Workbook - Spinal cord and spinal nerves Flashcards
What are the 3 layers of meninges surrounding the spinal cord?
- Dura mater
- Arachnoid mater
- Pia mater
How many layers does the dura mater consist of in the spinal cord?
One.
What are the denticulate ligaments?
Expansions of pia mater in cervical and thoracic regions.
-provide stability for the spinal cord against movement
What is the functional difference between the dorsal and ventral nerve roots?
Dorsal roots - sensory.
Ventral roots - motor.
Where do the dorsal and ventral nerve roots unite to form the spinal nerves?
Within the intervertebral foramen.
What do dorsal rami of the spinal nerves supply?
Intrinsic back muscles (epaxial) and a small strip of skin.
What do the ventral rami of the spinal nerves supply?
Most other skeletal muscles (hypaxial), limbs, trunk and skin.
Where is the epidural space located?
Between the dura mater and bone of the vertebral canal.
What is the filum terminale?
A delicate strand of fibrous tissue extending from the conus medullaris to the coccyx.
-pia mater modification
What is the conus medullaris?
Cone-shaped end of the spinal cord.
-around L1-2
Which spinal nerves does the cauda equina consist of?
- L2-5
- S1-5
- Co
What does the cauda equina descend through?
Lumbar cistern.
What is the lumbar cistern?
Enlargement of the subarachnoid space between the conus medullaris (~L2) and the inferior end of subarachnoid space and dura mater (~S2).
What does the lumbar cistern contain?
- Cauda equina
- Filum terminale
- CSF
What is the lumbar cistern used for clinically?
- Lumbar puncture
- Spinal anaesthesia
Where does the spinal cord terminate in the foetus?
Coccyx.
Where does the spinal cord terminate in newborns (neonates)?
~L3.
Where does the spinal cord terminate in adults?
~L1-2.
Where does the subarachnoid space terminate inferiorly?
Lower S2.
Where does the subarachnoid space terminate superiorly?
Cranial cavity.
What does the subarachnoid space contain?
CSF.
What are the diagnostic purposes of obtaining CSF samples?
- Meningitis
- Subarachnoid haemorrhages
- Guillain-Barre syndrome
Where is a needle normally inserted for lumbar puncture?
In the midline, between vertebrae L3/L4.
What surface landmarks are used to identify the site of lumbar puncture (between L3/L4)?
Horizontal line between the superior border of the posterior iliac crests»_space; L4 spinous process.
What are the layers pierced by a lumbar puncture needle?
- Skin
- Fascia/subcutaneous fat
- Ligaments
- Epidural space
- Dura mater
- Arachnoid mater
What are the signs and symptoms of L5/S1 nerve root compression?
- Leg pain (sciatica)
- Numb/weak legs
- Lower back pain
- Cauda equina syndrome
What are the nerve roots of the sciatic nerve?
L4-S3.
What is cauda equina syndrome?
Compression/damage to the cauda equina.
|»_space; lower back pain, leg pain/weakness, urinary incontinence
Which section of the spinal cord has the most white matter?
Cervical.
-all the fibres to the body travel here
What is the white matter of the spinal cord?
Paler tissue around the outside.
-consists of mainly nerve fibres and there myelin sheaths
What is the grey matter of the spinal cord?
Darker, butterfly-shaped centre.
-consists of mainly cell bodies and branching dendrites
What is confusing about the grey/white matter of the spinal cord?
When stained, the white matter appears dark and the grey matter appears light.
What are the main factors that help to determine the level of a spinal cord segment? (3)
- ratio of grey to white matter
- size of the ventral horns
- presence/absence of lateral horns
How does the ratio of grey to white matter differ throughout the cord?
General a larger proportion of white matter near the top of the cord.
-very little in the sacral region
At which spinal cord levels are the ventral grey horns enlarged, and why?
Cervical and lumbosacral enlargements.
-motor innervation to arms and legs
At which spinal cord levels is a lateral grey horn/column present, and what is it involved with?
T2-L1.
-contain cell bodies of the sympathetic division of the autonomic system
Where in the spinal cord is the dorsal white matter divided into 2 columns on each side?
Above T6.
- Gracile fascicle (med)
- Cuneate fascicle (lat)
What are the main 2 ascending sensory pathways from the body?
- Spinothalamic tract
- Dorsal column pathway
What type of information does the spinothalamic tract contain?
Pain and temperature.
-some touch
Does the spinothalamic pathway runs ipsilaterally or contralaterally in the cord?
Contralaterally.
-synapses at level of entry
In which region of the cerebral cortex does the spinothalamic pathway terminate?
Brainstem.
-venteromedial medulla
What does the spinothalamic pathway become at the medulla?
Spinal lemniscus.
Where does the 2* sensory area for somaesthetic information lie?
In the parietal lobe.
-posterior to the PCG
What type of information is carried in the dorsal column pathway?
- Discriminative tough (2-point)
- Proprioception
Where do the fibres of the dorsal column pathway run at the level of the spinal cord?
Ipsilaterally.
-in gracile/cuneate fascicles
Where do the fibres of the dorsal column pathway run at the level of the closed medulla?
Ipsilaterally (/contralateral).
-gracile/cuneate nuclei
Where do the fibres of the dorsal column pathway run at the level of the open medulla?
Contralaterally.
-medial lemniscus
Where do the fibres of the dorsal column pathway synapse and cross over?
At the level of the closed medulla.
What does the dorsal column pathway become at the medulla?
Medial lemniscus.
Where does the gracile fascicle carry information from?
Below T6 & lower limb.
Where does the cuneate fascicle carry information from?
Above T6 & upper limb.
If there is a lesion below T6 involving one side of the spinal cord, why might light touch and pressure sensitivity still be present over the whole body?
Both pathways do a bit of touch and pressure.
-compensation
CASE STUDY
- proprioception and vibration sense lost in left leg
- analgesia and thermoanaesthesia in right leg
Where is the lesion?
Left side of spinal cord below T6.
- dorsal column runs ipsilaterally
- spinothalamic tract runs contralaterally
What effect would a left sided hemisection below T6 have on leg movements?
Upper motor neuron deficit»_space; loss of proprioception on LHS.
-Can move legs, but don’t know how
