Neuromotor Control Of Speech

Question 1

Motor System

Answer 1

Complex (14 sounds/sec)
Requires strength & precision

Hierarchical (higher centers = more refinement, inhibit lower centers if damaged)

• Idea/intention (prefrontal cortex)
• Movement planned/programmed
• Plan refined/coordinated
• Movement executed

Question 2

Motor Planning & Programming

Answer 2

Premotor Cortex

• Bilaterally active
• Program novel voluntary movements and posture fixation
• Receives motor intention from prefrontal cortex and tactile/visual signals from parietal lobe

Supplemental Motor Area

• Preprograms motor sequences already in motor memory
• Unilateral damage causes problems initiating motor movements on contralateral side
• Bilateral damage causes severe movement initiation problems, including speech

Question 3

Pyramidal System

Answer 3

Voluntary Movement
(Including muscles for speech)

Corticospinal Tract

• Voluntary/skilled movement in limbs/digits
• How it enters/travels???

Corticonuclear Tract

• Voluntary neural pathways that innervate cranial nerves via the brainstem
• Terminate at motor nuclei of cranial nerves at various points in the brainstem
• More ipsilateral fibers than corticospinal tract; some decussate

Corticopontine Tract

• Neural fibers project from primary motor cortex to ipsilateral pontine nuclei in ventral pons
• Carries info used in planning/initiating movements

Question 4

Extrapyramidal System

Answer 4

Involuntary Movement
Indirect activation pathway for movements
-Regulates reflexes, posture, and tone

Brainstem

• Reticulospinal Tracts: posture, tone, stabilize anchors
• Vestibulospinal Tracts: postures for sitting, standing
• Tectospinal Tracts: reflexive movements of head/eyes to stimuli
• Rubrospinal Tracts: duplicate corticospinal trains from midbrain to spinal cord

Basal Ganglia

• Voluntary/stereotypic movement
• Connections between cortex and thalamus
• Uses dopamine to function
• Inhibits unnecessary movement, adjusts automatic movements, and learned reflex/motor control
• Know thy anatomy, especially which parts get primary input and which send output!!

Cerebellum

• Interacts with pyramidal and extrapyramidal
• Ensures smooth coordination of muscles (posture/balance/sequential movements like walking; rapid/alternating/repetitive movements like speech)
• Error-control device for timing, strength, and motion
• Compares efferent commands against the intended targeted movements and adapts.adjusts to make more accurate
• Know thy anatomy and all those reciprocal connections

Question 5

UMN / LMN

Answer 5

Upper Motor Neurons

• All within CNS
• Synapse with the PNS, ire to activating effect on LMNs
• Send axons along corticospinal and corticonuclear tracts

Lower Motor Neurons

• Send motor axons into cranial/spinal nerves
• Carry out final complex movements
• Motor unit = LMN (nuclei, peripheral axon + branches) + innervated muscle fibers + myoneural juncture

Question 6

Bilateral Symmetry

Answer 6

Midline speech muscles and their CN nuclei are bilaterally innervated

• Makes speech more efficient
• Safety/compensatory mechanism so lesions don’t create severe weakness

Neuromuscular juncture = where nerves synapse wit muscle fibers