Spinal Cord Flashcards
Where do corticobulbar fibres go ?
To the contralateral side
What information does the dorsal column carry information on ?
Fine touch, proprioception and vibration
Describe the path of the dorsal column
1st order neurone enters spinal cord through the dorsal horn and goes upwards to the nucleus in the medulla where it synapses. It then decussates and runs to the thalamus. Synapsing again the neurones run to the post central gyrus through the internal capsule.
What Brodmann’s numbers are given to the post-central gyrus ?
2, 1 and 3
What information is carried via the lateral spinothalamic tract ?
Pain and temperature
Describe the path of the lateral spinothalamic tract
Neurone enters spinal cord through the dorsal horn and synapses onto the 2nd order neurone. It then decussates and begins to run upwards to the thalamus. At the thalamus it synapses again onto a 3rd order neurone and runs through the internal capsule to the post-central gyrus.
What is a reflex ?
An involuntary movement brought about by a sensory stimulus
What type of reflex is the stretch reflex ?
Monosynaptic or polysynaptic
Monosynaptic
What type of reflex is the flexor reflex ?
Monosynaptic or polysynaptic
Polysynaptic
UMN signs (5)
- Increased tone
- Spasticity
- Hyperreflexia
- No muscle wasting
- Babinski’s sign
LMN signs (4)
- Decreased tone
- Flaccidity
- Absent reflexes
- Muscle wasting
What are the 5 components of a reflex arc ?
- Receptor
- Sensory neurone
- Interneurone
- Motor neurone
- Muscles
May or may not include the interneurone.
What is Motor Neurone Disease ?
Disease affecting LWN in the ventral horn of the spinal cord. The neurone dies and as a result the muscle it supplied atrophies.
What is dysarthria ?
Dysarthria is a speech disorder caused by disturbance of muscular control. Leads to slurred speech.
What is dysphasia ?
Dysphasia can be receptive or expressive. Receptive dysphasia is difficulty in comprehension, whilst expressive dysphasia is difficulty in putting words together to make meaning.
What is dysphagia ?
Difficulty swallowing
What is reciprocal inhibition ?
When inhibitory interneurones inhibit the activation of a motor neurone.
What does Babinski’s sign show us ?
Extension of the toes indicates an UMN lesion.
How does a spinal cord transection present?
Think spinal shock
Initially there is flaccid areflexive paralysis with autonomic refeatures. After some days to weeks spinal cord shock wears off and this then present with spasticity and hyperrefelxia.
What motoneurones innervate extramural muscle fibres ?
Alpha
What motoneurons innervate intramural muscle fibres ?
Gamma
What sensory fibres respond to the rate of change of muscle length ?
1a
What sensory fibres respond to the change in tension of a GTO ?
1b
What type of fibres provide information of position sense of a still muscle ?
Type 2
Which muscles are controlled by lateral pathways ?
Distal
Which group of pathways control posture?
Ventromedial
What are the two Ventromedial pathways ?
Vestibulospinal and Tectospinal
What does the VST do ?
Stabilises the head and neck movements
What does the TST do ?
Ensures the eyes remain stable when the body and head moves
Which pathways don’t decussate ?
Pontine and medullary RST
What do the RST pathways do ?
Use information on balance, posture and limb position to reflexively maintain postion.
Which muscles does the RST innervate ?
Trunk and antigravity muscles
Which part of the ‘motor brain’ innervates distal muscle units ?
Supplementary motor area
Which part of the ‘motor brain’ innervates proximal muscle units via the RST ?
Premotor area
Where do decisions on movement from the frontal and parietal lobes converge ?
(Broadmann’s area)
Area 6
Which subcortical region does information come from that travels to area 6 ?
Thalamus (Vlo/Ventrolateral nucleus)
What part of the basal ganglia fibres before limb movements ?
Putamen
What part of the basal ganglia fibres before eye movements ?
Caudate nucleus
Describe the Direct pathway of control
At rest the GP is constantly firing inhibitory messages to the Vlo. When the putamen is activated this inhibits the inhibitory signals from the GP and result in the Vlo activating the SMA. This results in the selection of specific motor actions.