Week 3 Lecture 8: The forebrain Flashcards
What is the cerebrum/ forebrain composed of?
Two parts:
- telencephalon (outer brain)
- inner brain (diencephalon)
During embryonic development, what structure connects the two swellings that grow to be the cerebral hemispheres? What does this structure become in the adult brain?
- developing telencephalon is connected via lamina terminalis
- lamina terminalis goes on to become the corpus callosum and anterior commissure
What is the anterior commissure?
white matter tract connecting two temporal lobes of the central hemispheres across the midline
What two swellings appear as the diencephalon develops and what divides the two swellings?
- thalamus, dorsally and hypothalamus, ventrally
- hypothalamic sulcus forms the division between the thalamus and hypothalamus
What is the function of the ventricular system of the brain?
production, transport and removal of cerebrospinal fluid
Where is CSF produced?
choroid plexus
How is the lateral ventricle connected to the third ventricle?
interventricular foramina (of Monroe)
What connects the 3rd and 4th ventricle?
cerebral squeduct
Which lobe are each of these structures in the lateral ventricle found in:
- anterior horn
- inferior horn
- body
- posterior horn
- frontal lobe
- temporal lobe
- parietal lobe
- occipital lobe
What is the 3rd ventricle found between?
right and left thalami
What are the four divisions of the diencephalon?
- thalamus: relay station between parts of the CNS
- hypothalamus: autonomic and neuroendocrine functions
- subthalamus: functionally part of basal ganglia and involved in motor control
- epithalamus
Where is the pineal gland found and what does it secrete?
- found in the epithalamus
- secretes melatonin
What are thalami?
large bi lateral egg shaped masses of grey matter (collection of nuclei)
How can the two thalami communicate?
they are connected at the interthalamic adhesion (massa intermedia)
What is the function of the thalamus?
- “receptionist” of the brain - information is sent to the thalamus and the thalamus decides where to next send it
- relay nuclei send fibres to cerebral cortex
- sensory processing (except olfaction)
- motor processing through connections with the basal nuclei (ganglia) and cerebellum
Which structures/ systems send information to the thalamus?
- basal ganglia
- cerebellum
- somatosensory, auditory, visual, vestibular and other inputs
- reticular formation
- limbic system
What is the function of the limbic system?
functional lobe that deals with emotion and memory
How is the thalamus divided into 3 main areas?
- anterior nuclear group
- medial nuclear group
- lateral nuclear group
Where does the anterior nuclear group send information to?
cingulate cortex (part of limbic system)
Where does the medial nuclear group send information to?
prefrontal cortex (cerebral cortex covering the frontal lobe)
In the lateral nuclear group, there are further nucleic divisions.
Where do the following key nuclei send their information to?
1. Ventral posterior lateral
2. Ventral posterior medial
3. Lateral geniculate
4. Medial geniculate
- somatosensory cortex
- somatosensory cortex
- visual cortex
- auditory cortex
What is the hypothalamus involved in?
homeostasis and autonomic control e.g sexual response, body temperature and blood pressure
What is the corpus striatum?
- internal structure of grey matter (nuclei) of each cerebral hemisphere
- part of the basal nuclei (basal ganglia)
- involved in motor control
What 3 structures is the corpus striatum composed of?
- global pallidus (internal and external)
- putamen
- caudate nucleus
What is the lentiform nucleus made up of?
globus pallidus and putamen
What is the name given to the structure made up of the lentiform nucleus and caudate nucleus?
corpus striatum
What forms the lateral wall of the lateral ventricke?
head and body of caudate nucleus
What dorms the roof of the inferior horn of the lateral ventricle ?
tail of caudate nucleus
What are the 5 structures of the limbic system?
- hippocampus
- thalamus
- amygdala
- hypothalamus
- fornix
What forms the floor of the inferior horn of the lateral ventricle?
hippocampus
Where does the fornix course?
follows a C shape over the thalamus to reach the hypothalamus
What are the fimbria of fornix?
a collection of white matter fibres that converge to form the crus of the fornix
Explain the structure of the fornix
- columns of fornix
- body of fornix
- crus of fornix
What are the 3 classes of fibres in the white matter of the hemispheres?
- association fibres
- commissural fibres
- projection fibres
What is the function of association fibres?
- interconnect areas within a hemisphere and adjacent gyri
- e.g we can have short association fibres connecting the pre and post central gyri
What is the function of commissural fibres?
-interconnect areas between hemispheres
What is the biggest collection of commisural fibres and what is it made up of?
- corpus callosum aka “great cerebral commissure”
- made up of rostrum, genu, body, splenium
Other than the corpus callosum, give another example of a structure made of commisssural fibres?
anterior commissure a.k.a rostral commissure
What structure connects the crus of the fornix?
commissure fibres of fornix aka hippocampal commissure
What is the function of projection fibres?
interconnect the cerebrum with the rest of the CNS e.g via corona radiata
What are the 3 parts to the internal capsule?
- anterior limb
- genu
- posterior limb
