Cerebral motor control Flashcards
What is the definition of functional segregation?
Different areas that control particular aspects of movements
What type of tracts are the corticospinal and corticobulbar tracts?
Pyramidal tracts (major descending)
What is the corticospinal tract responsible for?
The corticospinal tract is a motor pathway that carries efferent information from the cerebral cortex to the spinal cord. It is responsible for the voluntary movements of the limbs and trunk.
Where are the first order neurones located in terms of the corticospinal tract?
Primary motor cortex
What is the function performed by the corticobulbar tract?
Provides voluntary movements of body and face
What are the four types of extrapyramidal tracts?
1) Vestibulospinal
2) Tectospinal
3) Reticulospinal
4) Rubrospinal
Where is the primary motor cortex located?
Resides within the precentral gyrus anterior to the central sulcus.
What is the function performed by the primary motor cortex?
Such a cortex is responsible for controlling fine, discrete, precise voluntary movements and transmits descending signals to execute movements.
What is the function performed by the premotor cortex?
Concerned with movement planning and regulates externally cued movements
What area is responsible for planning internally cued movements?
Supplementary motor area
What structure is included in the midbrain?
Cerebral peduncles
Where do the majority of descending motor fibres decussate?
Medulla
What tract is formed from decussated upper motor neurone fibres?
Lateral corticospinal tract
What tract is formed from the ipsilateral upper motor neurone fibres?
Anterior corticospinal tract
Which muscles are innervated by the anterior corticospinal tract?
Trunk (axial) muscles
Which muscles are innervated by the lateral corticospinal tract?
Limb muscles
Who is the primary motor cortex arranged?
Somatopically
Which brainstem cranial nuclei are responsible for innervating the extra-ocular muscles?
Oculomotor, trochlear and abducens nerve
Where do the upper motor neurones synapse within the corticobulbar tract?
Synapse within the brainstem cranial nuclei
What structures are innervated by the facial nerve?
Muscles of the face
What structure is innervated by the hypoglossal nerve?
Tongue
What structures are innervated by the trigeminal nerve?
Muscles of mastication
Where are the lower motor neurones located within the extrapyramidal tracts?
Within the brainstem nuclei
Which extrapyramidal tract is responsible for stabilising the head during body movements, and coordinates with eye movements?
Vestibulospinal tract
What is the function of the vestibulospinal tract?
Stabilises head during body movements or as head moves. Coordinate head movements with eye movements and mediates postural adjustments.
What is the function of the reticulospinal tract?
Most primitive descending tract – from medulla and pons. Changes in muscles tone associated with voluntary movement and concerned with postural stability.
What is the function of the tectospinal tract?
From superior colliculus of midbrain. Orientation of head and neck during eye movements.
Where within the midbrain are the lower motor neurones arise from for the tectospinal tract?
Superior colliculus
Where do the lower motor neurones arise from for the rubrospinal tract?
Red nucleus of the midbrain
What is the function of the rubrospinal tract?
Innervates lower motor neurones of flexors of the upper limb. The corticospinal tract dominates rubrospinal activity.
What are the negative signs for a patient with an upper motor neurone lesion?
There is a loss of voluntary motor function
Paresis (graded weakness of movements)
Paralysis (plegia): Complete loss of voluntary muscle activity
What are the four main positive signs of an upper motor neurone lesion?
Spasticity: Increased muscle tone
Hyperreflexia: Exaggerated reflexes
Clonus: Abnormal oscillatory muscle contractions
Babinski’s sign