Tracts Flashcards
What are the descending pyramidal tracts
corticospinal and corticobulbar
What type of tract is the corticospinal tract
Descending motor pyramidal tract
What does the corticospinal tract do
Conscious motor control of skeletal muscles
What are the two parts of the corticospinal tract and what is their function
Lateral = limb control Anterior = axil muscle control
What is the pathway of the corticospinal tract
From the pyramidal cells of the cerebral cortex, through the posterior limb of the internal capsule, through the cerebral peduncle, to the brainstem and anterior medulla, form medullary pyramids, decussation of the pyramids, form lateral and anterior tracts down to spinal cord
Where does the corticospinal tract decussate
85% in the medulla (lateral)
15% remain ipsilateral until reach white matter of spinal cord at the level of exit (anterior)
What happens if there is damage to the corticospinal tract
Contralateral symptoms
Upper motor neuron syndrome
- Hypertonia
- Hyperreflexia
- Clonus
- Babinski sign
- Muscle weakness
What type of tract is the corticobulbar tract
Descending motor pyramidal tract
What does the corticobulbar tract do
Movement of muscles of the head Swallowing Phonation Movements of tongue Facial expression
What does the corticobulbar tract do in terms of decussation
Most don’t decussate (remain ipsilateral)
Except the hypoglossal nerve
And the facial nerve that supplies the lower half of the face
Which nuclei does the corticobulbar tract supply
Trigeminal Facial Vagus Accessory Hypoglossal
What happens if the corticobulbar tract is damaged
If unilateral damage - mild muscle weakness
Hypoglossal - spastic paralysis of contralateral tongue muscles, deviation of tongue to contralateral side
Facial - spastic paralysis of muscles of contralateral quadrant of the face (lower face)
What is the path of the corticobulbar tract
From the ventral motor cortex, to the internal capsule, to the midbrain/pons/medulla
What is the function of the extrapyramidal tracts
Involuntary and autonomic control of all musculature
What is the role of the vestibulospinal tract and what is it’s pathway and is it ipsilateral/contralateral
Balance and coordination
From vestibular nuclei to spinal cord
Ipsilateral
What is the role of the reticulospinal tract/ what is it’s pathway and is it ipsilateral/contralateral
Medial - from pons to spinal cord, contralateral, facilitates voluntary movement and increases muscle tone
Lateral - from the medulla to the spinal cord, contralateral, inhibits voluntary movement and reduces muscle tone
What is the role of the rubrospinal tract/what is it’s pathway and is it ipsilateral/contralateral
Fine control of motor hand movements
red nucleus to spinal cord
contralateral
What is the role of the tectospinal tract, what is it’s pathway and is it ipsilateral/contralateral
Visual reflexes
from superior colliculi of midbrain to spinal cord
contralateral
What are the ascending sensory tracts
Dorsal-column medial lemniscus
Anterolateral system (spinothalamic)
spinocerebellar
What is the function of the dorsal column tract
Fine touch, vibration and proprioception
What are the two parts of the dorsal column pathway and what is their role
Lateral - fasciculus cuneatus = upper limb
medial - fasciculus gracilis = lower limb
Where does the dorsal column decussate
Medulla
What is the pathway of the dorsal column pathway
From the lower/upper limb to the nucleus gracilis/cuneatus, through the medulla (decussates), travel up as the medial lemniscus, to the thalamus, to the primary sensory cortex
What happens if you damage the dorsal column pathway
Loss of fine touch, vibration and proprioception
If in spinal cord, loss is ipsilateral
