Neuroanatomy and Physiology of Vision

Question 1

Which laminae of the lateral geniculate ganglion carry information from the contralateral retina?

Answer 1

1, 4, 6

Question 2

What Brodmann areas do the:
1) Primary visual cortex
2) Secondary visual cortices
correspond to?

Answer 2

Primary: Brodmann area 17
Secondary: Brodmann areas 18 and 19

Question 3

In the optic radiation, do the nerve fibres from the peripheral retina pass peripherally or centrally?

Answer 3

Peripherally

Question 4

In the optic radiation, what information is carried by:

• The temporal loop (Meyer’s loop)
• The parietal loop (Baum’s loop)?

Answer 4

Temporal loop: Information from inferior quadrant of retina

Parietal loop: Information from superior quadrant of retina

Question 5

In the primary visual cortex, is the macula represented more anteriorly or more posteriorly?

Answer 5

More posteriorly

Question 6

What is the length of the intracranial portion of the optic nerve and what is its blood supply?

Answer 6

10mm

Supplied by the ophthalmic nerve and pial branches of the hypophyseal artery

Question 7

What are the dimensions of the optic chiasm and what is its blood supply?

Answer 7

4 x 8 x 12mm

Supplied by surrounding arteries esp. the internal carotid and superior hypophyseal artery

Question 8

What is the blood supply of the optic tract?

Answer 8

Anterior choroidal artery and posterior communicating artery

Posterior cerebral artery runs below and parallel to it

Question 9

Where do the fibres of the optic tract synapse?

Answer 9

Lateral bundle (90%) --> lateral geniculate body --> conscious vision
Medial bundle (10%) --> other subcortical nuclei particularly the superior colliculus, pretectal and suprachiasmatic (hypothalamic) nuclei

Question 10

What is the blood supply of the lateral geniculate body?

Answer 10

Anterior choroidal and posterior cerebral artery

Question 11

What is the blood supply of the optic radiations?

Answer 11

Anterior choroidal, lateral striate (from MCA)

PCA

Question 12

What is the blood supply of the visual cortex?

Answer 12

PCA (calcarine artery) and posterior anastomoses with MCA

Question 13

Do the veins of the orbit contain valves?

Answer 13

No

Question 14

Name four sinuses which communicate directly with the cavernous sinus.

Answer 14

Contralateral cavernous sinus
Superior petrosal sinus (to transverse sinus)
Inferior petrosal sinus (to internal jugular)
Sphenoparietal sinus

Question 15

What are the three roots of the ciliary ganglion?

Answer 15

Sensory: short ciliary –> nasociliary (trigeminal)
Sympathetic: from internal carotid plexus
Parasympathetic (myelinated): Preganglionic from Edinger-Westphal nucleus

Question 16

Where is the ciliary ganglion located?

Answer 16

1cm anterior to the annulus of Zinn
Lateral to the ophthalmic artery
Between the optic nerve and lateral rectus

Question 17

Which layer of the primary visual cortex projects to the superior colliculus?

Answer 17

Layer V

Question 18

Which layer of the primary visual cortex receives the myelinated nerve fibres from the lateral geniculate? What anatomical feature is associated with this?

Answer 18

Layer IV

White striae of Gennari

Question 19

Where is the superior hemiretina represented in the lateral geniculate nucleus?

Answer 19

Medially

Question 20

Describe the layers of the primary visual cortex.

Answer 20

6 layers
Retinotopic organisation in dominance columns
Layer 2 and 3: project to secondary visual cortex. Layer 2 projects to contralateral visual cortex via corpus callosum
Layer 4: receives afferents from LGN (stellate cells)
Layer 5: projects to superior colliculus
Layer 6: projects back to LGN

Question 21

Does the sympathetic second order neuron leave the spinal cord via the anterior or posterior ramus?

Answer 21

Anterior ramus

Question 22

What do the superior and inferior salivatory nuclei supply?

Answer 22

Inferior salivatory nucleus: Parotid gland

Superior: Lacrimal, submandibular and sublingual gland

Question 23

Are ocular dominance columns present for the entire visual field?

Answer 23

No, the temporal crescent does not have a contralateral dominance column and is represented only ipsilaterally in the visual cortex

Question 24

Which is the part of the extrastriate cortex responsible for processing colour vision?

Answer 24

V4

Question 25

What are the dorsal and ventral streams of information for the extrastriate cortex?

Answer 25

Dorsal: Motion processing and binocular depth perception

Ventral (temporal): Recognition of form and colour