Spinal Cord Flashcards
Dorsal column medial lemniscus (DCML) function.
Ascending sensory tract
Fine touch, conscious proprioception
Corticospinal tract function.
Descending motor tract
Controls body muscles
Spinothalamic tract function.
Ascending sensory tract
Pain, temperature, pressure
What is the difference between the pyramidal and extrapyramidal motor tracts structurally and functionally?
Structurally: pyramidal tracts pass through the pyramids of the medulla and extra-pyramidal don’t
Functionally: pyramidal control conscious movement, extrapyramidal control unconscious movement
Where does the dorsal column medial lemniscus (DCML) tract cross the midline?
Cross in the medulla
Where does the spinothalamic tract cross the midline?
Segmentally
Where does the corticospinal tract cross the midline?
Decussation of the pryamids in the medulla
What spinal cord tract crosses
- segmentally
- in the medulla
- at the decussation of the pyramids
Segmental: spinothalamic
Medulla: dorsal column medial lemniscus
Decussation: corticospinal
Describe the dorsal column medial lemiscus pathway.
First order neurons carry sensory information from the skin to the medulla
Second order neurons carry information from the medulla across the midline the the thalamus
Third order neurons carry information from the thalamus to the somatosensory cortex
In the _______ tract, what is the name of the area which carries information from the upper limb and the lower limb?
Dorsal column medial lemniscus (DCML)
Upper limb: fasciculus cuneatus
Lower limb: fasciculus gracilis
Which is medial and which is lateral?
Fasciculus cuneatus
Fasciculus gracilis
Fasciculus cuteatus: lateral
Faciculus gracilis: medial
Describe the spinothalamic tract pathway.
First order neurons carry sensory information from the skin to the dorsal horn of the spinal cord
Second order neurons carry information from the dorsal horn across the midline to the the thalamus
Third order neurons carry information from the thalamus to the somatosensory cortec
Where is the somatosensory cortex?
Postcentral gyrus
Describe the corticospinal tract pathway.
Upper motor neurons cross the midline at the decussation of the pyramids and carry information from the motor cortex to the anterior horn of the spinal cord
Lower motor neurons carry information from the anterior horn of the spinal cord to the muscles
What happens to
- tone
- muscle wasting
- fasciculation
- reflexes
- plantar reflex
- clonus
in UMN injuries?
Tone: increased Muscle wasting: none Faciculation: none Reflexes: increased Plantar reflex: up-going Clonus: present
What happens to
- tone
- muscle wasting
- fasciculation
- reflexes
- plantar reflex
- clonus
in LMN injuries?
Tone: reduced Muscle wasting: present Faciculation: present Reflexes: reduced Plantar reflex: down-going Clonus: none
If there are upper motor neuron signs, where must the lesion be?
Above the anterior horn of the spinal cord
spinal cord, brainstem, motor cortex
If there are lower motor neuron signs, where must the lesion be?
In the anterior horn or distal to anterior horn
anterior horn, spinal nerve
What causes upper motor neuron signs?
Loss of muscle inhibition from brain
What are fasciculations?
Twitches
What is clonus?
Involuntary, rhythmic, muscular contraction and relaxation
What is posturing and what does it indicate?
involuntary flexion/extension of limbs
brain injury
What are the two types of posturing?
Decorticate
Decerebrate
What occurs in decorticate posturing and what part of the brain is injured?
Arms flexed, legs extended
Cerebral hemispheres
What occurs in decerebrate posturing and what part of the brain is injured?
Arms extended, legs extended
Brainstem
What causes Brown-Sequard syndrome?
How does it present? Explain why.
Hemisection of the spinal cord
Ipsilateral paralysis
- corticospinal tract damage
- ipsilateral as it crosses the midline at the pyramids before reaching the spinal cord (left hemisection disrupts information for the left side of the body = ipsilateral)
Ipsilateral loss of proprioception and fine touch
- DCML damage
- ipsilateral as it crosses the midline in the medulla after travelling through the spinal cord (information from the left hand side of the body is disrupted by a left hemisection = ipsilateral)
Contralateral loss of pain and temperature
- damage to spinothalamic tract
- contralateral as it crosses as it enters the spinal cord and before ascending. it crosses and then ascends, where it would meet a hemisection (sensation from the left is disrupted by a hemisection on the right = contralateral)
A ____ spinal cord lesion would cause:
a) UMN signs
b) LMN signs
a) central
b) lateral
Disease progression of cervical myelopathy.
- Clumsy hands
- Loss of fine function of hans
- Loss of gross motor function of hands
- Impaired mobility
What is cervical myelopathy?
Central disc prolapse in the cervical spine
