VISUAL PATHWAY
| A | Optic nerve–> optic tract–> optic chiasma –> optic radiation–> visual cortex | |
| B |
Optic nerve–> optic chiasma–> optic tract–> optic radiation–> visual cortex |
|
| C |
Optic nerve–> optic radiation–>optic chiasma–>optic tract–> visual cortex |
|
| D |
Optic nerve–> optic chiasma–>optic radiation–>optic tract–> visual cortex |
Which of the following represents the CORRECT visual pathway in humans?
| A |
Optic nerve–> optic tract–> optic chiasma –> optic radiation–> visual cortex |
|
| B |
Optic nerve–> optic chiasma–> optic tract–> optic radiation–> visual cortex |
|
| C |
Optic nerve–> optic radiation–>optic chiasma–>optic tract–> visual cortex |
|
| D |
Optic nerve–> optic chiasma–>optic radiation–>optic tract–> visual cortex |
Ans.B
The visual pathway starts with the optic nerve which consists of fibers carrying a 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 terminate 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).
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 |
- Homonymous hemianopsia is a condition in which a person sees only one side―right or left―of the visual world of each eye.
- It can be congenital but is usually caused by brain injury such as from a stroke, trauma, tumors, infection, or following surgery.
- Vascular and neoplastic lesions from the optic tract, to the visual cortex, can cause 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.
Lesion at which part of visual pathway causes homonymous hemianopia?
| A |
Optic tract |
|
| B |
Optic nerve |
|
| C |
Optic Chiasma |
|
| D |
Retina |
A left homonymous hemianopsia can be caused by a lesion in the right optic tract or the right side of the brain.
| 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 |
- 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.
- Also called lazy eye, amblyopia begins during infancy and early childhood. In most cases, only one eye is affected.
The visual pathway consists of all of these except:
| A |
Optic tract |
|
| B |
Geniculocalcarine tract |
|
| C |
Inferior colliculus |
|
| D |
Lateral geniculate body |
C i.e. Inferior colliculus
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)Lateral Geniculate Body.
Part (Arrow) in the visual pathway as shown in the photograph above represents the optic tract.
Optic tract relays the information to the 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)
