Sensory Systems

Question 0

What is the difference between conduction and sensorineural deafness?

Answer 0

Conduction: prevents sound from reaching Organ of Corti. Ex) obstruction, otitis medius, defect in middle/external ear
Sensorineural: disease of the cochlea/ nerve

Question 1

Where does CN VIII enter the brainstem? Where do fibers of the auditory pathway decussate?

Answer 1

Cerebellopontine angle. Decussates in Trapezoid Body.

Question 2

What are the Weber and Rinne hearing tests?

Answer 2

Weber: Tuning fork at top of skull–> should hear equally in both ears.

Rinne: Vibrating tuning fork on mastoid process, then when in front of hear–> Air conduction > bone conduction.

Question 3

Describe the results of Weber and Rinne test in Conduction and Sensorineural deafness

Answer 3

Conduction: Weber (louder on affected side). Abnormal Rinne test.
Sensorineural: Weber (louder on unaffected side). Normal Rinne test.

Question 4

Which sensory modality is NOT relayed to the thalamus?

Answer 4

Olfactory

Question 5

What can Vit. B1 (Thiamine) intoxication lead cause?

Answer 5

Strachan Syndrome: sensorineural deafness, optic atrophy, and spinal ataxia.

Question 6

What is Kallman Syndrome (lack of formation of oflactory tract)?

Answer 6

Hypothalamic neurons rely on olfactory tract to migrate to destinations. GnRH neurons do not migrate.
Symptoms: anosmia, hypogonadism, and infertility

Question 7

Which nucleus does taste travel to? From which cranial nerves?

Answer 7

Solitary Nucleus.
CN VII (anterior 2/3 tongue) and IX (posterior 1/3 tongue)

Question 8

What is a common finding in Neurofibromatosis Type 2?

Answer 8

Bilateral acoustic neuroma. Rinne test is normal. Weber test may be normal is both ears affected equally.

Question 9

Describe the Pacinian and Meissner and Merkel corpuscles.

Answer 9

Pacinian: coarse spatial differences. Deep pressure, vibration, skin stretch.
Meissner/Merkel: fine spacial differences. Light touch, pressure.