TRIGEMINAL SYSTEM Flashcards Preview

JAMES D FIX fey > TRIGEMINAL SYSTEM > Flashcards

Flashcards in TRIGEMINAL SYSTEM Deck (12)
1

1. All of the following statements concerning the spinal trigeminal tract are correct EXCEPT
A. it contains axons from the trigeminal ganglion
B. it mediates pain and temperature sensation
C. it is equivalent to the dorsolateral tract of Lissauer
D. it is the afferent limb of the jaw jerk reflex
E. it extends from C3 to a midpontine level

1-D The afferent limb of the jaw jerk reflex, a myotatic (muscle stretch) reflex, is mediated by the pseudounipolar neurons of the mesencephalic nucleus; the efferent limb is mediated by the motor neurons of the trigeminal motor nucleus.

1

2. All of the following statements concerning the ventral trigeminothalamic tract are correct EXCEPT
A. it transmits pain and temperature information
B. it consists of axons from the spinal trigeminal nucleus
C. it receives axons from the principal sensory nucleus of CN V
D. it projects to the contralateral ventral posteromedial (VPM) nucleus of the thalamus
E. First order neurons are located in the mesencephalic nucleus

2-E The mesencephalic nucleus does not contribute to the ventral trigeminothalamix tract. The ventral trigeminothalamic tract consists of axons from the spinal trigeminal nucleus that transmit pain and temperature informatin on the contralateral ventral posteromedial (VPM) nucleus. In addition, it receives and transmits tactile discriminatory input from the principal sensory nucleus of CN V to the VPM nucleus.

1

3. An aneurysm of the cavernous sinus could result in all of the following EXCEPT
A. ptosis
B. anesthesia of the tongue
C. paralysis of the superior oblique muscle
D. complete internal ophthalmoplegia
E. diplopa

3-B An aneurysm of the cavernous sinus would not involve the mandibular nerve (CN V3), which does not pass through the wall of the sinus. The mandibular nerve provides the sensory innervation of the anterior two thirds of the tongue. Involvement of the oculomotor nerve (CN III), if complete, would result in internal ophthalmoplegia because of interruption of preganglionic parasympathetic fibers (a fixed, dilated, unresponsive pupil).

1

4. All of the following statements concerning trigeminal neuralgia are correct EXCEPT
A. it is characterized by recurrent paroxysms of sharp, lancinating pain
B. it occurs in any of the three divisions of the trigeminal nerve
C. it usually occurs in people over 50 years of age
D. It is more common in men than in women
E. it may result from pressure on the nerve from a nearby artery

4-D Trigeminal neuralgia is more common in women than in men, and it occurs most often on the right side of the face. A redundant loop of the superior cerebellar artery may impinge on the trigeminal nerve, causing electric “chatter,” which is felt as pain. This type of trigeminal neuralgia has been successfully treated by placing a small sponge between the artery and the nerve. Classic idiopathic trigeminal neuralgia is treated with carbamazepine. An anticonvulsant frug.

1

5. All of the following statements concerning the trigeminal ganglion are correct EXCEPT
A it lies in the Meckel cave
B. it lies the middle cranial fossa
C. it contains bipolar ganglion cells
D. it contains first order neurons of the dorsal trigeminothalamic tract
E. its destruction results n abolition of the corneal reflex and the jaw jerk reflex

5-C The trigeminal (gasserian) ganglion lies within a dural duplication, the Meckel cave, located in the trigeminal fossa of the petrous portion of the temporal bone in the middle cranial fossa. It contains pseudounipolar ganglion cells similar to those found the dorsal root ganglia. These first order neurons give rise to the ventral and dorsal trigeminothalamic tracts. Destructtion of the trigeminal ganglion interrupts the afferent limbs of the corneal (CN V-1) and jaw jerk (CN V-3) reflexes. The motor root of CN V lies between the ganglion and the petrous bone.

1

6. All of the following statements concerning the maxillary nerve are correct EXCEPT
A. it runs in the lateral wall of the canvernous sinus
B. it exits the cranial vault via the foremen rotundum
C. it contains only general somatic afferent (GSA) fibers
D. it innervates the skin of the dorsum of the nose
E. it innervates the palate

6-D The maxillary nerve (CN V-2) contains only general somatic afferent (GSA) fibers, runs in the lateral wall of the cavernous sinus, and exits the cranial vault via the foremen rotundum and canalis rotundus, it innervates the palate via the palatine nerves. The dorsum of the nose is in nervated by the ophthalmic nerve (CN V-1)

1

7. All of the following statements concerning the mesencephalic nucleus are correct EXCEPT
A. it project to the cerebellum
B. it is located in the pons
C. it mediates the afferent limb of the jaw jerk reflex
D. it contains bipolar neurons
E. it receives input from muscle spindles

7-D The mesencephalic nucleus CN V contains pseudounipolar neurons that mediate the afferent limb of the jaw jerk reflex, it is located in the rostral pons and in the mesencephalon and gives rise to collaerals that project to the cerebellum via the superior cerebellar peduncle. It receives input from muscle spindles and pressure and joint receptor.

1

8. All of the following statements concerning the dorsal trigeminothalamic tract are correct EXCEPT
A. it is an uncrossed tract
B. it mediates two point tactile discrimination
C. it mediates the corneal reflex
D. it projects to the ventral posteromedial (VPM) nucleus of the thalamus
E. its first order neurons are found in the trigeminal ganglion

8-C The dorsal trigeminothalamic tract mediates discriminative tctile and pressure sensation (including two pont discrimination), is an uncrossed tract, and projects to the ventral posteromedial (VPM) nucleus. First order neurons are in the trigeminal ganglion, second order neurons lie in the principal sensory nucleus of the rostral pons, and third order neurons are located in the VPM nucleus of the thalamus. This tract corresponds in function to the dorsal column medial lemniscus system. The dorsal trigeminothalamic tract does not mediate the corneal reflex.

1

9. All of the following statements concerning the principal sensory nucleus of CN V are correct EXCEPT
A. it projects to the ipsilateral ventral posteromedial (VPM) nucleus of the thalamus
B. it projects to the contralateral VPM nucleus of the thalamus
C. it receives input from Meissner and Pacini corpuscles
D. it is located in the medulla and pons
E. it is a homolog to the dorsal column nuclei

9-D The principal sensory nucleus CN V is located in the rostral pons at the level of the motor trigeminal nucleus; it receives input from Meissner and Pacini corpuscles. It projects to the ipsilateral ventral posteromedial (VPM) nucleus of the thalamus via the dorsal trigeminothalamic tract and to the contralateral VPM nucleus of the thalamus via the ventral trigeminothalamic tract. The principal sensory nucleus is homologous to the dorsal column nuclei (gracile and cuneate nuclei)

1

10. All of the following statements concerning the trigeminal nerve are correct EXCEPT
A. it is nerve of the first branchial arch (mandibular nerve)
B. it contains only general somatic afferent (GSA) and somatic visceral efferent (SVE) fibers
C. it innervates the stapedius muscle
D. it innervates the dura of the anterior and middle cranial fossae
E. it mediates the afferent limb of the corneal reflex

10-C The trigeminal nerve (CN V) is the nerve of the firs branchial arch (mandibular nerve) and contains only general somatic afferent (GSA) and special visceral efferent (SVE) fibers. It in nervates the supratentorial dura of the anterior and middle cranial fossae. The dura of the posterior cranial fossa is innervated by the vagal nerve (CN X) and the second and third spinal nerves (C2 and C3), which hitchhike with the hypoglossal nerve (CN XII). The tensor tympani muscle is innervated by the trigeminal nerve; the stapedius muscle is innervated by the facial nerve (CN VII). The ophthalmic nerve (CN V-1) mediates the afferent limb of the corneal reflex: the facial nerve (CN VII) mediates the efferent limb of the corneal reflex (orbicularis oculi muscle)

1

11. All of the following lesions could interrupt the corneal reflex EXCEPT
A. occlusion of the anterior inferior cerebellar artery
B. occlusion of the posterior inferior cerebellar artery
C. an acoustic neuroma
D. an aneurysm of the cavernous sinus
E. destruction of the principal sensory nucleus of CN V

11-E The principal sensory nucleus of CN V mediates tactile discriminatory sense and position sense, homologous to the gracile and cuneate nuclei. The anterior and posterior cerebellar arteries both interrupt the afferent corneal pathway as may an aneurysm of the cavernous sinus. An acoustic neuroma interrupts the efferent limb of the corneal reflex (CN VII)

1

12. All of the following statements concerning the corneal reflex are correct EXCEPT
A. it is a bisynaptic reflex
B. it is abolished ipsilaterally by transection of the facial nerve
C. it is abolished by a transection of the spinal trigeminal tract made within its caudal medullary extent
D. it is mediated via axons found in the spinal trigeminal tract
E. it is mediated via axons arising from the spinal trigeminal nucleus

12-C The afferent corneal reflex pathway is as follows; First order neurons of the ophthalmic nerve (CN V) are found in the trigeminal ganglion. Their axons enter the pons and descend in the spinal trigeminal tract. They enter the spinal trigeminal nucleus in its rostral portion and synapse on second order neurons. Which project to the ipsilateral and contralateral facial nuclei. Axons from third order neurons in the facial nuclei innervate the orbicularis oculi muscles bilaterally (directly and consensually). Trigeminal tractotomy at caudal levels produces facial anesthesia without interruption of the corneal reflex.