12.1 Flashcards
List modifiable risk factors for stroke.
- Obesity
- Hypertension
- Diabetes (increases risk by 2-4 times)
- AF
What is the target BP?
<130/80
What is the tentorium?
A transverse dural fold which separates the cerebrum from the cerebellum and brainstem
What type of bleed is a subdural haematoma?
Venous
What type of bleed is a extradural haematoma?
Arterial
What is clinical response to brain injury?
- Altered consciousness levels
- Dizziness
- Pain
- Vomiting
- Retrograde amnesia
What is the effect of secondary injury?
- Ischaemic = reduced perfusion to brain
- Infection = meningitis
- Seizures = use up a lot of brain substrate
How is cerebral blood flow autoregulated?
Vasodilation and vasoconstriction
What is an uncal herniation?
Transtentorial downward brain herniation
Define stroke.
Sudden focal neurological deficit due to vascular lesion lasting longer than 24hrs.
Define TIA.
Focal deficit lasting a few seconds to 24hrs with complete clinical recovery
What are the 4 arteries which run to the brain?
- 2 vertebral arteries
- 2 internal carotids
20% of strokes are what?
80% of stroke are what?
Haemorrhagic 20%
Ischaemic 80%
ICD-10 definition of dementia
o A syndrome due to disease of brain
o Usually of a chronic or progressive nature
o Disturbance of multiple higher cortical functions
o Consciousness is not clouded – this distinguishes dementia from delirium
o Cognitive impairments are commonly accompanied by deterioration in emotional control, social behaviour, motivation
o Impairment sufficient to impact on activities of daily living (ADLs)
Anterior spinothalamic tract
Crude touch
Lateral spinothalamic tract
Pain + temperature
What is dementia?
Syndrome due to disease of the brain, usually chronic or progressive.
What are the different types of dementias?
- Alzheimer’s - most common
- Vascular dementia
- Mixed dementia - Alzheimers and vascular dementia
- Lewy-body dementia
- Fronto-temporal dementia
- Others e.g. Parkinson’s disease with dementia
Differential diagnosis of dementia.
- Ageing
- Mild cognitive impairment
- Depression
- Delirium
- Physical health problem e.g. thyroid
Features of Alzheimer’s
- Insidious onset with gradual progression
- Memory loss
- Language impairment
- Decline in motor skills and ADL
- Loss of recognition skills
- Disorientation
What is the normal role of tau protein?
Allows messaging between cells
What is the normal role of amyloid?
Protects against calcium influx and glutamate excite-toxicity
- Drugs used in Alzheimer’s
1) AChesterase inhibitors. used in mild-moderate AD (e.g. donepezil, galantamine, rivastigmine)
2) NMDA receptor antagonists, to reduce glutamate, used in moderate-severe AD (e.g. memantine)
What is vascular dementia?
Dementia due to problems with blood supply to the brain - posterior circulation
Risk factors include hypertension, high cholesterol, diabetes, smoking, IHD
Difference between dementia with lewy bodies and parkinsons disease with dementia.
Dementia with lewy bodies = early cognitive symptoms, rapidly progressing dementia, fluctuation, hallucination,
Parkinsons disease with dementia = motor symptoms for more than a year, apathy, slowing of thought and executive functioning
Which feature is prominent early on in dementia with Lewy bodies?
Visual hallucinations
Fuctuations in cognition/performance, visual hallucinations, parkinsonism
Which brainstem area is degenerated in dementia with Lewy Bodies?
Substantia nigra - involved in dopamine production
Features of fronto-temporal dementia
- Mainly early onset- 10% familial
- Mutation in tau protein
3 main syndromes of fronto-temporal dementia.
- Dementia of frontal type - presents with emotional/behavioural change rather than STM loss
- Progressive non-fluent aphasia - progressive difficulty with words
- Semantic dementia - loss of knowledge of meaning of words
Result of a lesion in the right internal capsule or motor cortex.
Contralateral upper motor neuron weakness
Result of a lesion in the right cranial nerve nuclei.
Ipsilateral lower motor neuron weakness
Motor result of a lesion on the right side of the spinal cord.
Ipsilateral upper motor neuron weakness
Lesion in the parietal cortex
Contralateral sensory deficit
Sensory result of a lesion on left side of spinal cord.
Contralateral spinothalamic loss - pain, temp
Ipsilateral dorsal column loss - fine touch, vibration, proprioception
Are motor structures represented medially or laterally in the nervous system.
Medially (sensory are lateral)
Lesion in substantia nigra
Parkinsonian features
Lesion in red nucleus
Cerebellar like features
Role of vestibulocerebellum (Flocculonodular lobe anatomically)
Balance, posture, eye movements
Role of spinocerebellum (vermis and paravermis anatomically)
Postural control
The spinocerebellum contains sensory maps as it receives data on the position of various body parts in space: in particular, the vermis receives fibres from the trunk and proximal portions of limbs.
While the intermediate parts of the hemispheres receive fibres from the distal portions of limbs.
The spinocerebellum is able to elaborate proprioceptive input in order to anticipate the future position of a body part during the course of a movement, in a “feed forward” manner.
Role of cerebrocerebellum (lateral parts of hemispheres).
Fine co-ordination with planning of limb movements about to occur
Features of cerebellar dysfunction.
V - vertigo A - ataxia N - nystagmus I - intention tremor S - slurred, staccato + scanning speech H - hypotonia D - dysmetria, dysdiadokinesia
IPSILATERAL LIMB SIGNS
Lateral rectus eye muscle supplied by what?
Abducens (CN6)
Superior oblique eye muscle supplied by what?
Trochlear (CN4)
Complete oculomotor nerve lesion.
- Eye down and out
- Pupil dilated
- Partial ptosis from paresis of levator palpebrae superioris
Horners syndrome
- Smaller pupil
- Cluster headache
- C8/T1 pathology
- Ptosis
- Anhydrosis
Upper motor neuron lesion signs
Muscle wasting +
Increased tone
Increased reflexes
Decreased power
Spastic posturing
Lower motor neuron lesion signs.
Muscle wasting ++
Fasiculations
Decreased tone
Decreased reflexes
Decreased power
Hyoglossal nerve palsy
- Tongue deviates to side of weakness
- Unilateral in LMNL
- Contralateral in UMNL
UMNL flexors
Stronger than extensors - this is why in cerebral palsy hand is flexed in front
When are fasciculation’s present?
When there is a problem with the anterior horn cell LMN
Increased tone - spastic
Increased tone - rigid
Spastic: Initially stiff but it gets easier
Rigis: Constant stiffness - parkinsonian syndromes
Decorticate positioning.
CORTICAL LESION
- Adduction stronger than abduction
- Abnormal flexion
- Foot plantar flexed
Decerebrate positioning
- Arms extended
- Damage to upper brainstem
- Wrists pronated
Plantar response
- Up going big toe = pathology (hence positive Babinski’s sign)
- Positive test indicates UMNL or normal in new born
Supinator reflex
C5 C6
Biceps reflex
C5 C6
Triceps reflex
C6 C7
Ankle reflex
S1 S2
Knee reflex
L3 L4
Central cord lesion e.g. syringomyelia
Tube within spinal cord
Dissociative sensory loss - dorsal columns not affected
UMN signs below level if pressure on corticospinal tracts
Anterior spinal artery syndrome
Anterior 1/3rd of spinal cord supplied by anterior spinal cord
- If anterior artery occluded, people end up with total paralysis below the level
- Complete bilateral motor loss below the level
- Preservation of sensation carried by dorsal columns
- Bilateral loss of spinothalamic function below
Romberg’s test
- Patient stands with feet together + ask them to close their eyes
- If they wobble there is a problem with vestibular system
Virchow’s triad
Virchow’s triad or the triad of Virchow describes the three broad categories of factors that are thought to contribute to thrombosis.
- Blood vessel wall
- Blood flow
- Blood constituents - too many red cells or too many platelets = clot, not enough clotting factors = bleed
- endothelial injury
- hypercoagulability
- stasis of blood flow
Sites of brain haemorrhage (Intracerebral)
Subarachnoid - arterial
Subdural - venous
Extradural - arterial
Intracerebral haemorrhage causes
- Rupture of aneurysm
- Arteriovenous malformation
- Cavernoma
- Bleed into infarct
- Bleed into tumour
- Trauma
Define sedation
Allows patient to tolerate unpleasant diagnostic or surgical procedures - verbal contact can be maintained
Define coma
State of extreme unresponsiveness where there is no voluntary movement or behaviour
Define anaesthesia
If GA then drug induced and predictably reversible coma
Classes of anaesthetic agents
GA
IV or inhaled Local - esters and amides
Neuromuscular blocking agents - depolarising/non-polarising
Analgesia - opioids
How do GA work?
Act on GABA, glutamate and other NMDA receptors
- Volatile act on alpha and beta subunits or GABA.
- Intravenous act on beta subunit of GABA.
Principal effects of anaesthesia
Unconsciousness - can still feel pain but can’t form memories
Loss of reflexes
Analgesia
Difference between onset of volatile and IV GA
Rapid onset for IV.
Slow onset for volatile.
Examples of volatile GA
NO, isoflurane, sevoflurane
Examples of intravenous GA
Propofol, ketamine, thiopentone
Side effects of GA?
Cardiac suppression and respiratory depression
MOA of local anaesthetic
- Block voltage sensitive Na+ channels
- Pain still sensed by nociceptors but transmission to brain and spinal cord is inhibited
Effect depends on:
- Diffusion gradient
- Fibre size
- Myelination
A fibres
There are 4 subdivisions: alpha (ɑ), beta (β), gamma (ɣ), and delta (δ).
A-alpha:
- Large diameter (13-20μm)
- Myelinated
- Proprioception
- Include type Ia (muscle spinle) and Ib (golgi tendon) sensory fibres of the alternative classification system
A-beta:
- Smaller diameter (6-12μm)
- Myelinated
- Touch
A-gamma:
- Smaller diameter (5μm)
- Type of LMN invoved in muscle contraction
- Role = keeping muscle spindles taut, thereby allowing the continued firing of alpha neurons, leading to muscle contraction
A-delta:
- Smaller diameter diameter (1-5μm)
- Myelinated
- Pain and temperature
B fibres
Group B nerve fibers are axons, which are moderately myelinated, which means less myelinated than group A nerve fibers, and more myelinated than group C nerve fibers.
Their conduction velocity is 3 to 14 m/s.
They are usually general visceral afferent fibers and preganglionic nerve fibers of the ANS
C fibres
- Small diameter (0.2-1.5μm)
- Unmyelinated,
- Low conduction velocity
- Pain, temperature, itch
They include postganglionic fibers in the ANS for vasodilation, and nerve fibers at the dorsal roots (IV fiber). These fibers carry sensory information.
Neuromuscular blocking drugs - antagonists
- Non-depolarising
- Competitive
- E.g. tubocurarine + atracurium
Muscle relaxation in surgery
Neuromuscular blocking drugs - agonists
- Depolarising
- Non-competitive
- Acts on nicotinic receptors
- E.g. suxamethonium
Muscle paralysis
Are nicotinic receptors mostly post-synaptic or pre-synaptic?
Pre-synaptic
MOA of suxamethonium (aka succinylcholine)
Binds to ACh receptors which causes depolarisation of muscles
MoA: “persistent” depolarization of the neuromuscular junction. This depolarization is caused by Succinylcholine mimicking the effect of acetylcholine but without being rapidly hydrolysed by acetylcholinesterase. This depolarization leads to desensitization.
4 stages of anaesthesia
- Induction - initial administration to loss of consciousness
- Excitement - excited and delirious activity - RR + HR may become irregular
- Surgical anaesthesia - skeletal muscles relax
- Overdose - too much medication relative to amount of surgery resulting in severe brainstem or medullary depression
Reliable clinical signs of anaesthesia.
Muscle tone - jaw
Light reflex
Eyelid reflex
Lacrimation
Balance
Term used to describe the dynamics of body posture to prevent falling
Centre of Mass
Weighted average of CoM of each body segment in 3D space
Centre of Gravity
Vertical projection of COM onto ground
Postural control
Keeping body’s CoG over during quiet stance and within Base of Support (BoS) during active movements
Stretch (myotatic) reflex
- Muscle spindles lengthen in response to postural control
- Signalled by afferent nerve fibres
- Connect directly to motor neurons
- Activates that same muscle
Monosynaptic reflex
Afferents connect directly to efferents without interneurons
Ankle strategy
- In response to small, slower disturbances
- Shifts CoG about ankle joint
- Used on surfaces with low resistance to shear forces
Hip strategy
- In response to larger, faster disturbances
- Shifts CoG about hip joint by flexion/extension
Stepping strategy
- In response to largest, fastest disturbances
Sensory components of balance
Somatosensory - skin receptors
Proprioceptive - muscle spindles + golgi tendon organs
Visual - eyes
Vestibular - inner ear
Lesion at optic chiasm
Lose lateral part of left and right eye (hemianopia)
Where does light enter the eye?
Cornea
Glaucoma
Damage to the optic nerve due to an overproduction of aqueous humour, in which the trabecular meshwork cannot keep up with drainage of.
Causes an increase in pressure which pushes the optic nerve into the cavity in the back of the eye, causing damage to the axons
Fovea
Region of highest resolution vision
Structure of retina
3 basic layers:
- Outer ganglion layer
- Middle layer of amacrine and bipolar cells
- Bottom layer of photoreceptors (rods + cones)
Rods
Black and white.
Night conditions
Cones
Colour Daytime vision
Role of horizontal and amacrine cells
Integrate information laterally - allow communication horizontally between cells
3 different cone types
Long wavelength (L) cones - red, orange, yellow
Middle wavelength (M) cones - green
Short wavelength (S) cones - blue - not X linked recessive like the 2 above but instead is on chromosome 7
Choroid
Dense network of vasculature
o Connective tissue + dense vascular network that provides nutrients to outer surface retina
o Choroid receives its blood supply from central retinal artery (that emerges from back of eye)
o Retinal arteries + veins supply the inner surface of retina is (come in through optic nerve fasciculus)
o Choroid provides all eye layers w/ 90% of their blood supply
Dichromat
Only have 2 different cone types
Protanopia
Lack L cones - red
Deuteranopia
Lack M cones - green
Tritanopia
Lack S cones - blue
Protanomalous trichomat
Weak L cone
o Weak red cones, they shift their sensitivity to higher wavelength (more sensitive to green) making it difficult to distinguish between red + green
Deuteranomalous trichomat
Weak M cone
o Weak green cones, they shift their sensitivity to lower wavelength (more sensitive to red) making it difficult to distinguish between red + green
Tritanomalous trichomat
Weak S cone
o Weak blue cones
Test for colour blinded
Ishihara plate
Visual receptive field
All of the photoreceptors that feed in information to that bipolar cell
How many layers of Lateral geniculate nucleus?
The lateral geniculate nucleus is a sensory relay nucleus in the thalamus of the brain
SIx.
It has multiple layers:
4 sets of ‘parvocellular layers’ – Small cells
2 sets of ‘magnocellular layers’ – Large cells
o Each layer receives input from a different eye (contralateral or ipsilateral), information from each eye is kept separate
How many parvocellular layers and which ones are they?
Four.
3, 4, 5, 6
Small cells, top 4 layers
Receive input from B (midget) ganglion cells – smaller
Separate information from the 3 cone types
Most of these cells (90%) have colour-opponent receptive fields (sensitive to different colour lights)
• Can use these layers to discriminate different colours
Lesion – impairs colour vision, visual acuity, fine stereopsis, texture discrimination, doesn’t affect speed/motion discrimination
How many magnocellular layers and which ones are they?
Two.
1, 2
Large cells, bottom 2 layer
Receive input from A (parasol) ganglion cells – larger
Combine info from all 3 cone types so sensitive to black and white vision (changes in brightness)
Lesion – impairs ability to discriminate movement, doesn’t affect colour vision or visual acuity
Magnocellular
Receives information from A (parasol) ganglion cells which combine information from all 3 cones.
Sensitive to black and white and changes in brightness.
Parvocellular
Receives information from B (midget) ganglion cells - separates the 3 cone types
Able to differentiate colour
Magnocellular lesion
- Impaired ability to discriminate movement
- Impairs low spatial frequency (coarse, blurry patterns)
- Doesn’t affect colour vision
- Doesn’t affect visual acuity
Parvocellular lesion
- Impaired colour vision
- Impaired visual acuity
- Impaired fine stereopsis (depth, 3D vision)
- Impaired texture discrimination
- Doesn’t affect speed discrimination
P (parvo) stream
- Prefers high spatial frequencies
- Prefers slow movement
- Is colour selective
- Essential for texture discrimination
- Essential for fine stereopsis
M (magno) stream
- Prefers low spatial frequencies
- Essential for fast flicker and motion detection
- No colour selectivity
How many layers does the striate (primary visual cortex) have?
6
Where do the magno and parvocellular streams project into?
Different areas of layer 4 of the striate cortex
What do the koniocellular cells carry?
Information from S cells
Where do the koniocellular cells project to?
Layers 2 and 3
Ocular dominance
Vertical stretch of striate cortex that responds primarily to information from 1 eye
Where is centre of visual field processed?
Very back of brain
Where is peripheral vision processed?
Anterior of occipital lobe
Specialisation of extrastriate areas
V2 - unknown
V3 - depth perception and visual acuity
V4 - colour
V5 - motion
Which higher level visual area recognises faces?
Fusiform face area
Which higher level visual area recognises scenes?
Parahippocampal place area
Which higher level visual area recognises objects?
Lateral occipital cortex
Where pathway
Parvocellular route to V1 –> dorsal route to V5 –> posterior parietal cortex
What pathway
Magnocellular route to V1 –> ventral route to V4 –> infers-temporal cortex
Striate cortex lesion
At least partially blind but still able to navigate
Blindsight pathway
Retina –> superior colliculus –> pulvinar –> posterior parietal cortex
Balint-Holmes syndrome
Impairment in using visual information to guide motor movements
What is the ‘what pathway’ also known as?
The ventral stream
What is the ‘where pathway’ also known as?
The dorsal stream
What is the dorsal stream involved in?
Processing the object’s spatial location relative to the viewer and with speech repetition
What is the what pathway involved with?
Object and visual identification and recognition
Describe visual form agnosia
Unable to recognise objects
How many cranial nerves?
24 (12 pairs)
Cerebral nuclei-cranial openings
I, II
Midbrain nuclei-cranial openings
III, IV
Pontine nuclei-cranial openings
V, VI, VII, VIII
Medullary nuclei-cranial openings
IX, X, XI, XII
Eye movement CNs
III, IV, VI
Special sensory CNs
I, II, VIII
Parasympathetic CNs
II, VII, IX, X
Olfactory nerve - CN I
Pathway: Olfactory epithelium in superior nasal mucosa –> perforations in cribriform plate –> mitral cells of olfactory bulb –> olfactory tract - secondary neurons –> primary olfactory cortex + amygdala
No thalamic precortical relay - doesn’t run through thalamus
Test - can you smell? Unilateral ansomia - fracture/meningioma Bilateral anosmia - cold/viral infection
Optic nerve - CN II
Enters skull through optic canal with ophthalmic artery and projects to LGN. From LGN you get optic radiations to the primary visual cortex in occipital lobe
Test - confrontational visual field, pupillary response + visual acuity (snellen)
Light goes in through optic nerve and then pupil constriction caused by oculomotor nerve
Oculomotor nerve - CN III
2 nuclei in midbrain 1. Oculomotor nuclei - motor 2. Edinger-Westphal - PS
Runs through cavernous sinus and exits through superior orbital fissure PS nerve fibres on outside of nerve
Space occupying lesion = dilated pupil - you would get this before muscle paralysis
PS constricts pupil - runs to sphincter papillae and ciliary muscle
Test with trochlea and abducens
SUPPLIES MEDIAL RECTUS = ADDUCTS
Trochlear - CN IV
Comes out of back of midbrain inferior to inferior colliculus before running around the side of the midbrain and exiting via the cavernous sinus + superior orbital fissure and runs to superior oblique muscle.
Turns eye down + out
Only CN to exit brainstem on dorsal surface
Abducens - CN VI
Exits brainstem at pontine medullary junction. Runs through cavernous sinus and exits via the superior orbital fissure.
Supplies lateral rectus.
Black tract = main central connection of oculomotor, trochlea and abducens
SUPPLIES LATERAL RECTUS = ABDUCTS
List the eye movements each eye muscle is responsible for.
Superior oblique - depresses, abducts and medial rotation
Inferior oblique - elevate, abduct and lateral rotation
Superior rectus - elevate, adduct and medial rotation
Inferior rectus - depresses, adducts and lateral rotation
Medial rectus - adduction
Lateral rectus - abduction
Which extraocular muslce is innervated by the trochlear nerve?
Superior oblique muscle
Mnemonic for simplified actions of the eye muscles:
- Obliques Abduct whereas Rectii Adduct (except LR)
- Superiors Intort whereas Inferior Extort
- Rectii act according to their names whereas Obliques act opposite to their names
Which extraocular muscles are innervated by the oculomotor nerve (CNIII)?
- Superior rectus
- Inferior rectus
- Medial rectus
- Inferior oblique
Levator palpebrae superioris
What is the function of the levator palpebrae superioris muscle?
Elevates + Retracts upper eyelid
Which extraocular muscles does the abducens nerve innervate?
- Lateral rectus
- Retractor bulbi
Pupillary light reflex
- Light comes in via optic chiasm
- Runs to LGN but bypasses it and synapses at pre-tectal nucleus
- After pre-tectal nucleus, transmits bilaterally to oculomotor nucleus
- From oculomotor nucleus runs to ciliary ganglion and constrictor pupillae
Trigeminal nerve - V
- Ophthalmic - runs in cavernous sinus and exits through superior orbital fissure. Sensory.
- Maxillary - exits skull through foramen rotandum. Sensory.
- Mandibular - exits skull through foramen oval.
Mixed nerve.
Exits via side of pons and forms ganglion which sits in middle cranial fossa
Test - corneal reflex, sensation of face, palpate masster and temporalis, jaw jerk
Facial - VII
Mixed nerve - exits at pontine medullary junction
Runs into internal auditory meatus with vestibulocochlear + intermediate nerve with special sensory fibres.
Some PS fibres from superior salivatory nucleus which are distributed to:
Nasal glands
Palatine and lacrimal glands
Submandibular and sublingual glands
Special sensory from anterior 2/3rds of tongue run up chorda tympani over handle of malleus and synapses and geniculate ganglion.
Testing - facial expression
Ramsey-Hunt syndrome
Varicella zoster of facial nerve
Vestibulocochlear - VIII
Cochlear and vestibular nerve which run together
Exits at pontine-medullary junction
Enters skull through internal auditory meatus and is distributed to structures within the ear
Test - Rinne and Weber
Glossopharyngeal - IX
Medullary - PS + motor
Exits skull at jugular foramen with vagus and spinal accessory nerve + runs to parotid, carotid body and pharynx
Test - gag reflex
Vagus - X
Medulla
Comes out of brainstem inferior to rootlet of glossopharyngeal.
Exits skull through jugular foramen.
Branch to muscles of larynx, pharynx, thorax and abdomen.
Test - say ahhh (this is with cranial accessory nerve) - uvula points to normal side
Accessory - XI
Cranial and spinal segments
Spinal from upper 3 cervical segments and runs through foramen magnum into cranium.
Exits through jugular foramen.
Supplies sternocleidomastoid and trapezius
Test - turn head against resistance and shrug shoulders
Hypoglossal - XII
Medulla
Exits brainstem between pyramid and olive of medulla.
Runs through hypoglossal canal into the area just inferior to the angle of the mandible.
Supplies intrinsic muscles of the tongue
Test - stick tongue out (tongue points to side of lesion)
Define seizure
An abnormal paroxysmal discharge of neurons sufficient enough to cause clinically detectable intermittent disturbance of consciousness, behaviour, motor and sensory function
Define status epilepticus
Status epilepticus is a single epileptic seizure lasting more than five minutes or two or more seizures within a five-minute period without the person returning to normal between them.
Partial complex seizures
Loss of consciousness.
No loss of postural control.
Affects only a single brain lobe
But individual loses awareness (becomes dazed)
Individual gets an aura (odd taste/smell) before becoming dazed (doesn’t lose consciousness)
Simple complex seizures
No loss of consciousness.
Seizure in frontal lobe:
• May affect motor cortex
• Symptoms may just be contralateral muscles twitching w/ full consciousness + awareness
Seizure in temporal lobe:
• May just cause off taste in mouth for few seconds
3 types of seizures?
1) Generalised - tonic/clonic, absence, myoclonic, atonic. Note causes complete LoC.
2) Focal/partial - simple partial (no loss of consciousness), complex partial (loss of con)
3) Focal with secondary generalisation - seizure starts in 1 lobe but then spreads to all brain
Tonic-clonic seizure
GRAND MAL
Type of generalised seizure that affects the entire brain
Causes convulsions (alternate contractions/extension of muscles)
Loss of consciousness + there is a postictal phase
- Electrical discharge starts at centre then spreads to cerebral cortex
- Sudden loss of consciousness follow by tonic phase
- body is stiff, breathing stops (may be cyanotic)
- Clonic phase: rhythmical shaking, may bite tongue, eyes roll back, loss of bowel or bladder control
Absence seizure
Patient suddenly stares vacantly
May be myoclonic jerks
Individual appears ‘absent’ for a while + may or may not have postictal disorientation
Brief loss + return of consciousness, generally not followed by a period of lethargy
Define epilepsy
A condition where seizures recur, usually spontaneously
Seizures only happen in cerebral cortex (doesn’t happen in. cerebellum, brainstem)
Atonic seizure
Sudden loss of tone of postural muscles causes patient to fall
Involves loss of muscle tone for >1 second, individual may collapse
Also called drop seizures, akinetic seizures or drop attacks
Brief lapse in muscle tone that are caused by temporary alterations in brain function
The seizures are brief – usually less than 15 seconds
Frontal lobe - normal role
o Intellectual function
o Inhibition
o Bladder continence
o Saccadic eye movement – in seizures, eyes move opposed the side of lesion
o Motor function
o Expression of language – seizure may cause inability to speak
Frontal lobe seizures
o Jacksonian seizures – one sided o Adversive seizures o Todd’s paresis – paralysis of one side o Very brief + often nocturnal o Hyperkinetic behaviour, vocalisation o Retained consciousness o ASNFLE – genetic o EEG can be normal because the frontal lobe is so large
Parietal lobe - normal role
o Sensory integration
o Receptive language function
Parietal lobe seizures
o Positive sensory disturbance (paraesthesia)
o Motor activity in affected body parts follows in 50% of cases
o D/D TIA, migraine
Temporal lobe - normal role
- Memory - Smell - Hearing - Emotion - Vestibular
o Memory – seizures may cause memory hallucinations (déjà vu)
o Smell – seizures may cause olfactory hallucinations (weird smell that doesn’t exist)
o Hearing – seizure may cause auditory hallucination (hearing sound that doesn’t exist)
o Vestibular – seizure may cause vestibular hallucinations (feeling of falling/moving/vertigo)
o Emotion – seizure may cause emotional disturbance
Temporal lobe seizures
o Gradual evolution over 2-3 minutes, lasts 2-5 minutes
o Aura – epigastric, smell, taste, déjà vu, fear
o Auditory/visual hallucinations
o Pallor, flushing, changes in heart rate
o Speech arrest or repetitive vocalisation
o Motionless stares
o Automatism – lip smacking, fidgeting, fumbling (odd behaviours)
o Postictal confusion, headache, dysphasia, nose rubbing
o Second generation seizure less common
Occipital lobe - normal role
Vision
Occipital lobe seizures
Visual hallucinations
Visual disturbances – unformed, circular, multi-coloured, confined to hemifield
What is the most common type of seizure?
Focal that originates in temporal lobe and then spread to generalised
Tonic seizure
Increased tone of postural muscles
Function of pinna (auricle)
To funnel sound into ear canal and can pick up human speech over background noise
Myoclonic seizure
Involuntary movements that can involve the whole body or just parts of it
Secondary generalised seizures
- Temporal only
- Partial seizure where the epileptic discharge spreads to both cerebral hemispheres
- Once the discharge reaches the RAS, consciousness is lost - Results in generalised seizure
Anatomy of external auditory meatus
- Sigmoid canal
- 7mm diameter
- 25mm long
- 1st 1/3rd surrounded by cartilage
- 2/3rd surrounded by bone
- Cells in cartilaginous zone include: hair, sebaceous, ceruminous glands
Function of external auditory meatus
Amplifies sound
Syncope
- Sudden loss of consciousness with loss of postural muscle tone
- Due to reduced cerebral perfusion
Orthostatic hypotension
Syncope when standing up
Anatomy of tympanum
Collagenous membrane
Overall function of outer ear
Convert acoustic energy to kinetic energy
3 ossicles (external to internal aka lateral to medial)
Malleus
Incus
Stapes
Sound waves travelling from external ear
Sound waves travel from external ear to stapes.
Stapes vibrates oval window.
Vibration then flows in perilymph from scala vestibuli and then to scala tympani.
Causes displacement of basilar membrane and organ of corti.
Point at which wave passes basilar membrane depends on the sound.
- High frequency at base
- Low frequency further along cochlea
Role of organ of corti
Transducer pressure waves in action potentials
What happens to hair cells when the basilar membrane is displaced?
- Hair cells are sheared
- Opens non-selective transduction ion channels
- Leads to depolarisation
What happens if hair cells are displaced towards the kinocilium?
Stimulates vestibulocochlear nerve.
Inhibits if against
Auditory pathway
SLIM mnemonic
Superior olivary nucleus –> lateral lemniscus –> inferior colliculi –> medial geniculate nucleus
Where does the auditory pathway decussate?
Decussation occurs between the cochlear nuclei and superior olivary complex, and at inferior colliculi
Decussation enables inputs from left + right ears to be compared in superior olivary nuclei (SON) + localise sound
Where is difference in sound intensity located?
Lateral superior olivary nucleus
Detects differences in sound intensity reaching each ear
• Localisation of high-frequency sound (>1600Hz) occurs by detection of differences in sound intensity at each ear
Where is the difference in time of sound located?
Medial superior olivary nucleus
Detects differences in the time that sounds reach each ear
• Localisation of low-frequency sound (<800Hz) occurs by detection of time differences in sound reaching each ear
How does localisation of low frequency sounds occur?
Detection of time difference.
Medial SON
How does localisation of high frequency sounds occur?
Difference in sound intensity
Lateral SON
Causes of sensorineural hearing loss
Presbycusis – naturally occurs damage to cochlea when ageing
Noise-induced – regular + prolonged exposure to loud sounds
Ototoxic drugs - gentamycin, loop diuretics, cisplatin
Inflammatory disease e.g. measles, mumps, meningitis, syphilis
Complications at birth
Congenital
Physical trauma
Benign tumours on the auditory nerve
Meniere’s disease
Causes of conductive hearing loss
Infection – otitis externa + otitis media
Build-up of earwax
Perforated eardrum
Fluid in the middle ear
Membrane tension
Damage to the small bones within the middle ear
Rinne test findings
Air > bone - normal or sensorineural loss
Bone > air - conductive loss
Weber test findings
- Normal - hear both the same in both ears
- Conductive - louder in defective ear
- Sensorineural - louder in normal ear
Vestibulospinal tract
- Keep head balanced on shoulders
- Sensory input from vestibular labyrinth
- Vestibular nuclei to spinal cord
Tectospinal tract
- Information from visual system
- Retina to superior colliculus
Pontine reticulospinal tract
- Information from pons
- Lower limb extensors
Medullary reticulospinal tract
- Information from medulla
- Relaxes extensor tone
What do ventromedial pathways control?
- Posture
- by affecting axial or proximal musculature
- Topographic
- Medial proximal and lateral distal
Muscles of middle ear
Tegmen tympani - supplies malleus
Stapedius - supplies stapes
Overall role of inner ear
Converts kinetic energy of ossicles into hydraulic energy of fluid and then into electrochemical energy via vestibulocochlear nerve
Eustachian tube
- Links middle ear to nasopharynx
- Allows pressure equalisation
Nerve which supplies the stapes
Stapedial nerve
Nerve which supplies anterior 2/3rds of tongue
Chorda tympani + lingual nerve (sensory)
Hypoglossal CN XII (motor)
Acoustic reflex
Where the tegmen tympani and the stapedius contract in response to high intensity sound
3 parts of cochlea
- Scala vestibuli
- Scala media
- Scala tympani
Which part of cochlea contains perilymph?
Scala vestibuli + scala tympani (K+ containing)
Basilar membrane
Separates scala tympani and scala media
Which part of cochlea contains endolymph?
Scala media (Na+ containing)
Reissner’s membrane
Separates scala vestibuli and scala media
What is decerebrate rigidity?
Increased extensor tone
Utricle
- Horizontal
- Macula - sensory epithelium
- Matrix of supporting cells and hair cells
- Hair cells contain cilia which can penetrate gelatinous cap
- Otoliths encrust the surface of this cap
- Kinocilia towards stroll
Saccule
- Vertical
- Macula - sensory epithelium
- Matrix of supporting cells and hair cells
- Hair cells contain cilia which penetrate gelatinous cap
- Otoliths encrust the surface of this cap
- Kinocilia away from striola
Directional hair cells
- Have baseline firing of action potentials
- Kinocilia longer than stereocilia
- Stereocilia towards kinocilia = depolarisation
- Stereocilia away from kinocilia = hyper polarisation
- Utricle kinocilia towards striola = depolarisation
- Saccule kinocilia away from striola = hyper polarisation
Semicircular canals
- Filled with endolymph
- Main sensory structure of each canal in the ampulla
- Information about rotational movements
What is the cupula?
The ampullary cupula, or cupula, is a structure in the vestibular system, providing the sense of spatial orientation.
The cupula is located within the ampullae of each of the 3 semicircular canals.
The cupula itself is the gelatinous component of the crista ampullaris that extends from the crista to the roof of the ampullae.
When the head rotates, the endolymph filling the semicircular ducts initially lags behind due to inertia. As a result, the cupula is deflected opposite the direction of head movement. As the endolymph pushes the cupula, the stereocilia is bent as well, stimulating the hair cells within the crista ampullaris.
What happens to cupula when head is turned to the left?
- Head turns to left
- Endolymph moves to right
- Cupula displaced to right
- Hair cells then depolarise
Where does the vestibular nuclei send projections to?
- Extraocular muscles
- Cerebellum
- Neck/limb motor neurons
Vestibular-ocular reflex
- Important in posture
- Damage may mean everything is blurry
A rotation of the head is detected, which triggers an inhibitory signal to the extraocular muscles on one side and an excitatory signal to the muscles on the other side. The result is a compensatory movement of the eyes.
For example, when the head moves to the right, the eyes move to the left, and vice versa.
Vestibular-ocular reflex in unconscious patient
- Irrigate ear with warm or cold water
- Convection currents in endolymph
- Disturbs cupula to increase rate of firing of the afferent
- Induces vestibular-ocular reflex
Limb placing postural reflex
Spinal reflexes
- Ia muscle afferents increase firing of alpha neurons to increase muscle tone of extensors
Protective postural reflex
- Axons from medial vestibular nucleus to C spine
- Regain CoM over base of support
Feedforward postural reflex
- Make adjustments before voluntary movements
- Reticular formation important here
Feedback postural reflex
- Responses to stimuli following postural disturbance
- Vestibular nuclei important
Meniere’s disease - umbrella term for conditions such as tinnitus, hearing loss, aural fullness, and recurrent, spontaneous episodes of vertigo.
Symptoms:
- Dizziness
- Tinnitus
- Deafness
- Increase in volume of endolymph
- Ruptures membrane of labyrinth
- Damage to inner ear
o Endolymphatic hydrops
o Idiopathic increase in volume of endolymph distrust function of membranous labyrinth of inner ear
o Symptoms: attacks of vertigo, deafness, tinnitus (because endolymph also in cochlea)
o Treatment: no cure, but can treat vertigo, nausea + vomiting with: prochlorperazine + antihistamines
Benign paroxysmal vertigo syndromes
Symptoms:
- Dizziness when turning head certain way
- Disrupts flow of endolymph in semicirclar canals
- Calcium carbonate crystals dislodged from otolith organs
An example of a fibrous joint
Cranial suture
Difference between a 1st degree and 2nd degree cartilaginous joint
1st degree - 1 type of cartilage between bones - epiphyseal
2nd degree - 2 types of cartilage between bones - pubic symphysis
What are stability factors of bones?
Muscles + tendons
Ligaments
Bony congruence
Hiltons law
If a muscle crosses a joint and therefore moves the joint, the nerve that supplies the muscle supplies the joint and the skin above
Sternoclavicular joint
- Atypical synovial joint - surfaces covered by fibrocartilage rather than hyaline cartilage
- Articular disc separates joint into 2 cavities
- Capsule reinforced by anterior and posterior STERNOCLAVICULAR ligaments and COSTOCLAVICULAR ligaments
- Joint supplied by medial supraclavicular nerve (C3-C4)
Acromioclavicular joint
- Atypical synovial joint
- Capsule
- Support from coracoclavicular ligament (trapezoid and conoid ligaments)
- Lateral supraclavicular nerve
What is the glenoid labrum?
Fibrocartilage rim which attaches to margins of glenoid cavity, serves to deepen glenoid fossa.
Name the 2 most important bursae in the shoulder?
Subacromial - overlies tendon of supraspinatous (below acromion).
Subscapular - separates tendon of subscapularis from subscapular fossa.
What are the roots of the musculocutaneous nerve?
C5, C6, C7
What are the roots of the axillary nerve?
C5, C6
What are the roots of the radial nerve?
C5, C6, C7, C8, T1
What are the roots of the median nerve?
C5, C6, C7, C8, T1
What are the roots of the ulnar nerve?
C8, T1
Where is the axillary nerve in relation to the axillary artery?
Posterior to axillary artery
What does the axillary nerve supply?
Deltoid and Teres minor
What does the musculocutaneous nerve supply?
Coracobrachialis, biceps brachii and brachialis
What does the radial nerve supply?
Triceps brachii, anconeus, brachioradialis* (flexor), supinator and posterior compartment extrinsic hand muscles
What does the ulnar nerve supply?
Forearm - flexor carpi ulnaris + flexor digitorum profundus (medial half)
Hand - deep branch of ulnar nerve:
- At its origin it innervates the hypothenar muscles.
- As it crosses the deep part of the hand, it innervates all the interosseous muscles and the third and fourth lumbricals.
- It ends by innervating the adductor pollicis and the medial (deep) head of the flexor pollicis brevis.
Glenohumeral joint
- Synovial ball and socket
- Joint capsule which is lax inferiorly
- Rotator cuff tendons support
- Lateral pectoral nerve, suprascapular + axillary nerve
Epidemiology of RA
- 1% of population- More women than men
What is the result of a lower brachial plexus injury?
Klumpke’s palsy
- Flopy hand
- Flexed wrist
- Fingers extended
- Horner’s syndrome may occur from T1 involvement
C8 + T1 affected
What is the result of an upper brachial plexus injury?
Erb’s palsy
C5+ C6 affected
What happens if you injure your ulnar nerve?
Ulnar claw - Little and ring finger flexed
What happens if you injure your median nerve?
- Hand of Benediction
- Parasthesia palmar aspect lateral 3.5 fingers
- Forearm stuck in supination
- Can abduct or oppose thumbs
- Thenar wasting
What happens if you injure your radial nerve?
- Wrist drop
- Loss of sensation over dorsal web between thumb and index fingers
- Weakness of extensors
What does the median nerve supply?
Forearm - most of anterior compartment
What are the signs and symptoms of RA?
- Slow onset
- Joint swelling (particularly fingers, toes and wrists)
- Early morning stiffness greater than 30 minutes
- Dramatic NSAID response
- CHRONIC, SYMMETRICAL, INFLAMMATORY, DEFORMING, POLYARTHRITIS
What is the primary site of inflammation in RA?
Synovium
Role of cytokines in RA
- Trigger event (e.g. smoking, virus, genetics) triggers T cells
- T cells then cause: increase in fibroblasts, macrophages + B cells
- Macrophages + fibroblasts produce cytokines which can lead to cell activation, enzyme formation + inflammation = JOINT DESTRUCTION
- B cells produce antibodies which are involved in pathogenesis - RF
Epidemiology of OA
- Most common joint disorder
- 10-20% of population
- Most common cause of joint replacement therapy
Risk factors for OA
- Age
- Female
- Menopause
- Oestrogen deficiency
- Low bone mineral density
- Family history
- Obesity
Features of OA
- EMS less than 30 mins
- Better with rest, symptoms with activity
Causes of pain in OA
- Prostaglandins
- Venous congestion
- Muscle spasm
- Cytokines
Management of OA
- Patient education
- Physio
Epidemiology of gout
- More common in men than women
- 1-2% of adults in industrialised countries
Co-morbidities of gout
Renal impairment and CHD
Podagra
Gout affecting the metatarsal joint of the big toe.
Discomfort and swelling after an attack can lasts for days-weeks
Modifiable risk factors for gout
- High purine diet
- Alcohol
- Obesity
- Hyperuricaemia
- Diuretics
Uric acid formation
Adenosine –> inosine –> hypoxanthine –> urate.
Xanthine oxidase catalysises hypoxanthine to urate
MOA of allopurinol
Blocks xanthine oxidase
Key actions of TNF-alpha
- T lymphocytes and macrophages = increased adhesion molecules + increased pro-inflammatory cytokines (IL-1, IL-6, IL-8)
- Endothelium = increased vascular endothelium growth factors (VEGF) which increases angiogenesis
- Hepatocytes = increased acute phase response + increased CRP
- Epidermis = keratinocyte proliferation - skin plaques
- Synoviocytes = increase metalloproteinase synthesis - articular cartilage degradation
Presentation of gout
Rapid development of severe hot, red, swollen and very painful joint that has come on over the past few hours / day.
Pain often wakes people up from sleep. This is a gout attack
- Podagra initially (big toe affected)
- Then to mid foot, ankle, wrist, fingers + olecranon bursae
Diagnosis of gout
Aspirate synovial fluid
Presence of monosodium urate crystals
Septic arthritis
Single joint
IV drug users
Present with sepsis
Staphylococcus infection
Soft tissue injury definition
An acute connective tissue injury that may involve skin, subcutaneous tissues, muscle, ligament, tendon, nerve or blood vessel.
Character of soft tissue injury in child abuse
- Bruising
- Burns
- Older children more likely to have multiple injury sites
- Fractures more common in children under 1
- Atypical fracture patterns
Causes of soft tissue injuries in older people
- Falls
- Living in long term care
- Thinning of skin, loss of skin elasticity + loss of strength
1st degree soft tissue injury
Pathology: minor contusion with bleeding
Pain/bruising: minimal
Functional impairment: minimal
2nd degree soft tissue injury
Pathology:
Moderate contusion.
Some tearing of fibres.
Overall structure intact.
Pain/bruising: bruising, muscle spasm, pain.
Functional impairment: joint stable, some loss of muscle power
3rd degree soft tissue injury
Pathology: structural contusion
Pain/bruising: severe bruising, muscle spasm + pain
Functional impairment: instability and/or loss of muscle function
When to consider exploration of fracture
- Heavily contaminated
- Nerve damage suspected
- Vascular damage suspected
- Loss of tendon function
- Communicates with joint cavity - Underlying fracture
Closed fracture
Skin intact + fracture uncontaminated
Open (compound) fracture
Soft tissue and fracture are contaminated therefore risk of infection
Undisplaced fracture
Where there may be lots of cracks in bone in different directions but the fragment does not break off
Displaced fracture
Fracture where bone is out of normal alignment
Pathological fracture
Fracture occurring in abnormal bone.
Osteoporosis.
Osteitis deformans (aka Paget disease).
Page’s disease.
Tumour deposits.
Bone cysts
Avulsion fracture
Bone fragment tears away from bone
Stress fracture
Repeated abnormal stresses to bone
Aims of fracture management
Fracture heals in good position.
Joints have full range of movement.
Limb regains normal strength and function.
Person able to take up prior role in society
Physical signs of bone fracture
Deformity
Local bone tenderness
Swelling
Loss of function
Which imaging technique is best for soft tissue?
MRI
Principles of fracture treatment
Protection - assess neurovascular status, temporary dressing, IV antibiotics
Debridement - clearing of dead tissue from wound
Stabilisation
What do muscle fibres contain?
Myofibrils
What is muscle fibres surround by?
Sarcolemma
What does a muscle fascicle contain?
Muscle fibres
What surrounds the muscle fascicle?
Perimysium
Histology of skeletal muscle
Epimysium around the outside
Perimysium surrounds the fascicle
Fascicle contains muscle fibres
Muscle fibres surrounded by sarcolemma
Muscle fibres contain myofibrils
Myofibrils contain actin + myosin
Physiology of muscle contraction
- Calcium released from sarcoplasmic reticulum
- This causes a conformational change
- Tropomyosin moves from the myosin-binding site on the actin
- ATP binds to myosin head
- ATP hydrolyses ADP + Pi
- Myosin head cocks back to high energy position
- Phosphate released
- Cross-bridge rotates = power stroke
Define radiculopathy
In a radiculopathy, the problem occurs at or near the root of the nerve, shortly after its exit from the spinal cord.
Define plexopathy
Whole plexus effected e.g. Era’s
Define axonotmetis
Individual axons in bundle broken down
(in Greek tmesis signifies “to cut”)
The axons and their myelin sheath are damaged in this kind of injury, but the endoneurium, perineurium and epineurium remain intact.
Define neurotmesis
Cutting across nerve itself
(in Greek tmesis signifies “to cut”)
Both the nerve and the nerve sheath are disrupted.
Define neuropraxia
Compression and is usually temporary
Neurapraxia is a disorder of the peripheral nervous system in which there is a temporary loss of function due to blockage of nerve conduction, usually lasting an average of six to eight weeks before full recovery.
Which type of muscles do the anterior divisions of the brachial plexus supply?
- Musculocutaneous, median, ulnar
- Ventral muscles
- Flexors
- ADductors
- Pronators
Which type of muscles do the posterior divisions of the brachial plexus supply?
- Axillary and radial
- Dorsal muscles
- Extensors
- ABductors
- Supinators
Axillary nerve
- C5, C6
- Supplies deltoid and teres minor
- Runs around surgical neck of humerus
- Abduction to 90 degrees lost if injured
- Sensory loss to regimental badge area
Branches of radial nerve
- Deep - posterior interosseous nerve
- Superficial - supplies dorsal of hand
Common sites of injury of radial nerve
- Axilla - close to bone
- Spiral groove of humerus (aka radial groove )
Radial nerve
C5-T1
Emerges between brachialis and brachioradialis
Median nerve
C5-T1
Passes between 2 heads of pronator teres
Supplies thenar muscles
Effects of injury to median nerve
- Thenar atrophy
- Effects thumb movements
- Ulnar deviation on wrist flexion
- Ape hand
Erb-Duchenne paralysis
C5-C6
Waiters tip
Possible ipsilateral diaphragmatic paralysis
Lose C5, abduction of shoulder
Long thoracic nerve
C5, C6, C7
Supplies serratus anterior muscle.
Pathology causes winging of scapula.
Which disease would anti-CCPs be produced in?
RA
Which immunoglobulin is involved in RA?
IgG - forms immune complexes with RF which is deposited in joints and tissues
What type of hypersensitivity reaction is RA?
Type III
Which parts of the blood test may be raised in RA?
Rheumatoid factor (RF);
Cyclic Citrullinated Peptide (CCP);
Erythrocyte Sedimentation Rate (ESR);
C-Reactive Protein (CRP);
Antinuclear Antibody (ANA)
What type of anaemia in RA?
Normocytic, normochromic
What would an x-ray of RA show?
Loss of joint space, erosions, deformity
Ulnar nerve
C8-T1
Passes through 2 heads of flexor carpi ulnaris
Where does the ulnar nerve enter the hand
Guyon’s canal
What is the ulnar paradox
The more proximal you damage the ulnar nerve, the less damage it will cause
(however normally more proximal = greater damage so this is a paradox (unusual))
‘the closer to the Paw, the worse the Claw’.
Causes of ulnar nerve injury
Handlebar palsy
Wrist slashing
Fractured medial epicondyle
Describe the shape of the infraspinous fossa
Convex
Where does the infraspinatus muscle originate?
Infraspinatus muscle originates from the infraspinous fossa
Where does the supraspinatus muscle originate from?
Supraspinous fossa
What does the spine of the scapula divide?
Posterior scapula into inferior + supra-spinous fossa regions
Name the projection of the spine that arches over the glenohumeral joint.
Acromion
When does winging of the scapula occur?
Injury to the long thoracic nerve (which supplies the serratus anterior muscle) produces a winged appearance
Function of the serratus anterior muscle
Attaches to the costal face of the scapula + pulls it against the ribcage (1-8)
What is the name of the concave depression on the costal side of the scapula?
Subscapular fossa
To which part of the scapula does the short head of biceps brachii attach?
Coracoid process
Which fossa of the scapula articulates with the humerus?
Glenoid
List 4 fossae of the scapula
Infraspinous
Subscapula
Glenoid
Supraspinous
What part of the scapula articulates with the clavicle?
Acromion
Which muscle tendon attaches to the scapula to create the supraglenoid tubercule?
Long head of BICEPS brachii
Which muscle tendon attaches to the scapula to create the infraglenoid tubercule?
Long head of TRICEPS brachii
Which muscle attach to the coracoid process?
Short head of BICEPS brachii
The greater tubercle of the humerus serves as attachment site for 3/4 rotator cuff muscles. Which ones?
Supraspinatus
Infraspinatus
Teres minor
What runs through the intertubercular sulcus groove?
Long head of biceps brachii muscle
Tendons of which 3 muscles attach to the lip of the intertubercular sulcus of humerus?
Pectoralis major
Teres major
Latissimus dorsi
Which is more medial, greater or lesser humeral tubercle?
Lesser
Surgical neck fracture of the humerus is a risk to which 2 neurovascular structures?
Axillary nerve + posterior circumflex artery
Axillary nerve damage will result in paralysis to which muscles?
Deltoid + teres minor
What would be the effect of damage to the axillary nerve?
Patient will have difficulty performing abduction of affected limb.
Loss of sensation in the lower deltoid area
What is the deltoid tuberosity?
A roughened surface on lateral side of the humeral shaft where the deltoid muscle attaches
What is the radial groove?
A shallow depression that runs diagonally down the posterior surface of the humerus, parallel to the deltoid tuberosity.
What lies in the radial groove?
Radial nerve + profunda brachii artery
Which 4 muscles attach to the humerus along the anterior shaft?
Coracobrachialis, deltoid, brachialis, brachioradialis
Which muscles attach to the humerus along the posterior shaft?
Medial and lateral heads of the triceps
In the event of a mid-shaft fracture of humerus which neurovascular structures could be damaged
Radial nerve + profunda brachii artery
Injury to the radial nerve causes paralysis to the extensors of the wrist. What would this cause?
Unopposed flexion of the wrist
Wrist drop
There are 3 muscles located in the anterior compartment of the upper arm. What is the mnemonic I use?
BBC
Biceps brachii
Brachialis
Corcacobrachialis
What are all 3 muscles of the anterior compartment of the upper arm innervated by?What artery supplies the?
Musculocutaneous nerve.
Muscular branches of brachial artery
Where does the biceps brachii muscle originate + insert?
Originate:
- Long head = supraglenoid tubercle of scapula
- Short head = coracoid process of scapula
Insert:
- Radial tuberosity = a connective tissue sheet is given off (bicipital aponeurosis) which forms the roof of the cubital fossa
Generally what is the function of the anterior compartment of the upper limb muscles?
Flexion (at elbow, shoulder, or wrist)
Which lies deeper:
- brachialis
- coracobrachialis
- biceps brachii
Both coracobrachialis + brachialis lie deep to biceps brachii
Which muscle of the upper arm is most distal?
Brachialis
Where does coracobrachialis muscle attach?
Origin - coracoid process of scapula.
Inserts - medial side of humeral shaft at level of deltoid tubercle
Function of coracobrachialis + brachialis muscles?
Coracobrachialis - flexion of arm at shoulder + weak adduction.
Brachialis - flexion at elbow
Which upper arm muscle inserts into the ulna tuberosity?
Brachialis
Rupture of any tendon in the body is rare.
The long head of the biceps brachii is one of the more common tendons to rupture.
What characteristic sign does it produce on flexing the elbow?
A bulge where the muscle belly is, called the ‘Popeye Sign’
The patient wouldn’t notice much weakness in upper limb due to action of brachialis + supinator muscles
What muscle is found in the posterior compartment of the upper arm?
Triceps brachii - 3 heads
Which upper arm muscle has 2 heads?
Biceps brachii
Which upper arm muscle has 3 heads?
Triceps brachii
Which nerve supplies the flexor carpi ulnaris?
Ulnar nerve
Which nerve innervates palmaris longus, flexor carpi radialis, pronator teres?
Median nerve
From medial to lateral name the muscles of the anterior compartment (superficial group) of the forearm?
FPFP mnemonic .
Flexor carpi ulnaris.
Palmaris longus.
Flexor carpi radialis.
Pronator teres
** flexor digitorum superficialis is deep to the others listed above but still part of superficial anterior forearm compartment
List the 3 deep anterior forearm muscles.
Flexor digitorum profundus (most medial and largest)
Flexor pollicis longus.
Pronator quadratus (most distal)
Which nerves innervate the flexor digitorum profundus muscle?
Medial half - ulnar nerve.
Lateral half - anterior interosseous branch of median nerve
Where does flexor pollicis longus (FPL) lie compared to the flexor digitorum profundus (FDP)?
Laterally to the FDP
Which nerve innervates flexor carpi radialis?
Median nerve
What is the action of pronator teres?
Pronation of the forearm
Which of joints does flexor digitorum superficialis NOT act on but flexor digitorum profundus does?
Distal interphalangeal
Which nerve innervates the lateral half of flexor digitorum profundus?
Median nerve
Why is brachioradialis a paradoxical muscle?
It’s origin + innervation are characteristic of an extensor muscle, but it is actually a flexor at the elbow
It’s part of the posterior forearm compartment.
What is the acton of the brachioradialis?
Flexion of the elbow
What nerve innervates all the muscles in the posterior forearm?
Radial
What is the main action of extensor digiti minimi?
Extension of the little finger
What is the action of anconeus?
Abducts ulnar in pronation Also extends at elbow joint
What is the common site of origin for posterior forearm muscles?
Lateral epicondyle
Which of muscle tendon contribute to the borders of the anatomical snuffbox?
Abductor pollicis longus
Which border of the anatomical snuffbox does the tendon of extensor pollicis longus form?
Medial
Which joints does extensor pollicis brevis act on?
Metacarpophalangeal joints of the thumb
Muscles acting on the hand can be divided into which 2 groups?
Extrinsic + intrinsic
Where are extrinsic muscles located?
Anterior + posterior compartment of forearm
Where are intrinsic muscles of the hand located?
In the hand itself (not the forearm)
Extrinsic hand muscles control what type of movements?
Produce a forceful grup
Intrinsic muscles of the hand control what type of movements?
Fine motor function of the hand
Anatomy of the intrinsic muscles of the hand include what?
Adductor pollicis,
Palmaris brevis,
Interossei,
Lumbricals,
Thenar,
Hypothenar muscles
The thenar muscles are 3 short muscles located at the base of the thumb. What produces a bulge known as the thenar eminence?
The muscle bellies of the thenar muscles
Which nerve innervates all the thenar muscles?
Median nerve
What lies lateral to the trochlea?
Capitulum
What does the capitulum articulate with?
Radius
What does the trochlea articulate with?
Ulna
What is immediately distal to the supra-epicondylar ridges?
Lateral + medial epicondyles (projections of the distal humerus)
Which nerve passes into the forearm along the posterior side of the medial epicondyle?
Ulnar nerve
How do supraepicondylar fractures occur?
Falling on a flexed elbow - it is a transverse fracture, spanning between the 2 epicondyles
What is Volkmann’s ischaemic contracture?
Uncontrolled flexion of the hand, as flexor muscles become fibrotic + short due to direct damage or selling to blood supply of the forearm from the brachial artery
Which nerve could a medial epicondyle fracture damage?
Ulnar nerve
What does ulnar nerve damage in a medial epicondyle fracture result in?
Ulnar claw
And loss of sensation over the medial 1.5 fingers of the hand, on both the dorsal + palmar surfaces
Which muscle does not attach to the greater tubercle of the humerus?
Supraspinatus
Infraspinatus
Teres minor
Subscapularis
Subscapularis - it attaches to the lesser tubercle of the humerus
Which nerve can be damaged in a surgical neck fracture of the humerus?
Axillary nerve - located very close to surgical neck of humerus
Damage to which nerve causes hand of benediction?
Median nerve at forearm or elbow
Which digits are affected in ulnar claw and hand of benediction?
Ulnar claw - digits 4 + 5
Hand of Benediction - digits 2 + 3
What bone does the trochlea of the humerus articulate with?
Ulna
5 A’s of Alzheimer’s?
Amnesia–memory
Aphasia–speech
Apraxia–motor
Agnosia–recognition
Associated features: • Affective disorders • Perceptual disorders • Thought disorders • Personality changes • Behavioural disorders
Posterior circulation occlusion
o Occlusion in vertebral, basilar, posterior cerebral arteries (supply brainstem, cerebellum, posterior occipital lobe) Vertigo – damaged to CN VIII N+V Ataxia – balance problems Paresis – motor tracts Paraesthesia – sensory tracts Isolated hemianopia Branch occlusion
Perforating essel occlusion
o Symptoms of lacunar stroke:
Pure motor stroke – contralateral loss of power
Pure sensory stroke – contralateral loss of light touch + proprioception
Dysarthria – slurred speech
Ataxic hemiparesis
Sensorimotor stroke
o All the ascending + descending tracts rung through internal capsule, so small infarct here large deficit
Large vessel occlusion?
Acute blockage of proximal great vessels (e.g. carotid artery)
Symptoms of carotid artery occlusion:
Contralateral hemiplegia, hemisensory disturbance (blurring vision in ipsilateral eye)
Homonymous hemianopia (half vision lost, same side in both eyes)
Deterioration in consciousness level – because of increased intracranial pressure from large area of damage
Gaze palsy (eyes deviated to side of lesion)
Dominant hemisphere global aphasia
Expressive dysphasia (Broca’s) – difficult putting words together in meaningful way
Receptive dysphasia (Wernicke’s) – difficulty comprehension
Branch vessel occlusion:
Symptoms of middle cerebral artery occlusion:
Contralateral hemiplegia, hemianaesthesia, hemianopia
Dominant hemisphere – aphasia, acalculia, agraphia, alexia
Non-dominant hemisphere – sensory neglect, dressing apraxia, failure to recognise faces
Increased ICP can occur in 4 stages
Stage 1:
Compensatory reduction in CSF + blood volume –> no rise in ICP
Clinical S+S: none
Stage 2:
When the volume continues to increase beyond the point of compensation
ICP has no other resource but to increase
Clinical S+S: drowsy, headache
Stage 3:
Sustained increased ICP w/ dramatic changes in ICP w/ small changes in volume
Falling cerebral perfusion pressure
Clinical S+S: deteriorating conscious level; intermittent elevations in BP + bradycardia
Stage 4:
Cerebral perfusion pressure ceases
Widespread necrosis begins
Compression of brainstem respiratory centres –> respiratory arrest –> death
Clinical S+S: coma, fixed dilated pupils, death
Lesion on L optic nerve causes?
Monocular vision loss (only R eye will work)
Lesion at the L or R optic tract?
Contralateral homonymous hemianopia
Posterior cerebral artery is occluded. What type of visual loss will occur as a result?
Contralateral homonymous hemianopia with macular sparing
Miosis
o Pupil constriction o Iris sphincter active o Iris dilator relaxed o Response to light increase o Parasympathetic control o Relaxed state o Also helps focus (accommodation)
Mydriasis
o Pupil dilation o Iris sphincter relaxed o Iris dilator active o Response to light decreases o Sympathetic control o Elevated emotional/aroused state o Let’s in more light
Cataracts
o Cataracts is a leading cause for blindness worldwide
o Definition: opacification (clouding) of the lens caused by compaction + protein deposition
o Treatment: outpatient surgery – lens is removed under local anaesthesia + replaced w/ artificial lens
o Risk factors: aging, trauma, diabetes, smoking, UVB light (radiation) exposure, genetic
Glaucoma treatment
Treatment: o b blockers, o a-2-adrenoceptor agonist, o carbonic anhydrase, o prostaglandin analogues, o miotics (muscarinic agonist)
Causes of Horner’s syndrome?
idiopathic, cluster headache, carotid pathology, lateral medullary pathology, Pancoast syndrome, C8/T1 pathology
Most common cause = tumour eroding the cervicothoracic ganglion (apical lung tumour)
Cranial nerve III, IV and VI palsies.
CN III – eye adopts a position known as ‘down + out’
CN IV – no obvious effect of the resting orientation of eyeball
CN VI – affected eye will be adducted by resting tone of medial rectus
3 different cones - summary
‘L’ – Long wavelength: Often called red cones (sensitive to long wavelength end of spectrum – red, orange, yellow)
‘M’ – Middle wavelength: Often called green cones (sensitive to medium wavelength of spectrum - mainly green)
‘S’ – Short wavelength: Often called blue cones (sensitive to short wavelength of spectrum - mainly blue)
Dichromats have 2 cones working
- Protanopes – lack L (red) cones
- Deuteranopes – lack M (green) cones
- Tritanopia – lack S (blue) cones, not X-linked (chromosome 7)
Anomalous trichromats (people with 3 cone types, but one is ‘weak’, this is more common than dichromacy)
Protanomalous trichromat
o Weak red cones, they shift their sensitivity to higher wavelength (more sensitive to green) making it difficult to distinguish between red + green
Deuteranomalous trichromat
o Weak green cones, they shift their sensitivity to lower wavelength (more sensitive to red) making it difficult to distinguish between red + green
Tritanomalous trichromat
o Weak blue cones
Visual cortex
Primary visual cortex (striate cortex) – receives information directly from the LGN (lateral geniculate nucleus)
Visual information the flows through a hierarchy, these areas include V2, V3, V5 and area V5/MT
These secondary visual areas (extrastriate visual cortex) process a wide variety of visual primitives
Arterial supply to the cerebrum - summary
Anterior Cerebral Arteries:
Branches of internal carotid arteries, supplying the anteromedial aspect of the cerebrum
Middle Cerebral Arteries:
Continuation of internal carotid arteries, supplying most of the lateral portions of cerebrum
Posterior Cerebral Arteries:
Branches of basilar arteries, supplying the medial + lateral sides of cerebrum posteriorly
Cerebellum 3 functional/anatomical sections - summary
- Vermis (vestibulocerebellum) – balance + equilibrium
- Paravermis (spinocerebellum) – postural tone
- Cerebellar hemispheres (pontocerebellum/cerebrocerebellum) – fine co-ordination
DCML (sensory tracts)
Fine touch, vibrations, proprioception
Contralateral – decussate in medulla
In the spinal cord, info travels via the dorsal (posterior) columns
In brainstem, it is transmitted through the medial lemniscus
3 groups of neurones:
Spinothalamic tracts (sensory tracts)
- Anterior spinothalamic tract – crude touch + pressure
- Lateral spinothalamic tract – pain + temperature
Contralateral – decussate in spinal cord (2-3 levels above entry)
Spinocerebellar tracts (sensory)
Unconscious proprioceptive
Ipsilateral
They transmit info from muscles to cerebellum
Pyramidal descending tracts
Corticospinal: • Voluntary skilled motor activity: o Lateral controls distal movement o Anterior controls proximal movements • Contralateral – 90% decussate in medulla (lateral), 10% decussate in spinal cord (anterior) • Dorsolateral
Corticobulbar:
• Muscles of face + neck
• They are the upper motor neurons of cranial nerves
Extrapyramidal tracts (descending) summary
Vestibulospinal
• Balance, posture
• Ipsilateral
• Ventromedial
Tectospinal
• Orientation, flinching, navigational
• Contralateral
• Ventromedial
Reticulospinal
• Large movements of trunk + limbs
• Ipsilateral
• Ventromedial
Rubrospinal
• Distal arm + hand movement
• Contralateral
• Dorsolateral
Real Twats Don’t Call Back
Mnemonic for brachial plexus.
Roots - C5,6,7,8, T1
Trunks - Superior, Middle, Inferior
Divisions - Anterior + Posterior divisions of the trunks
(anterior: flexors + adductors)
(posterior: extensors + abductors)
Cords - Lateral cord, Posterior cord, Medial cord
(posterior division cords posterior cord, anterior division forms lateral cord + medial cord)
Branches - 5 major branches (musculocutaneous, axillary, median, radial, ulnar)
Which nerve supplies the gluteus maximus?
Inferior gluteal nerve (L5- S2)
Which nerve supplies the gluteus medius, gluteus minimus + tensor fasciae latae.
Superior gluteal nerve (L4-S1)
Medial to lateral list the contents of the femoral triangle.
C VAN
Femoral Canal
Femoral Vein
Femoral Artery
Femoral Nerve
- Myotomes most strongly associated with each movement
C5 – Elbow flexion C6 – Wrist extension C7 – Elbow extension C8 – Finger flexion T1 – Finger abduction L2 – Hip flexion L3 – Knee extension L4 – Ankle dorsiflexion L5 – Great toe extension S1 – Ankle plantarflexion
Action of gluteus medius?
Abduction of the thigh.
Internal rotation of thigh.
Where is the thickest region of the fascia lata?
Superiorlateral aspect of the thigh, originating from the fascial condnsations from gluteus maximus + medius
Where is the fascia lata thinnest
Where is covers the adductor muscle of the medial thigh
What does the deepest aspect of the fascia lata give rise to?
3 intermuscular septa that attach centrally to the femur.
This divides the thigh musculature into 3 compartments: anterior, medial, posterior
Which intermuscular septum is the strongest of the 3 due to reinforcement iliotibial tract?
Lateral
Where does the fascia lata end
At the prominences of the tibia it continues to become the deep fascia of the leg (crural fascia)
Where does the fascia lata begin most proximally?
Around iliac crest and inguinal ligament
Name the ovoid hiatus present in the fascia lata just inferior to the inguinal ligament
Saphenous opening.
N.B. Efferent lymphatic vessels and great saphenous vein passes through the opening
What does the great saphenous vein drain into?
Femoral vein
What is the tensor fascia lata?
A gluteal muscle that acts as a flexor, abductor + internal rotator of the hip.
It also tenses the fascia lata
What does the cribiform fascia cover?
The saphenous opening (ovoid hiatus) which develops inferomedially from a sharp margin of the gap (the falciform margin)
Which part of the brain is involved in planning and programming of skilled movements?
Premotor area
Which part of the brain is involved in speech prpduction?
Frontal lobe
Broca’s area is a region in the frontal lobe of the dominant hemisphere, usually the left.
Brodmann’s area 8
The frontal eye fields (FEF) are a region located in the frontal cortex, more specifically in Brodmann area 8 of the primate brain.
(FEF) plays an important role in the control of visual attention and eye movements.
In humans, it can be more accurately said to lie in a region around the intersection of the middle frontal gyrus with the precentral gyrus, consisting of a frontal and parietal portion.
What is the function of the insula?
The insula is believed to process convergent information to produce an emotionally relevant context for sensory experience
Where is the insula?
The insula is a small region of the cerebral cortex located deep within the lateral sulcus.
Lateral sulcus = large fissure that separates frontal + parietal lobes from temporal lobe.
Main function of subscapularis muscle?
Internal rotation of humerus
Which muscles does the suprascapular nerve supply?
2/4 rotator cuff muscles.
Supraspinatus + Infraspinatus.
N.B.
- Teres minor is innervated by axillary nerve.
- Subscapularis is innervated by subscapular nerve
Which 2 ligaments make up the coracoclavicular ligament?
Trapezoid + conoid
Which ligament connects lateral scapula to lesser tubercle of humerus?
A. Acromioclavicular ligament B. Coracoacromial ligament C. Coracoclavicular ligament D. Coracohumeral ligament E. Glenohumeral ligament
E
Which ligament connects coracoid process of scapular to greater tubercle of humerus?
A. Acromioclavicular ligament B. Coracoacromial ligament C. Coracoclavicular ligament D. Coracohumeral ligament E. Glenohumeral ligament
D
Which ligament connects the clavicle to acromion of scapula?
A. Acromioclavicular ligament B. Coracoacromial ligament C. Coracoclavicular ligament D. Coracohumeral ligament E. Glenohumeral ligament
A
Which ligament connects coracoid process of scapula to process of scapula?
A. Acromioclavicular ligament B. Coracoacromial ligament C. Coracoclavicular ligament D. Coracohumeral ligament E. Glenohumeral ligament
B
Which joint is frequently injured by falling on outstretched hands?
AKA FOOSH injury
Acromioclavicular joint
Are the following structures found anterior, posterior, superior or inferior around the shoulder?
Long head of triceps muscle, Axillary nerve, Posterior circumflex humeral vessels
Inferior
No (rotator cuff) muscles are on inferior portion of shoulder so dislocations are most common inferiorly
Are the following structures found anterior, posterior, superior or inferior around the shoulder?
Subscapularis muscle, Axillary vessels, Brachial plexus
Anterior
Are the following structures found anterior, posterior, superior or inferior around the shoulder?
Supraspinatus muscle, Subacromial bursa, Coracoacromial ligament, Deltoid muscle
Superior
Are the following structures found anterior, posterior, superior or inferior around the shoulder?
Infraspinatus muscle, Teres minor muscle
Posterior
Drugs used for bone protection (falls prevention)?
Bisphosphonates
Vitamin D/Calcium
HRT
S+S of RA?
Slow onset
Joint swelling that is symmetrical
MCPs, MTPs + wrists affected
Early morning stiffness lasting an hour
Dramatic NSAID response
Which cytokine in RA causes the systemic symptoms?
TNF alpha.
Acts on endothelium:
- angiogenesis, hepatocytes
- increase CRP, synoviocytes
- articular cartilage degredation
Basic pathology in RA
Hypertrophy in synovial fluid.
Inflammation of synovial cells.
Damage to cartilage surface.
Reduced joint space.
Damage to bone.
Consequences of chronic systemic inflammation (RA)?
Early ischaemic heart disease
Sarcopenia (weak muscles)
Hypercholesterolaemia
Pain sensitisation
Osteoporosis
Insulin resistance
Dementia
S+S of OA?
Older presentation than RA.
PIP + DIP, knees, hip + lower back affected.
Worse after activity.
Early morning stiffness lasts 15 minutes.
Prevalence of RA + OA?
RA = 1%
OA = 10-20% and increases with age. 80% in over 75s.
Causes of pain in OA?
Prostaglandins and cytokines
Synovitis
Periosteal elevation
Muscle spasms
Venous congestion
Biochemical effects
Modifiable risk factors of gout?
Hyperuricaemia
High-purine diet
Alcohol - beer
Certain meds - thiazide diuretics
Pathophysiology of gout?
Hyperuricaemia - uric acid crystals, enzyme xanthine oxidase drives this process.
Cause by either :
1) overproduction of urate or
2) underexcretion of urate (renal).
Sharp crystals deposits in joints and kidneys.
Repeated –> destruction of a joint
Classic presentation of septic arthritis
Joint swelling, recent increase
systemic: fever, sweats, rigors, confusion.
Predisposing: trauma, infection, IV drugs.
Drugs: steroids, antibiotics.
Antibiotic choice in septic arthritis?
Normally flucloxacillin
If high risk of gram -ve - cephalosporin
MRSA risk - vancomycin
MoA of bisphosphonates?
Decrease OC activity, increase OC apoptosis.
There are 2 types of bisphosphonates:
- Non-N containing - etridronate, inhibits ATP-dependent intracellular enzymes.
- – N-containing, more potent.
5 classes of drug used to treat RA?
NSAIDs (-coxib) Steroids DMARDs Biological agents Immunosuppression
Examples of DMARDs?
Hydroxycholorquine,
Methotrexate - also an anticancer drug.
Sulphasalazine - also used for Crohn’s disease.
What are cyclophosphamide and cyclosporin used for in RA?
Immunosuppression in RA
What are these?
Raloxifene
Tamoxifen
Selective oestrogen receptor modulators
