Auditory Tracts

Question 1

In the monaural auditory tract, what is the first brainstem nucleus (in the medulla) the tract passes through?

Answer 1

dorsal cochlear nucleus

Question 2

What is the blood supply in the medulla to the dorsal and ventral cochlear nuclei?

Answer 2

labyrinthine A (a branch of AICA)

Question 3

What is the name of the structural area where the fibers of the monaural auditory tract decussate in the pons?

Answer 3

dorsal acoustic stria

Question 4

From the pons to the midbrain, in what structure do the auditory tracts ascend?

Answer 4

lateral lemniscus

Question 5

What is the blood supply to the lateral lemniscus?

Answer 5

short circumferential branches of the basilar A.

Question 6

In what structure of the midbrain is the “second” neuron located in the monaural auditory tract?

Answer 6

inferior colliculus

Question 7

What is the blood supply to the inferior colliculus?

Answer 7

superior cerebellar A.
and/or
P3 (quadrigeminal A.)

Question 8

In what structure do the axons leave the inferior colliculus?

Answer 8

brachium of the inferior colliculus

Question 9

In what thalamic nucleus do the auditory tracts synapse?

Answer 9

medial geniculate nucleus

Question 10

What is the blood supply to the medial geniculate nucleus?

Answer 10

thalamogeniculate aa.

Question 11

Upon leaving the thalamus, what structure do the auditory tracts pass through?

Answer 11

sublenticular limb of the internal capsule

Question 12

What is the blood supply to the internal capsule?

Answer 12

lenticulostriate aa.

Question 13

What is the final brain structure to receive the auditory tract information?

Answer 13

-anterior transverse temporal gyrus

primary auditory cortex

Question 14

What is the blood supply to the primary auditory cortex?

Answer 14

M2 of the MCA

insular segment

Question 15

At the end of the monaural pathway, is the auditory information contralateral or ipsilateral?

Answer 15

contralateral

Question 16

In the binaural auditory tract, what is the first brainstem nucleus (in the medulla) the tract passes through?

Answer 16

ventral cochlear nucleus

Question 17

Does the binaural tract ascend ipsilaterally, contralaterally, or bilaterally?

Answer 17

bilaterally

Question 18

Through what structure does the binaural auditory tract pass to ascend bilaterally as it goes from the medulla to the pons?

Answer 18

trapezoid body

Question 19

Where is the “second” neuron in the binaural auditory tract located?

Answer 19

superior olivary complex

(medial and lateral superior olivary nuclei

Question 20

Do the fibers cross back and forth between contralateral and ipsilateral sides as they ascend in the binaural auditory tract?

Answer 20

Yes

Question 21

List the brain features (in order) that the language tract passes through in the central pathway.

Answer 21

1) Wernicke’s Area
2) Arcuate fasciculus
3) Broca’s Area
4) Oral/Throat Region of Sensorimotor Cortex

Question 22

Clinical manifestation of a unilateral lesion to the cochlear N.

Answer 22

• sensorineural deafness

- ipsilateral deafness

Question 23

Clinical manifestation of a unilateral lesion to a part of the central auditory pathway.

Answer 23

• NOT deaf, due to extensive crossing of info
• hard to localize sound
• trouble focusing on one sound amongst noise

Question 24

Clinical manifestation of a unilateral lesion to the primary auditory cortex.

Answer 24

• difficulty interpreting a sound

- difficulty localizing sound

Question 25

Clinical manifestation of Auditory Agnosia.

Answer 25

• inability to identify a sound
• inability to describe a sound that’s heard

-d/t damage of sensory association cortex on BOTH sides of brain causes this, thus it’s rare

Question 26

What part of the brain is Broca’s Area?

Answer 26

L hemisphere

inferior frontal gyrus

Question 27

What is the clinical presentation for Broca’s Aphasia?

Answer 27

• loss of fluent word production
• loss of grammar
• can’t comprehend or repeat complex sentences
• CAN understand written/spoken language
• naming is preserved

Question 28

What part of the brain is Wernicke’s Area?

Answer 28

-superior temporal gyrus, supramarginal gyrus, and angular gyrus

Question 29

What is the clinical presentation of Wernicke’s Aphasia?

Answer 29

• can’t understand written/spoken language
• can’t write comprehensible language (agraphia)
• impaired naming and repetition
• “word salad”
• normal grammar, word production, and rate of speech

Question 30

What is the clinical presentation of Global Aphasia?

Answer 30

• receptive deficits
• expressive deficits
• can’t understand reading or writing
• both Broca’s and Wernicke’s Areas are affected

Question 31

What is the clinical presentation of Conduction Aphasia?

Answer 31

• can’t repeat
• difficulty finding words
• impaired writing
• reading, grammar, comprehension, naming are fine

Question 32

What parts of the brain are affected in Conduction Aphasia?

Answer 32

• supramarginal gyrus

- arcuate fasciculus

Question 33

What is the clinical presentation of Transcortical Sensory Aphasia?

Answer 33

• impaired comprehension and naming
• fluent production of speech
• preserved grammar
• CAN repeat (main difference b/w Wernicke’s Aphasia)

Question 34

What area of the brain is affected in Transcortical Sensory Aphasia?

Answer 34

-MCA/PCA watershed area

Question 35

What is the clinical presentation of Transcortical Motor Aphasia?

Answer 35

• impaired production of speech
• normal comprehension
• preserved naming and repetition
• grammar okay (main difference b/c Broca’s Aphasia)

Question 36

What area of the brain is affected in Transcortical Motor Aphasia?

Answer 36

-ACA/MCA watershed area

Question 37

What area of the brain is affected in Mixed Transcortical Aphasia?

Answer 37

-both ACA/MCA and MCA/PCA watershed areas