Exam #6: Corticomotor Function Flashcards
What is the origin, termination, and function of the corticospinal pathway?
Lateral corticospinal tract
- Origin= motor areas of cerebral cortex
- Termination= lateral neurons in ventral horn
- Function= control of distal/ lateral muscles of the body
Anterior corticospinal tract
- Origin= motor areas of cerebral cortex
- Termination= anterior neurons in ventral horn
- Function= control of proximal muscles of the body
What is the origin, termination, and function of the corticonuclear (corticobulbar) pathway?
Origin= motor areas of the cerebral cortex Termination= muscles of the head & neck Function= motor output to muscles of the head and neck
What is the origin, termination, and function of the rubrospinal pathway?
Origin= red nucleus Termination= same muscles as upper lateral corticospinal tract Function= questionable role in arm, hand, and finger movement
List the effects of lesions in the corticospinal tract.
1) Weakness
2) Extensor plantar reflex
Where is the motor cortex located, and what is its function?
Brodmann 4
- Voluntary movement i.e. implementation of the motor plan
Where is the premotor cortex located, and what is its function?
Brodmann 6
- Motor planning and learning activated or guided by external stimuli
*Develops the “motor plan” that is transmitted to the primary motor cortex
Where is the supplementary motor area, and what is its function?
This is a subset of nuclei located in Brodmann 6 (premotor cortex)
- Motor planning and preparing for sequential motor acts influenced by internal stimuli
- Coordinates movement between sides of the body
- Anticipatory postural adjustments
*Develops the “motor plan” that is transmitted to the primary motor cortex
Where are the frontal eye fields located, and what are their functions?
Brodmann 8
- Influences voluntary and memory guided eye movements
Describe the presentation of a lesion to the motor cortex.
A small lesion to the primary motor cortex will produce contralateral weakness without spasticity
Describe the presentation of a lesion to the premotor cortex.
Premotor area has a role in visually guided movement e.g. reaching & grasping
Describe the presentation of a lesion to the supplementary motor area.
Difficulty initiating or suppressing movement
Describe the presentation of a lesion to the frontal eye fields.
- Inability to make saccades not guided by an external target
- Cannot voluntarily direct eyes away from a stimulus
What is the difference between an ACA & MCA infarct based on the rough topographical map of the motor cortex?
ACA=
- Leg area of primary motor cortex
- Supplementary motor cortex
- Cingulate gyrus
MCA=
- Trunk, hand, and face area of primary motor cortex
- Premotor area
What is quadriplegia? What is tetraplegia?
These are two different terms for the same thing: paralysis of four limbs
- Caused by cervical transection
What is paraplegia?
Paralysis of lower two limbs
- Caused by transection below the cervical spine
What is paresis?
Weakness to voluntary muscle
What is quadriparesis?
Weakness in all four limbs
What is hemiparesis?
Weakness in one half of the body (2x limbs)
What is monoplegia?
Weakness to one limb
Explain the crossed paralysis found with some brain stem lesions.
Crossed paralysis is found in brainstem lesions & produces an “alternating hemiplegia”
List the symptoms and signs associated with an upper motor lesion.
Hyperreflexia
Hypertonia
Primitive reflexes
List the symptoms and signs associated with a lower motor lesion.
Weakness
Hypotonia
Hyporeflexia
Explain the pathophysiology of Brown-Sequard Syndrome.
This is a hemisection of the spinal cord that causes motor and sensory deficit
- No feeling at the level, ipsilateral to the lesion
- DC/ML lost on ipsilateral side
- Pain & temperature lost contralateral
- Monoplegia ipsilateral to the lesion
- Ipsilateral Babinski
What are the effects of lesions in the internal capsule (general motor and sensory deficits)?
Loss of motor and sensory contralateral to the side of the lesion
