Left hemisphere role
Dominant for language (in most people)
Handles:
Grammar (syntax)
Word meaning (semantics)
Speech production
Precise language processing
What is a stroke?
Loss of blood flow → brain tissue damage
What is aphasia
Language impairment due to brain damage
Apraxia of Speech (AOS)
Planning/programming problem
3 key signs:
Inconsistent errors
Worse with longer words
Choppy prosody
4 steps
L MMM
Linguistic
motor planning, motor execution, monitoring
Arcuate fasciculus
Function: Connects Broca’s ↔ Wernicke’s
Location: White matter tract in left hemisphere
Damage → Conduction aphasia:
Poor repetition
Types
Ischemic (most common): blockage
Hemorrhagic: bleeding
4 modalities
Speaking
Listening
Reading
Writing
Dysarthria
Execution problem (muscle weakness)
Which cranial nerve is especially important for phonation (laryngeal control)?
Vagus nerve (10)
Angular gyrus
Function: Reading & writing (links visual + language)
Location: Parietal lobe
Damage:
Alexia (reading problems)
Agraphia (writing problems)
Ischemic stroke signs and treatment
Signs:
Sudden weakness (one side)
Speech problems
Vision loss
Treatment:
Clot-busting drugs (tPA)
Non-fluent aphasias
Broca’s
Frontal
Effortful speech
Transcortical motor
Frontal
Similar to Broca’s but good repetition
Global
Large lesion
Severe impairment in all areas
5 domains of cognition
Attention
Processing speed
Memory
Executive function
Social cognition
What are the speech roles of CN V, CN VII, CN X, and CN XII?
Trigeminal 5- jaw movement
Facial 7- facial expression, lip movement
Vagus 10- resonance, phonaiton
Hypoglossal 12- tongue movement
“Zone of language”
A network in the left hemisphere including:
Broca’s area
Wernicke’s area
Arcuate fasciculus
Angular gyrus
Hemorrhagic stroke signs and treament
Signs:
Severe random headache
Nausea/vomiting
Rapid decline
Treatment:
Surgery
Fluent aphasias
Wernicke’s
Poor comprehension
Transcortical sensory
Like Wernicke’s but good repetition
Conduction
Poor repetition
Anomic
Focal vs diffuse TBIS
Focal → specific area
Diffuse → widespread damage
What is the role of the basal ganglia in motor speech?
Selection and scale
Broca’s area
Function: Speech production (motor planning for language)
Location: Left frontal lobe (inferior frontal gyrus)
Damage → Broca’s aphasia:
Non-fluent, effortful speech
Short phrases (“telegraphic speech”)
Good comprehension
Aware of errors → frustration
Brain systems
Frontal → executive control
Frontoparietal → attention
Temporal/hippocampus → memory
Brainstem → arousal
Lesion patterns
Anterior (frontal): non-fluent
Posterior (temporal): fluent
Types of TBIS
Closed (no skull break)
Open (penetrating)
What is the role of the cerebellum in motor speech?
Timing and error correction