Flashcards in B06W08 Deck (336):
What is the main purpose of neurological examination?
To refine location of a lesions after a solid differential has been made from the history
Describe at least 2 positive and 2 negative motor symptoms in neurology
Positive = jerking, tremor, flailing. Negative = weakness, slowness, clumsiness
Describe at least 2 positive and 1 negative sensory symptoms in neurology
Positive = tingling, burning, pain. Negative = loss of sensation.
Describe at least 2 positive and 1 negative visual symptoms in neurology
Positive = flashing lights, zig zag lines. Negative = blindness
What should be considered the 'first clue' in what has happened to a patient presenting with a neurological defect?
Whether the symptoms (motor, sensory, visual) are positive or negative
List at least 2 neurological pathologies that follow a transient time line?
Headaches (migraine), epilepsy, faints, TIAs
List at least 2 neurological pathologies that have a sudden onset
Vascular lesions (infarcts or haemorrhage)
What kind of neurological pathologies typically have an onset over hours to days? Name at least 2 causes.
Infective or inflammatory causes
What sort of neurological pathologies typically have an onset over days to months? Name at least 2 possible causes
Inflammatory, malignant, nutritional
What sort of neurological pathologies typically have an onset over years?
List at least 4 factors which may exacerbate neurological symptoms
Posture, time of day, lack of sleep, excess coffee or stimulants, exercise, anxiety
Posture can be an exacerbating factor for which types of neurological problems?
Headaches, postural hypotension
Time of day can be an exacerbating factor for which types of neurological problems?
Lack of sleep or excess coffee can be exacerbating factors for which types of neurological problems?
Exercise can be an exacerbating factor for which types of neurological problems?
Myasthenia (continued muscle use result in increasing weakness), subclavian steal
What is myasthenia gravis?
chronic autoimmune neuromuscular disease characterized by varying degrees of weakness of the skeletal (voluntary) muscles of the body. The name myasthenia gravis, which is Latin and Greek in origin, literally means "grave muscle weakness
What is subclavian steal?
a constellation of signs and symptoms that arise from retrograde (reversed) blood flow in the vertebral artery or the internal thoracic artery, due to a proximal stenosis (narrowing) and/or occlusion of the subclavian artery. The arm may be supplied by blood flowing in a retrograde direction down the vertebral artery at the expense of the vertebrobasilar circulation. This is called the subclavian steal
Anxiety can be an exacerbating factor for which types of neurological problems?
Tremors, non-epileptic seizures
List at least 5 parts of the nervous system that can be affected in neurological pathologies
Consciousness, higher cognitive functioning, special senses, motor system, sensory system and sphincters
To assess higher cognitive function when taking a history from a patient with neurological symptoms, what should you ask about?
Consciousness, memory, speech and attention
To assess the motor system when taking a history from a patient with neurological symptoms, what should you ask about?
Motor issues to face, eyelids, eye movements, swallowing, breathing and limb movements
To assess the sensory system when taking a history from a patient with neurological symptoms, what should you ask about?
Sensory changes to face, limbs, trunk and perineum
To assess sphincters when taking a history from a patient with neurological symptoms, what should you ask about?
Bladder, bowel and sexual function changes
Describe a feature/symptom that would help differentiate between a spinal cord lesion and Guillain-Barre syndrome
There will be bladder distubance with a recent onset of quadriplegia in a spinal cord lesion patient, but not in someone with Guillain-Barre
What is Guillain-Barre syndrome?
rapid-onset muscle weakness caused by the immune system damaging the peripheral nervous system. The initial symptoms are typically changes in sensation or pain along with muscle weakness, beginning in the feet and hands. This often spreads to the arms and upper body with both sides being involved. The symptoms develop over hours to a few weeks
Describe a feature/symptom that would help differentiate between an epileptic seizure and a faint
Post-ictal confusion after an episode of loss of consciousness is common in epileptic seizures, but absent in a simple fainting episode
Describe a feature/symptom that would help differentiate between a migrine and tension-type headache
Nausea and vomiting with the headache suggests a migraine, whilst absence of nausea suggests a tension-type headache
Describe a feature/symptom that would help differentiate between primary generalised epilepsy and lesion-related epilepsy
Myoclonic jerks in a patient with seqizures suggests primary generalised epilepsy, whereas these will be absent in a case of lesion-related epilepsy
What is a myoclonic jerk?
Myoclonus is a brief, involuntary twitching of a muscle or a group of muscles. usually caused by sudden muscle contractions (positive myoclonus) or brief lapses of contraction (negative myoclonus). The most common circumstance under which they occur is while falling asleep (hypnic jerk). Myoclonic jerks occur in healthy persons and are experienced occasionally by everyone. However, when they appear with more persistence and become more widespread they can be a sign of various neurological disorders. Hiccups are a kind of myoclonic jerk specifically affecting the diaphragm
List at least 3 neurological conditions where a positive family history is helpful in making the diagnosis
Huntington's disease, familial spastic paraparesis, Leber's hereditary optic neuropathy, benign essential tremor, juvenile myoclonic epilepsy, Gerstmann-Straussler-Cheinker syndrome
Define what is meant by 'stroke'
A clinical syndrome characterised by an acute loss of focal (one area) and brain function lasting more than 24 hours or leading to death (i.e., if a patient recovers within 24 hours, it is called a TIA)
Which 2 causes of death are consistent with a diagnosis of stroke?
Spontaneous haemorrhage or inadequate blood supply to a part of the brain as a result of low blood flow, thombosis or embolism associated with disease of the arteries, heart or blood.
What is a TIA?
A clinical syndrome characterised by an acute loss of brain or monocular function with symptoms lasting less than 24 hours, due to inadequate cerebral or ocular blood supply due to low blood flow, arterial thrombosis or embolism associated with disease of the arteries, heart or blood
What are the definitions and differences between stroke and TIA as outline by Sacco et al in 2013? What is problematic about these definitions?
TIA = transient ischaemia specifically without evidence of tissue damage. Stroke = evidence of tissue damage, including silent infarctions (this is based on MRI, which is not accessible to everyone/all services)
What is amaurosis fugax?
(Latin fugax meaning fleeting, Greek amaurosis meaning darkening, dark, or obscure) is a painless transient monocular or binocular visual loss (i.e., loss of vision in one or both eyes that is not permanent)
The majority of TIAs resolve within what time frame?
List 3 eky issues in the diagnosis of stroke/TIA
1. Focal neurological deficit 2. Usually negative symptamatology 3. Usually sudden onset and maximal at onset
List some factors in a history that would suggest a stroke has occurred
Increasing age of patient, sudden onset with syptoms maximal at onset (i.e., patient may wake with symptoms), negative neurological symptoms, preceding TIAs, symptoms are focal and usually referable to a single arterial territory
List the 4 key cardiovascular risk factors for stroke
1. Hypertension 2. Diabetes 3. Smoking 4. Hypercholesterolaemia (also includes any pre-exitsting cardiac abnormality)
Describe a mechanism by which injury to the neck may cause stroke
Dissection of carotid arteries or vertebral arteries
Name at least 3 cardiac abnormalities which predispose to stroke
Recent MI, known valvular disease, known AF, patent foramen ovale, atrial septal defect
What is a paradoxical embolus?
a kind of stroke or other form of arterial thrombosis caused by embolism of a thrombus (blood clot), air, tumor, fat, or amniotic fluid of venous origin through a lateral opening in the heart, such as a patent foramen ovale
Assuming vasculitis were the underlying cause of a stroke, what other features would be expected to be observed?
Rash, other organ involvement, pain
List at least 2 diseases which cause hyperviscosity and thereby predispose to stroke
Sickle cell anaemia, leukaemia, myeloma
What sort of features in a history may suggest a patient is in a hypercoagulable state?
Previous DVT or PE, miscarriages
Which 2 connective tissue diseases can predispose to stroke?
Marfan's syndrome and Ehlers-Danlos syndrome
List at least 4 features of a relevant past medical history for a stroke patient
Previous CVD, known diseases which cause hyperviscosity, features which suggest hypercoagulable state, features which suggest bleeding tendency and connective tissue diseases
List at least 2 types of medication that are relevant in taking a stroke history
Warfarin (or any anticoagulant), anti-platelet agents (aspirin, clopidegrel), OCP
Transient ischemia of whole brain is referred to as ____, whilse focal transient ischaemia is a ______
Blood supply to the brain is achieved by which 4 major arteries?
2 internal carotids, 2 vertebral arteries
In a stroke patient with unilateral arm weakness, which vessel is likley to be affected?
Branch of middle cerebral artery
In a stroke patient with unilateral leg weakness, which vessel is likley to be affected?
Branch of the anterior cerebral artery
In a stroke patient with unilateral face, arm and leg weakness, which vessels is likley to be affected?
Total anterior and middle cerebral artery OR iternal capsular (lacunar) infarct
Define each classification in the Oxfordshire community stroke project classification system
1. PACI (oartial anterior circulation infarct) 2. TACI (total anterior circulation infarct) 3. LACI (lacunar infarct) 4. POCI (posterior circulation infarct)
Monoplegia, hemiparesis, hemianaesthesia and either diplopis or hemianopia is suggestive of which stroke classification?
Hemiparesis, hemianaesthesia and both dysphasia and haemianopia is suggestive of which stroke classification?
Pure unilateral motor or sensory deficit, unilateral weakness and ataxia is suggestive of which stroke classification?
Brainstem/cerebellar features with or without hemianopia is suggestive of which stroke classification?
List at least 4 important causes of headaches that should not be missed
Subarachnoid harmorrhage, meningitis, encephalitis, temoral arteritis, sleep apnoea, raised ICP, low-pressure headaches
What are low pressure headaches?
Refers to low ICP (can happen after a spinal tap etc.)
Raised ICP headaches tend to occur at what time of day?
Tension-type headaches tend to occur at what time of day?
Cluster headaches tend to occur at what time of day?
Middle of the night
What is a cluster headache?
Cluster headache (CH) is a neurological disorder characterized by recurrent, severe headaches on one side of the head, typically around the eye. There are often accompanying autonomic symptoms during the headache such as eye watering, nasal congestion and swelling around the eye, typically confined to the side of the head with the pain.
What is an icepick headache?
sharp, stabbing pains occurring as a single stab or as a series of stabs, occurring mostly in the eye and orbit, temple, or parietal regions. Stabs last a few seconds, and may recur throughout the day, usually at irregular intervals
List some autonomic features that may accompany headache
Red eye, watering eye, blocked nose (in cluster headache)
What sort of headache is exacerbated by standing up?
What sort of headache is exacerbated by lygind down or valsalva?
What sort of headache is usually accompanied by continuous pain?
What is lancinating pain?
Characterized by piercing or stabbing sensations
What sort of headache is usually accompanied by throbbing pain?
What sort of headache is usually accompanied by lancinating pain?
A pure motor or pure sensory stroke is likley to be an infarct in what area/what type of stroke?
Lacunar infarct (LACI)
In opthalmoscopy, the pinhole glasses overcome which 2 factors?
1. Refractive error 2. Medial opacity
For patients with vision less than 6/60, what other 4 factors should be tested and recorded?
1. Hand movements 2. Count fingers 3. Perception of light 4. No perception of light
Which pharmacological agent is used in the non-dominant eye during opthalmoscopy?
In pupillary reactions, what is miosis? What things may cause it?
Pupil constriction, e.g., illumination, parasympathetic innervation and drugs
In pupillary reactions, what is myadriasis? What things may cause it?
Pupil dialates, e.g., loss of illumination, sympathetic innervation, drugs and coning
Parasympathetic innervation causes the pupils to _____, whilst sympathetic innervation causes pupils to ______
What is the absolute contraindication to pupil dilation drops??
What are the relative contraindications to pupil dilation drops?
Narrow angle, contact lens in situ, pregnancy
Herniation of the cerebellum through the foramen magnum, leading to brain stem compression, is also known as what?
What is the cause of death in coning?
Compression of brainstem leading to cardiac and respiratory arrest
Describe the pupillary reflexes observed in coning, and comment on why this is significant
Pupillary reflex pathway runs through brainstem > reflex malfunctions. Results in dilation of the pupil ipsilateral to the insult, and signifies impending death
What is meant by a 'narrow angle' in the eye?
when the colored portion of your eye (iris) is pushed or pulled forward. This causes blockage of the drainage angle of the eye, where the trabecular meshwork allows outflow of fluids > causes acute narrow-angle glaucoma
Painful visual loss is suggestive of which eye disease?
How may an artery be distinguished from a vein in opthalmoscopy?
Arteries appear narrower and brighter, whilst veins are darker and wider
Raised ICP is a relative contraindication to which invasive procedure? Why?
Lumbar puncture - can precipitate coning
What is spontaneous venous pulsation in opthalmoscopy, and why is it significant?
CSF pulsations result from change of blood volume in the closed cranio-spacial cavity. The retinal vein pulses as the pressure grdient between the intracranial and intraocular compartment varies > loss of venous pulsation is a sensitive index of raised ICP
10% of normal patients lack a spontaneous venous pulsation in opthalmoscopy. Explain how this sign may be elicited in this group
Retinal vein will pulse readily when light pressure is applied to the globe through the lid
Mydriatic drugs have what effect?
What is strabismus?
Abnormal alignment of the eyes; the condition of having a squint.
What is the first sign of raised ICP/pappiloedema in opthalmoscopy?
Loss of spontaneous venous pulsation
What is the technique/instrument of choice for viewing the peripheral retina?
What is delerium?
Confusion with agitation and hallucination
What is stupor?
Unresponsiveness with arousal only by deep and repeated stimulation
What is a persistent vegetative state?
Prolonged coma of over 1 month in duration, with some preservation of brainstem function and motor reflexes
What is akinetic mutism?
Prolonged coma with apparent alertness and flaccid motor tone
Consciousness requires the integrity and interaction between what brain structures?
Cerebral hemispheres and the rostral reticular activating system (RAS)
Where is the RAS located?
Between the rostral pons and diencephalon
In what ways can disturbances in metabolic processes cause coma?
Disrupts substrate delivery and can alter neuronal excitability
List the 3 differential diagnoses for coma
1. Coma with focal signs 2. Coma without focal signs but with signs of meningeal irritation 3. Coma without focal signs and without signs of meningeal irritation
What sort of processes can cause coma with focal signs?
Trauma (haemorrhage in any of the dural spaces, parenchymal haemorrhage), vascular (intercerebral haemorrhage, thromboembolism) and brain abscess
What sort of processes can cause coma with no focal signs and meningeal irritation?
Infection (meningitis, encephalitis) and vascular (sub-arachnoid haemorrhage)
What sort of metabolic states can cause coma with no focal signs or meningeal irritation?
Hyponatremia, hypoglycemia, hypoxia, hypercapnia, hypo/hyperthermia and hyper/hypo-osmolar states
What sort of processes can cause coma with no focal signs or meningeal irritation?
Endocrine (hypothyroidism, adrenal insufficiency, hypopituitarism), seizure disorders and organ failure (hepatic and renal), toxic drug (sedatives, narcotics, alcohol, psychotropic and carbon monoxide)
What is the purpose of grading a coma?
Allows prognostication in certain diseases and facilitates clinical management decisions
Which 2 factors/patient responses does the GCS take into account?
Patient's response to command, patient's response to physical stimulus
What are the 3 components of the GCS?
Eyes opening, Verbal response and Motor response
Eye response when testing GCS is based on which 4 responses?
Spontaneous, to speech, to pain and nil
Verbal response when testing GCS is based on which 5 responses?
Oreintated, confused, inappropriate, incomprehensible, nil
Motor response when testing GCS is based on which 6 responses?
Obeys commands, localises to pain, withdraws to pain, abnormal flexion, extensor response, nil
Cherry red skin with coma can be a sign of what sort of poisoning?
Spider naevi and jaundice with coma may be a sign of what?
Puffy skin with coma may be a sign of what endocrine disorder?
A sallow complexion with coma may be a sign of what disorder?
Petechiae skin lesions with coma may be a sign of what disease?
Needle marks on the skin with coma suggests what underlying cause?
Bullous skin with coma suggests what underlying pharmacological cause?
Dry skin with coma may suggest what underlying causes?
DKA, anticholinergic overdose
Preorbital haematoma with coma is suggestive of what type of fracture?
Anterior basal skull fracture
Nuchal rigidity with coma is suggestive of which 2 underlying neurological causes?
Sub-arachnoid haemorrhage and meningeoencephalitis
What are the normal measurements/observations for pupillary responses?
2-5mm, eual and demonstrate direct and consensual light reflex
List at least 1 cause of unilateral miosis
Homer's local pathology
Least at least 3 causes of bilateral miosis
Pontine lesions, thalamic haemorrhage, metabolic encephalopathy, organophosphate, barbituates, narcotics
List at least 1 cause of unilateral mydriasis
Mid-brain lesion uncal herniation
Pupils >5mm are described by what term?
Least at least 2 causes of bilateral myadriasis
Massive midbrain haemorrhage, drugs (atropine, tricyclic antidepressants, sympathomimetics)
Intubation should be used for a patient with a GCS of less than what?
For a patient in a coma, what should be administered iv?
50ml 50% glucose (and thiamine)
In a patient in a coma, who has evidence of fixed dilated pupils/hypertension/bradycardia, what drug should be considered?
What pharmacological agent can be used to control seizures in a coma patient?
List at least 4 lab investigations that should be ordered for a patinet in a coma
Glucose (bedside), electrolytes, ABG, liver and renal function, osmolality, FBC, toxicology screen
The brainstem is related posteriorly to the ____ and ____ ventricle of the brain
Cerebellum; fourth ventricle
The pons rests on which strucure of the occipitl bone?
The brainstem is continuous rostralling with the cerebral ____ and _____
Peducles; forebrain (thalamus)
How long is the brainstem?
The trigeminal system information converges on which 3 nuclei?
Spinal trigenimal, principal trigeminal and mesencephalic nuclei
Auditory fibres from the cochlear nerve synapse in the ___ nucleus, which then projects to the opposite )____ ____
Cochlear; inferior colliculus
In which part of the brainstem is the auditory field spatially mapped?
In the inferior colliculi (opposite side to cochelar nerve providing input)
Discuss visual field mapping in the superior colliculus and which layers receive which input
Direct retinal projects to superior colliculus are mapped onto the superficial layers of the superior colliculus. Deeper layers get somatosensory as well as auditory inputs from the inferior colliculus.
What is the purpose of auditory and visual field mapping?
Coordinates eye movements and head/neck movements to accommodate reflex-like responses to external events
Which nucleus is known as the 'gatekeeper' of cardiovscular and cardiorespiratory control?
Where is the solitary nucleus located?
What information is mapped onto the solotary nucleus?
Nerves carrying afferent info (chemoreceptors) about internal environemnt (taste VII, IX; blood chemistry IX and X, gut sensations X)
The solitary nucleus + reticular formation + periaqueductal grey influence what feelings?
Wellbeing, satisfaction, attention and sleep cycles
Circuits in the dorsolateral open medulla regulate what functions?
Cardiovascular control - through HR and arteriolar paripheral resistance (note there are also cells in this area that regulate sympathetic activity in the lateral horn neurons)
What features can be seen on a cross section at the pyramidal decussation?
Crossing of pyramidal fibres, spinal trigeminal nucleus. Dorsal columns still look like the do in the spinal cord, but the nucleus gracillis can now be seen
Where are the medul lary cardiovasular and repiratory control centres located?
What features can be seen on a cross section at the closed medulla?
Axons of neurons coming from the nucleus gracilis and cuneatus sweep ventrally and medially as the internal arcuate fibres - they cross the midline and form the medial lemniscus. Can now see the inferior olivary nucleus and the spinal trigeminal nucleus which appeared in the pyramidal decussation is still visible
What features can be seen on a cross section at the open medulla?
All dorsal column system migrated into medial lemnicus by this point - nothing remains dorsal to the central canal, which open to form the 4th ventricle. Can now see inferior cerebralle peduncles and can still see the inferior olivary nucleus, which arose at the lower level of the closed medulla
Where do the inferior cerebela peduncles takes fibres from?
Dorsal cerebellar and nuneo-cerebellar tracts and from the C/L inferior olivary nucleus to the cerebellum
What is the cerebromedullary bottleneck? Why is it clinically significant?
Many fibres in the pons squeezed into a small space - this is vulnerable due to the way the blood supply is arranged. A lesions in the basillar artery can interrupt supply to almost the entire pons
How is 'locked in syndrome' diagnosed?
Presence of eye movements
Where do the axons from pointine cells go?
Cross the midline and enter the C/L cerebellum via the middle cerebellar meduncle
What features can be seen on a cross section at the pons?
Fibres of the superior cerebellar peduncles can be seen dorsolateral to the 4thventricle
What features can be seen on a cross section at inferior colliculus?
Substantial bigra and cerebral penduncles prominent ventrally. Main feature is the crossing of the superior cerebellar peduncles centrally. The cerebral aqueduct can now also be seen (and the superior cerebellar penuncles are still visible)
Which CN features prominently in the inerpeduncular fossa of the inferior colliculus?
What features can be seen on a cross section at the superior colliculus?
Superior cerebral peduncles have crossed and enter the red nucleus at this level. Fibres of CN III cross thorugh the red nucleus and SCP fibres.
The cerebral peduncles are seen ventrallly in the midbrain and are separated by the ______
Which structures of the ventral midbrain contain all of the descending tracts that originate in the cerebral cortex?
The cerebral peduncles
List at least 4 of the regulatory functions of the reticular formation
1. Respiratory and cardiovascular control 2. Arousal and sleep-wake cycle 3. Control of gait 4. Autonomic
Explain briefly how the reticular formation has a greater range of influence and can effect hundreds of thousands of neurons
Transmitter released into extracellular space, not confined to post-cynaptic cleft > therefore more diffuse
List the 3 distinct groups of cells in the reticular formation and comment on their fucntions
1. Median/raphe - seratonergic 2. Paramedial: magnocellular (upper) and gigantocellular (lower) - motor 3. Lateral: parvocellular - sensory
Describe the inputs and outputs of the solitary nulceus and tract that function as respiratory control
Inputs from CNs carrying information from chemoreceptors (VII, IX and X), also from carotid body (IX) and arotic arch (X); outputs to reticular formation, hypothelamus, thalamus (taste - cortex), parasympathetic and sympathetic nuclei
The respiratory control centre of the brainstem (solitary N and tract) integrates activity of the dorsal respiratory nucleus to influence which respiratory function?
The cventral respiratory nucleus (dorsal to the nucleus ambiguous) regulates which function of respiration?
Which nucleus is the pacemaker of respiration? Where does it get it's input from and what functions does this regulate?
uParabrachial nucleus > input from amygdala and periaqueductal grey matter > increased breathin rate in anxiety states (including fear and pain
Circuit through DMNX (parasympathetics) have what effect on heart rate? What is the name of this response?
Slows heart rate = barovagal response
Circuit through lateral reticular nucleus has what effect on heart rate? What is the name of this response?
Decreases sympathetic tone in arteriolar smooth muscle > decreases peripheral resistance = barosympathetic response
What is the functional significance of the pyramids?
Contain descending fibres from motor cortex
What is the functional significance of the pons?
Contains fibres that cross the midline to enter the cerebellum
What is the functional significance of the cerebral peduncles?
Contains descending fibres from all over the cortex, which terminate in the brainstem (corticobulbar) or spinal cord (corticospinal)
What is the functional significance of the mamillary bodies?
Part of the hypothalamus
What is the functional significance of the occulomotor nerve?
Supplies motor fibres to 4 out 6 extra ocular muscles, and includes parasympathetic fibres to the iris and ciliary body
What is the functional significance of the facial nerve?
Innervates muscles of facial expression
What is the functional significance of the trigeminal nerve?
Sensory nerve to the face
What is the functional significance of the thalamus?
All fibres on their way to cerebral neocortex pass through the thalamus.
What is the functional significance of the optic tract?
Carries axons from both eyes, that encode information from the opposite visual hemifield
What is the functional significance of the pineal gland?
Endocrine gland that regulates our circadian rhythms by releasing melatonin
What is the functional significance of the trochlear nerve?
Fourth cranial nerve which provides motor innervation to the superior oblique muscle
What is the functional significance of the superior colliculus?
Receives a mapped input from the retina, which guides reflexes responses to stimuli of auditory (e.g. scary sound), somatosensory (e.g.,creepy crawlies on the skin), or visual (e.g. ducking to avoid a fast moving /dangerous object coming towards you unexpectedly) origin
What is the functional significance of the dorsal columns?
Carry pressure and fine touch fibres from the body surface (proprioception)
What is the functional significance of the middle cerebellar peduncle?
Comprises the major descending input from cortex to cerebellum: cortico-pontine > ponto-cerebellar fibres
The lateral horn of the spinal cord is only present at which spinal cord levels?
What are the 3 divisions of CN V?
V1: ophthalmic division V2: Maxillary division V3: Mandibular division
What are the main functions of V1 (CN V)?
Ophthalmic division: sensory to upper face and eye, anterior nasal cavity and some sinuses
What are the main functions of V2 (CN V)?
Maxillary division: sensory to the middle face, maxillary sinus and nasopharynx
What are the main functions of V3 (CN V)?
Mandibular division: sensory to the lower face, motor supply to msucles of mastication
What are the main functions of CN VII (facial)?
Motor to muscles of facial expression. Parasympathetic/secretomotor supply to lacrimal, sublingual and submandibular glands. Taste (special sense) to anterior 2/3 of tongue
What are the main functions of CV VIII?
Vestibulocochlear: special senses hearing (cochlear) and balance (vestibular apparatus)
What are the main functions of CN X?
Vagus - Visceromotos fibres (from dorsal motor nucleus of vagus - parasympathetic) to heart and bronchi, digestive tract as far as the left colic flexure. Sensory to external acoustic meatus and part of auricle. Carries motor fibres to striated muscles of larynx and pharynx (derived from nucleus ambigulous via cranial accessory nerve)
What are the main functions of CN XII?
Hypoglossal: motor fibres to the intrinsic muscles of the tongue (four paired intrinsic muscles of the tongue originate and insert within the tongue, running along its length. They are the superior longitudinal muscle, the inferior longitudinal muscle, the vertical muscle, and the transverse muscle)
List the name of the nuclei, location and function of the occulomotor nerve
1. Motor nucleus at level of superior colliculus - controls SR, MR, IR and IO muscles of the eye. 2. Edinger Westphal nucleus at level of superior colliculus - controls ciliary and pupillary muscles
What ganglion serves the Edinger Westphal nucleus of the occulomotor nerve?
List the name of the nuclei, location and function of the trochelar nerve
Motor nucleus at level of inferior colliculus - controls the SO muscle
List the name of the nuclei, location and function of the trigeminal nerve
1. Motor nucleus at level of superior colliculus - pons: controls muscles of mastication, tensor vali palinitin, tensor tympani and anterior digastric 2. Principal V nucleus at the level of the pons: controls sensation (touch) to the face 3. Spinal V nucleus at the level of the medulla - upper spinal cord: controls sensation (pain and temperature) of the face 4. Mesencephalic nucleus at the level of the superior colliculus - upper pons: controls sensation (proprioception) of face
Which ganglion serves the Principal V and spinal V nuclei of the trigeminal nerve?
List the name of the nuclei, location and function of the abducens nerve
Motor nucleus at level of the pons - controls LR muscle of the eye
List the name of the nuclei, location and function of the facial nerve
1. Motor nucleus at lower pons - muscles of facial expression, stapedius, posterior digastric and stylohyoid 2. Super salivatory nucleus at lower pons - lacrimal, submandibular and sublingual glands 3. Solitary nucleus (taste) in medulla for taste to anterior 2/3 tongue 4. Spinal V nucleus in medulla - upper spinal cord for somatic sensation around the ear
Which ganglion serves the super salivatory nucleus of the facial nerve?
Pterygoipalatine and submandibular (parasympathetic)
Which ganglion serves the solitary nucleus and spinal V nucleus of the facial nerve?
List the name of the nuclei, location and function of the vestibulocochlear nerve
1. Superior, lateral, medial and inferior vestibular nuclei at the ponto-medullary junction for balance 2. Cochlear nucleu at the ponto-medullary junction for hearing
Which ganglion serves the vestibular nuclei of the vestibulocochlear nerve?
Which ganglion serves the cochelar nuclei of the vestibulocochlear nerve?
Spiral ganlgion (sensory)
Where are the rostral and caudal solitary nuclei of the glossopharyngeal nerve located, what ganglion are they served by, and what is the function of each?
Located within open and closed medulla and served by inferior ganglion of IX (in jugular foramen). Rostral is responsible for taste in the posterior 1/3 of tongue and caudal is responsible for baroreceptors and chemoreceptors (carotid)
List the 5 nuclei of the glossopharyngeal nerve
1. Solitary (rostral) 2. Solitary (caudal) 3. Spinal V 4. Nucleus ambigulous 5. Inferior salivary
Which ganglion serves the spinal V nucleus of the glossopharyngeal nerve?
Superior ganglion of IX (in jugular foramen)
Which ganglion serves the inferior salivatory nucleus of the glossopharyngeal nerve?
Where is the spinal V nuclei of the glossopharyngeal nerve located and what is it's function?
Medulla - upper spinal cord, responsible for somatic sensation behind auricle of ear
Where is the nucleus ambiguous of the glossopharyngeal nerve located and what is it's function?
Open and closed medulla - responsible for branchiomeric muscles of the pharynx and larynx
Where is the inferior salivatory nucleus of the glossopharyngeal nerve located and what is it's function?
Open medulla and responsible for action of parotid gland
List the name of the nuclei, location and function of the vagus nerve
1. Dorsal motor nucleus of X in open medulla - thoracic and abdominal organs (visceral afferent) 2. Spinal V nucleus in medulla - upper spinal cord for somatic sensation to external ear, external auditory canal, external surface of tympanic membrane 3. Solitary nucleus in open and closed medualla for taste (epiglottis); pharynx, larynx, trachea, esophagus, thoracic and abdominal viscera (visceral afferent)
Which ganglion serves the dorsal motor nucleus of X (vagus)?
Walls of viscera (parasympathetic)
Which ganglion serves the Spinal V nucleus of the vagus nerve?
Superior ganglion of X (in jugular foramen)
Which ganglion serves the solitary nucleus of the vagus nerve?
Inferior ganglion of X (in jugular foramen)
List the name of the nuclei, location and function of the accessory nerve (cranial)
Nucleus ambiguous in open and closed medulla - responsible for intrinsic muscles of the larynx
List the name of the nuclei, location and function of the hypoglossal nerve
XII motor nucleus in open and closed medulla - responsible for muscles of the tongue except that palatoglossus
The hypoglossal nerve is responsible for all muscles of the tongue EXCEPT for which one?
What are the main functions of the medulla?
contains theÊcardiac,Êrespiratory,ÊvomitingÊandÊvasomotorÊcenters and therefore deals with the autonomic functions ofbreathing,Êheart rateÊandÊblood pressure
What are the open and closed parts of the medulla?
Superior part is openÊwhere the dorsal surface is formed by theÊfourth ventricle (creates the caudal half of the rhomboid fossa (floor of the 4th ventricle). The inferior part is closed, where the fourth ventricle has narrowed and surrounds part of theÊcentral canal.
Describe the location of the tectum
On the dorsal surface of the midbrain
Which CNs exit from the midbrain?
III (occulomotor) and IV (trochlear). Note that the trochlear nerve is the only nerve to exit dorsally from the brainstem
Which CNs exit from the pons?
V (trigeminal), VI (abducens) and VII (facial)
Which CNs exit from the medulla?
VIII (vestibulocochlear), IX (glossopharyngeal), X (vagus) and XII (hypoglossal)
What is the clivus, and what brain structure is it closely related with?
part of theÊcraniumÊat the skull base, a shallow depression behind theÊdorsum sell¾Êthat slopes obliquely backward. The pons sits on the clivus.
What is the sella turcica, and what brain structure is it closely related with?
a depression in the sphenoid bone, containing the pituitary gland
What is the optic groove (chiasmatic groove), and what brain structure is it closely related with?
Ridge on the superior body of the sphenoid that forms the anterior border of a narrow, transverse groove, theÊchiasmatic groove, above and behind which lies theÊoptic chiasmaÊof cranial nerve 2 (the optic nerve)
Consider CNI: What is the site of nerve attachment and the site of exit from the skull?
Olfactory bulb; cribiform plate
Consider CNII: What is the site of nerve attachment and the site of exit from the skull?
Lateral geniculate nucleus (thalamus) and midbrain; optic canal
Consider CNIII: What is the site of nerve attachment and the site of exit from the skull?
Interpeduncular fossa; superior orbital fissure
Consider CNIV: What is the site of nerve attachment and the site of exit from the skull?
Midbrain tectum inferior to inferior colliculus; superior orbital fissure
Consider CNV: What is the site of nerve attachment and the site of exit from the skull?
Lateral margin of the mid-pons; V1 exits at superior orbital fissure, V2 exits at foramen rotundum and V3 exits at foramen ovale
Consider CNVI: What is the site of nerve attachment and the site of exit from the skull?
Medial edge of pontomedullary sulcus; superior orbital fissure
Consider CNVII: What is the site of nerve attachment and the site of exit from the skull?
Lateral edge of pontomedullary sulcus; internal acoustic meatus
Consider CNVIII: What is the site of nerve attachment and the site of exit from the skull?
Lateral edge of pontomedullary sulcus (lateral to CN VII); internal acoustic meatus
Consider CNIX: What is the site of nerve attachment and the site of exit from the skull?
Lateral to the olive of the medulla; jugular foramen
Consider CNX: What is the site of nerve attachment and the site of exit from the skull?
Lateral to the olive of the medulla; jugular foramen
Consider CNXI: What is the site of nerve attachment and the site of exit from the skull?
Lateral surface of the upper vercial spinal cord; jugular foramen
Consider CNXII: What is the site of nerve attachment and the site of exit from the skull?
Between pyramid and olive of medulla; hypoglossa canal
Which 3 CNs exit the skull through the superior orbital fissure?
III, IV and V1
Which 2 CNs exit the skull thorugh the interal acoustic meatus?
VII and VIII
Which 3 CNs exit the skull through the jugular foramen?
IX, X, XI
Describe where the first, second and third order neurons of themedial lemniscal pathway (dorsal column system) arise and synapse
First-order neurons reside in dorsal root ganglia and send their axons through theÊfasciculusÊgracilis andÊcuneatous. The first-order axons make contact with second order neurons at the gracilis and cuneate nuclei in the lowerÊ(closed) medulla. The second-order neurons send their axons to theÊthalamus. The third order neurons arise from thalamus to the postcentral gyrus
Fibres from which other nerve join with the dorsal column system information is it travels upwards as the medial lemniscus?
Fibres from the trigeminal nerve
Describe where the first, second and third order neurons of the spinothalamic pathways arise and synapse
First order have cell bodies in dorsal root ganglion and synapses in dorsal root of spinal cord on the ipsilateral side. Second order neurons cross the cord and send fibres upward to synpase in the thalamus. Third order neurons are sent up to the somatosensory cortex in the post-central gyrus
What information do the spinocerebellar tracts convey?
information to the cerebellum about length and tension of muscle fibers (i.e., unconscious proprioceptive sensation)
The dorsal spinocerebellar tracts carries information from which receptor types?
Muscle spindles and golgi tendon organs (i.e., information about skeletal muscle and joint proprioception)
Briefly describe the dorsal spinocerebellar tract
Proprioceptive information is taken to the spinal cord via dorsal root gangliaÊ(first order neurons). Central processes travel through theÊdorsal horn, where they synapse with second order neurons ofÊClarke's nucleus. Fibres from Clarke's Nucleus convey information in the spinal cord in the peripheral region of theÊfuniculus posteriorÊipsilaterally. The fibers continue to course through the medulla oblongataÊand theÊponsÊof theÊbrainstem, at which point they pass through theÊinferior cerebellar peduncleÊand into the cerebellum. This tract involves twoÊneuronsÊand ends up on the same side of the body
What information do the dorsal spinocerebellar and cuneocerebellar tracts relay?
Both relay proprioceptive information, but the former is more concerned with forearm, trunk and lower limb, which cuneate is concerned with the arm
Vry briefly describe the ventral spinocerebellar tract
The ventral spinocerebellar tract will cross to the opposite side of the body first in the spinal cord as part of theÊanterior white commissureÊand then cross again to end in the cerebellum (referred to as a "double cross")
Sound is what sort of wave?
Longitudinal sound waves at higher pressure are called ____, whilst the interspersed areas of lower pressure are called _____
What are the 2 physically different physical aspects of sound?
1. Pressure and 2. Displacement
What physical aspect/component of sound is usually measured?
Sounds pressure is measured in what unit?
What is the normal atmospherics pressure, in pascals? Compare this with the faintest sound that can be heard through the ear
AP = 100,000 Pa. Faintest sound = 20 micropascals (1 in 10 billion th of atmospheric pressure can be heard by the human ear)
Sound power is measures in which units?
What is the equation for sound power (watts)?
Sound power = pressure x particle velocity
The loundness of sound is measures in what unit?
What do decibels measure?
The loundness of sound - how much bigger the sound is (logarithmically) relative to the average human hearing threshold
What is the normal hearing threshold, in micropascals and decibels?
20 micropascals (= 0dB)
Decibels over ____dB is considered a cautionary sound intensity, where potential damage may be incurred
Where is the cochelar located?
Just below eye level, deep within the skull (i.e., it is really a cavity carved out of the bone of the skull)
List the 3 bones of the inner ear
Malleus, incus and stapes
What is the smallest bone in the human body?
What stuctures make up the outer ear?
Pinna to ear drum
What structures make up the middle ear?
the 3 ossicles (bones) in an air space - malleus (hammer), incus (anvil) and stapes (stirrup)
What structures make up the inner ear?
Cochlea and semicircular canals
What is the purpose of the middle ear and it's ossicles?
Impedence matching, i.e., air strikes the tympanic membrane with much motion and little force, and this is converted by the middle ear bones to little motion with much force in the water/liquid of the middle ear
The base of the stapes bone sits in the _____ window
The tympanic membrane is ____ cells thick
What is the purpose of the lever arrangement of the malleus, incus and stapes in the middle ear?
Transfers motion/dispacement of tympanic membrane into a much larger force (but smaller motion)
What is the purpose of the round window membrane in the ear?
Controls pressure (resorbs)
What are the smallest striated muscles in the human body? Which of these is the smallest?
Middle ear muscles. Smallest = stapedius muscle
What is the function of the stapedius muscle and tendon?
Pulls and adjusts postiion of the tympanic membrane
What is the function of the tendon of vestipedius in the middle ear?
Control the setting of the bones in the middle ear and, in the process, can adjust the sensitivity of the cochlear
What is the main purpose of the middle ear muscles?
Protects the cochlear (loud sounds above 90dB leads to the acoustic reflex - muscle contraction)
The stapedius muscle of the ear is innervated by which nerve? What pathology is associated with dysfunction of this nerve?
Facial nerve (CN VII) - Bell's palsy
The tensor tympani of the middle ear is innervated by which nerve?
Mandibular part of trigeminal nerve (V3)
How is the cochlear protected from loud internal body sounds (i.e., like chewing)
Tensor tympani muscle is innervated by V3, which also innervates chewing and speakng etc. These actions cause contraction of the tensor tympani muscle to protect the cochlear from the loud internal sounds
Where is perilymph located?
Cochelar and semicircular canals (i.e., whole inner ear)
List the 2 tendons of the middle ear
Tensor tympani tendon and stapedius tendon
Which 3 nerves pass through the internal acoustic meatus to supply the inner ear?
Favial, vestibulo and cochlear
What is the purpose for having the hardest bone in the human body surrounding the cochlear?
Need to be able to detect tiny changes in pressure and vibration - therefore do not want any give in the bone surrounding the apparatus
Endolymph is rich in ______, whilst perilymph is rich in ______
What is the organ of Corti?
Name given to all sensing cells/surface in cochlear. It carries rows of inner hair cells (1 row) and outer hair cells (3 rows)
Describe the structure of the organ of corti
It is the sensory surface of the cochlear and carried rows of inner hair cells and outer hair cells
The inner hair cells of the organ of corti carry what kind of axons? What is their function?
Afferent axons - hearing receptors
The outer hair cells of the organ of corti are contacted by what kind of nerve fibres? Where do these come from?
Efferent fibres from CNS
What is the purpose of the outer hair cells of the organ or corti?
They control the gain (sensitivity) of the system - they are also efferent so have motor-like functionality
Compare the number of outer vs inner hair cells in the organ of corti
Only about 3000 inner cells (afferent) but 10,000 outer cells (efferent)
Describe the travelling wave theory of hearing
Pushing of stapes bone gives rise to pressure difference across basilar membrane and it moves up, causing sterocilia on hair cells to bend against tectorial membrane > this produces hearing sensation
In hearing, the displacement of which structure by sound ultimately leads to the bending of hair bundles on top of hair cells?
Displacement of the basilar membrane
The base of the cochlear is tunes to ____ frequencies, whilst the apex is tuned to _____ frequencies
Travelling waves propagate along the ______ membrane, from ____ to _____
Basilar membrane, from base to apex
Describe how the bending of steroicilia in cochlear hair cells results in communication with the auditory nerve
Bending of the cilia depolarises the cell and sends a signal to the nerve: Sound vibration induced MET channel opens, causing K entry and depolarisation of the inner hair cell. This opens voltage dependent Ca channels in the inner hair cell membrane. Calcium entry causes NT release (glutamate) at the inner hair cell-spiral ganglion cell synapse. Glutamate activates AMPA receptors in the spiral ganglion cell which results in depolarisation and AP firing of the spinal ganglion cell. APs are carried by the auditory nerve to the brain
Endolymph in the inner ear originates from?
Endolymph sac in the dura mater
Perilymph in the inner ear originates from?
Arachnoid spaces in the brain
What is meant by nerve connections from the cochlea to the auditory cortex are tonotopic?
There is regular mapping of frequency of sounds to location within the cortex
Why are the outer hair cells of the cochlea considered to be active?
They move when stimulated and produce a faint sound of their own (otoacoustic emissions)
What cells are the basis of the cochlear amplifier? What does this mean?
Outer hair cells of the cochlea. Means that sounds in the cochlea is amplified before it is detected by the inner hair cells and a signal sent to the brain
List the 4 types of otoemissions that can be elicited by the cochlea
1. Spontaneous 2. Evokes 3. Distortion-product 4. Stimulus frequency
It is likley that the ability of the human brain is based on the size of which particular area of the brain?
Describe how scaling laws predict cortical size
Input (thalamus) determine shte size, and increase in cortical volume is matched by that of the thalamus
What is the gold standard test for newly diagnosed epileptic patients?
How does EEG work?
Tracks local electrical fields caused by underlying currents
Local depolarising (inward) current results in _____ EEG polarisation, whilst local hyperpolarising (outward) current leads to ___ EEG polarisation
Currents read by EEGs are mostly caused by activity in which part of the neural circuitry?
What is required by AP currents in order to be visible on a EEG (as in epilepsy)
Current from summed activity of many neurons require large extent of synchronisation
What factor determines polarisation in an EEG?
Underlying current flow
What does an EEG represent?
The spatial summation od all neuronal activity in time and space (population response)
In an EEG, ______ causes a current sink at a synaptic location
If there is an EPSP causing a current sink at a synaptic location in later IV, where is the current sourced from? What is the result as recorded by EEG?
Apical tufts (positive deflection in EEG)
If there is an IPSP causing a current source at a synaptic location in layer IV, where is the current sunk from? What is the result as recorded by EEG?
Current is sunk from apical tufts (negative defection in EEG)
If there is an IPSP causing a current source at a synaptic location on apical tufts, what is the result as recorded by EEG?
Positive deflection in EEG
List the 5 rhythms identifiable on EEG?
Alpha, beta, gamma, theta and delta
What frequency do EEG alpha waves correspond to? Comment on the brain function/physical state at this frequency
8-12Hz (relaxed, eyes closed)
What frequency do EEG beta waves correspond to? Comment on the brain function/physical state at this frequency
13-25Hz (concentration, motor activity)
What frequency do EEG gamma waves correspond to? Comment on the brain function/physical state at this frequency
26-70Hz (perception, consciousness)
What frequency do EEG theta waves correspond to? Comment on the brain function/physical state at this frequency
0.5-3Hz (slow wave sleep)
What frequency do EEG delta waves correspond to? Comment on the brain function/physical state at this frequency
4-7Hz (arousal, drowsiness)
What are the signs of synchronisation in EEG?
High frequency spikes and spike wave features
In EEG, action potentials of ~1ms are also called what? Why are they usually undetectable in EEG?
Cellular spikes; too brief to summate effectively so unable to be detected
EEG spikes at 5ms correspond to what features on EEG?
Highly synchronised synaptic acitivity and therefore volleys of APs and visibility on EEG
The mammalian neocortex has how many layers?
Describe the basic composition of the mammalian neocortex
6 layers with roughly uniform cellular composition, with lots of inhibitors cell types and few excitatory cell types
According to Stricker, how does a uniformly structures neocortec process sensory, cognitive and motor information?
Due to the nature of it's multipotent processing modules: microcircuits
What are the excitatory cell types in the cortical microcircuit?
Pyramidal cells and spiny stellate cells
Simple neuro networks are important in what kind of information processing?
Sensory afferent processing (hearing, vision, proprioception)
In simple neuro networks, there is divergence from 1st neuron and convergence at a 2nd neuron. List the pros and cons of this arrangement
Pro = improve transmission of small signals requiring integration of several afferents; con = loss of precision in localising source
What is the advantage of lateral inhibition in a neuronal network
At each level, there is sharpening of discharge strength to the centre (strength of inhibition): emergence of centre-surround inhibition (receptive fields)
Why is a severed spinal cord able to produce movement when simulated?
Because segmental networks remain in tact even though there are no command signals being received from higher control centres
In a neural microcircuit, state when excitation is entering, where it is relayed to, and where it projects
Excitation enters at L4, is relayed to L2/3, then to L5 which projects outside the cortex