Brain anatomy and organisation Flashcards
How much does the brain weigh and what percentage is this of total body weight?
1.3-1.4kg, 2% - unusually large brain:body ratio!
What does the Central Nervous System comprise?
The brain and spinal cord.
What does the cranium contain?
- The brain (80%), 100bn neurons, 1000bn glia.
- 10% blood
- 10% cerebrospinal fluid - surrounds brain and fills ventricles. Produced from blood, provides nourishment.
What sections are there during very early development of the neural tube?
Forebrain, midbrain and hindbrain.
What’s in the brain during early development?
Forebrain (telencephalon, diencephalon), midbrain and hindbrain.
What’s in the brain during later development and the final shape?
Forebrain: - Telencephalon (cortex, basal ganglia) - Diencephalon (thalamus, hypothalamus) Midbrain: - Tectum - Tegmentum Hindbrain: - Cerebellum - Pons - Medulla Spinal cord.
What’s the difference in the brain between late development and the final shape?
Telencephalon grows more and changes shape, diencephalon more rounded, midbrain shrinks, spinal cord vertical, cerebellum becomes round. I.e. looks more brain-like.
What is a saggital view?
Side view
What is a coronal view?
Back view
What is an axial view?
From top
What do rostral/caudal and anterior/posterior refer to?
Left/right on a side view.
What does dorsal/superior refer to?
Above.
What does ventral/inferior refer to?
Below.
What does medial mean?
Middle from left-right (lateral) front view.
What is ipsilateral?
On the same side - opposite = contralateral.
What does afferent mean?
Conducting towards the brain (sensory)
What does efferent mean?
Conducting away from the brain (motor)
What did Descartes claim was the seat of the soul?
The pineal gland.
What are subcortical structures?
In the middle, under the cortex:
- Forebrain (basal ganglia and limbic system)
- Diencephalon (thalamus and hypothalamus)
What subcortical regions are part of the basal ganglial circuit?
- Caudate
- Putamen
- Globus pallidus
- Substantia Nigra
- Subthalamic nucleus
What is the role of the basal ganglia and in what disorders is it damaged?
Motor control and reward (dopamine).
Damaged in Huntington’s and Parkinson’s disease.
What is the limbic system?
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).
What is in the thalamus?
- Many nuclei in circuits with cortex
- Lateral Geniculate Nucleus - relay between retina and primary visual cortex.
What’s the role of the hypothalamus?
Control of hormones and ANS.
What’s in the midbrain?
The tectum and tegmentum.
What is the tectum involved in?
- Superior colliculi - vision and eye movements
- Inferior colliculi - audition.
What is the tegmentum involved in?
- Reticular formation (arousal/sleep)
- Periaqueductal grey (pain, defensive behaviour)
- Red nucleus (motor control)
- Substantia Nigra (linked to basal ganglia, produces dopamine).
What percentage of neurons are in the cerebellum?
50%
Describe the structure of the cerebellum.
Dense and regular with cortex and nuclei.
What does the cerebellum do?
- Precise control of action
- Timing
- Learning
- Cognition
What’s in the hindbrain?
- Pons (relay between cortex and cerebellum)
- Medulla Oblongata (breathing and heartbeat)
Define sulcus.
A groove or inward fold.
Define gyrus.
A bulge outwards.
What is grey matter?
Cell bodies.
What is white matter?
Myelinated neurons.
What is the main connection between the two hemispheres?
The corpus callosum (cut in split brain patients to prevent epilepsy).
What are the lobes of the cortex?
Frontal, parietal, occipital and temporal.
What did Brodmann do?
Classified cortical areas on the basis of cytoarchitecture (cell arrangement).
What brain regions are part of the visual cortex?
LGN (thalamus), V1-5.
What brain regions are part of the auditory cortex?
Brainstem, thalamus, primary auditory cortex and secondary auditory areas.
Describe the primary motor cortex.
- Strip in front of central sulcus
- Topographical, crossed distorted map thing
Describe the somatosensory cortex.
- Strip behind the central sulcus
- Topography and crossing, map.
What are association areas?
- Less topography
- Less lateralisation
- Many smaller regions with unknown functions
What are the different association areas?
- Occipital = complex visual processing
- Parietal = space and action
- Temporal = objects, memory, semantics and language
- Frontal = planning, control, decision and language.
