HNN Week 1 Flashcards
1
Q
Draw and describe the branchial plexus:
A
- roots = C5 - T1
- C5 + C6 = superior trunk
- C7 = middle trunk
- C8 + T1 = inferior trunk
- each of the three trunks divide into an anterior and posterior branch
- all posterior branches form posterior cord
- anterior branches of superior and middle trunks form lateral cord
- anterior division of inferior trunk forms medial cord
- lateral cord becomes musculocutaneous nerve
- posterior cord splits and becomes axillary branch and radial branch
- medial cord becomes ulnar nerve
- branch of lateral and medial cords becomes median nerve
2
Q
Name the 11 relevant branches of the brachial plexus and where they arise from:
A
- long thoracic nerve = C5 + 6 + 7
- dorsal scapular nerve = C5
- suprascapular nerve = superior trunk
- subclavius nerve = superior trunk
- lateral pectoral nerve = lateral cord
- lower subscapular nerve = posterior cord
- upper subscapular nerve = posterior cord
- thoracodorsal nerve (middle subscapular nerve) = posterior cord
- medial pectoral nerve = medial cord
- medial antibrachial cutaneous nerve = medial cord
- medial cutaneous nerve = medial cord
3
Q
Describe the anatomy of the root of the neck:
A
- C8 and T1 spinal roots join after passing either side of the cervical sympathetic ganglion and pass over the superior surface of the first rib
- subclavian artery and vein also pass over the first rib
- the apex of the lung reaches up to the level of the first rib and so a tumour of the apex of the lung can cause nerve compression
- there are three scalene muscles which are responsible for elevating the ribs and tilting the head to the same side
- > anterior scalene = passes between subclavian vein and artery and attaches from transverse processes of C3-C6 to first rib
- > middle scalene and posterior scalene = pass behind the subclavian artery and the middle attaches to the first rib and the posterior attaches to the second rib
4
Q
How can the thoracic inlet be divided into three compartments?
A
- anterior compartment: sternum to anterior scalene muscle
- middle compartment: anterior to posterior scalene muscle
- posterior compartment: after the middle scalene muscle onwards
5
Q
What is the definition of Horner’s syndrome and the classic triad of presenting features?
A
- due to disruption of sympathetic nerve supply to the eye causing:
1) ptosis - drooping of eyelid
2) miosis - partially constricted pupil
3) anhydrosis - absence of sweating and dryness of the face, usually unilateral
6
Q
Why does ptosis occur?
A
lack of sympathetic innervation to the müller muscle which elevates the eyelid
7
Q
Why does miosis occur?
A
lack of sympathetic innervation to the pupillae dilator muscle (which normally dilates the pupil) so the pupillae constrictor muscle is unopposed
8
Q
Why does anhydrosis occur?
A
due to lack of sympathetic innervation to the sweat glands of the face
9
Q
What are the causes of Horner’s syndrome?
A
1) Issue in the brain:
- brainstem demyelination (e.g. MS)
- cerebral infaraction
2) Cervical sympathetic trunk issues
- cord tumour
- syringomyelia = fluid filled cyst that forms in the spinal cord
3) Damage to T1 root
- apical lung tumour
- first rib damage
- brachial plexus trauma
4) Damage to sympathetic chain and carotid artery in neck
- carotid artery accidentally dissected in surgery (as post-ganglionic fibres from the superior cervical ganglion ascend as a plexus around the carotid artery to supply structures in the head like pupillae dilator muscle)
5) Miscellaneous
- congenital
- idiopathic
10
Q
What is the pathophysiology of Horner’s syndrome:
A
- due to a lesion at any point along the sympathetic pathway
1) 1st order neuronal fibres descend from the hypothalamus down the brainstem and terminate in the spinal cord at the grey matter in C8-T2 (ciliospinal centre)
2) preganglionic (second order) sympathetic neurons project out into the ganglia of the sympathetic trunkk and ascend to the superior cervical ganglion
3) from the superior cervical ganglion, pre-ganglionic fibres synapse with 3rd order post-ganglionic fibres which continue up towards the head and form a plexus round the carotid artery
11
Q
What is the anatomical location of the superior cervical ganglion?
A
- anterior to the bifurcation of the common carotid artery at the level of vertebrae C1-3
12
Q
What muscle is involved in controlling eyelid elevation?
A
Levator palpebrae superioris muscle
- has skeletal and smooth parts
- the smooth part is called the müller muscle and receives sympathetic innervation to open the eyelid
- the skeletal part is supplied by cranial nerve 3 (occulomotor)
13
Q
How can you investigate possible Pancoast tumour?
A
- X-ray difficult to view the area around the apex of the lung
- may be able to detect a large mass or tumour at the apex of the lung
- CT scan with contrast used to diagnose the cancer
- (MRI has no advantage over CT of examining the mediastinum)
- biopsy may be taken
14
Q
How can Pancoast tumour be treated?
A
- if cancerous cause, treat with radiotherapy if tumour has not spread
- surgery is very difficult and should be carried out by a specialist
- > arteries in the area may need to be replaced by plastic tubing to maintain good blood supply to the arm on the affected side
- use of biological/immunotherapies (stimulate body’s immune system to act against cancer cells)
15
Q
What is a pancoast tumour?
A
- type of lung tumour found at lung apex
- named after professor who discovered it
- most pancoast tumours are non-small cell carcinomas (NSCC)
- NSCC are 87% of lung cancers
16
Q
What 3 types of cancer collectively come under the name NSCC?
A
1) adenocarcinoma
2) squamous cell carcinoma
3) large cell carcinoma
17
Q
What are the risk factors and aetiology of pancoast tumours?
A
(same risk factors as for any cancer)
- smoking
- prolonged asbestos exposure
- secondary smoke exposure
- exposure to industrial elements (gold, nickel)
18
Q
What are the signs and symptoms of a pancoast tumour?
A
- general cancer symptoms -> weight loss, fever, fatigue, nausea
- severe shoulder pain
- brachial plexus compression
- pain/sensory loss in hand/arm
- compression of recurrent laryngeal nerve = hoarse voice and coughing
- the tumour compresses other structures in the neck and around the thoracic inlet where the first rib surrounds the top of the lung
19
Q
How do you investigate and diagnose Horner’s syndrome?
A
- use eyedrops containing small amounts of coccaine in each eye to test pupil reflexes
- carry out imaging to look for tumour (CT best)
20
Q
What is a dermatome?
A
- region of skin supplied by a single spinal nerve
21
Q
What is a myotome?
A
- group of muscles that a single spinal nerve innervates
22
Q
How does sensory loss in dermatomes arise?
A
- damage to the spinal nerve root fibres that innervate that particular area result in numbness
- adjacent dorsal roots innervate overlapping areas of the skin and usually three adjacent dorsal rots have to be damaged in order to achieve complete sensory loss in one dermatome
23
Q
Describe the dermatomes of the upper limb:
A
see stripy notebook HNN notes page 1 (posterior of arm is the same)
24
Q
Draw a spinal cord segment and describe all the main components:
A
(see stripy notebook HNN p1 notes)
25
Describe the basic structure of a neuron:
- cell body contains nucleus and dendrites branch off it
- from the cell body an axon extends down which may be covered by a myelin sheath or not
- there are then branches off the bottom of the axon and axon terminals synapse onto other tissues/other dendrites to transmit a signal
26
What is hemiparesis?
Weakness on one body side
27
What is aphasia?
When there is SPEECH difficulty - a patient struggles to comprehend or formulate speech due to damage to specific brain regions
28
What is the motor cortex?
Part of the frontal lobe that gives rise to descending pathways controlling voluntary movement
29
Name the lobes of the brain:
- frontal
- parietal
- occipital
- temporal
30
Describe the two main groups of motor tracts:
1) Pyramidal tracts: originate in the CEREBRAL CORTEX and carry motor fibres to the spinal cord and brain stem, are responsible for VOLUNTARY control of face and body muscles
2) Extrapyramidal tracts: originate in BRAINSTEM and carry motor fibres to spinal cord and are responsible for INVOLUNTARY control of body muscles
31
What is the pyramidal decussation?
At the junction of the medulla and spinal cord, where the pyramidal tract crosses over to the opposite side (this is why one side of the brain controls the opposing side of the body)
32
What is the corpus callosum?
Broad band of nerve fibres joining the two hemispheres of the brain
33
How does the medulla oblongata become the spinal cord?
Medulla continues on and the gracile tubercle of the medulla becomes continuous with the spinal cord
34
How many vertebrae are there and how are they organised?
33 vertebrae:
- 7 cervical
- 12 thoracic
- 5 lumbar
- 5 sacral (fused)
- 4 coccyx (fused)
35
How many spinal nerves are there and how are they organised?
31 nerves:
- 8 cervical
- 12 thoracic
- 5 lumbar
- 5 sacral
- 1 coccygeal
- Nerves C1-7 pass ABOVE the corresponding vertebral body
- C8 passes below the body of C7
- the spinal nerves C8 onwards pass through the intervertebral foramen BELOW the appropriate vertebrae
36
What is the lower limit of the spinal cord?
L1/2 (in children is it L3-4 as their vertebrae grow and get longer leaving the spinal cord behind)
37
What is the structure of the grey/white matter at cervical level?
average (see stripy notes page 1)
38
What is the structure of the grey/white matter at thoracic level?
smaller grey matter (see stripy notes page 1)
39
What is the structure of the grey/white matter at lumbar level?
much larger grey matter (this makes sense as lumbar nerves supply a large area of the body and so a lot of spinal processing occurs) (see stripy notes page 1)
40
What is the structure of the grey/white matter at sacral level?
(see stripy notes page 1)
41
What are the parts of grey matter and their function?
- dorsal horn = where sensory information enters
- intermediate horn = contains neurons innervating pelvic and visceral organs
- ventral horn = where motor neurons leave to go and innervate skeletal muscle
42
What are the parts of white matter and their function?
- dorsal funiculus
- lateral funiculus
- ventral funiculus
43
What are the meninges?
3 tissue layers that surround and protect the brain and spinal cord
- dura mater
- arachnoid mater
- pia mater
44
Describe the dura mater:
- outermost layer
- thick and inelastic
- has a periosteal layer and a meningeal layer
45
Describe the arachnoid mater:
- the middle meningeal layer which is thin and fibrous
- it has trabeculae which bridge the gap between the arachnoid mater and the pia mater across the subarachnoid space
- dura mater and arachnoid mater are separated by subdural space
- contains CSF
46
Describe the pia mater:
- innermost meningeal layer
- is a UNICELLULAR layer which envelopes the spinal cord
- forms denticulate ligaments which attach laterally to the arachnoid and dura layers for spinal cord stability
- is separated from the spinal cord by the subpial space
47
What is the difference between the meninges in the brain and in the spinal cord?
- in the brain the periosteal layer of the dura mater fuses with the skull, but in the spinal cord there is the epidural space between the vertebrae and the dura mater
48
List the layers and spaces of the spinal cord coverings starting with the epidural space:
- epidural space -> between vertebrae and dura mater
- dura mater
- subdural space
- arachnoid mater
- subarachnoid space (containing CSF)
- pia mater (unicellular)
- subpial space
- spinal cord
49
What is the name of the veins in the epidural space and what is their significance?
Baston veins: they have no valves
50
What is the conus medullaris and what extends from its end?
- the lowest point of the spinal cord
| - filum terminale extends off its end and anchors it stopping the end of the spinal cord from deviating laterally
51
What is the cauda equina?
The collection of spinal nerves that come off the conus medullaris (looks like horses tail)
52
What is the arterial supply of the spinal cord?
- anterior spinal artery: travels in the median fissure and is made from branches of vertebral arteries
- two posterior spinal arteries: originate from vertebral arteries and anastomose in the pia mater
53
Describe the production and what is the composition and function of CSF?
- produced by the choroid plexus = cells in the ventricles of the brain (mainly produced in lateral ventricles but some is made in all ventricles)
- 500ml produced per day and 140ml in subarachnoid space at any one time
- provides mechanical and immunological protection to the brain and spinal cord
- the fluid can be reabsorbed into the venous system of the head
- is a filtrate of plasma and contains many ions like Na, Mg etc. and is slightly more acidic than plasma (pH 7.33 where as plasma is 7.35-7.45)
54
What is the anatomy of an intervertebral disc?
- nucleus pulposis in the middle -> jelly like material made mainly of water
- annulus fibrosis on the outside -> strong layers of collagen fibres
55
Describe the different anatomical parts of a vertebrae:
- vertebral body
- pedicles
- transverse processes (come off pedicles)
- superior articular processes (come off pedicles)
- lamina (backwards extensions of pedicles that meet in midline)
- spinous process (formed by lamina meeting)
56
What is the dermatome map of the lower limb and foot?
see HNN p2 stripy notebook
57
What is the myotome map of the upper limb and hand?
see HNN p2 stripy notebook
58
What is the myotome map of the lower limb and foot?
see HNN p2 stripy notebook
59
What spinal nerves are damaged if knee reflex is lost?
L3/4 (corresponds with myotomes)
60
What spinal nerves are damaged if ankle reflex is lost?
S1 (corresponds with myotomes)
61
What is the definition of pain?
An unpleasant sensory AND emotional experience associated with actual/potential tissue damage
62
How can pain be classified?
- acute or chronic
- cancerous or non-cancerous
- nociceptive or neuropathic
63
What is neuropathic pain?
- pain due to NERVE damage
64
What is nociceptive pain?
- pain due to TISSUE damage
65
What is nociceptive pain and its classifications?
- pain due to TISSUE damage
- > Somatic
- well-localised
- dermatomal
- sharp and constant
- > visceral
- vague distribution
- diffuse spreading to body surface
- dull and cramping
- usually periodic
- can have other symptoms of sweating, nausea and vomiting
66
What are nociceptors?
- free branching unmyelinated nerve fibres that are activated by any stimuli that has the potential to cause tissue damage
- > mechanical force
- > chemicals
- > extreme temperature
- > O2 deprivation
67
What chemicals can activate nociceptors?
bradykinin, 5-HT
68
What chemicals can sensitise nociceptors?
prostaglandins, noradrenaline, ROS
69
What is referred pain?
- when visceral nociceptor activation is felt as cutaneous pain
- nociceptor axons from viscera enter the spinal cord the same route as cutaneous axons and in the spinal cord there may be mixing of information from these sources e.g. in angina, there is pain felt in the left shoulder and upper chest although the visceral pain is coming from the heart
70
What is the gate control theory of pain?
- when an individual is injured they 'rub' the area to alleviate the pain
- this shifts input signals and signals are transmitted along A-Beta fibres (mechanoreceptors) away from pain
- the relay of signals along a neuron is gated by inhibitory interneuron
- inhibitory interneurons target second order neurons of the spinothalamic pathway
- inhibitory interneurons can be EXCITED or INHIBITED
- C fibres INHIBIT inhibitory interneurons so that pain signals still reach the spinal cord so that pain is felt, are slow transmitting therefore dull pain felt
- A-delta fibres EXCITE inhibitory interneurons, and put the brakes on pain so that we don't feel it
71
Describe the function and anatomy of the spinothalamic pathway:
- an ascending pathway
- sends information about PAIN to the brain
- conveys info about PRESSURE, PAIN, THERMAL SENSATION and NON-DISCRIMINATIVE TOUCH
- primary neuronal axons enter the spinal cord from the periphery
- they synapse with secondary neurons in the dorsal horn of the grey matter in the spinal cord
- the fibres IMMEDIATELY DECUSSATE at the level of the spinal cord where they entered and then ascend up the spinal cord in the SPINOTHALAMIC TRACT
- fibres pass through the spinal lemniscus area in the medulla
- fibres continue up to synapse with tertiary neurons in the VP (ventral posterior) nucleus in the thalamus
- fibres then continue through the internal capsule and into the cerebral cortex where they synapse in the post-central gyrus
72
Describe the function and anatomy of the dorsal medial lemniscus pathway:
- an ascending pathway
- sends information about TOUCH and PROPRIOCEPTION to the brain
- primary neuronal fibres enter the spinal cord
- fibres then ascend in either the FASICULUS GRACILIS column (signals from the legs) area or the FASICULUS CUNEATUS column (signals from the arms)
- these fibres reach the nucleus GRACILIS or nucleus CUNEATUS respectively and then synapse with secondary neurons in these nuclear areas of the medulla
- these secondary neuron fibres then DECUSSATE and ascend to the VP nucleus of the thalamus
- the secondary fibres then synapse with tertiary neurons in the VP nucleus which continue up through the internal capsule to the post-central gyrus area
73
Describe lower back pain and its causes:
- can be acute or chronic
- can be nociceptive or neuropathic
- the episodes of back pain tend to be short-lived or self-limiting
Causes: MECHANICAL
- trauma = strain (muscle damage) or sprain (ligament damage)
- muscular / ligamentous pain
- postural issues
- disc prolapse due to herniation of nucleus pulposus
INFLAMMATORY:
- lumbar spondylitis (a type of arthritis where there are degenerative changes in the intervertebral discs)
- infections of the spine
METABOLIC:
- osteoporosis
- osteomalacia
- Paget's disease
NEOPLASTIC:
- metastases (myeloma = bone cancer)
74
How can people slip a disc in their back and why does it cause pain?
- slipping and falling
- lifting in a flexed position
- suppressing a sneeze
The herniated disc activates peripheral nociceptors causing nociceptive pain (as tissue is damaged).
There is compression and inflammation of nerve roots causing neuropathic pain (nerves affected).
75
What is radicular pain?
- Pain that radiates into the lower extremity along the pathway of a spinal nerve root.
- Pain may have other symptoms like numbess.
- Is caused by injury/compression/inflammation of a spinal nerve root due to a herniated disc or another process.
76
What are the risk factors for lower back pain?
- female
- increasing age
- psychological distress
- poor self-rated stress
- dissatisfaction with employment
77
Describe the pathophysiology of lower back pain (LBP):
- nociceptors detect the pain and then transduction occurs as it is converted into an electrical signal that can be sent along axons and other neurons to the brain to be processed
- there are various types of nociceptors:
- > mechanosensitive = sensitive to intense mechanical stimulation
- > thermosensitive = sensitive to intense heat and cold
- > polymodal = sensitive to heat/chemical/pain or mechanical stimulation
78
How do you investigate LBP?
- use NRS (numeric rating scale)
- use VAS (visual analogue scale)
- use BPI (brief pain inventory) which is a graph with level of functional impairment on Y axis and NR/VA scale of pain measurement on the X axis
- neurological examination
- REMS examination
- spinal X-ray -> if pain is persistent, patient is 20-50 or there are red flag symptoms
- MRI -> if there are neurological symptoms
- CT -> to look at bony pathology
- Bone scans -> for infective or malignant lesions
- FBC/biochemistry -> if pain is due to metastases or malignancy
79
What are red flag symptoms of lower back pain?
- long lasting symptoms
- pain is constant with no variation
- sudden onset that radiates
- if patient has family history of pain
80
How do you prevent lower back pain/injury?
- ergonomics (proper office seating and equipment)
- exercise
- lifting apparatus, mechanical devices
81
How do you treat or manage LBP?
- appropriate early management reduces long term disability
- exercise programmes
- patient stays active within limits of their pain
82
What is hyperalgesia?
- when the pain threshold is much lower so something that would normally not be sore like 'touching' is very painful due to lowered threshold of activation of nociceptors as inflammatory soup of chemicals is released after injury
83
What is allodynia?
- the opposite, where the pain threshold is raised
84
How do you distinguish between acute and chronic pain?
ACUTE
- lasts less then 3-6 months
- directly related to tissue damage
- provoked by a specific injury or disease
- serves a useful biological purpose and is self limiting
CHRONIC
- pain that lasts more than 3-6 months, past the stage of tissue healing
- less directly related to an identifiable cause e.g. tissue/structural damage
- the pain outlasts the normal time of healing
- it has no useful biological purpose
85
What are the detrimental effects the LBP can have on a patient?
- financial (unemployment)
- mood
- anxiety
- depression
- stress
- person loses confidence in their own strengths and abilities
86
Describe the multidisciplinary team involved in LBP patient care:
chiropracter
osteopath
physiotherapist
87
What is the role of the chiropracter?
- complimentary therapy not available on the NHS
- are trained to diagnose, treat and manage MSK disorders
- hands on manipulation, lifestyle advice, ice, heat
88
What is the role of the physiotherapist?
- work in NHS as part of multidisciplinary teams in hospitals
- can help reduce your illness risk or injury risk
- help restore movement and function after being affected by an injury
89
What is the role of the osteopath?
- must be registered with general osteopathic council to be allowed to practice
- use a range of techniques but no surgery or drugs
- physical manipulation and stretching to improve muscle tension and joint mobility
- NICE recommends it for lower BP but there is limited evidence at it being effective for other conditions
90
What are the language areas of the brain and their function?
- Brocca's area = involved with output of speech
| - Wernicke's area = involved in perception of speech, in the auditory cortex
91
What is MS and what are its symptoms?
- caused by discrete lesions that affect myelin surrounding CNS axons
- presents as 'plaques' that destroy white matter
- presents as a pattern of signs/symptoms that cannot be explained by one focal lesion
- > partial loss of vision
- > double loss of vision
- > motor symptoms like weakness, ataxia
- > sensory changes and numbness
92
What is ataxia?
A group of conditions that affect balance, co-ordination and speech
93
Describe the anatomy of the peripheral nervous system:
- is the nerve fibres that travel to/from the spinal cord
- they innervate our body and leave the spinal cord as spinal nerves
- spinal nerves form plexuses in the body:
= lumbosacral plexus supplies lower limb
= brachial plexus supplies upper limb
- nerves which leave plexuses are called peripheral nerves
94
How can peripheral neuropathy arise?
- due to vitamin D deficiency
- patients get 'stocking and glove' symptoms where only their hands and feet are affected as these have the longest axons
- "dying back" neuropathies where the distal terminals of the longest fibres are affected first and then the symptoms of sensation loss progresses proximally
95
What does the sympathetic NS do to:
- heart rate?
- gut activity (motility and secretion)?
- pupil dilation?
- HR increased
- gut activity decreased
- pupils dilated
96
What does the parasympathetic NS do to:
- heart rate?
- gut activity (motility and secretion)?
- pupil dilation?
- HR decreased
- gut activity increased
- pupils NOT dilated
97
Describe the anatomy of the sympathetic NS:
- T1-L3
- preganglionic fibres are short and fibres synapse in the sympathetic trunk that runs parallel to the spinal cord
- post ganglionic fibres are long
98
Describe the anatomy of the parasympathetic NS:
- CN3,7,9,10 and S2-4
- preganglionic fibres are long and ganglia are found near the visceral organs that they innervate
- post ganglionic fibres are short
99
What do all preganglionic neurons release?
- are all cholinergic and release ACh
100
What do postganglionic neurons release?
- post ganglionic neurons that are SYMPATHETIC are adrenergic and release NA (except those innervating sweat glands which are cholinergic and release ACh)
- postganglionic fibres of the parasympathetic system are cholinergic and release ACh
101
Where are cell bodies of pre/postganglionic neurons found?
- cell bodies of preganglionic neurons are always found in the CNS
- cell bodies of post-ganglionic neurons are always found somewhere outside the CNS in a ganglion
102
What are the benefits of pain?
- warns
- protects
- for survival
103
What are the disadvantages of pain?
- induces a catabolic response which is good for wound healing but bad in chronic pain
- catabolic response involves:
- > CNS = anxiety, depression, sleep disturbance
- > CVS = increase HR and BP
- > respiratory issues = hyperventilation
- > GI = vomiting, nausea
- > GU = urinary inhibition
- > muscle issues = restless, immobility
104
Which fibres types are fast at transmitting?
A-alpha, A-beta and A-delta fibres
105
Which fibres types are slow at transmitting?
C fibres
106
What are the 4 stages of nociception?
1) transduction - sensing the stimuli
2) transmission - to the CNS
3) modulation - amplifying/dampening the signal
4) perception - feeling pain
107
What areas of the brain are involved in how we sense pain and how intense it is?
The ACG (anterior cingulate gyrus) and the prefrontal cortex (PFC)
108
How can you differentiate referred and radicular pain?
Radicular pain has other symptoms associated with it like numbness, and radicular pain does not
109
What characteristics should be assessed in pain?
- site
- radiation
- relieving factors
- exacerbating factors
- quality
- duration
- frequency
- periodicity
- impact on quality of life
- perpetuating factors
- patients knowledge and expectations
110
What is multi-modal pain treatment (the 6P's)?
```
1 - prevent
2 - physical therapies
3 - pathology
4 - pharmacotherapy
5 - procedural
6 - psychological
```
111
Describe drugs used in the three step analgesic ladder:
STEP 1
- paracetamol
- NSAIDS (can cause GI upset so monitor use)
STEP 2
- codeine
- dihydrocodeine (is a prodrug that is converted into morphine, but is not effective in all people as needs P450 enzyme to work and 10% caucasians and 2% asians have P450 deficiency)
STEP 3
- tramadol
- morphine
- methadone
- hydromorphine
- diamorphine
112
What is fibromyalgia?
long term condition causing pain all over the body
113
What is NNT and its values for ibuprofen, paracetamol and codeine?
Number needed to treat (i.e. number of patients who get treated so that there is one beneficial outcome)
- ibuprofen = 2
- paracetamol = 5
- codeine = 17
114
What is the difference between psychiatry and psychology?
```
Psychiatry = medically ill brains
Psychology = normal brains under distress
```
115
What is cauda equina syndrome?
Damage to the cauda equina nerves resulting in a loss of function in the lumbar plexus (a lower motor neuron lesion)
116
What is pulsed radiofrequency and how is it used?
- electrical field created around an electrode- technique used to treat pain
- the electrode is the size of a needle
- energy pulsed through the electrode so it doesn't get hot and needle tip placed near nerve and treatment applied for 2-8 minutes
117
What is the typical resting membrane potential of neurons?
-60 to -70mV
118
How is RMP produced and how can it be measured?
- Due to the ion distribution in cells, there is more Na and Cl inside cells and more K outside of cells
- measured by electrophysiology = placing an electrode into a cell body and measuring the difference between the internal and external environment
119
What is an action potential and how is an action potential generated?
It is a brief and dramatic change in membrane potential of a cell, that causes a neuron to become a lot more positive (depolarises) and it reaches a threshold value when the action potential then fires.
- ions pass through ion channels on the neuronal membrane
- 1) voltage gated ion channels open/close depending on membrane voltage of the cell
2) ligand gated channels open/close when a ligand binds
120
What is the equilibrium potential (reversal potential)?
When there is no net gain or loss of ions and the number of ions entering equals the number of ions leaving
121
Describe the pattern of membrane potential changes that occur when a cell fires an action potential:
1) threshold value is reached and voltage gated Na channels open up and Na enters the cell
2) as the cell becomes more positive, the Na channels close (peak is reached on graph)
3) The slow opening of voltage gated K channels triggers repolarisation and K ions move out of the cell (it becomes less +ve and graph decreases)
4) voltage gated K channels are slow to close and more K ions leave than necessary = hyperpolarisation - where the cell becomes slightly more negative than the RMP
122
What triggers depolarisation of a cell?
Fast opening of voltage gated Na channels
123
What triggers repolarisation of a cell?
Slow opening of voltage gated K channels
124
Describe how drugs used therapeutically work and give examples:
- lidocaine: local anaesthetic that is a Na antagonist stopping opening of Na channels and blocking synaptic transmission
125
What is an axon hillock?
A specialised part of a neuron cell body where an axon connects to it and where an action potential is initiated
126
How does a wave of depolarisation occur down a nerve?
When a cell body depolarises due to an AP, the area in front of the cell also depolarises
127
What features of a neuron increase AP propagation speed?
1) increasing axon diameter
2) insulating the axon with myelin = this causes saltatory conduction as action potentials 'jump' between the nodes of Ranvier
-> current always takes the path of least resistance
128
What produces myelin in the:
a) CNS?
b) PNS?
a) oligodendrocytes
| b) schwann cells
129
What is Güillan-Barré syndrome?
an infection that causes an inflammatory response and the inflammatory cells damage the myelin preventing AP conduction
- presents with progressive motor weakness, motor and sensory loss
130
Describe what happens in response to an action potential at a neurosynaptic terminal:
- action potential causes depolarisation of the pre-synaptic terminal
- voltage gated Ca channels open and there is Ca influx into the presynaptic terminal
- vesicles containing neurotransmitter fuse with the presynaptic membrane and release their chemicals into the synaptic space
- the neurotransmitters interact with receptors on the post-synaptic membrane and this can cause depolarisation to occur in the post-synaptic cell
131
What are the two types of post-synaptic terminal?
1. Excitatory post-synaptic potentials (EPSP's)
| 2. Inhibitory post-synaptic potentials (IPSP's)
132
Describe how EPSP's function:
- these post-synaptic terminals show a graded response (unlike AP where it has an all or nothing response)
- EPSP's cause the post-synaptic membrane potential to move closer to the threshold and increase the probability that an AP will be fibres from the post-synaptic terminal
133
Describe how IPSP's function:
- these cause hyperpolarisation of the post-synaptic membrane and cause it to move further away from its threshold, and reduces the probability that an action potential is fired
134
What is temporal summation?
- depends on frequency of firing
- EPSP's can add up and when a 2nd EPSP comes into the post-synaptic terminal shortly after a 1st one, their energies can build up and the cell is driven to threshold and an AP fired
135
What is spacial firing?
- when firing occurs at the same time but at multiple sites on a cell
- inputs come into the post-synaptic cell at different areas but all at the SAME TIME
- their energies build up and result in the firing of an action potential
136
Name an excitatory amino acid neurotransmitter:
glutamate
137
Name an inhibitory amino acid neurotransmitter:
GABA - gamma-aminobutyric acid
138
Describe two conditions that can occur from disruption of cholinergic nerve synaptic transmission:
1) botulism - the botulinum toxin disrupts exocytosis of the neurotransmitter and no release of ACh = muscle weakness and paralysis of diaphragm -> respiratory failure
2) myasthenia gravis - inflammatory disease where AB's bind to ACh receptors on post-synaptic membrane and causes mild muscle weakness, especially in limbs and throat
139
What is divergence in terms of neurons?
Where one neuron synapses onto many different neurons in a network and the signals dissipate out into a much wider network
140
What is convergence in terms of neurons?
When one post synaptic membrane receives multiple inputs from a number of different pre-synaptic cells
141
Name some methods of localising cerebral function:
1 - EEG = electroencephalography which records brain electrical activity and allows the activity of the brain to be examined when carrying out cognitive functions is response to a stimulus
2 - TMS = transcranial magnetic stimulation where an electromagnet is used to stimulate brain activity causing depolarisation and an electrical coil over the scalp stimulates certain brain areas
3 - PET
4 - functional MRI looks at blood flow to active brain areas
142
What are the fibres like that make up grey matter?
Unmyelinated
143
What are the fibres like that make up white matter?
Myelinated
144
Describe the anatomy of the central sulcus:
Divides the frontal and parietal lobes
145
Where is the pre-central gyrus found and what is its function?
anterior to the central sulcus, is where motor output is initiated
146
Where is the post-central gyrus found and what is its function?
posterior to the central sulcus and is where sensory input is received
147
How many neurons are involved in:
a) Ascending pathways?
b) Descending pathways?
a) 3
| b) 2
148
Between what structures does the corticospinal tract conduct impulses?
- brain to spinal cord
149
Between what structures does the corticobulbar tract conduct impulses?
- brain to cranial nerves
150
Describe the route of the corticospinal pathway:
- corticospinal neurons arise in precentral gyrus
- they pass through internal capsule into brainstem
- once in the medulla the fibre decussate in an area called the pyramid of the medulla (only 75-90% fibres decussate)
- the fibres that decussate travel down the lateral corticospinal tract and synapse onto a secondary neuron in the anterior horn of spinal cord grey matter
- the fibres that didn't decussate in the medulla travel down the ventral corticospinal tract and then decussate at spinal cord level to synapse with secondary neuron in the anterior horn of spinal cord grey matter
- neurons from the anterior horn then project to limb and axial muscles
- the fibres that decussate in the medulla control limb movement
- the fibres that decussate in the spinal cord and NOT at the medulla control less precise trunk movements
151
Describe the route of the corticobulbar pathway:
- corticobulbar neurons are found in the precentral gyrus and their neuronal extensions synapse with interneurons/motor neurons that are located in cranial nerve nuclei
- cranial nerve nuclei of all cranial nerves (except CN 1 and 2) are found in the brainstem
- axons of corticobulbar tracts terminate in the nuclei of the cranial nerves
- the lower motor neurons of cranial nerves leave the nuclei
152
What are the parts of the brainstem and what cranial nerve nuclei are found in each section?
- midbrain
- > CN 3 and 4
- pons
- > CN CN 5, 6, 7 and 8
- medulla
- > CN 9, 10, 11 and 12
CN giving motor supply are found more medially and CN giving sensory supply more laterally. The CN that give both have two nuclei.
153
What is a gyrus?
A ridge on the cerebral cortex that is surrounded by sulci
154
What does the lateral sulcus separate?
Parietal and temporal lobes
155
What are the divisions of the temporal lobe?
superior temporal gyrus
middle temporal gyrus
inferior temporal gyrus
156
Describe the anatomy of the ventricular system of the brain:
- ventricles are the chambers in the brain where CSF is found
- CSF is mainly made in the lateral ventricles but some is produced in all ventricles by the choroid plexus (an invaginated area of pia mater with a spongy appearance)
- 500ml CSF produced per day
- route of CSF travel:
- > lateral ventricles (posterior and anterior horns) -> interventricular foramen -> third ventricle -> cerebral aqueduct -> 4th ventricle -> central canal (passes though the brainstem and down into the spinal cord)
157
Where is the hippocampus found and what is its function?
Elongated ridges on the floor of each lateral ventricle involved in memories and 3D spacial awareness
158
What are basal ganglia and what is their function?
- areas of grey matter in the brain that influence motor activity and inhibit unwanted/inappropriate movements
159
Describe the anatomy of a coronal section of the brain including the basal ganglia:
(see stripy notes page 3 HNN revision)
- internal capsule is a column of white matter that carries information past the basal ganglia and separates the basal ganglia
- medial to internal capsule = caudate nucleus (superior) and thalamus (inferior)
- lateral to internal capsule = putamen (superior) and globus pallidus (inferior)
- putamen + globus pallidus = lentiform nucleus
- lentiform nucleus + caudate nucleus = corpus striatum
- the corpus callosum is a sheet of nerve fibres that connects and allows communication between the two hemispheres
160
What is the anterior commissure?
All areas of the corresponding hemispheres are connected by the corpus callosum except the temporal areas which are connected by the anterior commissure
161
What are the 4 parts of the corpus callosum?
- rostrum (anterior)
- genu
- trunk
- splenium (posterior)
'Really good thanks Sir'
162
What are the corona radiata?
The most prominent projection fibres hat radiate through each cortex and come together in the brainstem
163
What is the insular cortex?
Region of the cerebral cortex that is deeply folded in the lateral sulcus and involved in consciousness, emotion and homeostatic regulation
164
Describe the diameter, myelination and function of:
1) A-alpha fibres
2) A-beta fibres
3) A-delta fibres
4) C fibres
1) myelinated, 13-20um, proprioceptors
2) myelinated, 6-12um, mechanoreceptors
3) myelinated, 1-5um, pain and temperature sensors
4) unmyelinated, <1.5um, pain and temperature and information about itch
165
What is periaqueductal grey matter?
- grey matter located around cerebral aqueduct (connecting 3rd and 4th ventricles) in the midbrain
- receives afferent signals from nociceptive neurons
- has enkephalin-producing neurons that suppress pain
- PAG neurons release chemicals that bind to opioid receptors on incoming C and A-delta pain fibres
- this stops pain being transmitted up the spinothalamic tract to the VPL nucleus in the thalamus
- involved in modulation of pain
166
What does fasciculus mean?
A bundle or axons
167
What does funiculus mean?
A tract of axons
168
Describe how the neural tube develops:
- neural plate forms (thickened area of cells on the ectoderm)
- neural plate thickens and is called the neuroectoderm
- neuroectoderm thickens and lateral edges elevate
- depressed mid region is called neural groove
- thickened edges are called neural folds
- neural folds approach each other in the midline forming the neural tube
- neural tube sinks into the mesoderm below and the overlying ectoderm repairs itself
- rostral end of neural tube becomes brain and the rest the spinal cord
169
Describe the anatomy of the neural tube:
- there is a floor plate (anteriorly) and a roof plate (posteriorly)
- the alar plate is the posterior half and contains sensory nerve components, will become the dorsal horns of the spinal cord
- the basal plate is the anterior half and contains motor nerve components, will becomes the ventral horns of the spinal cord
- the sulcus limitans separates the alar and basal plates
170
What two fibre types are involved in a monosynaptic reflex arc?
- proprioceptive afferent and a motor neuron efferent
