Neuroanatomy Flashcards
2 types of nervous systems
Central nervous system
Peripheral nervous system
Major divisions of the central nervous system
Brain (encephalon)
Forebrain (prosencephalon)
Midbrain (mesencephalon)
Hindbrain (rhombencephalon)
Pons
Medulla
What two parts is the forebrain made up of?
Telencephalon
Diencephalon
Rostral
Towards the head
Caudal
Towards the tail
Grey matter
More complex
Contains neurones and processes and synapses
Cerebral cortex
The grey matter surrounding the cerebrum is known as the cortex of the brain
White matter
White colour comes from myelin
Simpler
Composed of axons
Cabling of the brain- carries impulses across the brain
What are Association fibres?
a type of white matter tract that connects different areas in the same hemisphere
Types of association fibres
Short association fibres- carry info within a hemisphere
Long range association fibres- connect distant part of the cerebral cortex in the same side
What are commissural fibres?
Type of white matter tract that connect an area in one hemisphere with an area in the opposite hemisphere
Largest set of commissural fibres
Corpus callosum
This crosses between the two hemispheres- left and right
What are projection fibres?
are a type of white matter tract that connects the cortex with other areas in the CNS
They may be efferent (motor) or afferent tracts (sensory)
Carry fibres up/down
Eg corticospinal tract- carries motor signals from the cerebrum to the spinal cord
Main lobes of the forebrain
Frontal lobe
Temporal lobe
Cerebellum
Occipital lobe
Parietal lobe
What is the function of the pre central sulcus?
Location of Where the upper motor neurones control motor functions
What is the insula and operculum?
The operculum is the cortical structure which forms the lid over the insular cortex, overlapping it and covering it from external view
Functions of the insula and operula
disgust
emotion
homeostasis
perception
motor control
self-awareness
cognitive functioning (thinking/reasoning)
interpersonal experience
Frontal lobe
Motor function, problem solving, memory, judgement, impulse control, higher cognitive function, language, executive function.
Motor cortex- homunculus
topographic representation of the body parts and its correspondents along the precentral gyrus of the frontal lobe
Motor cortex- homunculus
Dedication of particular size of brain to body is determined by the complex movements of that part of the body
Eg; similar amount of brain dedicated to tongue as to the trunk (which is massive)
Temporal lobe
Semantic processing (the meaning and identity of things), memory, Language, primary auditory cortex
Facial recognition
Parietal lobes
Somatosensory- pain and sense s
Dominant (usually left) perception, language and mathematics
Non dominant (usually right): visuospatial function
Occipital lobes
Visual
Where is the The neocortex
The neocortex comprises the largest part of the cerebral cortex and makes up approximately half the volume of the human brain
6 layers of the neocortex
These layers have different functions
These layers are differently distributed throughout the brain
near to the pia mater, to the innermost layer VI – near to the underlying white matter
Functions of the neocortex
2- Input from other cortical areas
3- Projections to other cortical areas
4- Input from thalamus
5- Projects to brainstem and spinal cord
6- Projects to thalamus
Broca’s area
Largely associated with producing language
Wernickes area
Understanding language
Corpus callosum
Nips two sides of the brain together
Coverings of the brain
Slide 30
Dura matter is the covering of the brain and also acts as periosteum- the membrane of blood vessels and nerves that wraps around most of your bones
Arachnoid matter contains csf and is loosely attached
Pia matter is closely attached
Dura matter
Slide 31
Arachnoid mater and arachnoid cisterns
Slide 32
Blood brain barrier’s 4 key elements
Endothelial cell tight junctions- lines blood vessels
Lack of BM fenestrations
Astrocytic end feet- support cells, envelope the CNS capillaries- extend upto and around blood vessels
Pericytes- regulates blood-brain barrier permeability, blood flow and vascular immunity
Arterial territories
Slide 37-40
Superficial veins and sinuses
Veins drain into sinuses (these are large pool of venous blood) which are present in the channels between the 2 layers of dura
The vasculature of the spinal cord
42-44
Ependymal cells
Line the ventricles
Ciliated cells- cilia beat regularly to move the Cerebrospinal fluid along
Choroid plexus
A network of blood vessels and cells in the ventricles (fluid-filled spaces) of the brain. The blood vessels are covered by a thin layer of cells that make cerebrospinal fluid.
These cells are ependymal cells
Interstitial fluid drainage
Interstitial fluid drains into the CSF via perivascular channels- gaps containing interstitial fluid that span between blood vessels and their host organ
CSF drains via
-Arachnoid granulations which allow allow the CSF to be drained into the superior sagittal sinus
-Peripheral nerves to lymphatics (importantly the nasal mucosa lymphatics and deep cervical lymph nodes)
Limbic system and the Papez circuit
Includes:
-Mammillary bodies
-Fornix
-Hippocampus
-Cingulate gyrus
-Cingulum- fibre bundle deep inside the cingulate gyrus
-Thalamus
-amygdala
-basal ganglia
All of these structures are connected in a circuit, which are important for memory, motivation, emotion and fight or flight
Amygdala- sits in front of hippocampus
Important for fight or flight
Hippocampus
Sits in medial temporal lobe
Lay down memories rather than store them
Vulnerable to hypoxic ischaemic chain, epilepsy
Scarring of hippocampus can cause epilepsy
Look on slide
The Diencephalon and internal capsule
The Diencephalon is the first set of structures above the midbrain that begin to split apart
Ppt
Thalamus
Contains 3 main groups of nuclei:
-sensory relays
However smell bypasses the thalamus but others pass through
-cerebellum and basal ganglia relays to motor frontal lobe
connected to associative and limbic areas of cerebral cortex
Damage causes loss of sensation, pain, or movement disorders
Thalamus has a point of communication between other basal ganglia structures, cerebellum and parts of the motor frontal lobe
Thalamus connections
Thalamus projects to various parts of forebrain
Lateral geniculate nucleus projects to the visual cortex of the brain and receives the first point of synapse of incoming data from the retina
So the optic nerve projects to the lateral geniculate nucleus
The medial geniculate nucleus projects onto the auditory cortex and serves a similar function
Both of these communicate with the superior and inferior colloquially at the back of the midbrain
Ventral lateral projections go to motor and somatic sensory cortex
Basal ganglia
a group of subcortical nuclei containing
o Striatum: putamen and caudate nucleus
o Globus pallidus- separated into GPe and GPi
o Substantial nigra- pars compacta and pars reticulata
responsible primarily for motor control, as well as other roles such as motor learning, executive functions and behaviors, and emotions.
Caudate nucleus and putamen form the striatum
Striatum is important in initiating movement
Dorsal striatum: caudate nucleus and putamen
Ventral striatum: part of limbic system
Receives a lot of dopaminergic input from the substantia nigra in the midbrain
2 broad circuits through the previously explained structures that are referred to as basal ganglia
Direct and indirect pathways- related to when to decide to do a movement
Substantia nigra has an important role in directing this to happen
The hypothalamus
Sits on top of pituitary gland
Main output is to pituitary gland which produces hormones that regulate homeostasis
Slide 80
Substantia nigra pars compacta (output to the basal ganglia) releases dopamine which activates direct pathway of basal ganglia and inhibits indirect pathway
Activation of direct pathway allows for movement
Dopamine binds D1 and D2 receptors - D1 receptor: direct pathway activation, D2 receptor: indirect pathway inhibition
Whether direct pathway is activated or indirect pathway is inhibited is dependant on the whether D1 or D2 receptor on postsynaptic neurone
GABA is an inhibitory neurotransmitter
If you release GABA you inhibit, if you prevent release of GABA you activate
D1 receptors bind with dopamine activating the Direct pathway: movement initiated
- Cortex relays signals to striatum via glutamate (neurotransmitter)
- Striatum releases GABA which inhibits globus pallidus (Gpi) from releasing GABA. This disinhibits the thalamus and allows for movement
D2 receptors bind to dopamine inhibiting the Indirect pathway: stops movement
Cortex relays signal to striatum via glutamate
- Striatum releases GABA, inhibiting GPe from releasing GABA
- This inhibits Subthalamic nucleus (type of basal ganglia) , which stimulates GABA release from GPi, inhibits the thalamus
