Organization of the Medulla

Question 1

Describe the pathway of the corticobulbar tract:

Answer 1

Descend from motor cortex through the internal capsule and crus cerebri. Innervate muscles directly or through the reticular formation.

Question 2

Describe the path of the corticopontine fiber tract:

Answer 2

Descend through the internal capsule and crus cerebri. Synapse with ipsilateral pontine nucleus. Become pontocerebellar fibers which crosses the midline and enters the cerebellar cortex via the middle cerebellar peduncle.

Question 3

Function of hypoglossal nucleus?

Answer 3

Innervates ipsilateral tongue muscles

Question 4

Function of Dorsal Motor nucleus of the vagus?

Answer 4

Innervates postganglionic parasympathetic neurons. (slow heart speed, constrict bronchia, peristalisis)

Question 5

Function of Nucleus Ambiguus?

Answer 5

Innervates striated muscle of the pharynx and larynx. (Speech, swallowing, vomiting)

Question 6

Function of accessory spinal nucleus?

Answer 6

Shoulder and head movements

Question 7

Sagging of shoulder muscles on the left side would indicate which type of lesion?

Answer 7

Lesion of accessory spinal nucleus on the left side

Question 8

Weakness in turning the head toward the left indicates what type of lesion?

Answer 8

Lesion of accessory spinal nucleus on the right side.

Question 9

Paralysis of the pharynx and larynx on the left side would indicate what type of lesion?

Answer 9

lesion of the vagus nerve on the left.

Question 10

Dysphonia would indicate what type of lesion?

Answer 10

Lesion of the vagus nerve

Question 11

Loss of the gag reflex on the right would indicate what type of lesion?

Answer 11

Lesion of the glossopharyngeal nerve on the right or nucleus ambiguus.

Question 12

Loss of taste and sensation from the posterior third of the tongue would indicate what type of lesion?

Answer 12

Lesion of the glossopharyngeal nerve.

Question 13

Give a description of the gag reflex pathway:

Answer 13

Glossopharyngeal nerve receives sensory information which it conveys to the spinal trigeminal nucleus; projects to the nucleus ambiguus which effects motor reflex via CN IX, X.

Question 14

Which nerve(s) and nucleus mediate the salivatory reflex?

Answer 14

facial nerve, glossopharyngeal nerve, rostral solitarius (sensation), salivatory nuclei, facial and glossopharyngeal (motor)

Question 15

Which nerve(s) and nuclei mediate the baroreceptor reflex?

Answer 15

glossopharyngeal and vagus nerves, caudal solitarius (sensation), dorsal motor vagus nerve and vagus (motor)

Question 16

Give a description of the Baroreceptor reflex:

Answer 16

Increased blood pressure stretches areterial walls. Baroreceptors are activated and send axons to the caudal solitarius which activates the dorsal motor nucleus of the vagus. Vagal output reduces heart rate.

The Solitarius also has inhibitory influence on the rostro ventrolateral medulla. When blood pressure drops this influence decreases and the medulla increases heart rate.

Question 17

Which vessels supply blood to the medulla?

Answer 17

Anterior spinal, vertebral, PICA, AICA

Question 18

Stroke in PICA or Vertebral arteries would produce which well known syndrome? What are its symptoms?

Answer 18

Lateral Medullary Syndrome. Ipsilateral loss of facial pain (via spinal trigeminal nuclei). Contralateral loss of body pain (spinothalamic tract). Ataxia (inferior cerebellar peduncle), Nausea (solitarius), Dysphonia (nucleus ambiguus), vertigo (vestibular nuclei)

Question 19

Inferior Alternating Hemiplagia would be caused by what malady? What are the symptoms of this syndrome?

Answer 19

Stroke of the Anterior Spinal Artery. Ipsilateral paralysis of the tongue (Hypoglossal Nucleus). Contralateral hemiplagia (pyramidal tract). Loss of two point discrimination (medial lemniscus).

Question 20

What tracts feed into the inferior cerebellar peduncle?

Answer 20

Olivocerebellar Fibers, Posterior spinocerebellar fibers, cuneocerebellar tract, vestibulocerebellar tract.

Question 21

Function of corticobulbar fibers:

Answer 21

Innervation of muscles of face and neck, also modulate ascending sensory information.

Question 22

Name the motor and sensory nuclei associated with CN III.

Answer 22

No sensory nucleus, Oculomotor Nucleus

Question 23

Name the motor and sensory nuclei associated with CN IV.

Answer 23

No sensory nucleus. Motor nucleus of nerve IV

Question 24

Name the motor and sensory nuclei associated with CN V.

Answer 24

Trigeminal nucleus, Motor nucleus of nerve V.

Question 25

Name the motor and sensory nuclei associated with CN VI.

Answer 25

No sensory nucleus. Motor nucleus of nerve VI

Question 26

Name the motor and sensory nuclei associated with CN VII.

Answer 26

Sensory: Nucleus of the Solitary Tract, Nucleus of the Spinal Trigeminal tract.
Motor: Motor nucleus of nerve VII, Superior Salivatory nucleus

Question 27

Name the motor and sensory nuclei associated with CN VIII.

Answer 27

Sensory: Cochlear Nucleus, Vestibular Nucleus.

No motor nucleus.

Question 28

Name the motor and sensory nuclei associated with CN IX.

Answer 28

Sensory: Nucleus of the Solitary Tract, Nucleus of the Spinal Trigeminal Tract
Motor: Inferior Salivatory Nucleus, Nucleus Ambiguus.

Question 29

Name the motor and sensory nuclei associated with CN X.

Answer 29

Sensory: Nucleus of the Solitary Tract, Nucleus of the Spinal Trigeminal Tract
Motor: Dorsal Motor Nucleus of X, Nucleus Ambiguus

Question 30

Name the motor and sensory nuclei associated with CN XI.

Answer 30

No sensory nucleus

Motor: Motor Nucleus of nerve XI.

Question 31

Name the motor and sensory nuclei associated with CN XII.

Answer 31

No sensory nucleus

Motor: Motor nucleus of nerve XII (hypoglossal nucleus)