Describing the Brain Flashcards
Which embryological layer mainly forms the nervous system?
Ectoderm
Neurulation is
the process through which the nervous system forms (mainly from the ectoderm layer)
Neuralation Steps:
- formation of the neural tube
- forms from ectoderm layer
- neuroectoderm cells receive
inductive signals from the notochord - causes neuroectoderm cells to
thicken forming the neural plate - the lateral neural plate margins fold
inwards to form the neural tube - neural crest cells develop along the
length of the neural folds - just below the neural fold is the
notochord
Neurulation
Neural Tube:
- meeting of two neural crests
- cranial end gives rise to brain
- most of its length gives rise to the
spinal cord
Anencephaly:
- failure of the anterior neuropore to
close (cranial end) - fatal
Spina bifida:
- failure of the posterior neural tube
to close - divided by a cleft
- leads to an open vertebral canal
Spina bifida occulta:
- hidden, vertebral arch defect only
Spina bifida cystica:
meninges projects out
Neural Tube:
Primary Brain Vesicles:
- vesicle = fluid filled space
- bulges within the neural tube
- 3 brain vesicles lead to the
developments of the main brain
areas - prosencephalon (forebrain),
mesencephalon (midbrain).
rhombencephalon (hindbrain) - 3-4 week embryo
Primary Brain Vesicles:
Secondary Brain Vescicles:
- three primary brain vesicles develop
into five secondary vesicles - prosencephalon leads to
telencephalon and diencephalon - mesencephalon stays the same
- rhombencephalon leads to
metencephalon and myelencephalon
Secondary Brain Vesicles:
Adult Brain:
- the brain is divided into forebrain,
midbrain and hindbrain - and the structures from which these
have been developmentally derived
Adult Brain: Forebrain(3):
- cerebral hemispheres
(telencephalon) - Thalamus (diencephalon)
- Hypothalamus (diencephalon)
Adult Brain: Forebrain:
hypothalamus (triangle)
Adult Brain: Midbrain:
- midbrain (mesencephalon) (just below thalamus)
Adult Brain: Midbrain:
Adult Brain(3): Hindbrain:
- cerebellum (metencephalon)
- pons (metencephalon)
- medulla oblongata (myelencephalon)
Adult Brain: Hindbrain:
Cerebrum/Cerebral Hemispheres:
- derived from telencephalon
- largest component of the brain
- divided into right and left
hemispheres - comprises of the cerebral
hemispheres, components of the
limbic system and the basal ganglia
Cerebral Hemispheres:
superior view and mid-sagittal view
The forebrain or cerebral cortex is divided by anatomical landmarks into lobes.
What are gyri and sulci?
gyri = projections on the brain
sulci = depressions on the brain
Forebrain: Lobes:
- frontal
- parietal
- occipital
- temporal
- insula
- limbic?
Forebrain: Frontal Lobe:
- location (3)
- functions (3)
- posterior to frontal bone
- anterior to the parietal lobe;
separated by the central sulcus - anteriorsuperior to the temporal
lobe; separated by the lateral sulcus - primary motor cortex
- executive functions (attention)
- ability to think and consider
Forebrain: Temporal Lobe:
- location (2)
- functions (3)
- medial to the temporal bone
- inferioposterior to the frontal lobe;
separated by the lateral sulcus - primary auditory cortex
- primary olfactory cortex
- implicated in learning and memory
Forebrain: Parietal Lobe:
- location (3)
- function (1)
- medial to the parietal bones
- superior to the occipital lobe;
separated by the parietooccipital
sulcus - posterior to the frontal lobe;
separated by the central sulcus - primary somatosensory cortex (pain,
touch and proprioception (stimuli
produced and perceived within an
organism))
Forebrain: Occipital Lobe:
- location
- function (1)
- anterior to the occipital bone
- posterior to the parietal lobe;
separated by the parietoocipital
sulcus - posterior to the temporal lobe
- primary visual cortex
Forebrain: Lobes:
Label the lateral view of the right hemisphere
Forebrain: Lobes:
Label the medial view of the left hemisphere
Forebrain: Insular Lobe:
- location (2)
- function (2)
- deep within the lateral sulcus
- where temporal, parietal and frontal
lobes meet - involved in desire, craving, addiction
- neuropsychiatric disorders
Forebrain: Lobes:
What lobe is shown below?
insula lobe
What fissure must be opened up to access the insular lobe?
the lateral fissure
Where is the lateral fissure located?
Between the parietal,frontal and temporal lobes
White Matter:
- colour due to
- composed of
- location
- function
- function
- function
- %
- pale due to lipid components
- composed of long myelinated axons
- found in cortex and surface of spinal
cord - transmits both sensory and motor
impulses between the PNS and grey
matter - controls involuntary functions of
body such as BP - communication between different
grey areas and grey and rest of body - makes up 60% of the brain
Grey Matter:
- pinkish-grey due to neuronal cell
bodies and capillary vessels - composed of cell bodies, axon
terminals and dendrites - found on the surface of the brain
and inside the spinal cord - processes the retrieved informatio
from white matter and sends
instructions through white matter to
effector organs - controls senses of the body
- 40%
Grey matter is mainly made up of ——, whereas white matter is mainly made up of ——-
cell bodies whereas white matter is made up of myelinated axons
Coronal section of the brain:
- **thalamus = deep in brain = grey
matter = nuclei
Corpus Callosum:
- white matter tract linking cerebral
hemispheres - divided into three: genu, body,
splenium - genu = latin = flexure/bend
- splenoid = latin = pad (thick)
What is shown here? Which view?
- corpus callosum
- midsagittal view
What is shown here? Which view?
- corpus callosum
- coronal view
What is shown here? Which view?
- corpus callosum
- midsagittal view
What is shown here? Which view?
- corpus callosum
- coronal view
Deep Brain Structures:
- multitude of brain nuclei and white
matter tracts running through them
Basal Ganglia:
- deep brain structure
- heavily involved in the control of
posture and voluntary movement
Limbic System:
- spans
- corpus collosum
- structures (4)
- functions
- spans the telencephalon and
diencephalon - the corpus collosum is not involved
- cingulate cortex lies just superior to
corpus collosum - fornix = white matter tract = sits on
the floor of the lateral ventricles =
relay center - thalamus, hypothalamus, mamillary
bodies
(above is part of frontal lobe)
- in the temporal lobe; hippocampus
and amygdala - involved in memories, behavioral
and emotional responses
Label the fornix on the diagram below.
- base of ventricles, two round white
matter tracts
Hippocampus function:
involved in long term memory formation
Amygdala function:
involved in stress and fear response
Limbic System:
Diencephalon:
- comprises of
- thalamus, hypothalamus,
subthalamus, epithalamus,
mamillary bodies
Diencephalon:
note corpus callosum and fornix are not part of the diencephalon but used for orientation
All sensory input must pass the
thalamus from where it will be passed to other areas
Thalamus: Major Relay Centre:
Thalamus:
- is
- connections
- functions
- paired grey matter structure,
interconnected between left and
right, connected with other
diencephalon structures - involved with voluntary movement,
personality and consciousness
Thalamus: Label:
lies lateral on either side of the third ventricle (which lies inferior to the lateral ventricles which lies under the corpus callosum)
Thalamus: Label:
lies lateral on either side of the third ventricle (which lies inferior to the lateral ventricles which lies under the corpus callosum)
Hypothalamus:
- location (2)
- function (2)
- lies inferior to the thalamus, superior
to pituitary - heavily involved in homeostatic
control - receives inputs from the limbic
system
Brainstem:
- derived from the
- function (4)
- grey or white matter?
- mesencephalon and
rhombencephalon - connects the cortex to the spinal
cord - vital respiratory and cardiovascular
centres - vomiting centre
- nuclei involved with motor control,
sleep - white matter tracts
Highlighted blue region is
the brainstem
Cerebellum:
- derived from
- functions (4)
- metencephalon(rhombencephalon)
- motor control
- control of posture
- co-ordinating and planning limb
movements - control of eye movements
Cerebellum relation to brainstem is
cerebellum is posterior to the brainstem
what is highlighted?
cerebellum
What view of brainstem?
Anterior/ventral view of brainstem
What view of the brainstem?
Posterolateral view of brainstem
medulla oblongata continues as the
spinal cord (myelencephalon)
Cerebral Peduncles are
white matter tracts connecting pons with diencephalon
Midbrain: External Features:
4 large bulges posteriorly = colliculus
Midbrain: Internal Features:
(sliced high up on midbrain)
- cerebral peduncles = connects
brainstem to thalamus
- substantia nigra = darker area =
basal gangli = dopamine release
- red nucleus = motor coordiantion
between cortex and cerebellum
Pons:
include cerebellar peduncles
The pons is continuous with the cerebellum and sits below the cerebellum.
True or False?
False
continuous and sits at the same level
Pons function
relays information to the cerebellum
What structures connect the cerebellum and the pons
- 3 cerebellar peduncles: superior,
middle and inferior - transverse fibers
- connections between the
cerebellum and pons
Which is the largest cerebellar peduncle?
Middle cerebellar peduncle
Medulla Oblongata:
- is
- function
- lowest aspect of the brainstem
- contains nuclei that are important in
controlling respiration and the
cardiovascular system
Medulla Oblongata:
decussation is where the fibres cross over (right to left)
Cerebellum:
- location
- location of white and gray matter
- hemispheres
- lobes
- contains
- posterior to brainstem
- outer gray matter
- underlying white matter
- two hemispheres
- three lobes
- contains nuclei
Cerebellum Functions:
- motor control
- posture
- coordinating and planning limb
movements - control of eye movements
Cerebellum
insert diagram
Cerebellum:
insert MRI
What connects the cerebellar lobes?
vermis
Sagittal view cerebelllum
insert picture
What is the marked area?
Parietal lobe
What is the marked area?
Corpus Callosum
Embryologically, which part of the brain is the pons derived from?
- telencephalon
- mesencephalon
- diencephalon
- metencephalon
metencephalon
What is the marked area?
Midbrain
Identify the labelled structure.
Vermis
