anatomy of spine and tracts Flashcards
What sensations does the DCML pathway convey?
Fine touch, 2-point discrimination and proprioception.
describe the DCLM pathway
responsible for fine touch, proprioception and vibrations
1st order neurons
synapse to 2nd
decussate at medulla
Nucleus cuneatus in medulla for upper limb and nucleus gracillis for lower limb
synapse to 3rd in thalamus
primary somatosensory cortex in 4th
difference between ascending and descending pathways
asc- body yo brain
dec- brain to body
Describe the spinothalamic pathway.
response to pain, crude touch
reaches DRG from noicereceptors
decussation at 1 or 2 spinal levels above ventral horn for the anterior tract
Lateral synapses with first order neuron the same level it enters the spinal cord
ascends to contralateral thalamus
synapse in thalamus to third order
synapse to fourth order to carry various messages
Where is the somatosensory cortex located?
Post-central gyrus in parietal lobe.
What sensations is the lateral spinothalamic tract responsible for?
Pain and temperature.
What sensation is the anterior spinothalamic tract responsible for?
Crude touch.
What is the function of the spinocerebellar tracts?
They carry unconscious proprioceptive information to the ipsilateral cerebellum.
Do the fibres decussate in the spinocerebellar tracts?
No! They go to the ipsilateral cerebellum.
describe spinocerebellar pathway
1st order drg to spinal cord
2. Synapse to a second order neuron.
Ventral - deccusate then ipsilaterally then inferior peduncle
Dorsal - ipsilaterally with superior peduncle
Decussates within the cerebellum.
BOTH END UP IPSILATERAL
name 4 ascending pathways
dclm
Spinothalamic
spinocerebellar
spinoreticular
What sensation does the spinoreticular and spinotectal convey?🌍
deep chronic pain
Reflexive eye and head movements towards painful stimuli
What do corticobulbar tracts do
Supply the musculature of the head and neck on the motor nuclei on cranial nerves
Pathway of corticospinal tract
UMN leaves the motor cortex through corona radiata, internal capsules and descends to brain stem in cerebral peduncles
Travel down to form pyramids
Anterior supplies proximal muscles ie trunk via ventral root
Lateral supplies distal muscles involved with fine movement via ventral root
Base of pyramid. 90% decussate and travel to opposite side of body
10% stay on the same side
Function of lateral corticospinal tract
Distal muscles such as hands
Function of anterior corticospinal tract
Proximal such as the trunk
Symptoms of UMN SYNDROME
weakness
Paralysis
Decreased muscle tone
What is cauda equina
Spinal nerves from lower spinal cord that hang obliquely downwards
What are pyramidal tracts responsible for
Voluntary fine control and balance
What are extra pyramidal tracts responsible for
Coordination , posture and muscle tone
What is rubrospinal tract responsible for
Movement coordination
What is vestibulospinal tract responsible for
Posture and balance
What is tectospinal tract responsible for
Movement in response to visual reflexes
Symptoms of complete spinal cord lesion
Weakness in all muscle groups below lesion
Complete sensory loss below lesion
Spasticity and hyperflexia
UMN weakness signs
Increased muscle tone
Muscle atrophy
Hyper reflexia
Spasticity
LMN weakness
Decreased muscle tone Flaccid Muscle atrophy No plantar response Absent tendon reflexes
What can cause UMN weakness
Ms brain tumour
Stroke
What can cause lmn weakness
Slipped disc
Neuropathies
Damage to axons
Damage to axons
Difference between pyramidal and extra pyramidal tracts
Extra have deep nuclei in the brain stem
Pyramidal starts in the brain stem
Difference between dorsal and ventral root
Dorsal carries sensory info from the body to spinal cord via Dorsal root
Ventral , motor info from spinal cord to the body
Where can you find lateral horns and what do they do
In T1-L3
Between dorsal and ventral horns
Has cell bodies of pre ganglionic neurons of the sympathetic nervous system
Mediates fight or flight
Difference between pyramidal and extrapyramidal tract
Pyramidal originate in the cerebral cortex
Extra don’t and instead they’re UMN are located within nuclei in the brain stem and they send their axons down the spinal cord
Where does the rubrospinal tract originate
Red nucleus of midbrain
What are most spinocerebellar tracts react to
Proprioception
