Neurosciences Flashcards
What is rostral acording to brain?
The front caudal is the back
What is rostral in terms of te spinal cord?
Towards the head
What are the main parts of the brain?q
Cerebrum, Cerebellum and brain stem
What are the outer layers of the brain called?
The meninges
What are the parts of the brainstem?
Medulla oblongata, Pons, Midbrain, Diencephalon
What are dermatomes?
The area of skin supplied by nerves from a specific spinal level
What are the lobes of the brain?
Occipital, parietal, temporal and frontal
What are some of the names of important fissures or giri?
Sylvian fissure(lateral) central fissure, cingulate girus, calcarine sulcus, parahippocampal girus
Where is the primary mortor cortex?
The precentral girus in fron of central sulcus
What is the premotor cortex?
the seccondary motor area
Where is the primary somatosensory cortex?
The post central girus
Where is the pituitary?
Below the optic chiasma, in from of the pons
What is mindbody dualism?
The belief that the mind and the body are not linked and can be separated
What are the criticisms of dualism?
What is non physical substance that makes the mind. how can an immaterial thing create physical effects? is it linked to supernatureal
What is reductive physicalism?
Everything is explicable by the physcical giving a view of depression as biological
What is interactionism?
Entities can have an effect on one another, mental distress casues symptoms and vice versa
What are the consequences of dualistic thinking?
Makes us thing things are explicable by biomedical model but we have the mind that has an effect but we can’t study it medically unexplained symptoms are hard.
What is the reptillia brain?
Part in development about homeostasis arousal survival and reflexed that most animals have
What is the mamalian or limbic brain?
Emotions nurturing habits and memory are in this part from development
Which part of the brain gives us the most distinct features?
The frontal lobe
Where does dopamine affect?
The frontal cortex givind rewards euporia motor function and compulsion
Where does serotonine afect?
all but occipital , mood memory and processsnin sleep cognition
How can you test the frontal lobe ?
Proverb interpretation, similarities test, cognitive estimates, wisconsin card-sorting test
What are the symptoms of schizophrenia?
Delusions, thought disorder when its hard to make sense of what someone says. hallucinations they can get worse and become withdraw and appear unemotional lose interest stop looking after themeselves and find it hard to do normal tasks
What the biological correlates for schizophrenia?
brain volume functional imaging neurotransmitter abnormalites and genetic factors.
Dopamin blockers seem to work and this can be negated by other drugs such as for parkinsons
What is the non biological correlates for schizophrenia?
social migration to cities could cause it psychosocial treatments have an effect, associated with repeat childhood trauma. associated with stress
What are problems with classification and diagnosis of mental disorders?
have to set arbirary limits on thinds like depression, leads to stigma and prejudice, economy of thought may lead to oversimplification
What does evolution show about systems level architechture of the brain?
The brain always had the same parts just developed into different sizes but maintained function over time
What is the mechanism that the brain uses for defence at a low level?
It has receptors that go to the spinal cord and does motor autonomic endocrine responses.
What does the brain use for the avoidance of loom dangers?
Visual processing or auditory and goes to sensorimotor mid-brain to the effectors at a subconscious level
What is the highest level of avoidance pathway?
Learned threat which includes the cortex and limbic system
How can you look at the hierarchy of of bain function?
Lowest is spinal cord reflexes, hindbraind does sudden distal stimuli for the startling, midbrain and hypothalamus does species specific threat like fight or flight, then it is the thalamus sensory cortex and hippocampus using amygdala for complex avoidance
what is in the CNS?
Brain and spinal cord
What is the peripheral nervous system?
all the nerves other than the spinal cord and brain
What are the divisions of the peripheral nervous system?
Somatic under conscious control and autonomic which is subconscious nervous system
What is the spinal cord separated into?
cervical, throacic lumbar and sacral
What do cervical nerves usually do?
Head and neck diaphragm and the arms and hands
What do thoracic nerves usually do?
chest muscles breathing abdominal muscles
What do the lumbar nerves usually do?
Legs and feet
What do the sacral nerves do?
Bowel and bladder control as well as sexual function
What are the dorsal roots of the spinal cord?
The dorsal is the sensory receptor signals entering afferent signals
What is the ventral root of the spinal cord responsible for?
The motor function signals coming from the brain efferent signals
What is in the ganglion where the dorsal and ventral roots join?
The dorsal root ganglion for the sensory neurons.
What are the three biggest divisions of the brain?
Forebrain, Midbrain and Hindbrain
How can the forebrain be split up?
into the telencephalon and the diencepalon
What is in the telencephalon?
cerebral cortex basal ganglia and limbic system
What is the diencephalon made from?
The thalamus and hypothalamus
What is the midbrain?
The mesencephalon
What is the mesencephalon made of?
The tegmentum and tectum
What is the hindbrain made from?
the metencephalon and the myelencephalon
What is the metencephalon?
Pons and cerebellum
What is the myelencephalon?
The medulla
What is the function of the medulla?
Contains tracts with signals to the rest of the brain, low sensorimotor such as balance, involved with sleep and wakefullness, movement and maintenance of muscle tone, cardiac, circulatory and excretory reflexes
contains reticular formation
What is the function of the pons?
The bridge or relay between the cortex and the mid brain to the cerebellum, it contains lots of neuronal fibers and has the pontine reticular formation which is used in pattern generation
What does the cerebellum do?
It is mainly involved with motor functions. It is unvolved with fine regulation of movement and correcting motor errors. could have a role in cognitive emotions.
What does the tectum made of?
The superior and inferior colliculus
What does the superior colliculus?
Sensitive to sensory change and orienting defensive movements. gets topical inputs of signt
What does the inferior colliculus do?
it is involved in subconscious auditory events.
What is the tegmentum made of?
The periaqueductal grey, red nucleus and substantia nigra
What does the periaqueductal grey do?
Role in defensive behaviour, role in pain ascending and descending signals, role in reproduction
What does the red nucleus do?
Relay station involved with the motor signals from the cortext and cerebellum and a role in pre-cortical motor control
What does the substantia nigra do?
It is involved in dopanin production involved in parkinsons disease
What is the thalamus doing?
Has specific nuclei and relays signals to the cortex and limbic systems for all sensations other than smell. It has non-specific nuclei and has a role in regulating state of sleep and wakefullness and arousal it is a relay fro the basal ganglis and the cerebellum back to the cortex
What does the hypothalamus do?
Regulates the pituitary gland which regulates the hormones, tole in hormonal control of motivational behaviour hunger thirst sex pleasure pain temperature
What can the forbrain be split into?
The forebrain or cerebral cortex can be subcortical or cortical
What are the sructures in the subcortical area of the forebrain?
Basal ganglia and the limbic system
What is the function of the basal ganglia?
Involved in the initiation of motor function and involves loop organisation
What are the constituets of the limbic system?
The Amygdala, hippocampus, fornix, cingulate gyrus and septum and mamillary bodies
What is the function of the amygdala?
almond associated with sensory stimuli with emotional impact
What is the function of the mammillary body?
They are important for the formation of recollective memory
What is the function of the hippocampus?
Involved with memory long term and spatial memory
What is the function of cigulate gyrus?
linking behavioural outcomes to motivation and autonomic control
What is the function of the septum?
Involved in defense and aggression
What is the function of the fornix?
It is involved with carying signals from te hippocampus to the mamillary bodies and septal nucleus
How many layers of cortical lobes are there?
6 layers of cell bodies made of white and grey matter
What are some important areas in the cortical lobes?
The primary motor cortex which is the origin of descending motor pathways
also premotor and supplementary motor areas wich have higher level motor plans and initiation of voluntary movement
What is the frontl lobe responsible for?
Executive planning and judgmental roles it has the short term memory and controls behaviour based on setting.
What is the primary somatosensory cortex?
its in parietal lobe and recieves signals from the body. it maintains representations of the bodys position in spaces and predicting movement of moving objects
What is the temporal lobe involved with?
Primary auditary complex and it linkes with the limbic system and is involved with recognition of faces.
What is the occipital lobe doing?
The visual inputs with the primary visual cortex.
What is the dorsal stream?
The vision for movement where things are in relation to you.
What is the ventral stream?
It is used for identification of things meaning why it is important to us
What are the levels of description in neruological understanding?
Psychological, systems, mictocircuit, neruonal, intracellular and molecular
How are xrays useful for immaging the brain/spinal cord?
Not very good for the tissue but for the bone and for foreign objects.
How can x-rays be made more useful?
Using contrast x-ray. cerebral angiography can show you how well the blood vessels are working and if there is a blockage although they cant tell you about the brain function itself.
How is MRI used in neroscience?
very good for looking at the structure and composition of the brain for tumours and swellings. it is non-ionising and very high detail can be obtained from it.
What is functional magnetic resonance imaging?
It is tuning MRI to look at oxygenated and deoxygenated iron in the blood. this can tell you about what areas of the brain are using more oxygen and may be more active.
What does fMRI detecting?
Increased neuronal activity uses more oxygen which attracts more blood flow there so its slightly counterintuitive can’t differentiate between inhibitory or exitatory
What is the use of PET scanning?
Positron emission tomography is when a chenical that binds to or is uses is radio tagged and given to a patient then the emissions from this isotope are tracked as part of the scan to give a 3 d image. it can be useful for showing activity and/ tumours
What is a new type of scanner that could be good?
MRI PET/fMRI scanners that can be used
What are EEG scans?
Electroencephalography it detects activity of neurons but it shows summation of many neurons from the surface. not very spatial signals can use repetitions of tasks to see whats happening. to get event related potemtial
What is MEG?
Magnetoencephalography it pics up on magnetic activity from the flow of current through axons. it is a very big machine it is more indicative of actual activity due to less noise
What is TMS or TDCS?
Transcranial magnetic stimulation or transcrania direct current stimulation which passes current or magnetic filed through and an area of the brain to innactivate part of the brain to investigate function
What is galvanic skin conductors?
It is used for sweat measuring to measure the autonomic nervous system
What is important when considering which method to use?
Invasiveness and spatial and temporal investigations
What are the 3 Rs of animal models?
Replacement (can other methods be used?) Refinement can it be done in a better way that maximises the benefit, Reduction can it be done with fewer animals
Which animals are most used in research?
Mice, fish rats birds
What are some invasive measures usually used only in research?
Deep brain probes, intracellular investigaion of neurones. stimulate one region and record activity in another area. using tracer in neurones with anteriograde and retrograde tracers
What are the applications of invasive measures?
They can be mixed to look at the effect of pharmacological agents.
What are the uses of genetic engineering?
Knock out or excessive gene expression.
What is optogenetics?
Looking at stimulating with light with genetic implantation of receptors
What week in development do the eyes form?
3 weeks
Which week does the brain start to form properly?
6 weeks
When are the basic structures of the brain developed?
3 months
When are the CNS neurones myelinated?
at 5 months
What are some of the critical periods in deveopment in utero?
rubella can affect them 6th week eye malformations 9th week deafness 5th to 10th cardiac 2nd trimester CNS
What is fetal alcohol syndrome?
When alcohol from mothers blood passes to the baby, causes abnormalities like loss of cells loss of fibres motor and intellectual impairment, flat midface thin upper lip
What is the effect of opiates on babies?
withdrawl
What is the problem with cocaine usage?
withdrawl decreased cognition, hypoxia, or abortion
What is a stress response in the foetus?
not awareness but can cause uptake of lung fluid
What are primitive reflexes?
Ones present at birth that are usually repressed in adulthood and therefore a pathaloical sign in adults
What is the rooting reflex?
Turning the head in the direction of stroking of cheek
What is the suckling reflex?
Babies will such an opject that touches their lips
What is the moro(startle)reflex?
Back archs lega and arms flung out and then brougt back in when dropped
What is the grasping (palmar) reflex?
Babies grasp objects put in their hand
What is the stepping reflex?
The mimic walking when upright
What is the babinski reflex?
fan toes when sole of the foot is stroked
What is the tonic- neck reflex?
Turn head to one side and extend arm and leg
When is a baby able to track objects?
from birth
When can a baby converge the gaze?
at 7 or 8 weeks
Do neonates have perpheral vision?
no
When does taste develope?
At birth prevers sweet
When does smell develop?
at birth
When does dexterity develop?
at age 3
Where does development happen and how?
cranial to caudal, proximal to distal, simple to complex
What is the left hemisphere involved with?
Verbal speaking reading thinking and reasoning
What is the right hemisphere involved with?
nonverbal spatial patterns drawing recognition music emotionall ecpresssion
What are the types of malformation in development?
Miss development, things not developing, DNA is wrong the DNA is not executed orrectly
What can cause malformations?
toxins, Infections, Prematurity
What does cytomegalovirus do to a foetus?
Intracranial calcification as well as Aicardi-Goutières syndrome
What is lissencephaly?
Smooth brain neuronal migration disorder
How much alcohol can affect a foetus?
Binging very bad, 2 units a day can affect them
What can be looked for in the brain in an ultrasound scan?
Ventricular haemorrahge
What are some red flags in development of children?
Syndromic childen, history of brain injury, any loss of skill at any age, visually not fixing or following objects, hearing loss, low or high muscle tone, squint after 3 or 4 months 6th nerve. can’t hold object in hand, handed ness before 3 years old, cant point at oject to share intrest by 2 years, no speach by 18 months, persistent to walking, girls not walking by 2 years, gboys not walking by 18 months, can’t sit unsupported by 12 months
What do skeletal muscle fibres look like?
Myofibres in fascicles conected with epimysium perimysyuum and endomysium, they are in bundlles with nuclei around the edges.
What surrounds muscles?
Basement membrane syrrounding myofibriles collage and glycoproteins, there.
What is a motor unit?
The group of muscle fibres that are all innervated by the same nerve
What is the transmitter for the muscle?
Acetycholine
What are the proprioception muscles receptors?
Muscle spindles which are intrafusal fibres and Golgi tendons which are tension receptors
What is a primary muscle disesase?
A disorder in the muscle its self
What are the needs for a muscle biopsy?
cant put in formalin and is frozen and needs the right direction of slice also can look at it ultrastructurally
How can you look at fibre types?
Using histochemistry with enzymes to generate colour, oxidative enzymes
What are the types of muscle fibres?
slow twitch type 1 red which are oxidative and fatigue resistant
there are fast twitch which are very powerful but fatigue type 2: there are 2 A Glycolytic and oxidative intermediate and 2B glycolytic which are white and fatigue easily.
How do motor units structure?
they can overlap and intermingle, fibre type depends on innervation, the size is dependant on the amount of controlled
What happens in deinervatio of motor neurones?
Collateral sprouting of adjacent motor units which allows re innervation with larger motor units get conversion of fibre types
What is the Z disk?
The lines of protein with alpha actin titin nebulin and desmin that define the sarcomere
What is a sarcomere?
Basic unit of contraction repeating arrangement forms a fibre
What makes the A bands?
The myosin strands.
Do the I bands or A bands shorten?
I bands
What makes up thick fillaments?
Myosin
What does desmin do?
Links myofibrils to eachother and the sarcolemma
What is the structure of actin?
There are actin globular proteins, with tropomyosing strands and troponin to block the binding sites
What are the m lines?
The fibres that are in the middle of the a band
What causes shortening of the sarcomere?
The sliding of the fibres over eachother not the shortening of fibres, activated by CA2+
What provides energy for the contraction?
ATP
What can store ATP?
Creatine pospate and is replenished by creating kinase which is released when a muscle fibre is damaged.
What are mitochondrial cytopathies?
Problems with mitochondria, have maternal inherided DNA which is circular, mutations can occur in nucleus or in mitochondria, can have clinical presentations of CNS problems,
How can mitochondrial cytopathies be diagnosed histologcally?
take a muscle biopsy, ragged red fires transport cain deficites in cytochrome oxidates negative fibres
What is dystophin?
a protein that binds to actin and the sarcoglycans in the sarcolemma
What other proteins are involved with dystrophin?
Merosin dystroglycans, sarcoglycans, and actin
What can happen in problems with dystrophin problems?
When the muscle contracts the muscle loses weakness and can cause the destruction of muscle fibres they are genetic.
What is duchennes muscular dystrophy?
Deletion from gene that causes open reading phrame and short protein or no protein is produced.
what happens in neuromuscular transmission of nerve impulese?
ACh binds to receptor, cation entry results in depolarisation of the end plate the action potential crosses the membrane and into t tubule system where calcium is released from the sarcoplasmic reticulum.
What ends the contraction?
When ACh is hydrolyses by acetyl cholinesterase in the neruomuscular junction
What is myasthenia gravis?
Variabe weaknes progressive with sustained effort eyesign of ptosis. it is autoimune and anti Acetylcholine in a reduction of receptors.
What are the adaptations of the endoneurium and perineurium?
They have tight junctions to reduce transport of unwanted sustances
How many nerves can one swann cells look after?
For myelenated nervs it is only one but otherwise can be several
What are oligodendrocytes and how do they differe to Schwann cells?
They can myelenate many and they are only found in the CNS
What is a peripheral neuropatheis?
damage to motor and sensory neurons can be axonopathies or to demyelination
What is axonal degeneration/regeneration?
When an axon is damage distally the nerve dies but can regrow from there and Schwann cells can produce sprouts they won’t be as fast though
When does the neural tube close?
At the 4th week
Which important brain cells are derived from the ectoderm?
Melanocytes, Shwann cells, neurones
Which importan cells develop from the mesoderm?
Osteoblasts and osteoclasts, adipocytes and chondrocytes
What is it called when the neural tube fails to close at the head end?
anencephaly
What is it called when the neural tube fails to close in the spinal region?
Spina Bifida
What is a meningocele?
Protrusion of the meningesthrough where the vertebral spine should be
When does the anomaly scan take place?
Anomaly scan takes place at 20 weeks looking for development defects. ultrasound
What are the emryological areas of the brain called?
Prosencephalon, Mesencephalon and Rhombencephalon also the spinal cord
What does the Prosencephalon give rise to?
The frontal lobes and cortex, the telencephalon and diencephalon
What does the mesencephalon give rise to?
the thalamus and nuclei the mesencepalon
What does the rhombencephalon give rise to?
the cerebellum and brainstem
What can affect brain development in foetus?
Alcohol and valproate
What is the most comon developmental disorders?
Intellectual disability, from the malformation of the layers of the brain cortex
How much CSF is there?
About 120 mls
What are the causes of hydrocephalus?
Brain tumours menigitis, obstruction of the flow of CSF. There is also over production of non-obstructive.
What muscle is in the lower eye lid?
There isn’t one
What is the muscle that is there for theupper eye lid?
Orbicularis oculi to close the eyelid this is innervatied by 7th cranial nerve. there is levator palpebrae superiouis that elevates the eyelid innervated by the 3rd cranial nerve the occulomotor
what is the name of the rim of tissue in the eyelid?
The tarsal plate which contains meibimian/ tarsal glands
What innervation is there in the eyelid?
Motor and also sympathetic for horners gland smooth muscle
Where is the tarsal gland?
runs vertically upwards from the eye lid rim in both upper and lower lid
What is the conjunctiva?
It is a mucous membrane which covers the eyelid and frontal areas of the eyeball/globe. It merges with the cornea at the limbus
What is the conjunctivia like?
It is loosly attached to the globe and highly vasuclar alhtough the vessels are usually constricted
What are the layers of the tear film?
The anterior lipid layer from meibomian glands, aqueous layer from the lacrimal and acessory glands, the mucin layer which is crom conjunctival goblet cells
What is in the aqueous layer?
antibodies enzymes and vitamin C
What is the importance of the tear film?
protects the eye and supplies the cornea with oxygen and nutrients and gives a smooth clear anterior refracting surface.
What is the purpose of the mucin layer of the eye?
it helps the aqueous layer sit on the globe
what is the function of the lacrimal gland?
Wash away foreign bodies
What is the function of cornea?
Allow light into the eye and begin focusing of the light
What are the three layers of the cornea?
Epithelium, Stroma and endothelium
What is the epithelium of the cornea like?
Stratified non-keratinising and has limbal stem cells, it is very sensitive to pain via the 5th nerve
What is the stroma of the cornea like?
Recular lamina of collagen fibres it is avascular
What is the endothelium of the cornea like?
It is a single layer on the back of the eye and it is not replaced and is a fluid pump for the eye.
What is the need for pumping of the endothelium?
It stops clouding of the cornea from absorption of water and the pump stops it from swelling
What is the anterior chamber?
it is the space between the posterior surface of the cornea and the anterior surface of the iris and lens, it is filled with aqueous humour producesd by ciliary body
Where does fluid exit from the anterior chamber?
Exits via the AC angle, the trabecular meshwork is here
What are the special quirks of the anterior chamber?
Can see convection currents in the eye
What is the function of the iris?
A muscular diaphragm that controls light entry to the eye
What muscles of the iris?
Dilator muscle wich is sympathetically innervated and then the sphincter muscle which is parasympathetic with muscainic receptors
What are the two layers of the iris?
The anterior layer has stroma and gives iris colour,and the posterior pigment is all irides and muscle
Where is the cilliary body located?
Behind the iris beneath the conjunctiva and scleralateral to the lens.
What causes both pupils to be small?
Bright light extremes of age also opiates and cholinergic.
What are the causes of asymetric pupils anisocoria?
Horners syndrome RE, angle closure LE, 3rd nerve palsy LE adie pupil LE cholinergic drop RE anticolinergic drop LE symathomimetic drop LE
What are the causes of large pupils?
Low light exited or amphetamines anticholinergics or death
What is the function of the lens?
To focus the light or accomodation which is achieved by contraction of the ciliary body
How does accommodation work?
the cilliary body (circular muscle) contracts which causes tension in the zonule to reduce and the lens will become rounder for near vision. when teh ciliary body is relaxed it will put tension onthe zonule causeing it to flattern for the eye to focus on far objects
What is presbyopia?
The elasticity of the lens reduces over time and its ability to become round again is reduced leading to difficulty in seeing close up objects
what changes happen to the lens over time?
anterior epithelium produces fibres throughout life so the lens enlargens and the centre is the oldest, this can cause cataracts over time if the formation is imperfect
What is the aqueous humour?
the fluid that is found around the lens at the anterior portion of the eye
What is continuous with the choroid?
the ciliary body
What is the pars plicata?
the processes of the ciliary bodies tha secrete aqueous humour.
What are the innervation of the ciliary bodies?
3rd cranial nerve muscarinic receptors.
What causes pupils to dialate?
anticholinergic drugs like atropine which block the action of the muscles in the pupil
What is the vitreous humour?
Fills the space between te posterior surface of the lens and the retina. it is collagen fibres and large negatively charged glycosaminoglyans.it contains the remematns of blood vessels from te optic disc to the lens and becomes more liquid with age
What is the retina?
the area of the eye responsible for turning the light signals into nerve impulses
What are the layers of the retina?
Photoreceptors (rods and cones) 1st and 2nd order neurones (bipolar and ganglion cells) internerurones amacrine and horizontal cells, neruoglial cells pigment cells and supporting membranes
Describe the structure of the retina
There are rods and cones at the bottom lowest area of the eye above the bigment epithelium and choroid. above these layers there is the bipolar cells. The bipolar cells synapse with ganglion cells that transmit the signal to the optic nerve
what is the nutrient supply to the photo receptors?
no direct blood supply from diffusion from the choroidal blood supply
What are the properties of rods?
dim light perception but no colour
What are the properties of cones?
They allow perception of colour and are very concentrated in the fovea
What are the most common rods or cones?
Rods
What are horizontal cells?
recieve input from photo receptors and moduclate it and also control the activitiy of photoreceptors
What are muller of amacrine cells?
receive signals from bipolar cells and ganglion cells and modulate it
What is the optic disk?
An area with no rods or cones(blind spot) where the ganglion fibres leave as the optic nerve
What are the retinal blood vessels?
supply the inner part of the retina but not the photoreceptors the cast a shadow over photoreceptors
What is the Fovea?
the pit or depresssion at the centre of the macula that gives the best visual acuity. foveola is the most sensitive part of the retina contains only cones and no obscuring blood vessels.
What is the macula?
the portion of the eye at the centre of the retina that processes sharp clear straight ahead vision highest concentration of cones
Where is the macula?
in the temporal area.
What is the largest part of the uvual tract?
The choroid
What is the choroid?
it is highly vascular and heavily pigmented. it is the middle layer of the posterior eye it supplies blood to the outer retina which is controlled by retinal pigment epithelium
What is the optic disk?
Where ganglion cells leave the retina and there are lots of capillaries there are no photo receptors it has a central cup with an opening in the sclera and adventitial tissue the size is variable. good to see ocular and neurological problems
What is the sclera?
The tough outer protective layer and is the insertion point of the muscles. it is perforated by nerves and blood vessels and is opaque from collagen fibres
How many extraocular muscles are there in each eye?
- 2 vertical recti 2 horisontal recti and two oblique muscles
What is the innervation of most muscles other than the lateral rectus and superior oblique?
the occulomotor nerve CNIII
What is the innervation of lateral rectus?
the 6th cranial nerve the abducens
What is the innervation of the superior oblique?
the 4th cranial nerve trochlea
Where is the origin of most muscles of the eye?
the orbital apex apart from inferior oblique which has an anterior origin.
Which muscle is different to the others?
The superior oblique as it runs with a tendon through a trochlea or pully
What is the orbit?
the bony protection of the globe. medial ehtmoidal (thin) and lateral zygomatic wall (thick) and the floor maxllary and roof are thin. opens into middle cranial fossa
Which bones make up the orbit?
Frontal ethmoid maxilla, zygomatic plus manny more
What are the opennings of the orbit?
The optic canal and the superior orbital fissure
What runs in the optic canal?
Optic nerve and opthalmic artery and sympathetic plexus
What runs in the superior orbital fissure?
the occulormotor 3rd, trochelar 4th, brances of the trigeminal 5th opthalmic and the abducents 6th,
What affects the diameter of the pupil?
Changes in light intesity, proximity of object, state of arousal sympathetic nervous system .
What is involved in the afferent limb of the pupil?
The retina then the optic nerve which decussates at the chiasm and then the optic tracts
What is involved with the efferent limb of the pupil?
The edinger-westphal nucleus in the mid brain, parasympathetic fibres of the 3rd cranial nerve and they synapse in the ciliary ganglion in the orbit. and then short ciliary nerves inervate the sphincter
What are the differences in reflexes of pupils?
One eye affects the other, bilateral input to the pretectal nucleus. very quick response
Where is the nucleus for eye reflexes?
The superior colliculus
What normally happens when you shine a light in the left eye?
Simultaneous constriction of the pupils
What normally happens when you remove the light from the eye?
The pupils both dilate
What happens with an afferent pupillary defect with the left eye?
Poor or absent constriction of the left pupil and same on right when shined into left when shone on the right eye normal response. shows that can constrict but can’t sense it on the left
What happens with an efferent pupillary defect with the left eye?
Could have difference sizes to begin with eg left bigger. shining light in the left causes little or no response in left but good in right. removing the licht the left will stay similar and right dilates. when shining in the right it will causes poor or absent constriction of left an dnormal of right
What can cause optic nerve afferent defects?
Optic nere disease, severe retinal disease
What can cuase efferent defects?
3rd nerve palsy, adie pupil, iris damage, atropine drugs angle closure glaucoma
What is the dark response?
Active dilatation by sympathetic stimulation of dilator muscles and inhibition of sphincter muscle
What is Cliliospinal reflex?
pinching the neck on one side causes pupil dilation on that side,
What is the intraocular pressure?
15-20mmHg this allows the eye to move without being deformed
What is high intraocular pressure called and low?
Glaucoma and hypotony
What is the device used to measure intra ocular pressure?
Tonometer
What is the normal flow of aqueous humour?
producced in the ciliary body circulates around the lens and through the pupil and leaves the anterior chamber by the AC angle
what is conjugate movement?
Movement of the eyes together?
What is the purpose of eye movements?
Widens field of vision allow us to follow a target. stabilising vision acurate tracking and it maintains vision
What is the function of lateral rectus?
abduction
What does medial rectus do?
Adduction
What does superior recuts do?
elevates
What does inferior rectus?
depresses the eye
What does the superior oblique do?
Rotates eye inwards intortion
What does the inferior oblique do?
Rotates the eye outwards extortion
what is the blood supply for the eye?
Opthalmic artery, central retinal artery( inner retina) and ciliary arteries (outer retina circulation and anterior part of the globe). they can be affected in different ways.
What is the structure of the retina like?
Tight junctions in capillaries no lymohatics and there is a blood retinal barrier to protect it/
What are the chordal capillaries like?
They are leaky and transfer fluid to the retina limited by the retinal pigment epithelium which has a pump fumction it also has photoreceptors
What is the photopic visual system?
The system used in good lighting conditionsto give detail and clolour lots of cone receptors
What is scotopic visual system?
I is monocromatic for low light conditions and has a function of rod photoreceptors peripheral retina.
How long does it take for maximal sensitivity in dark?
10 minutes up to 30 minutes
How many types of cones are there?
3 RGB
What are the need for the types?
To percieve variety of coulours in our visible spectrum
What is abnormal colour vision?
colourblindnes can be caused by diseae or genetice can make it hard do distinguish
How wide is the visual field?
200degrees horizontal 150 degrees vertical
How are visual fields measured?
Angles from nose and edge of eye
What is it called if the eye is too long for the refractive power of the lens?
Myopia
What is is called if the eye is too short?
hyperopia
What is astigmatism?
When the refractive power of the cornea is not even
What is accomodation?
Changing the focussing of the lens to get a clear immage
What causes change in accommodation with age?
The lens is less elsastic called presbyopia
What is visual acuity?
The ability to see detail or resolution. it is best at the centre.
How do you test visual acuity?
Using a snellen chart which is most commonly used or other
Wat is binocular vision?
Seeing one image with both eyes.
What is stereopsis?
Depth perception. it is not present at birth
What is strabismus?
eyes looking in different ways
What is the visual pathway?
Retina optic nerve, optic chiasm, optic tracts, thalamus(lateral geniculate ganglion) optic radiations(teporal and parietal lobes) visual cortex and visual association cortex
What fibres cross over at the chiasm?
medial fibres of the eyes with information from the temporal field.
What type of fibres do the optic tracts carry?
Fibres from the temporal retina( nasal visual field from the same side and the nasal fibres from the temporal visual field from the oposite side to give depth
What fibres enter the parietal lobe radiation?
The superior fibres from the lower visual field
What fibres enter the temporal radiation?
The inferior fibres which convey iformation from the superior visual field
Where is the visual cortex?
In the calcarine sulcus either side on the medial surface of the occipital lobe
Where do the fibres from the macula go?
To the posterior pole where the lood supply is from the middle and posterior cerebral artery
What kind of problems are there with the retina?
Total loss of vision in one eye, loss of part of cisiual field in one eye, loss of upper or lower half of field of vision los of centre of vision macular degeneration and tunnel vision
What are problems relating to the optic nerve?
Enlarged blind spot(swollen optic disc, loss of centre of visions(optic neuritis), Loss of vision in and arc shape(glaucoma) glaucoma(tunnel vission)
What is bitemporal hemianopia?
The temporal field of each eye is gone. Often caused by pituitary tumours
What happens when the optic tracts is damaged.?
It caues contralateral loss with same part of each eye, homonymous left of each.
What is incongruous?
not the same on both sides
What happes in optic radiations?
Contralateral homonymus field defects
What is macular sparing?
when the macula is spared as there is a posterior cerebral artery stroke but area for macula is supplied by middle
What is a blow out fracture?
frontal sinus broken causing double vision
go back to eye lecture?
cvd
What are the areas of a neuron?
Dendrites, Cell body, Myelinated axon, Axon terminals
What are dendrites?
Areas of nerve cells that receive input from other neurons
where is the first action potential?
Axon hillock
When are neurons formed?
Most before birth lots later though
What is high concentration in cell body of a neuron?
Nissel substance which is rough endoplasmic reticulum
What are the two types of neronal commuication?
Chemical for most and also electrical which are less abundant
What are electrical synapses like?
They have gap junctions electron dense material either side of junction
How does a chemical synapse work?
calcium influx into the presynaptic bulb causes the release of neurotransmitters that bind to receptors on the post synaptic membranes
What are dendritic spines?
They are small projections from the dendrites that hace post synaptic membranes
What is plasticity?
The ability of the synapse to be changed gained lost and strengthened. the basis of learning
How doe neurones differ?
Size shape electical properties neurotransmitters.
What are upper motor neurones like?
Large exitatory glutaminergic and pyramidal cells
Wat are striateal interneurons?
Small inhibitory GABAergic
How many axons are there in one cell?
Many
What are oligodendrocytes?
They myelinate neurons in the CNS not schwann cells. They are helping saltatory conduction providing metabolic support for axons
How many neurones can one oligodendrocyte myelinate?
Many
What is a myelin sheath?
Multiple layers of membrane with high 70% lipid and 30%protein. involved in compaction
What are microglia?
They are derived from yolk sac progenitors, resident immune cells of the CNS the resting state have lots of procecess then when activated they retract and become motile
What do the microglia do?
They help with synaptic placitity and pruning, immune sureillance and phagocytosis debris/microbes
What are astrocytes?
Star shaped cells they are quite different, they have marker proteins they can be fibrous in white matter and protoplasmic in grey matter
What is the purpose of astrocytes?
Part of the blood brain barrier, also go into nodes of ranvier. they are progenitors of nerual cells, most abundant and give structure, homeostatic metabolic suport
How are fMRI and astrocytes linked?
They change blood flow in the brain
What are some special astroytes?
Radial glia, Bergman glia in cerebellum and Muller cells in the retina
What symptoms of MND are due to loss of…?
Motor neurons microglia and astrocytes
What are involved in CNS lesisons in MS?
Oligodendroytes but also T lymohocytes and neurons
What is a tract?
An abundance of axons in the same directions
What are commissures?
Fibres that cross the mid line
What is a nucleus in the brain?
An area with an abundance of nuclei
What is a ganclia?
Concentration of cell bodies in the PNS
What are some of the features of the blood brain barrier?
Tight junctions, foot proceses of astrocytes, pericytes basement membrane whcih lack fenestrations
Where are the Blood brain barrier thinner?
Pituitary, pineal gland, hypothalamus, and area postrema vomiting centre for body.
Where is CSF removed?
the arachnoid granulations and the lymphatics of the brain,along nerves
What are endymal cells?
Epithelial-like cells that line ventricles and central canal of spinal cord they produce CSF they are ciliated cells to give flow
What is the choroid plexus?
The frond like projections of ependymal cells vasuclarised and main site of CSF production.
What makes neurons negative inside relative to outside?
negative proteins inside the cytoplasm. potassium and chloride can leave. sodium can cross with difficulty and have sodium potassium pumps
What role does diffusion have in the maintenance of themembrane potential?
Chloride diffuses in against electrostatic pressure, sodium in with the electrostatic pressure and potassium out against the presure
Which ions are inside the cell?
Negative ions, potassium
Which ions are usually outside the cell?
Chloride,sodium
How is information transmitted through neurons even though they can only be on or off?
By the rate of firing of the cells
What doe neurotransmitters do?
They bind to ion channels and cause them to open.
What do exxcitatory neurotranmitter do?
Depolarise the membrane and increase the probability of an action potetnial taking place. excitatory post synaptic potential
What do inhibitory neurotransmitters do?
They hyperpolarise the cell membrane which makes it less likely for the cell generate an action potential called inhibitory post synaptic potentials
What is spatial sumation?
When signals from two neurons combine to form a larger signal making it more likely for the action potential to happen
What is the significance of the axon hilluck?
If it doesn’t get a big enough voltage at the hillock it won’t transmit down the axon
What happens once the threshold potential is met?
voltage gated sodium channels open and depolarise the membrane. then they close and potassium voltage gates open to depolarise. then becomes hyper polarised
What is the absolute refractory period?
When the membrane is depolarised up to when potassium channels change
What is the relative refractory period?
When the membrane becomes hyperpolarised.
What is the speed of myelinated axonal transmission?
Up to 150m/s
What is the speed of unmeylinated axons?
2-5m/s
What does novichok do?
It interferes with acetylcholine by stoping acetylcholine esterase from breaking down the ACh
How is neurotransmitter regulated?
Enzymatic breakdown,
What does atropine do?
Can remove ACh from receptors
What are the 5 fundamental processes of synaptic transmission?
Manufacture of neurotransmitters
Storage of the neurotransmitters
Release of thetransmitter via action potential
Interact with post-synaptic reveptors- diffusion across the synapse
inactivation- breakdown or re-uptake
What are some fast acting neurotransmitter?
Acetylcholine, Glutamate Gamma-aminobutyric acid
What are neuroodulaters with egs?
They are slower acting such as Dopamine noradrenalin Serotonin
What does procaine and lignocaine do?
local anaesthetics block sodium channels
What are the most useful imaging techniques?
MRI and CT, Cerebral angiography
What is x-ray useful for?
Skull damage MR safety
What scanner is used for angiography?
CT
What are some problems with CT?
High dose radiation, limited anatomical detain somewhat, contrast agents are allergic, better than MRI for bone topics
How are CT presented?
Looking from the bottom of the bed to the top
What is the strength of most MRI magnets?
T1.5 or T3
What are white matter fibre tracts?
Water diffusion along fibre pathways
What is PET-CT scanning?
used to locate brain tumours
What does an extradural haemotoma look like?
Between the dura and skull causes brain compression. blood next to skull
What colour is blood on a CT?
White
What is a cerebral contusion?
“bruise” on the brain where it is dammaged
What is diffuse axonal injury?
When white matter fibres are dammaged
What is a T2 scan?
CSF white
What is a T1 weighting?
CSF white
What is the use of weighting?
It can help distinguish what the lesions are
What can you see on stroke patients?
See which artery was damaged
