Case 2 Flashcards
which parts of the spine are convex anterior?
cervical and lumbar
which parts of the spine are concave anterior
thoracic and sacral
What is kyphosis?
A spine that is curving drastically outwards in the thoracic region
What can cause kyphosis?
Erosion of the anterior part of 1 or more vertebrae
What is lordosis?
A spine that is curving drastically inwards at the lumbar region
what can cause lordosis?
- Weakened trunk muscles
- Obesity
- Pregnancy
What is the spinous process of the vertebrae?
Bony projection that is directed backward and downward from the junction of the lamina
What are articular processes of the vertebrae?
Projections of the vertebrae that serve the purpose of fitting with adjacent vertebrae
What are transverse processes of the vertebrae? what attaches to them?
Lateral bony projections.
The ribs attach to them, as well as muscles and ligaments
What is the shape of the body of a cervical vertebra?
rectangular body
Is the superior aspect of a cervical vertebra concave or convex?
concave
Is the inferior surface of a cervical vertebra concave or convex?
convex
what is the shape of the vertebral foramen of cervical vertebrae?
triangular
Describe the spinous process of cervical vertebrae?
Short and usually bifid
What is the shape of the body of a thoracic vertebra?
columnar
What shape is the body of a thoracic vertebra in superior view?
heart-shaped
what is the shape of the vertebral foramen of thoracic vertebrae?
circular and small
What is the shape of the body of a lumbar vertebra?
massive columnar
What shape is the body of a lumbar vertebra in superior view?
Kidney shaped
what is the shape of the vertebral foramen of lumbar vertebrae?
triangular and intermediate in size
What are the three solid rods formed by the mesoderm after the notocord has developed?
paraxial mesoderm
intermediate mesoderm
lateral plate mesoderm
what does the lateral plate mesoderm segregate into?
somatic mesoderm and splanchnic mesoderm
What are the blocks of tissue formed by paraxial mesoderm and how many are there?
Somites, 44
What are the three regions that a somite develops into?
- sclerotome
- dermatome
- myotome
what does sclerotome develop into? (sclerotomal somitic mesoderm)
vertebral bone, cartilage, annulus fibrosis of the intervertebral disc
What does the dermatomal somitic mesoderm develop into?
dermis portion of the skin overlying the vertebral column
What does the myotomal somitic mesoderm develop into?
deep back and neck muscles associated with vertebral column
what does the notocord form in the intevertebral disc?
Nucleus pulposus
What is the nucleus pulposus?
the expansion of the notocord within the IV disk
What does the nucleus pulpuosis become surrounded by?
circularly arranged fibres constituting the annulus fibrosus
when do condrification centres appear in each vertebra?
6th week
what is the shape of the vertebral foramen of thoracic vertebrae?
afferent sensory neurons.
What type of nerve does the ventral root contain?
efferent motor neurons
Where do spinal nerves leave the vertebrae?
Through the intervertebral foramen.
What is a white ramus communicante?
Sympathetic fibres that carry information out of the spinal cord, to the sympathetic ganglion
What does a white ramus communicans connect
A sympathetic ganglion and its corresponding spinal nerve. When it enters the sympathetic ganglion it can travel up or down.
what type of nerve fibres do white ramus communicans contain?
myelinated pre-ganglionic sympathetic fibres.
What is a grey ramus communicante?
Sympathetic fibres that carry information from the sympathetic ganglion to the effector organ
What type of nerve fibre do grey ramus communicans contain?
unmylinated post-ganglionic sympathetic fibres.
What do grey ramus communicans originate from?
a sympathetic ganglion
What level does the spinal cord finish?
L2
what is the name given to the end of the spinal cord
Conus medullaris
what is the continuation of bundle of nerve fibres below the conus medullaris?
Cauda equina
What does a spinal nerve split into once it has passed through the intervertebral foramina what areas do the resultant structures innervate?
It splits into a dorsal and vetral ramus these innervate structures in front of and behind the vertebral column respectively.
what does the dorsal ramus of the spinal cord innervate?
structures posterior to the vertebral column
what does the ventral ramus of the spinal cord innervate?
structures anterior to the vertebral column
what is a dermatome?
an area of skin that is mainly supplied by a single spinal nerve
what are most abundant, unencapsulated nerve endings or encapsulated?
Unencapsulated
what is the combination of a nerve and its encapsulation often referred to as?
corpuscle
What information do ascending white matter tracts convey?
Sensory information to the brain.
What information do descending white matter tracts convey?
Voluntary motor control
How many laminae can the grey matter of the spinal cord be divided into.
10
How many lamina can the dorsal horn of the spinal cord be divided into?
6
What laminae constitute the superficial dorsal horn?
I & II.
What is the alternate name for lamina II of the grey matter?
The substansia gelatinosa
What is used to define the different laminae of the grey matter of the spinal cord?
Cell size.
What do laminae VII through IX of the grey matter contain?
The cell bodies of motor neurons, interneurones and the primary afferents from muscles and joints (proprioceptive afferents)
What are the three ascending systems in the spinal cord?
- anterolateral system
- dorsal column-medial lemniscus pathway
- tracts to cerebellum
What are the three main ascending tracts of the somatosensory system?
The dorsal column, the spinothalamic tract and the spinocerebellar tract.
What system does the spinothalamic tract come under?
-Anterolateral ascending system
what information does the spinothalamic tract convey?
pain temperature, non-disciminitive touch, temperature, pressure
What are the two tracts of the spinothalamic tract?
Ventral and lateral
what does the lateral spinothalamic tract convey?
pain and temperature
What does the ventral spoinothalamic tract convey?
non-discriminitve touch and pressure
Where do the 1st order neurones carrying pain temperature, non-disciminitive touch, temperature, pressure synapse?
Sunstantia gelatinosa of the dorsal horn of the spinal cord
What tract may fibres ascend of descend in when they first enter the spinal cord?
Lissauer’s tract
Where does the second order neurone decussate? (carrying information about pain temperature, non-disciminitive touch, temperature, pressure )
anterior white commissure
Where do the lateral and ventral spinothalamic tracts ascend to?
ventral posterior nucleus of the thalamus
What is the role of the dorsal column?
To convey information about discriminative touch, vibration and propriception
What is the role of the spinocerebellar tract?
to convey information regarding proprioception.
What type if nerve fibre is the spinocerebellar tract mediated by?
A-alpha fibres.
What do the three main ascending pathways all have in common?
They all have four neurons and they all decussate (cross over to the contralateral side). In each of the three pathways it is the second order neuron that decussates.
Where does the 1st order neurone carrying disciminitve touch and vibration synapse?
nucleus gracilis or cuteatus in the medulla
what are the two divisions of the dorsal column?
fasiculus gracilis and fasiculus cuneatus.
What is more medial, fasiculus gracilis or fasiculus cuneatus
fasiculus gracilis
Where do the second order neurons of the dorsal column pathway decussate?
medulla
Where do the second order neurons of the dorsal column pathway ascend to?
ventral posterior nucleus of the thalamus
What does the second order neuron of the dorsal column travel via?
The medial lemniscus pathway
What are the four brodmann’s areas of the somatosenrsory cortex?
1, 2, 3a and 3b
How much of the input from ventroposterior thalmus do brodmann’s areas 1&2 and 3a&3b receive respectively?
30% and 70%
What type of input does area 3b of the somatosensory cortex receive?
Cutaneous input.
What type of information does area 3a of the somatosensory cortex receive?
Proprioceptors in muscles.
What type of input does area 2 of the somatosensory cortex receive? what is it though to be important for?
Proprioceptors in joints. It is thought to be important for stereogenesis.
What type of input does area 1 of the somatosensory cortex receive? What is it thought to be important for?
input from rapidly adapting cutaneous mechanoreceptors. It is thought to be important for texture discrimination.
What are the four types of nerve endings that are though to be important for fine touch and proprioception?
Meiseners corpusles, Pacinian corpusles, Ruffini endings and Merkel endings.
What is the specialty of the meisener corpuscle?
Detection of vibrations between 10 and 50Hz
What is the specialty of the pacinian corpuscle?
Detection of vibrations around 250 Hz. They are far more sensitive to changes in pressure rather than consistent force. They are thought to be very important in the detection of pressure.
What is the specialty of a ruffini ending?
Stretch reception, it responds better to sustained pressure.
What is the specialty of a merkel ending
Detection of low frequency vibration 5-15 Hz
Where do the first order neurons of the spinocerebellar tract synapse?
Clarks nucleus.
What is the course of the second order neuron of the spinocerebellar tract?
It ascends the spinal cord to the cerebellum without decussating it then enters the cerebellum via the inferior cerebellar peduncle and terminates on purkinje cells.
What are the three components of the nociceptive system?
- peripheral nociceptive system
- central nociceptive system
- corticothalamic networks
What are the main functions of the nociceptive system?
protect the body from damage
inform the body when activity is putting excessive strain on the body
what are the three distinct types of pain?
Nociceptive/acute pain
Prolongued pain
Chronic pain
What is another name for chronic pain?
Neuropathic
what is another name for prolongued pain?
Inflammatory
What is the function of prolonged/inflammatory pain?
To prevent further damage
What is an example for prolonged/inflammatory pain?
sunburn
How does chronic pain differ from other types of pain?
It is different as it results from dysfunction or damage to the nervous system itself it is notably more difficult to treat, it also does not have a protective function
What is epicratic pain?
Fast, sharp pain
what is protopathic pain?
Long-lasting second pain
What type of fibre typically transmits fast pain?
A-delta.
What type of fibre typically transmits slow pain
C fbers
What is a polymodal receptor?
A receptor sensitive to more than one kind of stimulus.
Which type of fibres are polymodal?
C fibres
Which fibre has the biggest diameter? A-delta or C
A-Delta
Are A-delta fibre myelinated?
Thinly myelinated
Are C fibres myelinated
no
What are the different types of A-delta fibres?
mechanical and thermal
what do C fibres respond to?
chemical, mechanical and thermal stimuli
What does cell damage cause?
release of chemical mediators that can cause pain
What is the most powerful chemical mediator in causing pain?
Bradykinin
What substance made in anaerobic respiration can stimulate nociceptors?
lactic acid
what do prostaglandins do to pain receptors?
Increase the sensitivty of them
What is the axon reflex?
C-fibres transmit action potentials down their own branches back to the skin, leading to the release of chemical mediators
What is the result of chemical mediators released in the axon reflex?
Induce protein extravasation and vasodilation
where is nociceptive information transmitted to in the dorsal grey horn?
Nociceptive-specific neurones in rexed lamina 1 and 2
Other than Nociceptive-specific neurones, where as can pain be transmitted to?
Wide dynamic range neurones
What neurotranmitter do type A fibres use?
glutamate
What neurotransmitter do type C fibres use?
glutamate and substance P
what is peripheral sensitization?
reduction in the threshold for nociceptor activation
what is central sensitization?
activity-dependent increase in the excitability of the CNS
What causes peripheral sensitization?
An inflammatory ‘soup’ that activates receptors on nociceptos and makes them more sensitive to stimuli
What is hyperalgesia?
A stimulus is perceived as more painful than is should be
What is primary hyperalgesia?
decreased pain threshold at the core site of injury
what is secondary hyperalgesia?
Decreased pain threshold surrounding the core site of injury
what type of fibre is primary peripheral sensitisation mediated by?
C fibres
What type of stimuli is primary hyperalgesia responsive to?
thermal and chemical stimuli
what type of fibre is secondary peripheral sensitisation mediated by?
A-beta
What type of stimuli is secondary hyperalgesia responsive to?
mechanical
what is the process of central sensitization?
A-beta fibres now produce pain due to changes in sensory processing (i.e after a stimulus is picked up by A-beta fibres, it is changes to a pain signal at the level of the spinal cord)
What is modulation of pain?
Where ascending painful information is supressed
Wha are the two types of modulation of pain?
- segmental (local) antinociception
- Supraspinal (widespread) antinociception
How does TENS work?
delivers stimuli to stimulat alpha-beta fibres in hope that they will activate inhibitory neurones of lamina II (gate control theory)
What are the areas of the brainstem involved in supraspinal antinociception?
- periaqueductal gray (PAG)
- nucleus raphe magnus (NRM)
- locus coeruleus
Where is the PAG located?
Midbrain and upper pons, surrounds the cerebral aqueduct
Where is the nucleus raphe magnus located?
Lower pons and upper medulla
where is the locus coerulus located?
Posterior area of rostral pons
What initiates supraspinal antinociception?
Spinoreticular tract signals to the NRPG
What kind of neurones does the PAG contain?
enkephalinergic neurones
what is enkephalin?
Pentapeptide
what are the two types of enkephalin?
- one contains leucine
- one contains methionine
In supraspinal antinociception, what nuclei descend to the spoinal cord?
- NRM / nucleus raphe magnus
- LC / locus coeruleus
In supraspinal antinociception, what neurotransmitter does LC and NRM release in the spinal cord?
Serotonin
What is neuralgia?
Neuropathic pain
What is lacking in neuropathic pain?
A pianful stimulus/transduction
What is allodynia?
Pain arises from a touch that should not cause pain
What is hyperalgesia?
A painful stimulus is felt more painfully than is should be
what is paraesthesia?
unpleasant or painful feelings even when nothing is touching you
What is a prolapsed disk?
nucleus pulposus bulges out
what direction does the nucleus puplosus usually bulge in a prolapsed disc?
posterolaterally
why does nucleus puplosus usually bulge out posterolaterally in a prolapsed disc?
annulus fibrosis is relatively thin
where do most prolapsed discs occur?
L4-5 or L5-S1
What percentage of prolapsed discs occur at L4-5 or L5-S1
95%
What factor contributes to L4-5 or L5-S1 being the most common area for a prolapsed disc?
-movements are greater in this region
What is the most common nerve affected in a prolapsed disk?
Sciatic nerve
What two mechanisms cause sciatica?
- direct pressure
- chemicals which incite inflammation
what are osteophytes?
Bone spurs
What is the pharmological treatment for sciatica?
NDAIDs and painkillers
What is a discectomy?
Removal of the herniated nucleus pulposus
Why might you still feel back pain after a discectomy?
Formation of scar tissue near the nerve root
