USMLE Step 1 Neuroanatomy Review 27 04 Descending Motor Tracts

USMLE Step 1 Neuroanatomy Review 27 04 Descending Motor Tracts

On these “Gold Standard Step 1 Facts” pages you will find Free:

  • USMLE Audio Review files from our “Gold Standard USMLE Reviews”
  • Transcriptions of those files
  • And videos (as they become available)

The idea is that you can review for the USMLE online by:

  • Listening to the Audio
  • Following along with the transcription
  • Or by watching the video (if available)

If you like what you here, you can purchase the entire Gold Standard Step 1 MP3 audio USMLE review for your iPhone, iPod, or computer here.

Let’s start our USMLE Review with Anatomy from the Gold Standard USMLE Step 1 Audio Review program.

Play USMLE Audio MP3 27 04 Descending Motor Tracts Below

Begin 27 04 Descending Motor Tracts Transcription

Now we’re going to take a look at descending motor tracts.

Student doctor, what descending motor tracts contain crossing corticospinal fibers?

  • This is the pyramidal decussation.

Now, where are the uncrossed corticospinal fibers located?

  • In the pyramids.

What cerebellar structure conveys tracts to the cerebellum via the inferior cerebellar peduncle? 

  • The accessory cuneate nucleus.

 What tract contains rubroolivary and reticulothalamic fibers? 

  • This is our old friend, the central tegmental tract.

Student doctor, what relay nucleus located on the ventral surface of the pyramids, conveys fibers to the cerebellum, which become the stria medullaris of the rhomboid fossa? 

  • The arcuate nucleus.

What tract conveys fibers to the cerebellum and mediates unconscious proprioception from the lower extremities? 

  • The dorsal spinocerebellar tract.

Student doctor, which tract conveys fibers to the cerebellum and mediates unconscious proprioception from the lower extremities? 

  • The ventral spinocerebellar tract.

 Student doctor, what type of fibers does the inferior salivatory nucleus of cranial nerve nine give rise to? 

  • The inferior salivatory nucleus of cranial nerve nine gives rise to general visceral efferent fibers, GVE, which synapse in the otic ganglion.

 Now, what type of fibers does the hypoglossal nucleus of cranial nerve twelve give rise to? 

  • The hypoglossal nucleus of cranial nerve twelve gives rise to general somatic efferent fibers, GSE, which innervate the intrinsic and extrinsic tongue muscles.

  Student doctor, what type of efferent fibers does the nucleus ambiguus of cranial nerves nine, ten, and eleven give rise to? 

  • The nucleus ambiguus of cranial nerves nine, ten, and eleven contain special visceral efferent fibers, SVE, which supply the larynx and pharynx. 

  What kind of neurons does the ventral horn of cranial nerve eleven contain? 

  • The ventral horn of cranial nerve eleven contains motor neurons of the spinal accessory nerve. 

  What tract replaces the dorsolateral tract of Lissauer from C3 up to the midpons? 

  • The spinal trigeminal tract replaces the dorsolateral tract of Lissauer. 

 What nucleus does the spinal trigeminal nerve replace? 

  • The spinal trigeminal nucleus replaces the substantia gelatinosa of the spinal cord. 

  What nuclei of cranial nerve eight convey fibers to the cerebellum? 

  • The inferior and medial vestibular nuclei of cranial nerve eight convey fibers to the cerebellum. 

  Student doctor, what structure in the pons is involved in triggering vomiting in response to circulating emetic substances? 

  • The area postrema. 

  Now we are going to take a look at ascending sensory pathways.  Student doctor, what ascending sensory pathway conveys dorsal column modalities in the pons? 

  • The fasciculus gracilis and the fasciculus cuneatus. 

  What fibers do fasciculus gracilis and fasciculus cuneatus give rise to? 

  • The internal arcuate fibers. 

  What tract does the internal arcuate fibers give rise to? 

  • The contralateral medial lemniscus. 

  What are the modalities carried by the medial lemniscus? 

  • The medial lemniscus mediates dorsal column modalities to the VPL. 

What are the tracts contained in the spinal lemniscus? 

  • The lateral and ventral spinothalamic tracts and the spinotectal tract.

****END OF TRANSCRIPTION****

Want More USMLE Step 1 Review Facts?

boardprep.net

 

Leave a Reply