain
Proprioceptors: respond to stretch in skeletal muscles, tendons, joints,ligaments, and connective tissue coveting of bones and muscles and inform the brain of movements

Question 25

Structure of a nerve. What are the 3 connective tissue coverings called and where are they located?

Answer 25

Endoneurium: loose connective tissue that encloses axons and their myeline sheaths (most deep)
Perineurium: coarse connective tissue that bundles fibres into fascicles
Epineurium: tough fibrous sheath around a nerve

Question 26

Classification of nerves
Most nerves are mixtures of afferent and efferent fibres and somatic and autonomic (visceral) fibres
Types of fibres in mixed nerves:

Answer 26

Somatic: afferent and somatic efferent
Visceral afferent and visceral efferent
Peripheral nerves classified as cranial or spinal nerves
Ganglia (within PNS): contain neural cell bodies associated with nerves.
Dorsal root ganglia (sensory, somatic)
Autonomic ganglia (motor, visceral)

Question 27

Cranial nerves: 12 pairs of nerves associated with the brain
OOOTTAFVGVAH
Oh Oh Oh To Touch And Feel V Girls Vagina And Hymen

Answer 27

Olfactory
Optic
Oculomotor
Trochlear
Trigeminal
Abducens
Facial 
Vestibulocochlear
Glossypharyngeal
Vagus
Accessory 
Hypoglossal

Question 28

What is the motor area for speech called in the rain which directions the tongue and mouth movements called?

Answer 28

Brocas area