Scenario (4) Brainstem Cerebellum Flashcards
What does the brain stem consist off
Midbrain
Pons
Medulla- bulbar palsy/ pseudobulbar palsy
Where does the brainstem lie
Basal portion of occipital lobe (clivus)
Connected to cerebellum
Caudadlly- medulla continuous with spinal cord
Rostrally- midbrain continuous with diencephalon of fore brain
What is the brain stem
Rosteral expansion of the spinal cord
What’s in the brain stem
- Nucleus gracillis & cutaneous
(dorsal columns) - Red nucleus (Rubospinal pathway)
- Vestibular nuclei (vestibulospinal pathway)
- Reticular formation
(reticulospinal pathway/reticular activating system) - Pontine nuclei
- Cranial nerve nuclei
- Substantial nigra
- Periaqueductal grey matter
Where are the cell bodies of the cranial nerves
Within the brain stem structure
What are cranial nerves classified as
Lower motor neurones
Reticular formation
Complex matrix of neurons extends throughout length of
brainstem
Efferent and afferent connections with CNS multimodal functions
Long axons ascending and descending
Medial- cranial nerve nuclei
Respiratory and cardiovascular centre
Reticular formation
Descending influences
From the reticular formation to spinal-cord
- Motor control: Reticular nuclei
Upper pons and medulla reticulospinal tracts arise from here
Posture
- Pain modulation: Raphe nuclei
Caudal medulla receive info from Periaqueductal grey matter
Inhibit pain stimulus
Block pain
Reticular formation
Ascending influences
From the reticular formation upwards
- Arousal: reticular activating system
Go to cerebral cortex and thalamus increase responsiveness, awareness
Impairs consciousness
- Sleep: Raphe nuclei
Pons and mid brain go up to forebrain structures
Sleeping
Cardiovascular
Theromo control
- Stress response: locus ceruleus
Midbrain pontine border projects extensively to cerebral cortex
Responsiveness
Noradrenalin as transmitter
Sympathetic response to stress
Particular information
Consciousness
Controls consciousness
Aware of ones self
How does one respond to their environment
Asscess deterioration of conditions
Nuclei in midbrain
Superior colliculi Inferior colliculi Ocularmotor nerve Edinger westphal Red nucleus Trochlear nerve Trigmenial nerve
Nucluei in pons
Pontine Trigminal Abducens Motor facial Vestibular
Nuclei in medulla
Gracile nuclei Cuneate nuclei Trigminal Vagus Accessory Hypoglossal Ambigus Rollers Arcuate
Hydrocephalus
A build up of CSF which puts pressure on the brain and can damage it
Congenital present at birth
Acquired develops after birth
Normal pressure usually only develops in older people
Unconscious
Not aware or responding to ones environment
Coma
Deep state of prolonged unconsciousness where a person is unresponsive alive but can’t be woken and shows no signs of awareness won’t normally respond to sound or pain or be able to communicate/move voluntarily basic reflexs greatly reduced
Drowsiness
A feeling of being sleepy all the lethargic feeling abnormally sleepy during the day
Ataxia
Lack of muscle coordination it affects coordination balance and speech usually resulting from damage to the cerebellum
- Acquired: symptoms develop as a result of trauma/MS brand tumour nutritional deficiencies
- Hereditary: symptoms develop slowly over many years close by faulty gene is that a person and hats from the parents
- Idiopathic late onset cerebellar ataxia: Brain is progressively damaged over time for unclear reasons
What is CSF
Clear colourless liquid comprised mostly water that protects the brain and spinal cord from chemical and physical injuries
What does CSF carry
Small amounts of oxygen and glucose and other chemicals from the blood to the neurons and neuroglia
Small amounts of glucose proteins lactic acid urea sodium calcium potassium magnesium and chlorine HCO3 and white blood cells
Functions of CSF
1) Mechanical protection:
shock absorber medium protecting delicate tissues of brain and spinal cord cushions brain so it floats in cranial cavity
2) Chemical protection: optimal chemical environment for accurate neurological signalling for production of action potentials
3) Circulation: medium for minor nutrients and waste exchange between blood and adjacent nervous tissue
Blood brain barrier: Certain substances in and excludes others
Dura matter
Protection
Most superficial of three spinal meniges
Thick stronger and denser regular connective tissue
forms a sac from the occipital lobe to S2 vertebra
Outer periosteal+inner meningeal layer
Arachnoid matter
Thin avascular covering the comprised of cells and then loosely arranged collagen and elastic fibres
Spiders web arrangement of delicate collagen and some elastin fibres
Deep to Dura mater and continuous with foremen Magnum with arachnoid matter of brain
Subdural space contains IS fluid between dura and arachnoid matter
PIA matter
Inner most matrix produces CSF
Thin transparent connective tissue that adheres to surface of spinal cord and brain
Interlacing bundles of collagen fivers
Many blood vessles supplying oxygen and nutrients to spinal-cord
Denticulate ligaments = Extensions of pia matter which project spinal-cord against displacement and shock
Between arachnoid and PI a matter = subarachnoid space which contains CSF
What does the cerebellum do
Important in motor control system. Fine tunes motor output. Timing of movements
- Subconsciously
A) balance, equilibrium
B) muscle tone, posture
C) coordinate muscle during skilled activities
- Consciously
Damage to cerebellum
Poorly coordinated movements
Wrong timing
Ataxia Dysmetria Dysdiadokinesia Intention tremour Ataxia gate Ataxic dysarthria
lesions of cerebellum
Cerebellum Controls same side of body it has ipsalateral tracts
Cause effects on the same side of the body
Deep cerebellar nuclei
Fastigial
Dentate
(Interpose nuclei)
Globose
Emboliform
Pikinji cell
Integrate sensory information from various parts of the nervous system from cerebellar cortex to deep cerebellar cortex
Cerebrallar nuclei form output
1) Archicerebellum system
Bilaterally affects balance and eye movement
Sensory information from vestibular and reticular nuclei in brainstem ( via inferior peduncle) into cerebellar cortex
Then from cerebellar cortex sensory information goes to the fastigial nucleus
Then goes back to the vestibular and reticular nucleus in brain stem.
(Origin of vestibulospinal and reticulospinal tracts )= descending tracts
MOTOR OUTPUT
2) Paleocerebellum
Influences muscle tone and corrective postural activity Iva rubospinal pathways
Influence= ipsalateral
Spinocerebellar tracts = sensory information up the spinal cord to cerebellar cortex vis inferior and superior peduncles
From the cortex info synapse with the globose and emboliform nuclei
Then synapse with motor fibres (efferent) at red nucleus
(rubospinal tract)descending = MOTOR OUTPUT
3) Neocerebellar
Muscle coordination during skilled and learned activities
Originates in motor cortex synapse in pontine nuclei which go into cerebellar cortex ( middle cerebellar peduncle)
Project into lateral cerebellar peduncles
Then synapse with dentate nuclei
Then projects back up towards motor cortex via thalamus (contralateral)
What do the x3 cerebellar systems act as
Act as feedback loops an error detector
Sensory input into the cerebellum which then interpreted the information compares intended actions with actions that actually occur and then sends motor information via descending pathways which influences action
