Visual Pathway

VISUAL PATHWAY

Q. 1 Which of the following represents the CORRECT visual pathway in humans?
 A Optic nerve–> optic tract–> optic chiasm –> optic radiation–> visual cortex
 B Optic nerve–> optic chiasm–> optic tract–> optic radiation–> visual cortex
 C Optic nerve–> optic radiation–>optic chiasm–>optic tract–> visual cortex
 D Optic nerve–> optic chiasm–>optic radiation–>optic tract–> visual cortex
Q. 1 Which of the following represents the CORRECT visual pathway in humans?
 A Optic nerve–> optic tract–> optic chiasm –> optic radiation–> visual cortex
 B Optic nerve–> optic chiasm–> optic tract–> optic radiation–> visual cortex
 C Optic nerve–> optic radiation–>optic chiasm–>optic tract–> visual cortex
 D Optic nerve–> optic chiasm–>optic radiation–>optic tract–> visual cortex
Ans. B

Explanation: Visual pathway starts with the optic nerve which consist of fibers carrying nasal and temporal field of vision from both the eye. Both the nerves join together to form the optic chiasm (here the nasal fibers decussates) and then divides into two optic tracts. These tracts terminates in the lateral geniculate body. The optic radiation begins in the lateral geniculate body forms a band that winds around the inferior and posterior horns of the lateral ventricle and terminates in the visual cortex or striate area (Brodmann area 17).

Ref: Thieme Atlas of Anatomy: Head and Neuroanatomy By Erik Schulte, page 358.


Q. 2

Lesion in which of the following part of visual pathway result in homonymous hemianopia?

 A

Chiasma

 B

Optic tract

 C

Optic nerve

 D

Occipital lobe

Q. 2

Lesion in which of the following part of visual pathway result in homonymous hemianopia?

 A

Chiasma

 B

Optic tract

 C

Optic nerve

 D

Occipital lobe

Ans. B

Explanation:

Homonymous hemianopia can be congenital, but is usually caused by brain injury such as from stroke, trauma, tumors, infection, or following surgery.

 
Vascular and neoplastic lesions from the optic tract, to visual cortex can cause a contralateral homonymous hemianopia. Injury to the right side of the brain will affect the left visual fields of each eye. The more posterior the cerebral lesion, the more symmetric (congruous) the homonymous hemianopsia will be.

 


Q. 3

Lesion at which part of visual pathway causes homonymous hemianopia?

 A

Optic tract

 B

Optic nerve

 C

Optic Chiasma

 D

Retina

Q. 3

Lesion at which part of visual pathway causes homonymous hemianopia?

 A

Optic tract

 B

Optic nerve

 C

Optic Chiasma

 D

Retina

Ans. A

Explanation:

A left homonymous hemianopsia can be caused by a lesion in the right optic tract or the right side of the brain. 

With a tract lesion, the pupillary reflex is lost if light is only projected from the blind hemifield; the pupil reacts when the lesion is posterior to the geniculate body in the optic radiations or occipital lobe. 
 
Transient homonymous hemianopsia may occur with migraine.
 
Ref: LeBlond R.F., DeGowin R.L., Brown D.D. (2009). Chapter 7. The Head and Neck. In R.F. LeBlond, R.L. DeGowin, D.D. Brown (Eds), DeGowin’s Diagnostic Examination, 9e.

Quiz In Between


Q. 4

A 9 year old child presents with sudden partial loss of vision in one eye. On examination, visual acuity is reduced, there is an absence of organic disease of ocular media, retina or visual pathway.

 
Assertion: Most common cause for development of amblyopia are visual deprivation, light deprivation or abnormal binocular interaction.
 
Reason: There is lack of formation of clear image on the retina of a young child.
 A

Both Assertion and Reason are true, and Reason is the correct explanation for Assertion

 B

Both Assertion and Reason are true, and Reason is not the correct explanation for Assertion

 C

Assertion is true, but Reason is false

 D

Assertion is false, but Reason is true

Q. 4

A 9 year old child presents with sudden partial loss of vision in one eye. On examination, visual acuity is reduced, there is an absence of organic disease of ocular media, retina or visual pathway.

 
Assertion: Most common cause for development of amblyopia are visual deprivation, light deprivation or abnormal binocular interaction.
 
Reason: There is lack of formation of clear image on the retina of a young child.
 A

Both Assertion and Reason are true, and Reason is the correct explanation for Assertion

 B

Both Assertion and Reason are true, and Reason is not the correct explanation for Assertion

 C

Assertion is true, but Reason is false

 D

Assertion is false, but Reason is true

Ans. A

Explanation:

Amblyopia refers to a partial loss of vision in one or both eyes in the absence of any organic disease of ocular media, retinal and visual pathway. In this condition visual acuity is reduced. It can be caused by visual deprivation, light deprivation or abnormal binocular interaction which impair formation of a clear image on the retina. Most sensitive period for the development of amblyopia is first 6 months of life.

Ref: Comprehensive Ophthalmology By A K Khurana, 4th Edition, Page 319.

Q. 5

The visual pathway consists of all of these except:

 A

Optic tract

 B

Geniculocalcarine tract

 C

Inferior colliculus

 D

Lateral geniculate body

Q. 5

The visual pathway consists of all of these except:

 A

Optic tract

 B

Geniculocalcarine tract

 C

Inferior colliculus

 D

Lateral geniculate body

Ans. C

Explanation:

C i.e. Inferior colliculus


Q. 6

Part (Arrow) in visual pathway as shown in photograph below is related to ? 

 A

Olivary mucleus.

 B

Lat. Geniculate body.

 C

Medial geniculate body.

 D

Trapezoid body.

Q. 6

Part (Arrow) in visual pathway as shown in photograph below is related to ? 

 A

Olivary mucleus.

 B

Lat. Geniculate body.

 C

Medial geniculate body.

 D

Trapezoid body.

Ans. B

Explanation:

Ans:B.)Lateral Geniculate Body.

Part (Arrow) in visual pathway as shown in photograph above represents optic tract.

Optic tract relays the information to Lateral geniculate body.

Visual Pathway

  • Vision is generated by photoreceptors in the retina.
  • The information leaves the eye by way of the optic nerve, and there is a partial crossing of axons at the optic chiasm.
  • After the chiasm, the axons are called the optic tract.
  • The optic tract wraps around the midbrain to get to the lateral geniculate nucleus (LGN), where all the axons must synapse.
  • From there, the LGN axons fan out through the deep white matter of the brain as the optic radiations, which will ultimately travel to primary visual cortex(Areas 17,18 and 19)

Quiz In Between



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