Somatic and Visceral Sensory Systems of the Head Flashcards
How do axons from this nucleus reach the postcentral gyrus?
A. Internal capsule.
B. External capsule.
C. Extreme capsule.
D. Internal medullary lamina.
VPM axons reach the postcentral gyrus via the (posterior limb) internal capsule.
If this area was selectively destroyed on both sides, could vomiting be induced by either pharyngeal tickling or gastric distress?
A. Yes.
B. No.
Yes
Pharyngeal stimuli are mediated through nerves IX and X and not the area postrema. The area postrema responds to circulating substances because the blood brain barrier is absent in this area of the CNS.
A person with a lesion of this nerve, between the brain stem and the ganglion, would have difficulty with which of the following?
A. Chewing.
B. Swallowing.
C. Sensation from the cornea.
D. Pain from the anterior two thirds of the tongue.
Swallowing is mediated by nerves IX and X. The cell bodies of motor neurons important in swallowing are in the nucleus ambiguus.
Neurons of this nucleus have synaptic connections with the nucleus of nerve VII (facial nerve) that are essential for the corneal reflex. If the reflex is absent, because the afferent limb is interrupted, which of the following would be present upon stimulation of the side of the lesion?
A. Ipsilateral reflex present, contralateral absent.
B. Contralateral present, ipsilateral absent.
C. Ipsilateral absent, contralateral absent.
D. Ipsilateral present, contralateral present.
Ipsilateral absent, contralateral absent.
The corneal reflex* is important. If it does not occur, the cornea becomes infected (keratitis) and corneal erosion can lead to loss of vision. Blinking and tearing are essential to the health of the cornea. This is the descending nucleus of V where trigeminal axons terminate.
To what cortical region does this nucleus of the thalamus project?
A. Transverse temporal lobe.
B. Postcentral gyrus.
C. Precentral gyrus.
D. Prefrontal cortex.
Postcentral gyrus.
The postcentral gyrus is the primary somatosensory cortex and receives axons from VPL and VPM.
The area of the medulla containing the spinal nucleus of V may be supplied by this artery (arrow). Name the artery?
A. Anterior inferior cerebellar artery (AICA).
B. Superior cerebellar artery.
C. Anterior spinal artery.
D. Posterior inferior cerebellar artery (PICA).
E. Posterior cerebral artery.
Posterior inferior cerebellar artery (PICA).
Branches of PICA supply the dorsolateral medulla. You are looking at a lateral view of the artery.
Where are the cell bodies located for the axons that innervate the taste buds on the posterior third of the tongue?
A. Trigeminal ganglion.
B. Geniculate ganglion.
C. Petrosal or inferior glossopharyngeal ganglion.
D. Nodose or inferior vagal ganglion.
Petrosal or inferior glossopharyngeal ganglion.
Nerve IX innervates the taste buds on the posterior third of the tongue. Its cell bodies are located in the petrosal ganglion located just beneath the jugular foramen.
Would you expect all portions of the face to be represented equally in this nucleus?
A. Yes.
B. No.
No, The lips, tongue, and teeth have a denser innervation and, therefore, a larger area of representation in VPM. This would also be true for the finger region of VPL. Note that VPM (arrow) is located just medial to VPL.
What other cranial nerve is most likely to be affected if a tumor of nerve VIII produced pressure in the cerebellopontine angle (the circled region)?
A. XII.
B. V.
C. VI.
D. VII.
Nerve V is in the mid pons and is the next nerve most likely to be involved.
Where are the cell bodies located for the axons that form the descending tract of V ?
A. Trigeminal ganglion.
B. Dorsal root ganglion.
C. Descending nucleus V.
D. Chief sensory nucleus of V.
Trigeminal ganglion.
If a growth in the region of the arrow produces sufficient pressure on the middle cerebellar peduncle to cause degeneration of the incoming axons, which of the following will occur?
A. Loss of facial sensation.
B. Loss of sensation from part of the tongue.
C. Loss of corneal reflex.
D. A and C.
E. A, B, and C.
A, B, and C.
Circulating chemicals such as alcohol, ipecac, etc. stimulate this region in the floor of the fourth ventricle because:
A. There is no blood-brain barrier so substances have direct access to appropriate chemoreceptors.
B. The substances circulate through the ventricular system and directly stimulate the vomiting center.
C. They cause a decrease in threshold for neural circuits.
D. Visceral afferents in the tractus solitarius are hyperexcitable.
There is no blood-brain barrier so substances have direct access to appropriate chemoreceptors.
There is no blood-brain barrier so substances have direct access to appropriate chemoreceptors.
A person with a left facial paralysis who is also deaf in the left ear is tested for his corneal reflex.
A. Stimulation of left cornea does not produce a consensual reflex.
B. Stimulation of left cornea produces a consensual but not a direct reflex.
C. Stimulation of left cornea results in a direct but not a consensual reflex.
D. Stimulation of the right cornea produces a direct and consensual reflex.
Stimulation of left cornea produces a consensual but not a direct reflex.
The trigeminal is intact, so the afferent arm of the corneal reflex is intact. This would result in a normal consensual reflex. Since the facial muscles on the left side are paralyzed, the direct reflex would not be present. The term, direct reflex refers to the side stimulated.
Where is this ganglion located?
A. Pterygoid canal.
B. Pterygopalatine fossa.
C. Facial canal.
D. Posterior cranial fossa.
Facial canal
What nerve(s) innervate(s) taste bud receptors?
A. VII.
B. IX.
C. X.
D. A & B.
E. A, B & C.
A, B & C.
Is this tract efferent from or afferent to the descending nucleus of V?
A. Afferent.
B. Efferent.
Afferent.
Which cranial nerves contribute axons to this tract?
A. VII, IX, X.
B. V, VII, IX, X.
C. V, VII, X.
D. V, VII, IX.
VII, IX, X.
All three nerves contain special visceral afferent (taste) components. IX and X also contain general visceral afferent components.
This ganglion is a homologue of what structure associated with the spinal cord?
A. Stellate or superior cervical ganglion.
B. Celiac ganglion.
C. Pterygopalatine ganglion.
D. Dorsal root ganglion.
E. Sympathetic chain ganglion.
Dorsal root ganglion
Dorsal root ganglia and cranial nerve ganglia both contain cell bodies of primary sensory neurons. This is the trigeminal ganglion.
Which of the following is a sensory relay nucleus of the thalamus?
A. Pulvinar nucleus.
B. Anterior nucleus.
C. Ventral posteromedial nucleus.
D. Intralaminar nuclei (i.e., centromedian).
E. Dorsomedial nucleus.
Ventral posteromedial nucleus.
VPM fits the criteria. It relays specific sensory information and is a thalamic nucleus.
All of the following are sensory radiations from this structure EXCEPT:
A. Olfactory radiations.
B. Optic radiations.
C. Auditory radiations.
D. Somatosensory radiations.
Olfactory radiations
Axons from the olfactory bulb do NOT pass through the thalamus on their way to the olfactory cortex. Olfactory cortex is located in the region of the uncus. The thalamus is seen here in a horizontal section.
