Lecture 38: Auditory Pathways

Question 1

Conduction Deafness

Answer 1

• obstructed or altered sound transmission to TYMPANIC MEMBRANE or OSSICLE CHAIN

Question 2

Sensorineural (Nerve) Deafness

Answer 2

• damaged to COCHLEA, cochlear part of CN VIII, or COCHLEAR NUCLEI
• ipsilateral deafness

Question 3

Central Deafness

Answer 3

• damage to central pathways

- no actual deafness, but problems localizing sound and non-attentiveness to certain stimuli

Question 4

Wernicke’s Area

Answer 4

• comprehension of spoken and written language

Question 5

Broca’s Area (3)

Answer 5

• instruction for language output
• planning movements to produce speech
• providing grammatical function to words

Question 6

Area Analogous to Wernicke’s and Broca’s Area (Right Hemisphere)

Answer 6

W: interpret nonverbal signals from people

B: producing non-verbal communication including emotional gestures and intonation of speech

Question 7

What links Wernicke’s Area to Broca’s Area? What is its function?

Answer 7

Arcuate Fasciculations

• responsible for word repetition

Question 8

Lateral Temporal Cortex (what’s it do?)

Answer 8

• semantic knowledge (putting the pieces together)

- word recognition (meaning)

Question 9

Agnosia and Auditory Agnosia

Answer 9

A: inability to ID an object despite ability to perceive it

AA: inability to describe sound that is being heard

Question 10

Wernicke’s Area Lesion (“Word Salad”)

Answer 10

• receptive/fluent aphasia (defective language comprehension) –> expression is fine
• cannot understand what is said to them, cannot read (ALEXIA), cannot write comprehensible language (AGRAPHIA), display fluent paraphasic speech

Question 11

What is Alexia and Agraphia?

Answer 11

Alexia: unable to read

Agraphia: unable to write comprehensible language

Question 12

Broca’s Area Lesion

Answer 12

• expressive/non-fluent aphasia (defective expression) –> comprehension is fine
• severe = inability to speak (mutism)
• less-severe = short, habitual phases; slow, labored pronunciation

Question 13

Global Lesion

Answer 13

• non-fluent aphasia
• Lateral Sulcus lesion (hits Broca and Wernicke)
• receptive/expressive deficits, reading and writing impaired

Question 14

Transcortical Lesion (2)

Answer 14

• sensory (similar to Wernicke’s Lesion)
• motor (similar to Broca’s Lesion)
• can repeat

Question 15

Conduction Aphasia

Answer 15

• fluent aphasia
• supramarginal gyrus/articulate fasciculus lesion
• CANNOT repeat, speech interrupted by word-finding difficulties, writing impaired
• intact fluency, good comprehension, reading intact

Question 16

What does the Basilar Artery supply? (2)

Answer 16

• cochlea

- auditory nuclei of pons/medulla

Question 17

What does the Labyrinthine Artery supply?

Answer 17

• branch of AICA

- supplies inner ear and cochlear nuclei

Question 18

What does an occlusion of the AICA cause? (2)

Answer 18

• monoaural hearing loss

- can also cause ipsilateral face paralysis and inability to look toward side of lesion

Question 19

What does the Short Circumferential Branch of the Basilar Artery supply? (2)

Answer 19

• superior olivary complex

- lateral lemniscus

Question 20

What do the Superior Cerebellar and Quadrigeminal Arteries supply?

Answer 20

• inferior colliculus

Question 21

What do the Thalamogeniculate Arteries supply?

Answer 21

• medial geniculate bodies

Question 22

What does the M2 segment of the MCA supply?

Answer 22

• primary auditory and association cortices