Topography of the brain Flashcards
What is neurulation
- Development of the brain
How does the neural tube form?
- Neuroectoderm cells receive inductive signals from notochord
- Cells thicken to form neural plate
- Lateral neural plate margins fold inwards to form neural tube
What do neural crest cells differentiate into?
- Neurons and glia of the sensory and autonomic nervous systems
- Cells of the adrenal gland
- Epidermis
- Skeletal/connective tissue of the head
What are the layers of the neural tube(outermost to inner)?
- Ectoderm
- Neural crest
- Mantle layer
- Ependymal
- lumen
What does the mantle layer become?
- Brain parenchyma
- Gray matter
Where is the ependymal layer located?
- Lines ventricles
What does the lumen become?
- Ventricles + central canal
When do the layers of the neural tube further develop by into structures that we recognise?
- embryonic day 24
What is anencephaly?
- Failure of the anterior neuropore to close
- Fatal
What is spina bifida?
- Failure of the posterior neural tube to close which leads to open vertebral canal
- Divided by a cleft
What is spina bifida occulta?
- Hidden, vertebral arch defect only
- Can be indicated by hair patch on lower back
What is spina bifida cystica?
Meningocele - meninges project out
what are the primary vesicles and what do they develop into?
Prosencecepahlon - forebrain
Mesencephalon - midbrain
Rhombencephalon - hindbrain
What do the cerebral hemispheres develop from
- Prosencephalon –> telencephalon –> cerebral hemispheres
What do the eyes develop from?
- Prosencephalon –> optic vesicles –> eyes
What do the thalamus/hypothalamus develop from?
- Prosencephalon –> diencephalon –> thalamus/hypothalamus
What do the pons/cerebellum develop from?
- Rhombencephalon –> metencephalon –> pons/cerebellum
What does the medulla develop from?
- Rhombencephalon –> myelencephalon –> medulla
What are the secondary vesicles?
- Telencephalon
- Optic vesicles
- Diencephalon
- Metencephalon
- Myelencephalon
What does gray matter mainly consist of?
- Mainly neuronal bodies(eg cerebral cortex, brain nuclei)
What does white matter consist of?
- Mainly myelinated axons
What does the central sulcus divide?
- Divides frontal from parietal lobe
What cortex is the precentral gyrus a part of?
- Motor
What cortex is the postcentral gyrus a part of?
- Sensory
What does the lateral sulcus divide?
- Divides temporal from parietal lobe
What is the corpus callosum?
- White matter tract linking cerebral hemispheres
What is the limbic system involved in?
- Involved with emotion and memory
What is the fornix?
- Semi-circular white matter tract connecting the hippocampus with the mammillary bodies
What is is corpus striatum?
- Series of interconnected nuclei at the base of forebrain
What does the corpus striatum divide into?
- lentiform nucleus –> putamen + globus pallidus
- Caudate nucleus
Location of the lentiform nucleus
- Lens shaped and sits lateral to caudate nucleus
Location of the caudate nucleus
- C-shaped(due to embryonic folding) and sits in wall of lateral ventricle
What is the basal ganglia involved in?
- Control of posture and voluntary movement
What does the internal capsule form?
- Forms major white matter tract(connects cortex to brainstem)
Function of the thalamus
- Paired structure
- Relays sensory info to the cortex
- Involved with voluntary movement, personality and consciousness
Function of hypothalamus
- Inferior to thalamus
- Homeostasis
- Coordinates ANS and endocrine responses
- Involved in thermoregulation, feeding, drinking, circadian rhythms
- Receives inputs from limbic system
Location of the hypothalamus
- Sits between the optic chiasm and mammillary bodies
What forms the brainstem and cerebellum
Mesencephalon and rhombencephalon
What forms the midbrain
Mesencephalon
What forms the pons and medulla
Rhombencephalon
What does the brainstem contain
- Cranial nerve nuclei within all three regions
- Vital respiratory and cardiovascular centres
- Vomiting centre
- Nuclei involved with motor control, sleep
- White matter tracts
What do the cerebral peduncles contain?
- White matter tracts connecting pons with diencephalon
What is the superior colliculus responsible for?
Vision - eye movements
What is the inferior colliculus responsible for?
auditory - relay nuclei
Inferior colliculus receives info from the 8th cranial nerve - vestibulocochlear nerve
What is the red nucleus responsible for?
Motor coordination - relay between cortex and cerebellum
What is the substantial nigra responsible for?
Dopaminergic neurons
Part of basal ganglia
Why is substantial nigra black
Dopmainergic neurons contain melanin(gives substantial nigra) its black colour
What do the middle cerebellar peduncles consist of?
White matter tracts linking brainstem with cerebellum
What does the anterior part of the medulla oblongata contain?
- Pyramid
- Olive
What is the pyramid of medulla oblongata
- Corticospinal tract - main voluntary motor pathway
What is the olive of the medulla oblongata formed by?
- Formed by olivary nuclei
- Motor relay to cerebellum
What are the tubercles that form the posterolateral part of the medulla oblongata
- Cuneate tubercle
- Gracile tubercle
The nuclei form part of the ascending tract
What are the nuclei of the medulla oblongata important for?
Contains nuclei that are important in controlling respiration and the cardiovascular system
Describe what the cerebellum consists of
- Outer gray matter
- Underlying white matter
- Two cerebellar hemispheres
- Three lobes
- Contains nuclei
What are the main functions of the cerebellum
- Control of posture
- Coordinating and planning limb movements
- Control of eye movements
What are the three lobes of the cerebellum
- Anterior lobe
- Flocculonodular lobe
- Posterior lobe
What separates the two hemispheres of the cerebellum
the vermis
How is the cerebellum connected to the brainstem
Via cerebellar peduncles
What is the flocculonodular lobe responsible for?
Eye movements
What do emerging nerve fibres from the mantle layer form
- Neuroblasts to form the marginal layer(white matter)
