Chapter 1 Osteo1ogy.............................1 Chapter 2



Download 1.14 Mb.
Page19/21
Date conversion16.05.2018
Size1.14 Mb.
1   ...   13   14   15   16   17   18   19   20   21

A. total blindness of the right eye

B. right nasal hemianopsia

C. right homonymous hemianopsia

D. right bitemporal hemianopsia

E. left homonymous hemianopsia

5. It is discovered that a 35-year-old woman has a tumor pressing on the base of the brain where it is impinging upon the optic chiasm. She discovers that her field of vision is now seriously affected. The defect present in tiffs individual is .

A. total blindness of both eyes

B. bitemporal hemianopsia

C. right homonymous hemianopsia

D. binasal hemianopsia

E. left homonymous hemianopsia

6. A 49-year-old woman developed a severe headache for the last two days, and accompanied by vomiting and bitemporal hemianopsia for the visual field, CT scanning shows a pituitary tumor, which of the following structure for lesion owing to a pituitary tumor results in bitemporal hemianopsia for the visual field?

A. ophthalmic nerve

B. optic chiasma

C. trochlear nerve

D. optic nerve

E. oculomotor nerve

7. A routine magnetic resonance imaging (MRI) reveals the presence of a tumor situated in the left optic tract proximal to the lateral geniculate body. The patient complained of having a reduction in his field of vision. The likely visual deficit can be characterized as .

A. total blindness of the left eye

B. bitemporal hemianopsia

C. right homonymous hemianopsia

D. left homonymous hemianopsia E. right nasal hemianopsia

8. A routine eye examination reveals the presence of inflammation limited to the left optic disk, probably due to neuritis of this region. The likely visual deficit resulting from this disorder is .

A. total blindness of the left eye

B. left homonymous hemianopsia

C. left heteronymous hemianopsia

D. left enlargement of the blind spot

E. left nasal hemianopsia

9. Examination of a patient revealed a drooping left eyelid, together with weakness of adduction and elevation of the left eye, loss of the papillary light reflex in the left eye, and weakness of the limbs and lower facial muscle on the right side. A single lesion most likely to produce all these signs would be located in the .

A. left pontomedullary junction

B. left cerebral peduncle

C. pons on the left side

D. medulla on the left side

E. spinal cord on the left side

10. Paralysis of the right side of the lower face, right spastic paralysis of the limbs, deviation of the tongue to the right with no atrophy, and no loss of taste from any region of the tongue will likely result from a lesion of the .

A. right internal capsule

B. left internal capsule

C. left pontine tegmentum

D. base of the medulla on the right side

E. base of the medulla on the left side

B1

A. the spinal cord



B. the medulla

C. the pons

D. the midbrain

E. the telencephalon

1. The second-order fibers from the gracile and cuneate nuclei travel anteromedially and cross the midplane just above the pyramid in .

2. About 75% to 90% of the corticospinal tract crosses pyramidal decussation at .

A. medial lemniscus

B. lateral lemniscus

C. fasciculi gracilis and cuneatus.

D. anterior spinothalamic tract

E. lateral spinothalamic tract

3. After crossing, the internal arcuate fibers, the second-order fibers from the gracile and cuneate nuclei form .

4. The second order fibers ascend from the cochlear nuclei on both sides, the crossing fibers pass through the trapezoid bodies, and some of them synapse in the superior olivary nuclei. The ascending fibers course in .

A. bitemporal hemianopsia

B. monocular blindness

C. nasal hemianopsia

D. right homonymous hemianopsia

E. left homonymous hemianopsia

5. Damage to the left optic tract would produce .

6. Damage to the midplane of optic chiasm would produce .

7. Damage to the optic nerve would produce .

A. perception of joint position, two-point discrimination, and vibration

B. perception of pain and temperature

C. perception of crude touch and pressure

D. voluntary motor activity

E. the ability to read

8. Damage to the anterior spinothalamic tract would directly affect .

9. Damage to the lateral spinothalamic tract would directly affect .

10. Damage to the pyramidal cells of the cerebral cortex would directly affect .

True or False Questions

1. The conscious proprioceptive pathway carries highly localized joint sensation, two-point discrimination, and vibration sense from receptors to the cortex. ( )

2. The axons, with their first-order neurons in the spinal ganglion, reach the CNS through the posterior roots of spinal nerves and collect sensory information from different body areas for the conscious proprioceptive pathway. ( )

3. Axons from the posterior roots of spinal nerves ascend ipsilaterally within the fasciculus gracilis or the fasciculus cuneatus in the spinal cord. ( )

4. The fasciculus gracilis transmits pain sensation from the lower half of the body. This includes the afferent fibers entering the posterior funiculus from the sacral to midthoracic section of the spinal cord. ( )

5. The fasciculus cuneatus fibers carry "crude" sensation from the upper body and enter the spinal cord above the midthoracic level. ( )

6. The fasciculi gracilis and cuneatus ascend ipsilaterally the spinal cord posterior funiculus toward the brainstem and terminate at the gracile and cuneate nuclei. ( )

7. The internal arcuate fibers, the second order fibers from the gracile and cuneate nuclei, travel ventromedially and cross the midplane just above the pyramid in the medulla. ( )

8. After crossing, the internal arcuate fibers, the second-order fibers from the nuclei gracilis and cuneatus form the lateral lemniscus. ( )

9. The medial lemniscus fibers ascend along the midplane and posterior to pyramidal tract through the medulla. ( )

10. The medial lemniscus fibers are horizontally arranged in the pontine tegmentum. Then they migrate dorsolaterally in the midbrain to enter the ventral posteromedial nucleus of thalamus. ( )

11. Any lesion implicating fibers at the spinal or low medullary level will result in the loss of two-point discrimination, position sense and vibration sense in the half-body contralateral to the site of interruption. ( )

12. The fibers from spinal and pontine nuclei of trigeminal nerve, second-order neurons, cross midplane and form contralateral trigeminal lemniscus terminating the ventral posterolateral nucleus of thalamus, the third-order neurons. ( )

13. The lateral spinothalamic tract mediates the sensations of pain and temperature. ( )

14. The anterior spinothalamic tract mediates crude touch and pressure. ( )

15. The spinothalamic fibers terminate on the third-order neurons in the ventral posteromedial nucleus of thalamus. ( )

16. Thalamocortical fibers carry the information from the thalamus to the sensory cortex through the anterior limb of the internal capsule, then project to the upper two-thirds of the postcentral gyrus located in the parietal lobe and the posterior part of the paracentral lobule. ( )

17. The visual pathways also contain three orders of neurons. ( )

18. The first-order neurons, the bipolar cells in the retina, synapse the visual receptors, rod cells and cone cells. ( )

19. Bipolar cells synapse within the layer of ganglion cells, the second-order neurons. ( )

20. Axons from ganglion cells converge on the optic disc and form the optic nerve, then the optic nerve course through the optic canal of the skull to form the optic chiasm. ( )

21. The optic tract fibers synapse with third-order neurons in the medial geniculate body of the thalamus, whose axons project ipsilaterally by way of the optic radiation passing through the posterior limb of the internal capsule to the calcarine cortex in the occipital lobe. ( )

22. The pretectal area is the central portion of the pupillary light reflex. ( )

23. Efferent impulses pass along parasympathetic fibers of the oculomotor nerve to the orbit where they synapse in the ciliary ganglion. Postganglionic fibers pass to the eyeball to supply sphincter pupillae, which reduces the size of the pupil when it contracts. ( )

24. The corticospinal tract travels through the posterior limb of internal capsule of the telencephalon, and then descends through the intermediate 3/5 of the cerebral peduncle of the midbrain. Later it runs through the basilar part of the pons and continues to the pyramid of the medulla in the medulla. ( )

25. About 75%~ 90% of the corticospinal tract crosses pyramidal decussation at the caudal end of the medulla. ( )

26. After crossing, the lateral corticospinal tracts descend in the lateral funiculus of the spinal cord. These fibers terminate on the interneuron and lower motor neurons in the ipsilateral posterior horns of the spinal cord. ( )

27. The corticonuclear tracts extend through the posterior limbs of the internal capsule to the midbrain. ( )

28. The corticobulbar tracts terminate the bilateral motor nuclei of the cranial nerves (oculomotor, trochlear, motor nucleus of trigeminal nerve, ambiguous, accessory nuclei and superior part of the facial nucleus), and the contralateral hypoglossal nucleus and the inferior part of the facial nucleus. ( )

29. The first-order central processes, with cell bodies in trigeminal ganglion, geniculate ganglion, superior ganglion of glossopharyngeal nerve and vagus nerve, enter the brain stem. They turn downward, terminating in the spinal nuclei of the trigeminal nerve mediating pain and temperature sensation and in the pontine nuclei of the trigeminal nerve mediating touch sensation. ( )

Explanation of Terms

1. upper motor neurons

2. lower motor neurons

3. corticospinal tract

4. corticobulbar tract

5. visual field

6. bitemporal hemianopsia

7. nasal hemianopsia

8. homonymous hemianopsia

9. pupillary light reflex

10. optic radiation

11. medial lemniscus

12. fasciculus gracilis

13. fasciculus cuneatus

14. lateral and anterior spinothalamic tract

15. trigeminal lemniscus

Answer the Following Questions

1. Discuss three-order neurons of the conscious proprioceptive pathway for trunk and limbs.

2. What side of the body will lose position sense and two point discriminative touch after a left pontine lesion involving medial lemniscus? Why?

3. Discuss three-order neurons of the spinothalamic tract.

4. Describe functions of anterior and lateral spinothalamic tracts.

5. Discuss three-order neurons of the superficial sensory pathway of head and face.

6. Describe the upper motor neurons and lower motor neurons for the pyramidal system.

7. Describe clinical features of the upper motor neurons lesion.

8. Describe clinical features of the lower motor neurons lesion.

9. Describe the neuronal components and functions of the conscious proprioceptive pathway.

10. Specially discuss the visual field representation on the optic nerve, optic chiasm, lateral geniculate body, and visual cortex.

11. Describe the pathway of pupillary light reflex.

12. Outline course of pyramidal tract from motor cortex to spinal cord; differentiate between course and decussation point of the corticospinal and corticobulbar tracts.

ANSWERS

Multiple Choice Questions



A1

1. A 2. B 3. D 4. E 5. C 6. A 7. C 8. B 9. E 10. E 11. B 12. C 13. E 14. E 15. C 16. D 17. E 18. A 19. B 20. C 21. A 22. B. 23. E 24. E 25. E 26. D 27. D 28. C 29. B 30. A 31. D 32. A 33. E 34. B 35. E 36. C 37. D 38. E 39. A 40. A

41. B 42. D 43. A 44. B 45. C 46. E 47. D 48. D A2

1. C 2. C 3. D 4. B 5. B 6. B 7. C 8. D 9. B 10. B B1

1. B 2. B 3. A 4. B 5. D 6. A 7. B 8. C 9. B 10. D

True or False Questions

1. T 2. T 3. T 4. F 5. F 6. T 7. T 8. F 9. T 10. F 11. F 12. F 13. T 14. T 15. F 16. F 17. T 18. T 19. T 20. T 21. F 22. T 23. T 24. T 25. T 26. F 27. F 28. T 29. T

Explanation of Terms

1. The upper motor neurons are composed of the giant pyramidal cells (Betz cells) and other pyramidal cells in the precentral gyrus and anterior part of the paracentral lobule, and their axons (the corticonuclear tract and the corticospinal tract).

2. The lower motor neurons include the cranial nerve nuclei of the brain stem and motor nuclei of the anterior horn of the spinal cord, and their axons (cranial nerves and spinal nerves).

3. The corticospinal tract originates the pyramidal cells of the superior and middle parts of the precentral gyrus and anterior part of the paracentral lobule. It travels through the posterior limb of internal capsule of the telencephalon, and then descends through the intermediate 3/5 of the cerebral peduncles of the midbrain. Later it runs through the basilar part of the pons and continues to the pyramids in the medulla oblongata. About 75% to 90% of the corticospinal tract crosses pyramidal decussation at the caudal end of the medulla oblongata. After crossing, these fibers descend into the lateral corticospinal tract in the lateral funiculus of the spinal cord. These fibers terminate on the interneuron and lower motor neurons in the ipsilateral anterior gray horns of the spinal cord, and mainly control musculature of the limbs. About 10% to 15% of the corticospinal tract does not cross in the pyramidal decussation but descends in the anterior funiculus of the spinal cord (the anterior corticospinal tract). These fibers cross or uncross above the level of mid-thoracic segments, close to the anterior horns of spinal cord, and control the skeletal muscles of trunk. Up to 3 % of the decending fibers in the lateral corticospinal tract are uncrossed. The ipsilateral decending projections mainly control musculature of trunk.

4. Some axons of upper motor neurons (the pyramidal cells in the inferior part of the precentral gyrus) that conduct impulses for the control of skeletal muscles in the head extend through the genu of the internal capsule to the midbrain, where they join the corticobulbar tracts in the right and left of cerebral peduncles. Some of the axons in the corticobulbar tracts decussated at the midplane in the brainstem, whereas others have not. The axons terminate the bilateral motor nuclei of the cranial nerves (nucleus of oculomotor nerve, nucleus of trochlear nerve, motor nucleus of trigeminal nerve, nucleus ambiguus, accessory nucleus, superior part of the facial nucleus), and the contralateral hypoglossal nucleus and the inferior part of the facial nucleus.

5. The visual field is the area located external to the eyes. The visual field for each is divided into two half fields, the nasal and the temporal halves. Each of these for each eye is also divided into upper and lower quadrants. Retinal representation of the visual field for each eye is also divided into nasal and temporal halves, which are further divided into upper and lower quadrants. The image in the visual field image is projected to the retina in reversed and inverted form. Light rays from the temporal half of the visual field project to the nasal half of the retina, and rays from the top of the object strike the lower retina, and rays from the bottom of the object strike the upper retina.

6. A chiasmatic lesion (often owing to a pituitary tumor or a lesion around the sella turcica) can injury the decussating axons of retinal ganglion cells within the optic chiasm. These axons originate from the nasal halves of the two retinas. Thus, this type of lesion produces bitemporal hemianopsia, characterized by blindness in the lateral or temporal half of the visual field for each eye.

7. A pathology encroaching on one of the lateral edge of the optic chiasm selectively interrupts the fibers from the ipsilateral temporal portion of the retina, resulting in nasal hemianopsia in the corresponding eye.

8. Lesions behind the optic chiasm cause a field defect in the temporal field of one eye, together with a field defect in the nasal (medial) field of the other eye. The result is a homonymous hemianopsia in which the visual field defect is on the side opposite the lesion.

9. Light shone on the retina of one eye causes both pupils to constrict normally. The response in the eye stimulated is called the direct papillary light reflex, while that in the opposite eye is known as the indirect (or consensual) papillary light reflex.

10. The fibers of the optic tract synapse with third-order neurons in the lateral geniculate body of the thalamus, whose axons project ipsilaterally by way of the optic radiation passing through the posterior limb of the internal capsule to the calcarine cortex in the occipital lobe.

11. The internal arcuate fibers, the second order fibers from the nuclei gracilis and cuneatus, travel anteromedially and cross the midplane just above the pyramid in the medulla. After crossing, the internal arcuate fibers form the medial lemniscus.

12. Axons from the spinal ganglia ipsilaterally ascend within the fasciculus gracilis in the spinal cord. The fasciculus gracilis transmits deep sensations from the lower half of the body (below the fifth thoracic segment). These fibers ipsilaterally ascend in the posterior funiculus of spinal cord toward the brainstem and terminate at the gracile nucleus, the second-order neuron.

13. Axons from the spinal ganglia ipsilaterally ascend within the fasciculus cuneatus in the spinal cord. Fasciculus cuneatus fibers carry deep sensations from the upper body and enter the spinal cord above the level of the fourth thoracic segment. These fibers ipsilaterally ascend in the posterior funiculus of spinal cord toward the brainstem and terminate at the cuneatus nucleus, the second-order neuron.

14. The second-order neurons in Rexed lamina Ⅰ, Ⅳ and Ⅴ. After traveling upl-2 spinal segments, the second order fibers cross the midline in the anterior white commissure to ascend in the lateral and anterior spinothalamic tracts. The lateral spinothalamic tract mediates the sensations of pain and temperature. The anterior spinothalamic tract mediates rough touch and pressure.

15. Those fibers from the spinal and pontine nuclei of trigeminal nerve, the second-order neurons, cross midplane and form contralateral trigeminal lemniscus running upwards and terminating the ventral posteromedial nucleus of dorsal thalamus, the third neurons.

Answer the Following Questions

1. (1) First-order neurons

-are located in spinal ganglia at all levels.

-give rise to the fasciculus gracilis from the lower extremity.

-give rise to the fasciculus cuneatus from the upper extremity.

-give rise to axons that ascend in the dorsal columns and terminate in the gracile and cuneate nuclei of the medulla.

(2) Second-order neurons

-are located in the gracile and cuneate nuclei of the caudal medulla.

-give rise to axons, internal arcuate fibers that decussate and form a compact fiber bundle, the medial lemniscus. The medial lemniscus ascends through the contralateral brainstem to terminate in the ventral posterolateral (VPL) nucleus of the thalamus.

(3) Third-order neurons

-are located in the VPL nucleus of the thalamus.

-project via the posterior limb of the internal capsule to the postcentral gyrus, the somatosensory cortex (Broadmann's areas 3, 1, and 2).

2. The right side of the body will lose position sense and two point discriminative touch after a left pontine lesion involving medial lemniscus. Because the internal arcuate fibers, the second order fibers from the nuclei gracilis and cuneatus, travel anteromedially and cross the midline just above the pyramid in the medulla. After crossing, the internal arcuate fibers form the medial lemniscus. The medial lemniscus ascends along the midline and posterior to pyramidal tract through the medulla oblongata. The medial lemniscus is horizontally arranged in the pontine tegmentum. Then it posterolaterally migrates in the midbrain to enter the ventral posterolateral nucleus o{ the dorsal thalamus, the third-order neurons. Damage to the medial lemniscus that represents crossed fibers will lose position sense and two point discriminative touch on the contralateral half-body.

3. (1) First-order neurons

-are found in spinal ganglia at all levels.

-project axons into the central process to second-order neurons in the dorsal horn.

-synapse with second-order neurons in the dorsal horn.

(2) Second-order neurons

-are located in the dorsal horn.

-give rise to axons that decussate in the ventral white commissure and ascend in the contralateral anterior and lateral funiculi.

-terminate contralaterally in the VPL nucleus of the thalamus.

(3) Third-order neurons

-are found in the VPL nucleus of the thalamus.

-project via the posterior limb of the internal capsule and corona radiata to the postcentral gyrus, (Broadmann's areas 3, 1, and 2).

4. The first-order neurons, with their nuclei in the spinal ganglia, carry sensations from the receptors and enter the posterolateral sulcus of the spinal cord. After entering the spinal cord, these fibers travel up or down a few spinal segments in the dorsolateral fasciculus (Lissauer's tract), and synapse within the posterior horns, the second-order neurons in Rexed lamina Ⅰ, Ⅳ and Ⅴ. After traveling upl-2 spinal segments, the second order fibers cross the midline in the anterior white commissure to ascend in the lateral and anterior spinothalamic tracts. The lateral spinothalamic tract mediates the sensation of pain and temperature. The anterior spinothalamic tract mediates rough touch and pressure.

5. The cell bodies of the first-order neurons are situated in the trigeminal ganglion, which receive the superficial sensation of head and face. After the central branches of the trigeminal ganglion enter the pons, the pain and temperature sensation terminate in the spinal nucleus of the trigeminal nerve, while the tactile and pressure sensations terminate in the pontine nucleus of the trigeminal nerve. Those fibers from the spinal and pontine nuclei of trigeminal nerve, the second-order neurons, cross midplane and form contralateral trigeminal lemniscus running upwards and terminating the ventral posteromedial nucleus of dorsal thalamus, the third neurons. Third order sensory fibers from thalamus travel through the posterior limb of internal capsule and terminate in lower third of postcentral gyms, the primary somesthetic area of parietal lobe.

6. (1) Upper motor neurons (UMNs)

-are cortical neurons that give rise to corticobulbar or corticospinal tracts.

-are found in brainstem nuclei that influence lower motor neurons (LMNs).

-terminate directly on or via interneurons on LMNs.

(2) Lower motor neurons (LMNs)

-are neurons that directly innervate skeletal muscles.

-are found in the ventral horns of the spinal cord.

-are found in the motor nuclei of cranial nerves Ⅲ-Ⅶ and Ⅸ-Ⅻ.

7. Upper motor neuron (UMN) lesions

-are caused by damage to the neurons (or their axons) that innervate lower motor neurons (LMNs).

(1) Acute stage lesions

-result in transient spinal shock, including:

a. Flaccid paralysis

lx Areflexia

c. Hypotonia

(2) Chronic stage lesions

-result in:

a. Spastic paralysis

b. Hypertonia

-occurs with increased tone in antigravity muscles (i.e., flexors of the arms and extensors of the legs).

c. Reduction or loss of superficial abdominal and cremasteric reflexes

1   ...   13   14   15   16   17   18   19   20   21


The database is protected by copyright ©dentisty.org 2016
send message

    Main page