Chapter 3: STRUCTURES AND FUNCTION OF THE CNS

Question 1

What are the two subdivisions of the forebrain?

Answer 1

Telencephalon and diencephalon

Question 2

What does the telencephalon include?

Answer 2

• Most of 2 symmetrical cerebral hemispheres, which make up the cerebrum
• Principal structures of the cerebrum: cerebral cortex, basal ganglia, limbic system

Question 3

What is the cerebral cortex what is it’s appearance?

Answer 3

• surrounds the cerebral hemispheres
• Appears folded, convoluted: it has sulci (small grooves), fissures (large grooves) and gyri (bulges between adjecent sulci or fissures)
• Enables it to be wider but more concentrated
• Has a grey appearance (gray matter): because cell bodies predominate.

Question 4

What are the four lobes of the cerebral cortex? (see diagrams for locations)

Answer 4

• frontal lobe
• parietal lobe
• temporal lobe
• occipital lobe

Question 5

What are the three areas of the cerebral cortex that receive information from the sensory organs?

Answer 5

The whole is called the sensory cortex and consists of three areas:

• primary visual cortex
• primary auditory cortex
• primary somatosensory cortex

Question 6

What are the functions of the three parts of the sensory cortex?

Answer 6

• Primary visual cortex: receives visual information
• Primary auditory cortex: receives auditory information
• Primary somatosensory cortex: receives information from the body senses except olfaction and gustation

Question 7

What is the sensory association cortex and what does it do?

Answer 7

• Associates sensation and action: perceiving, learning, remembering, planning, acting.
• Receives information from primary sensory areas
• Rostral region: movement-related activities.
• Caudal region: perceiving and learning.

Question 8

What happens if someone has damage to the somatosensory association cortex?

Answer 8

• Deficits related to somatosensation and the environment in general
• ex: difficulty perceiving the shape of an object they touch (but they can if they just look at it), trouble drawing maps or following them

Question 9

What does the primary motor cortex do ?

Answer 9

• movement
• located in front of the primary somatosensory cortex
• neurons in different parts of body connected to different locations of the motor cortex

Question 10

What does the motor association cortex do? (also called premotor cortex)

Answer 10

• planning and execution of movements

- located rostral to the primary motor cortex

Question 11

What does the prefrontal cortex do?

Answer 11

• region of the fontal lobe rostral to the motor association cortex
• formulation of plans and strategies

Question 12

What does lateralization in the cerebral cortex mean?

Answer 12

• the 2 hemispheres cooperate, but do not perform the same functions
• Some functions are lateralized, located primarly on one side of the brain

Question 13

What is the left hemisphere specialized in?

Answer 13

• analysis of information
• good at recognizing serial events and controlling sequences of behavior
• example: talking, understanding speeches, reading, writing.

Question 14

What is the right hemisphere specialized in ?

Answer 14

-synthesis: putting isolated elements together, perceiving things as a whole.

Question 15

What does the corpus callosum do ?

Answer 15

• connects the right and left hemispheres

- perception and memories unification

Question 16

What is the limbic system formed of?

Answer 16

• limbic cortex (includes the cingulate gyrus)
• hippocampus
• amygdala

Question 17

What is the fornix?

Answer 17

-bundle of axons that connects the hippocampus to other regions of the brain including the mammillary bodies

Question 18

What are the mammillary bodies?

Answer 18

-protrusions on the base of the brain that contain part of the hypothalamus.

Question 19

What is the role of the limbic system?

Answer 19

-learning, memory and emotions

Question 20

What is the basal ganglia?

Answer 20

• Collection of nuclei below the cortex

- nuclei= groups of neurons of similar shape

Question 21

What are the three main parts of the basal ganglia, and what is its function?

Answer 21

• 3 parts: caudate nucleus, putamen, globus palladius

- Involved in control of movement (ex: Parkinson’s)

Question 22

What is the diencephalon and what are it’s 2 major structures?

Answer 22

• second major division of forebrain that surrounds the third ventricle
• Thalamus and hypothalamus

Question 23

How does the thalamus work what is its function?

Answer 23

• has two lobes
• Divided into several nuclei
• Most neural input to the cerebral cortex is received from the thalamus.
• Projects information to specific regions of cerebral cortex and receives information from it

Question 24

What are examples of thalamic nuclei and what are their functions?

Answer 24

• lateral geniculate nucleus: receives information from the eye and sends axons to the primary visual cortex
• medial geniculate nucleus: receives information from the inner ear and sends axons to the primary auditory cortex
• ventrolateral nuclei: receives information from the cerebellum and projects it to the primary motor cortex.

Question 25

What does the hypothalamus do?

Answer 25

- Controls the ANS (Autonomic Nervous System) and the endocrine system - Organizes behaviors related to the survival of species (fighting, escape, eating, and reproduction)

Question 26

What is the optic chiasm?

Answer 26

An X-shaped connection between the optic nerves, located below the base of the brain, just anterior to the pituitary gland.

Question 27

What is the anterior pituitary gland?

Answer 27

endocrine gland whose secretions are controlled by the hypothalamic hormones.

Question 28

How are hypothalamic hormones produced?

Answer 28

-Secreted by neurosecretory cells.

Question 29

What is the posterior pituitary gland and how does it work?

Answer 29

- endocrine gland that contains hormone-secreting terminal buttons of axons whose cell bodies lie within the hypothalamus - secretes oxytocin and vasopressin (secretion controlled by the hypothalamus)

Question 30

What are the functions of oxytocin and vasopressin?

Answer 30

-number of different physiological and behavioral functions such as pair bonding and parental behavior.

Question 31

How is the midbrain (also called mesencephalon) structured?

Answer 31

The tectum and the tegmentum

Question 32

How is the tectum structured?

Answer 32

- located on the dorsal portion of the mesencephalon | - 2 principal structures: superior colliculi and inferior colliculi

Question 33

What are the functions of the superior and inferior colliculi?

Answer 33

- superior: part of the visual system | - inferior: part of the auditory system

Question 34

What does the tegmentum consist of?

Answer 34

- Portion of the mesencephalon beneath the tectum - Includes: - the rostral end of the reticular - several nuclei controlling eye movement - the periaqueductal gray matter - the red nucleus - the substantia nigra - the ventral tegmental area

Question 35

What is the reticular formation?

Answer 35

- large structure consisting of many nuclei - receives sensory info by various pathways and projects axons to the cerebral cortex, thalamus and spinal cord. - Plays a role in sleep, arousal, attention, muscle tone, movement and various vital reflexes.

Question 36

What is the periaqueductal gray matter?

Answer 36

-contains neural circuits involved in species-typical behavior such as fighting or mating.

Question 37

What is the red nucleus?

Answer 37

-large nucleus of the midbrain that receives input from the cerebellum and motor cortex and sends axons to motor neurons in the spinal cord

Question 38

What is the substantia nigra?

Answer 38

A darkly stained region of the tegmentum that contains neurons that communicate with the caudate nucleus and putamen in the basal ganglia.

Question 39

How is the cerebellum structured?

Answer 39

- covered by cerebellar cortex - has a set of deep cerebellar nuclei (receives projections from cerebellar cortex and send projections to other parts of the brain) - each hemisphere attached to the pons by 3 bundles of axons : superior, middle, and inferior cerebellar peduncles

Question 40

What is the function of the cerebellum?

Answer 40

- receives visual, auditory, vestibular, and somatosensory information. - receives information about individual muscles movements - exerts a coordinating and smoothing effect on the movements

Question 41

What does cerebellar damage result in ?

Answer 41

jerky, poorly coordinated, exaggerated movements, and even difficulties to stand.

Question 42

What does the pons do ?

Answer 42

- contains part of the reticular formation, including nuclei important for sleep and arousal. - contains a large nucleus that relays information from the cerebral cortex to the cerebellum

Question 43

What is the medulla oblongata?

Answer 43

- Main structure of the myelencephalon - contains part of the reticular formation including nuclei that controls vital functions (regulation of the cardiovascular system, respiration, skeletal muscle tone)

Question 44

How is the spinal cord structured?

Answer 44

- Protected by a vertebral column: composed of 24 vertebrae - 2/3 as long as vertebral column - Other 1/3 is filled by spinal roots composing the cauda equina.

Question 45

What are the different types of vertebrae?

Answer 45

- cervical (neck) - thoracic (chest) - lumbar (lower back) - sacral and coccygeal (fused vertebrae located in the pelvic region)

Question 46

What is a caudal block?

Answer 46

The anesthesia and paralysis of the lower part of the body produced by injection of a local anesthetic into the cerebrospinal fluid surrounding the cauda equina.

Question 47

What are the functions of the spinal cord?

Answer 47

- distributes motor fibers to the effector organs of the body (glands and muscles) - collects somatosensory information for the brain - contains some reflex circuits