Functional Neuroanatomy Flashcards
Breakdown of the nervous system
Central. Peripheral
Brain. Spinal chord. Somatic. Autonomic
Sympathetic Parasympathetic
Somatic nervous system and its nerves
Interacts with external environment.
Afferent nerves: sensory organs to CNS
Efferent nerves: motor signals from CNS
Autonomic nervous system
Regulates the body’s internal environment, controlling the internal organs
Sympathetic vs parasympathetic
Sympathetic is energy expending, prepares the body for action. Fight or flight. Parasympathetic works when the body is at rest.
Things the CNS has that the PNS doesn’t.
- Glia do not support regeneration
- Neurons usually can’t regenerate
- Different main protein constituent of myelin differs
Spinal chord (structure, function and pathology)
Structure: innervation of 30 sensory and motor nerves, protected by the spinal chord
Function: relays and integrates sensory and motor info, controls basic reflexive behaviour
Pathology: lesions cause sensory and motor impairment
Structure of the skull
- Cranial plates: pieces of bone fused together over time, varying in strength and width
- Fossae: ridges at the base of the skull that keep the brain in place
- Foramina: holes at the base of the skull that let the nerves in
Function of the skull
Encases the brain as protection. Not perfect protection bc its rigid and the brain has nowhere to go, should swelling occur.
Structure of meninges (inner to outer)
Pia mater, subarachnoid space (CSF sits here), arachnoid membrane and dura mater
[lies between the spinal chord and column and the brain and skull, holding things in place]
Meningitis
Inflammation of the meninges, starts out with cold like symptoms but progresses to delirium, vomiting, photophobia and phonophobia
Structure of the Ventricular system
Four interconnected ventricles, allows CSF to flow through the body. The choroid plexus handles CSF circulation. This area gets distorted by brain damage.
Function of the ventricular system
It acts as a liquid buffer, keeping the brain floating and away from the ridged bones in the skull. It also removes waste from the brain
Pathology of the ventricular system - hydrocephalus
Intracranial pressure distorts the ventricles to keep the brain the right size.
Hydrocephalus: the over expansion of the brain, causing it to swell up and press against the skull. Too much CSF
3 symptoms of normal pressure hydrocephalus
- Gait and balance issues
- Urinary issues
- Cognitive problems like memory, attention etc
Function of the Vascular system
Predictable system that sends blood to and from the brain to ensure that neurons get the high levels of energy that they require to function properly
Circle of Willis
A circulation of blood within the brain that maintains supply to the brain if other sources are cut off. Near the base of the brain, former by cross brain arterial connections
Blood supply for anterior parts of the brain
Right and left carotid arteries - left and right cerebral arteries
Blood supply to the posterior part of the brain
Two vertebral arteries - basilar artery - left and right posterior cerebral arteries
Connections between the cerebral arteries
Left and right internal carotid: anterior communicating artery
Middle and posterior cerebrals: posterior communicating arteries
Reticular formation (RAS)
Diffuse arrangement of ascending and descending neurons that forms a network throughout the brain
RAS function
Non specific arousal, respiration and selective attention
Selective attention, in the hierarchy of cognition
Bottom of the hierarchy, process of deciding what information to filter out and what to allow for processing. Evolutionarily important as it prevents overworking the brain on things that are not important
First example of bilateral organisation within the brain
The thalamus
Brief description of the thalamus
Not well understood, as it sits right in the middle of the brain. It has dendritic and axonal connections to many brain regions and is the interaction centre for several different neurotransmitters
Functions of the hypothalamus
Body homeostatis, stress response, body temp, digest ions, circulation, circadian rhythms, development of secondary sexual characteristics
Damage to the hypothalamus
Generally by direct or indirect tumor, medial area damage associated more with behavioural issues.
Description of Thalamus
Relatively large, with two symmetric nuclei. Receive ascending and descending input from cerebral cortex ipsilaterally. It has well defined geographic regions, each unique in what it controls and communicating with different brain regions (the start of complex behaviour)
Function of the thalamus
Classifies, integrates and sends info, makes very basic decisions (good vs bad)
Pathology in the thalamus
Left: verbal deficits
Right: impaired spatial and facial recognition ability.
Often short lived deficits, the brain adjusts quickly due to the level of connectivity of the thalamus
Description of the cerebellum
Symmetric ‘mini-brain’ that sits at the level of the pons, containing 50% of the brain’s neurons. Heavily unfolded and is divided into lobes by deep fissures.
Function of the cerebellum (3)
- Ipsilateral control of general coordinated motor behaviour.
- Stores memory for simple learned motor responses
- Attentional sifting from one stimulus to another
Pathology of the cerebellum
Deteriorating coordinated movements, like involuntary tremors and resting tremors. Impaired balance and gait disturbances
Structure of the corpus callosum
Large bundle of intercerebral white matter tracts that sits between the two hemispheres
Function of the corpus callosum
Exchanging info between cerebral hemispheres
Pathology of the corpus callosum
Cutting it prevents diseases in on hemisphere from spreading to another but also limits the amount of communication between hemispheres
Structure of the Basal Ganglia (5 components)
Symmetrical subcortical grey matter.
- caudate nucleus
- putamen
- globus pallidus
- sunstantia nigra
- subthalamic nucleus
Basal ganglia system that works with info transfer from cortical to subcortical
Striato-pallido-thalamic loop (striatum = caudate nucleus and putamen)
What is the nigrostriatal system made up of and what does it do?
Caudate nucleus, putamen and substantia nigra. It works with dopamine and is linked to Parkinson’s
Function of the Basal Ganglia
Regulating voluntary movements, everything outside of the pyramidal system (motor and pre motor cortex)
Opposing theories around the function of the Basal Ganglia
Integrative vs relay station
What do recent studies suggest the basal ganglia has a role in?
Language: lesions result in difficulty with motor aspects of speech
Attention: lesions result in difficulty in switching tasks and mental flexibility
Behaviour: generation, inhibition and execution (particularly inhibition)
Pathology in the basal ganglia
Atypical movements, change in muscle tone, tardive dyskinesia (involuntary facial muscle movements)
Broca on the limbic system
A ring of tissue around the midbrain region
It consists of:
- cingulate gyrus
- subcallosal gyrus
- parahippocampal gyrus
- hippocampal formation
(Early conception of the limbic system, believed to be linked to olfaction)
Papez and MacLean on the limbic system
Papez: emotional processing
MacLean: functional system
Modern day ideas of what structures the limbic system includes
Medial and basal surfaces of cerebral hemispheres. Includes: - Broca's list - Amygdala - Fornix - Septum - Olfactory bulb - Mammiliary bodies - Anterior nucleus of the thalamus
3 sources of cortical input to limbic systems
- Posterior association cortex
- Inferotemporal cortex via entorhinal cortex
- Prefrontal cortex
3 outpost of the limbic system
- Mammillary bodies - anterior thalamus - cingulate
- Hypothalamus - PFC
- Amygdala - PFC
Functions of the limbic system
No one given function, great complexity due to the number of inputs and inter connectivity.
Individual structures within the limbic systems and their functions:
- Hippocampal formation: memory acquisition
2. Amygdala: emotional processing, namely fear conditioning
First four cranial nerves and their functions
- Olfactory: smell
- Optic: vision
- Oculomotor: eye muscles, movement and pupil dilations
- Trochlear: eye muscles and movement
Cranial nerves 5-8 and their functions
- Trigeminal: senses of skin on the face, nose and mouth, chewing and swallowing
- Abducens: sensation from eye muscles, eye movement
- Facial: take, facial expressions and crying
- Statoacoustic: hearing and equilibrium
Cranial nerves 9-12 and their functions
- Glossopharyngeal: taste and swallowing
- Vagus: taste, neck sensations, control of larynx, parasympathetic nerves to heart and viscera
- Accessory: movement of shoulders and head
- Hypoglossal: tongue senses and movement