Chapter 55 Flashcards
What is the function of the primary motor cortex?
- excites “movements” through excitation of a single motor neuron.
- topographically laid out (head and face laterally, hands arms, legs, then feet most medially and in the fissure
What is the fucntion of the premotor area?
- generate complex “patterns” of movement
- generates a “mirror image” of the action to be performed and then sends this “symphony” of actions to the posterior preomotor cotex
What is the function of the supplementary motor area?
-fucntions in concert with the premotor area to provide body-wide attitudinal movements, fixation movements of the head and eyes, and so forth, as background for the finer motor control of the arms and hands by the premotor area and primary motor cortex
What is the function of Broca’s area?
- Premotor function of “word formation”
- also associates the respiratory actions of speaking with the movements of the mouth and tongue.
What other areas are located superiorly to Broca’s area?
- voluntary eye movement area
- head rotation area
- hand skill area
What is the path of the corticospinal tract? Where does it decussate?
motor cotex–> posterior limb of the internal capsule–> middle thrid or the cerebral peduncle–> longitudinal fascicles of the pons (eggs)–> pyramids (deccusation in caudal medulla)–> lateral and anterior CST
What is the function of the Giant Betz cells?
receive signals from the motor cortex and send short collaterals back to the cortex which inhibit adjacent regions of the cortex and sharpen the excitatory signal.
What is the prupose of neurons passing form the cortex to the caudate and putamen then descending?
-control body posture and muscle contractions
Neurons from the cortex to the red nucleus continue to what tract?
rubrospinal
Motor nuclei that deviate into the reticular formation and vestbular nuclei go where? How about deviations into the cerebellum?
- Reticulospinal tract
- vestibulospinal tract
- reticulo and vestibulo cerebellar
Why is the corticorubrospinal system important? What is its clinical significance in the case of a lesion?
- red nucles contains somatographic representation of major muscle groups and serves as a pathway for the transmission of discrete movement from the cortex to the spinal cord
- In the case of a lesion above the red nucles, major movements like wrist movements and arm movements can still be ochestrated, but fine movements are absent.
What is the importance of vertical columns in the spinal cord?
- Typically act as a unit to stimulate a group of synergistic muscles
- can amplify and stimulate large numbers of pyramidal cells (leading to muscle excitation)
What is the rold of somatosenory feed back to the motor cortex?
-controls the precision of muscle contraction
What are some simple somatosensory signals that help modulate motor function?
- Muscle spindle tightness
- pressure on the skin during contraction of the hand to guage grip tightness
What is the result of a lesion involving the giant Betz pyramidal cells?
-varying degress of paralysis of the represented muscles
-definite loss of voluntary control of discrete movements of the distal segments of the limbs, especially of the hands and fingers. —-> THE ABILITY TO CONTROL FINE MOVEMENTS OF THE DISTAL LIMB AND FINGERS ARE GONE.
