Brain anatomy and organisation

Question 1

How much does the brain weigh and what percentage is this of total body weight?

Answer 1

1.3-1.4kg, 2% - unusually large brain:body ratio!

Question 2

What does the Central Nervous System comprise?

Answer 2

The brain and spinal cord.

Question 3

What does the cranium contain?

Answer 3

• The brain (80%), 100bn neurons, 1000bn glia.
• 10% blood
• 10% cerebrospinal fluid - surrounds brain and fills ventricles. Produced from blood, provides nourishment.

Question 4

What sections are there during very early development of the neural tube?

Answer 4

Forebrain, midbrain and hindbrain.

Question 5

What’s in the brain during early development?

Answer 5

Forebrain (telencephalon, diencephalon), midbrain and hindbrain.

Question 6

What’s in the brain during later development and the final shape?

Answer 6

Forebrain:
- Telencephalon (cortex, basal ganglia)
- Diencephalon (thalamus, hypothalamus)
Midbrain:
- Tectum
- Tegmentum
Hindbrain:
- Cerebellum
- Pons
- Medulla
Spinal cord.

Question 7

What’s the difference in the brain between late development and the final shape?

Answer 7

Telencephalon grows more and changes shape, diencephalon more rounded, midbrain shrinks, spinal cord vertical, cerebellum becomes round. I.e. looks more brain-like.

Question 8

What is a saggital view?

Answer 8

Side view

Question 9

What is a coronal view?

Answer 9

Back view

Question 10

What is an axial view?

Answer 10

From top

Question 11

What do rostral/caudal and anterior/posterior refer to?

Answer 11

Left/right on a side view.

Question 12

What does dorsal/superior refer to?

Answer 12

Above.

Question 13

What does ventral/inferior refer to?

Answer 13

Below.

Question 14

What does medial mean?

Answer 14

Middle from left-right (lateral) front view.

Question 15

What is ipsilateral?

Answer 15

On the same side - opposite = contralateral.

Question 16

What does afferent mean?

Answer 16

Conducting towards the brain (sensory)

Question 17

What does efferent mean?

Answer 17

Conducting away from the brain (motor)

Question 18

What did Descartes claim was the seat of the soul?

Answer 18

The pineal gland.

Question 19

What are subcortical structures?

Answer 19

In the middle, under the cortex:

• Forebrain (basal ganglia and limbic system)
• Diencephalon (thalamus and hypothalamus)

Question 20

What subcortical regions are part of the basal ganglial circuit?

Answer 20

• Caudate
• Putamen
• Globus pallidus
• Substantia Nigra
• Subthalamic nucleus

Question 21

What is the role of the basal ganglia and in what disorders is it damaged?

Answer 21

Motor control and reward (dopamine).

Damaged in Huntington’s and Parkinson’s disease.

Question 22

What is the limbic system?

Answer 22

A collection of regions on the edge of the cortex:

• Cingulate gyrus (cognitive control)
• Hippocampus, fornix and mamillary bodies (memory and navigation)
• Amygdala (emotion, fear).

Question 23

What is in the thalamus?

Answer 23

• Many nuclei in circuits with cortex

- Lateral Geniculate Nucleus - relay between retina and primary visual cortex.

Question 24

What’s the role of the hypothalamus?

Answer 24

Control of hormones and ANS.

Question 25

What's in the midbrain?

Answer 25

The tectum and tegmentum.

Question 26

What is the tectum involved in?

Answer 26

- Superior colliculi - vision and eye movements | - Inferior colliculi - audition.

Question 27

What is the tegmentum involved in?

Answer 27

- Reticular formation (arousal/sleep) - Periaqueductal grey (pain, defensive behaviour) - Red nucleus (motor control) - Substantia Nigra (linked to basal ganglia, produces dopamine).

Question 28

What percentage of neurons are in the cerebellum?

Answer 28

50%

Question 29

Describe the structure of the cerebellum.

Answer 29

Dense and regular with cortex and nuclei.

Question 30

What does the cerebellum do?

Answer 30

- Precise control of action - Timing - Learning - Cognition

Question 31

What's in the hindbrain?

Answer 31

- Pons (relay between cortex and cerebellum) | - Medulla Oblongata (breathing and heartbeat)

Question 32

Define sulcus.

Answer 32

A groove or inward fold.

Question 33

Define gyrus.

Answer 33

A bulge outwards.

Question 34

What is grey matter?

Answer 34

Cell bodies.

Question 35

What is white matter?

Answer 35

Myelinated neurons.

Question 36

What is the main connection between the two hemispheres?

Answer 36

The corpus callosum (cut in split brain patients to prevent epilepsy).

Question 37

What are the lobes of the cortex?

Answer 37

Frontal, parietal, occipital and temporal.

Question 38

What did Brodmann do?

Answer 38

Classified cortical areas on the basis of cytoarchitecture (cell arrangement).

Question 39

What brain regions are part of the visual cortex?

Answer 39

LGN (thalamus), V1-5.

Question 40

What brain regions are part of the auditory cortex?

Answer 40

Brainstem, thalamus, primary auditory cortex and secondary auditory areas.

Question 41

Describe the primary motor cortex.

Answer 41

- Strip in front of central sulcus | - Topographical, crossed distorted map thing

Question 42

Describe the somatosensory cortex.

Answer 42

- Strip behind the central sulcus | - Topography and crossing, map.

Question 43

What are association areas?

Answer 43

- Less topography - Less lateralisation - Many smaller regions with unknown functions

Question 44

What are the different association areas?

Answer 44

- Occipital = complex visual processing - Parietal = space and action - Temporal = objects, memory, semantics and language - Frontal = planning, control, decision and language.