Glossary of Lab 10.1: Cranial nerves and nuclei
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- What modality is carried by each cranial nerve: sensory, motor, or both?
- I-S; II-S; III-M; IV-M; V-B; VI-M; VII-B; VIII-S; IX-B; X-B; XI-M; XII-M
- What is a difference between cranial nerves and nuclei in terms of the modalities they carry?
- Cranial nerves are able to carry more than one modality, while the nuclei generally subserve only a single function.
- What modality does the spinal nucleus of CN V subserve? What cranial nerves synapse at this nucleus?
- *pain and temperature information from the face
*CN V, VII, IX, X
- Which nerves detect pain and temperature on the tongue? What nucleus recieves this information?
- CN V covers the anterior 2/3 of the tongue and CN IX covers the posterior 1/3. This information is carried to the spinal nucleus of V. Note that some light touch info is also carried by this circuit.
- Which nerves carry pain and temperature information from the ear? What nucleus receives this information?
- CN VII, IX, and X carry pain and temperature from the ear to the spinal nucleus of V.
- How is pain and temperature detected in the meninges? What nerves are used? What nucleus processes this information?
- Infratentorial meninges are innervated by CN X and the supratentorial meninges are innervated by CN V. This information is carried to the spinal nucleus of V.
- Which nerves mediate the corneal reflex? What is similar about this reflex and the pupillary reflex?
- CN V carries nociceptive information, while CN VII carried motor information. Both reflexes may be direct or consensual (i.e. are bilateral)
- What are the main functions of the solitary nucleus? How are these functions represented in the structure of the nucleus? List the nerves that synapse on this nucleus.
- *rostral portion is taste, caudal portion is visceral sensation
*CN VII, IX, X
- How is the sensation of taste detected? Which cranial nucleus is involved in this sense?
- *CN VII detects from the anterior 2/3 of the tongue
*CN IX detects from the posterior 1/3 of the tongue
*CN X detects from the epiglottis
*rostral portion of solitary nucleus
- How are the carotid bodies innervated?
- CN IX carries sensation from the carotid bodies to the solitary nucleus.
- Sensation from what structure is detected by both CN IX and CN X?
- What are the structures covered by the "visceral sensation" function of the solitary nucleus?
- Pharynx (CN IX,X), larynx (X), carotid bodies (IX), abdomen and thorax (X)
- Hoarseness can be a sign of a lesion in which cranial nucleus?
- Nucleus ambiguus.
- Which nerves control the gag reflex?
- *sensory information is carried by CN IX to the solitary nucleus
*motor information is generated by the nucleus ambiguus and carried by CN IX, X, and XI with some signals from the phrenic nerve
- Which cranial nerves synapse at the nucleus ambiguus? What is the function of this nucleus?
- *CN IX, X, and XI
*sends motor signals to the larynx and pharynx
- What kind of fibers project from the dorsal vagal motor nucleus? Which cranial nerve is involved? What is the target of these fibers?
- *preganglionic parasympathetic
*organs of the GI, respiratory, and cardiovascular systems
- In a cross-section of the mid-medulla, where is the nucleus ambiguus located?
- In the middle of the section, dorsal to the inferior olivary nucleus and ventromedial to the ICP and spinal nucleus of V.
- What are the 4 places that the vestibular nucleus sends output to?
- 1.Vestibulospinal tract
2.VP region of thalamus
- Describe the path of involuntary control of the lateral gaze.
- Each vestibular nucleus sends fibers to both abducens nuclei. Each abducens nucleus send fibers to the ipsilateral lateral rectus and (via the MLF) to the contralateral CN III nucleus, which controls the medial rectus.
- What structures are tested by the doll's head maneuver?
- The MLF, and nucleus and nerves of CN III, VI, and VIII.
- What is the normal response in the doll's head maneuver?
- The eyes lag behind as the head is passively turned - i.e. the eyes moves in the direction opposite of head rotation.
- What is the path of voluntary control of the lateral gaze?
- Each frontal eye field sends fibers to the contralateral PPRF. Each PPRF sends fibers to the ipsilateral abducens nucleus. Each aducens nucleus sends fibers to the ipsilateral lateral rectus, and (via the MLF) to the contralateral CN III nucleus.
- What will be seen if the doll's head maneuver is performed on a patient with bilateral damage to the MLF?
- Movements performed by the medial rectus (medial deviation) will be absent, although those performed by the lateral rectus will be observed. E.g. as the head is turned to the right, the right eye stops on the midline.
- What vascular syndrome can result in damage to the vestibular nucleus?
- An infarct of PICA, as seen in lateral medullary syndrome, can damage the vestibular nucleus.
- Describe the stimulation in the semicircular canals that occurs during the acceleration phase of a test of rotational nystagmus.
- There is stimulation in the semicircular canals on the leading side, and inhibition in the semicircular canals on the lagging side.
- Which is the slow component and which is the fast component during the acceleration phase of rotational nystagmus?
- The slow component is when the eyes lag in the direction opposite of rotation. The fast component is the quick jump the eyes make in the direction of rotation.
- What is observed during post-rotational nystagmus?
- The fast component changes direction and is opposite the direction of the previous rotation.
- Which tends to produce more severe deficits - damage to a cranial nerve or damage to a cranial nerve nucleus? Why?
- Damage to the cranial nerve will produce more severe deficits because it carries more than one modality. A nucleus usually subserves a single function.
- What will be observed if the doll's head maneuver is performed on a patient with bilateral damage to the abducens nucleus?
- There will be no movement of the eyes when the head is rotated in either direction
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